5 ABSTRACTS

01 Solid fuels (sources, winning, properties)

01 SOLID FUELS Sources, winning, properties 07/02050 Application of Box–Behnken design and response surface methodology for modelling of some Turkish coals Aslan, N. and Cebeci, Y. Fuel, 2007, 86, (1–2), 90–97. The aim of this research was to apply Box–Behnken experimental design and response surface methodology for modelling of some Turkish coals. As a base for this study, standard Bond grindability tests were initially done and Bond work indexes values were calculated for three Turkish coals. The Box–Behnken experimental design was used to provide data for modelling and the variables of model were Bond work index, grinding time and ball diameter of mill. Coal grinding tests were performed changing these three variables for three size fractions of coals (3350 + 1700 mm, 1700 + 710 mm and 710 mm). Using these sets of experimental data obtained by mathematical software package (MATLAB 7.1), mathematical models were then developed to show the effect of each parameter and their interactions on product 80% passing size (d80). Predicted values of d80 obtained using model equations were in good agreement with the experimental values of d80 (R2 value of 0.96 for 3350 + 1700 mm, R2 value of 0.98 for 1700 + 710 mm and R2 value of 0.94 for 710 mm). This study proved that Box–Behnken design and response surface methodology could efficiently be applied for modelling of grinding of some Turkish coals.

07/02051 Application of particle size distribution analysis in evaluating the weathering in coal mine rejects and tailings Devasahayam, S. Fuel Processing Technology, 2007, 88, (3), 295–301. Particle size distribution (PSD) analysis of the Gregory mine coal rejects, over a period of time is presented. The PSD has important implications on several processes contributing to the acid mine drainage. In this paper, correlation between the particle breakdown in the coal rejects and the rate of oxidation of sulfides is presented. Difference between the initial and the subsequent values of particle size distribution coefficient over a period of time indicated a change in particle breakdown mechanisms. An initial physical breakdown due to structural breakdown/rearrangement caused by wetting of the sample, and subsequent breakdown caused by the combined effects of physical and chemical weathering are proposed. Total number of particles increased with time, as the mean size of the distribution decreased. Increase in surface area calculated form the PSD analysis followed a power law with respect to time. The pyrite oxidation rate is dominated by diffusion and mass transfer processes initially, and as the total surface area is increased, contributed by breakdown of larger particles, a phase boundary control dominates the oxidation process.

07/02052 Formation of the structure of chars during devolatilization of pulverized coal and its thermoproperties: a review Yu, J. et al. Progress in Energy and Combustion Science, 2007, 33, (2), 135–170. The paper provides an overview of current studies on the behaviour of coal during devolatilization, especially the experimental studies and modelling efforts on the formation of char structure of bituminous coals in the open literature. Coal is the most abundant fossil fuel in the world. It dominates the energy supply in the future and plays an increasing role particularly in the developing countries. Coal utilization processes such as combustion or gasification generally involve several steps: i.e. the devolatilization of organic materials, homogeneous reactions of volatile matter with the reactant gases and heterogeneous reactions of chars with the reactant gases. The devolatilization process exerts its influence throughout the life of the solid particles from the injection to the burnout, therefore is the most important step which needs to be understood. When volatile matter is generated, the physical structure of a char changes significantly during the devolatilization, some accompanying a particle’s swelling. The complexity of a char’s structure lies in the facts that the structure of a char itself is highly heterogenous inside an individual particle and between different particles and the chemistry of a char is strongly dependent on the raw coal properties. A char’s structure is strongly dependent on the heating conditions such as temperature, heating rate and pressure. Understanding the swelling of coal and the formation of char’s pore structure during the devolatilization of pulverized coal is essential to the development of advanced coal utilization technologies. During combustion and gasification of pulverized coal, the behaviour of individual particles differs markedly due to the variation of their maceral composition. Particles with different maceral constituents generate different types of char structure. The structure of a char has a

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significant impact on its subsequent heterogeneous reactions and ash formation. The review also covers the most recent studies carried out by the authors, including the experimental observations of the thermoplastic behaviour of individual coal particles from the density fractions using a single-particle reactor, the experimental analysis on chars prepared in a drop tube furnace using the density-separated coal samples, the development of a mathematical model for the formation of char’s pore structure based on a simplified multi-bubble mechanism and the investigation on the effect of pressure on char formation in a pressurized entrained-flow reactor.

07/02053 Lead contamination of fluvial sediments in an eroding blanket peat catchment Rothwell, J. J. et al. Applied Geochemistry, 2007, 22, (2), 446–459. Over the past few years there has been growing concern over the mobilization of anthropogenically derived, atmospherically deposited Pb from upland blanket peat soils to receiving surface waters. The near-surface layer of blanket peat soils of the Peak District, southern Pennines, UK, is severely contaminated with high concentrations of Pb. Erosion of peat soils in this upland area may be releasing large quantities of previously deposited Pb into the fluvial system. Samples of fluvial sediments (suspended, floodplain, streamside fan, trash-line and channel bed) were collected from a severely eroding blanket peat catchment in the Peak District in order to investigate Pb contamination of fluvial sediments, to determine the mechanism for fluvial Pb transport and to determine if erosion of contaminated peat soils in the catchment is releasing Pb into the fluvial system. Concentrations of Pb associated with fluvial sediments are considerably higher than those in the catchment geology, but not as high as those in peat soils in the catchment. Intra- and inter-storm variability in the Pb content of suspended sediments can be explained by differences in organic matter content of these sediments and differences in erosion processes operating within the catchment. High Pb concentrations are associated with suspended sediments that have a high organic matter content. The results of this study suggest that organic matter is the principal vector for sediment-associated Pb in the fluvial system. Erosion of contaminated peat soils in the Peak District is releasing Pb into the fluvial system. The extent to which this is a problem in other peatland environments is an area requiring further research.

07/02054 Property of upgraded solid product from low rank coal by thermal reaction with solvent Sato, Y. et al. Fuel Processing Technology, 2007, 88, (4), 333–341. The upgrading process for the production of clean solid fuel from subbituminous and brown coals is receiving current attention. Upgrading of low rank coal with solvent at 350–450  C under 2 MPa of initial nitrogen atmosphere was proposed. Upgrading of German Fortuna brown coal (heating value: 25.4 MJ/kg, daf) at 440  C in the presence of t-decalin gave 66 wt.% of solid products with heating value of 35.4 MJ/kg, daf. Gaseous product consisted of mainly carbon dioxide (80 wt.%) and methane. Therefore, cracking of carboxylic functional group took place effectively in this condition. Ignition temperature of the upgraded solid product, measured by thermogravimetry under airflow, increased to higher than 400  C, while raw brown coal showed corresponding temperature of 290  C. From the XRD patterns by X-ray diffractometry for the upgraded product, distribution of aromatic stacking layer number (N) shifted to larger N by upgrading with solvent. Effective carbonization occurs under these conditions. This suggests the possibility of being able to produce valueadded solid fuel or carbonaceous liquid and solid chemicals, from low rank coal, whose quality is comparable to the bituminous coal.

07/02055 Qualitative comparison between raw peat and related humic acids in an ombrotrophic bog profile Zaccone, C. et al. Organic Geochemistry, 2007, 38, (1), 151–160. A peat core (10  10  81 cm3) removed from Etang de la Grue`re (Switzerland) was divided into 27 slices of 3 cm and the peat samples were freeze-dried and milled very finely. Humic acids (HA) were extracted from each slice. Both raw peat and HA were analysed with respect to ash content, moisture and elemental (C, H, N, and S) analysis. In addition, they were analysed using Fourier transform infrared spectroscopy (FT-IR) and UV–Vis spectroscopy (E4/E6 ratio). Physical and chemical properties of the peat core appear to show different conditions along the profile; in fact, these data could indicate the presence of three distinct zones in the bog: (i) an acrotelm, or zone of active decay, which may be oxygenated, depending on the season, (ii) a catotelm, which is always anoxic, and where only a very slow and partial organic matter decomposition is possible, and (iii) a ‘transitional’ layer, in which complex interactions between organic and inorganic compounds most possibly happen. E4/E6 trend and FT-IR spectra on purified HA appear to confirm this hypothesis and underline different stages of humification of organic matter along the profile showing a greater degree of aromatic condensation in the deeper horizons than in the surface layer.

01 Solid fuels (derived solid fuels)

Preparation 07/02056 Mechanical/thermal dewatering of lignite. Part 3: physical properties and pore structure of MTE product coals Bergins, C. et al. Fuel, 2007, 86, (1–2), 3–16. The mechanical thermal dewatering (MTE) process has been shown to effectively dewater high moisture content low rank coals via the application of mechanical force at elevated temperatures. Using mercury intrusion porosimetry (MIP) as an investigative tool, this study examines how MTE processing conditions, such as temperature and pressure, affect the compressibility, pore size distribution, apparent (skeletal) density and shrinkage behaviour of three low rank coals sourced from Australia, Greece and Germany. As both pore filling and sample compression occurred at high mercury intrusion pressures, all MIP data were corrected for compression effects by using compressibility values derived from mercury extrusion data. The MTE process is shown to produce a low porosity coal, which, depending upon the processing conditions used, undergoes further shrinkage upon oven drying at 105  C. An increase in MTE temperature (above about 85  C) led to an increase in mesopore volume, which is caused by a hardening of the coal structure, leading to pore volume retention and a consequent reduction in percent shrinkage on oven drying. The increase in measured mesopore volume is also associated with an increase in measured surface area. The reverse trend is seen with increasing MTE pressure, where both the macro and mesopore volume decrease with pressure, causing the percent shrinkage to increase accordingly. This effect may be due to an increase in capillary forces caused by a decrease in the average pore diameter. The percent shrinkage increased up to a pore volume of about 0.1 cm3/g, beyond which no further reduction in pore volume was achieved. The decrease in mesopore volume is also associated with a decrease in measured surface area. Compressibility values derived from mercury extrusion data show that the MTE process has little impact on the network strength of the skeletal network structure of all three coals investigated. Likewise, the skeletal density remained relatively unchanged. The reduction in water content, pore volume and the changes in shrinkage behaviour under increasingly severe MTE conditions are suggestive of the physical changes that accompany increased coalification (rank) within the lignitic range.

07/02057 Mercury emission control in coal-fired plants: the role of wet scrubbers Diaz-Somoano, M. et al. Fuel Processing Technology, 2007, 88, (3), 259–263. When coal is combusted, the combination of the elevated temperature and the volatility of mercury and its compounds results in the presence of gaseous elemental mercury and mercury compounds in the combustion flue gas. In January 2005, the European Commission adopted a mercury strategy that envisages a number of measures to reduce mercury levels in the environment and human exposure. A number of options for mercury removal from coal-fired power plants have been investigated. However, more effort is needed to achieve an efficient and cost-effective technology. The main objective of this work was to investigate the influence of scrubber parameters on mercury removal efficiency to establish effective measures for mercury control. In order to attain these objectives, theoretical predictions based on thermodynamical equilibrium data and lab-scale experimental tests were carried out. The results obtained point to pH and slurry concentration as the most critical parameters for converting flue gas desulfurization unit into a multipollutant control technology.

Transport, storage 07/02058 Resorcinol-formaldehyde based porous carbon as an electrode material for supercapacitors Zhu, Y. et al. Carbon, 2007, 45, (1), 160–165. Porous carbon materials were prepared using resorcinol and formaldehyde catalysed by KOH in a sol–gel process followed by carbonization, during which the KOH serves as an activating agent and generates pores mainly located in the micropore range. With an increase of mass ratio of KOH to resorcinol from 1 to 4, both the specific surface area and the pore volume of the carbons increased, from 522 to 2760 m2/g and 0.304 to 1.347 cm3/g, respectively, but the average pore diameter decreased from 4.4 to 2.5 nm. Samples were investigated as electrode materials in supercapacitors and the relevant electrochemical behaviour was characterized by cyclic voltammetry, electrochemical impedance spectroscopy and constant current charge– discharge experiments using 30% KOH aqueous solution as electrolyte. The highest specific capacitance of up to 294 F/g was obtained at a

current density 1 mA/cm2 for the sample with mass ratio of KOH to resorcinol of 2. Only a slight decrease in capacitance for the same sample, from 294 to 242 F/g, was observed when the current density increased from 1 to 30 mA/cm2. The specific capacitance only decayed 3% at a current density 30 mA/cm2 after 1000 cycles, which indicates that the sample possesses excellent power property and cycle durability.

Economics, business, marketing, policy 07/02059 Concentration and distribution of uranium in Chinese coals Yang, J. Energy, 2007, 32, (3), 203–212. Representative coal uranium concentrations are essential not only to better estimate the environmental and health effects associated with the uranium emissions from coal utilization but also to utilize the potentially valuable uranium in coal combustion by products. The average uranium concentrations of coals in China are estimated based on uranium analyses of 1535 coal samples and coal reserves tonnage. The results showed that the estimated average weighted uranium concentrations of Late Carboniferous and Early Permian (C2–P1), Late Permian (P2), Late Triassic (T3), Early and Middle Jurassic (J1–2), Late Jurassic and Early Cretaceous (J3–K1), and Eogene and Neogene (E– N) coals are 2.91, 5.43, 3.67, 1.18, 1.84, and 3.92 mg/g, respectively. The overall average weighted uranium concentration of coals in China is 2.31 mg/g. The background values of uranium in coals of China were dominated by detrital materials of terrigenous origin, but the anomalous enrichments of uranium were attributed to synsedimentary volcanic ashes and epigenetic low-temperature hydrothermal fluids and magmatic hydrothermal inputs.

Derived solid fuels 07/02060 First-principles study of carbon diffusion in bulk nickel during the growth of fishbone-type carbon nanofibers Zhu, Y.-A. et al. Carbon, 2007, 45, (1), 21–27. Ab initio plane wave density functional theory calculations are performed to investigate the carbon diffusion in bulk nickel during the growth of fishbone-type carbon nanofibres (CNFs). Results indicate that the octahedral interstitial sites are preferred for C dissolution relative to the tetrahedral sites. And the heat of solution of C in paramagnetic (PM) Ni is larger than that in ferromagnetic (FM) Ni because the induced C atom quenches the magnetic moments of neighbouring Ni atoms. The bulk diffusion has been successfully described under two different C concentrations. At the initial CNF growth stage, the C concentration in bulk Ni is low and the calculated energy barriers for the diffusion of an isolated C atom are 1.641 eV and 1.678 eV in the Ni FM and PM state, respectively. When the C content is increased to 20 at.%, two models are established. In one case, it is assumed that all C atoms hop in the same direction at the same time, and the calculated activation energies are 1.137 and 1.126 eV. In the other case, only one C atom is permitted to move with the neighbouring C atoms fixed at the octahedral sites and the corresponding barriers are decreased to 0.972 eV in the Ni FM state. Through these calculations, it is concluded that the magnetic state has a minor effect on the diffusion energy barrier which can be substantially lowered by the increase of C concentration in bulk Ni. Comparing the activation energy for bulk diffusion with the surface diffusion results, the reason for the formation of different CNF morphologies has been revealed.

07/02061 Formation of fullerenes by pyrolysis of 1,20 -binaphthyl and 1,3-oligonaphthylene Amsharov, K. Y. et al. Carbon, 2007, 45, (2), 337–343. High-temperature pyrolysis of two fullerene precursors – 1,20 binaphthyl and 1,3-oligonaphthyl – has been investigated. An oligomer of naphthalene with the appropriate orientation of fragments, which contains all 60 carbon atoms, 12 of 20 six-membered rings and 71 of 90 carbon–carbon bonds required to form the C60 fullerene cage was synthesized in a three-step synthesis from naphthalene. The formation of fullerene during pyrolysis was confirmed by MALDI-TOF and HPLC analysis of the toluene extract obtained from the raw soot. It was found that the toluene extract contains free C60 fullerene but the main share of fullerenes exists in the form of their derivatives. The yield of free C60 was estimated as 0.1% by HPLC but the overall yield of C60 seems to be higher and was estimated as 1%.

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02 Liquid fuels (sources, properties, recovery) 07/02062 Formation of fullerenes by pyrolysis of perchlorofulvalene and its derivatives Amsharov, K. Y. and Jansen, M. Carbon, 2007, 45, (1), 117–123. In a retro-synthetic approach, [60]fullerene might be accessible by condensing six fulvalene fragments. In order to explore the potential of such a route for direct synthesis of [60]fullerene, the pyrolysis of perchlorofulvalene (PCF) was investigated. Low temperature pyrolysis of PCF at 250  C resulted mainly in the formation of dimers, trimers, tetramers and products of subsequent intramolecular condensation of these oligomers. Increasing the temperature to 300–350  C leads to the formation of perchlorinated polynuclear aromatic hydrocarbons. Pyrolysis at 400–450  C gives a cross-linked polymer structure which is the result of intermolecular condensation of the polynuclear aromatic intermediates. Pyrolysis at higher temperatures (>500  C) mainly leads to graphite. It was found that the two-step pyrolysis of PCF (heating first at 450  C, after that at 750  C) yielded a fullerene containing soot via an intermediate polynuclear aromatic net. High temperature rearrangement of the latter gave fullerenes C60 and C70. The best results were obtained when a PCF oligomer obtained by Ullmann condensation was used as a precursor. By two-step pyrolysis and further high vacuum sublimation of the soot the fullerenes C60 and C70 were obtained in extractable amounts.

07/02063 Low-cost carbon-based briquettes for the reduction of no emissions from medium–small stationary sources La´zaro, M. J. et al. Catalysis Today, 2007, 119, (1–4), 175–180. In this paper, a novel method for preparing low-cost carbon-based briquettes is described. This procedure includes the briquetting of the carbon material, subsequent activation and finally an equilibrium adsorption impregnation of the active phase. A local low-rank coal was used for the preparation of the carbon briquettes, while both a model vanadium compound (V2O5) and the ashes of a petroleum coke (PCA) were used as the precursors of the active phase. The catalytic briquettes have been tested for NO reduction. The effect of a HNO3-oxidation previous to the impregnation has been also evaluated. The reduction tests have been carried out in presence of oxygen and with the addition of ammonia as reducing agent. The briquettes have shown to be active for NO reduction at low temperature (100–300  C). Surface chemistry as well as the porous structure of the support, affect the catalyst behaviour. In general terms, higher NO reduction efficiencies were measured for the catalysts prepared using the pre-oxidized briquettes.

07/02064 Modeling combustion of straw–bitumen pellets in a fluidized bed Okasha, F. Fuel Processing Technology, 2007, 88, (3), 281–293. Recently, straw–bitumen pellets have been proposed as an alternative fuel. In this paper, a comprehensive model for steady state combustion of straw–bitumen pellets in a bubbling fluidized bed is presented. The combustor is divided into three sectors: a dense bed zone, a splashing zone and a freeboard zone. Relevant phenomena including volatile release and segregation, char comminution and elutriation, bed particles ejection, and post-combustion above the bed have been taken into consideration. Energy equations for the splashing and freeboard zones have been established. Model results indicate that about 53% of volatile burns within the bed while 60% of total heat is released. On the other side, fraction of heat released in the splashing zone is about 33% whereas the remaining part (7%) is released in the freeboard zone. Ejected sand particles, however, recover back to the bed about 83% of the heat released in the two latter zones. Model calculations yield axial concentration profiles of different species along the whole length of the combustor. In particular, the model furnishes an axial temperature profile for the splashing and freeboard zones which is characterized by two maxima. A small peak occurs in the splashing zone whereas the second maximum develops in the freeboard zone with relatively much higher overheating above the bed temperature. A parametric study demonstrates that overheating in the freeboard zone may be controlled by increasing bed temperature and excess air, and decreasing fluidization velocity. Bed temperature among others is found to have the highest impact on the combustion performance. Model predictions are shown to be in good agreement with measurements.

07/02065 Synthesis of carbon nanotubes by catalytic conversion of methane: competition between active components of catalyst Mordkovich, V. Z. et al. Carbon, 2007, 45, (1), 62–69. Catalytic growth of carbon nanotubes from methane was studied as competitive catalytic process in situ of both oxidative (partial oxidation) and non-oxidative (pyrolysis) conversion. Ni and Fe may act as either competing or cooperative catalyst components in the process of carbon nanotubes growth. The competition between Ni and Fe in the process of carbon nanotube growth on Ni–Fe-based stainless steel alloy during partial oxidation of methane results in suppression of Ni catalytic activity in favor of Fe. The discrimination is so strong that iron is segregated from Ni–Fe based stainless steel alloy leaving

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characteristic Ni-enriched corrosion caverns. Interaction between Ni and Fe during non-oxidative conversion, in contrast to the oxidative conversion, leads to cooperative effect; the activity of bimetallic catalyst increases as compared with monometallic one. Depending on particular catalyst bed composition, the nanotubes of various morphologies may occur. In particular, the use of perovskite-type catalyst for partial oxidation of methane leads to formation of ‘olivebranch’-like peculiar carbon nanostructures.

07/02066 Synthetic coal chars for the elucidation of NO heterogeneous reduction mechanisms Pevida, C. et al. Fuel, 2007, 86, (1–2), 41–49. In this paper, the mechanisms involved in NO–char heterogeneous reduction have been studied using a synthetic coal char as carbon source. Another synthetic char without nitrogen in its composition has also been employed in these studies. Isothermal reduction tests at different temperatures have been carried out. Two temperature regimes were considered: low temperature (T < 250  C) where NO chemisorption takes place and high temperature (T > 250  C) where NO–C reaction occurs. Step response experiments combining consecutive reaction stages with NO and 15NO were performed in order to determine the role of nitrogen surface complexes, C(N), in the reduction process. The results revealed N2 and CO2 to be the main reduction products under the experimental conditions employed in this work. NO chemisorption at lower temperatures results in N 2 emission and surface complexes (mainly oxygenated) formation, while char gasification by NO involves a direct NO attack on the char surface to form surface complexes. As a consequence of desorption of these complexes new sites of reaction are created.

07/02067

Waste pyrolysis and generation of storable char

Ryu, C. et al. International Journal of Energy Research, 2007, 31, (2), 177–191. Sustainable cities require the generation of energy from waste that cannot be economically reused or recycled. This study focuses on slow pyrolysis that can generate a high yield of char along with liquid and gas products from waste. Char is high in energy content, storable and transportable with low cost so that it can be used as an intermediate medium for high efficiency energy conversion. Pre-processed municipal waste pellets, wood and grass were pyrolysed in a batch type reactor for a final temperature ranging from 350 to 700 C, and the char products were characterized. The mass yields of char ranged from 55 to 20% for the tested temperature range, recovering 70–30% of energy and 62– 30% f carbon in the raw material. The gross calorific value of char was 30–35 MJ kg1 on a dry ash free basis. The ash content of raw materials was a key parameter for the quality of char, since its proportion increased by 2–4 times in char depending on the mass yield. A significant amount of volatile metals such as Hg. As and Pb in the waste sample was evaporated at 500 C. Therefore, evaporation of volatile metals was another important parameter in determining the pyrolysis temperature and fuel residence time. The char did not show significant morphological change in the tested range of temperatures. It was concluded that slow pyrolysis of waste for char production should be performed below 500 C in order to increase the energy yield and also to reduce the evaporation of heavy metals.

02 LIQUID FUELS Sources, properties, recovery 07/02068 Biomarker evidence for two sources for solid bitumens in the Subu wells: implications for the petroleum prospectivity of the East Papuan Basin George, S. C. et al. Organic Geochemistry, 2007, 38, (4), 609–642. Late Cretaceous sandstones from the Subu-1 and -2 wells (Aure Scarp, Papua New Guinea) contain patchily distributed solid bitumens. The solid bitumens vary in reflectance and geochemistry, indicating that they formed by the biodegradation of two different families of crude oils, termed Family A and Family B. Biomarker characteristics, such as the high abundance of rearranged hopanes and steranes, indicate that the Family A solid bitumens were derived originally from a clay-rich, marine source rock low in sulfur, which had significant input of terrestrial organic matter. These correlate with oils from the Iagifu-7X, Gobe-3X, Omati-1 and Puri-1 wells that are believed to be generated from sources of Jurassic age. The Family B solid bitumens and a fluid inclusion oil from Subu-1 have a high abundance of 2
-methylhopanes, bisnorhopanes, and dibenzothiophene and originated from a marine

02 Liquid fuels (sources, properties, recovery) source rock with a calcareous component. This source rock had a high proportion of prokaryotic organic matter input, a greater sulfur content, and a more reducing depositional environment than the Jurassic source rocks. The lack of correlation with other oils in Papua New Guinea suggests the presence of a second, so far unidentified, generative marine source rock in the East Papuan Basin. The finegrained samples in the Subu wells are thermally immature (VRE 0.5– 0.6%), organically lean, and contain type III organic matter with little hydrocarbon generation potential. Most of the solid bitumens have peak oil window thermal maturities (VRE 0.8–1.0%), but some have lowered maturities that are interpreted to be due to co-extraction of indigenous, detrital, low maturity organic matter. Low molecular weight n-alkanes, alkylcyclohexanes, methylalkylcyclohexanes, and alkylbenzenes in many of the samples are attributed to overprinting of pre-existing, variably biodegraded solid bitumens in the sandstones with pristine hydrocarbon charge with a condensate composition. This condensate charge has not undergone any major biodegradation or water-washing, implying that it is a relatively recent event. Solid bitumen from a vein in a Miocene volcanolithic sandstone from the Ouha anticline was generated from an early mature Palaeogene or late Cretaceous source rock that contained predominantly terrestrial organic matter deposited in an oxic environment. This sample proves the existence of a different oil generative source rock in the East Papuan Basin in addition to the two oil source rocks inferred from the Subu data.

07/02069 Diamondoid hydrocarbons as a molecular proxy for thermal maturity and oil cracking: geochemical models from hydrous pyrolysis Wei, Z. et al. Organic Geochemistry, 2007, 38, (2), 227–249. A series of isothermal hydrous pyrolysis experiments was performed on immature sedimentary rocks and peats of different lithology and organic source input to explore the generation of diamondoids during the thermal maturation of sediments. Oil generation curves indicate that peak oil yields occur between 340 and 360  C, followed by intense oil cracking in different samples. The biomarker maturity parameters appear to be insensitive to thermal maturation as most of the isomerization ratios of molecular biomarkers in the pyrolysates have reached their equilibrium values. Diamondoids are absent from immature peat extracts, but exist in immature sedimentary rocks in various amounts. This implies that they are not products of biosynthesis and that they may be generated during diagenesis, not just catagenesis and cracking. Most importantly, the concentrations of diamondoids are observed to increase with thermal stress, suggesting that they can be used as a molecular proxy for thermal maturity of source rocks and crude oils. Their abundance is most sensitive to thermal exposure above temperatures of 360–370  C (R0 = 1.3–1.5%) for the studied samples, which corresponds to the onset of intense cracking of other less stable components. Below these temperatures, diamondoids increase gradually due to competing processes of generation and dilution. Calibrations were developed between their concentrations and measured vitrinite reflectance through hydrous pyrolysis maturation of different types of rocks and peats. The geochemical models obtained from these methods may provide an alterative approach for determining thermal maturity of source rocks and crude oils, particularly in mature to highly mature Paleozoic carbonates. In addition, the extent of oil cracking was quantified using the concentrations of diamondoids in hydrous pyrolysates of rocks and peats, verifying that these hydrocarbons are valuable indicators of oil cracking in nature.

07/02070 Effect of lubricating oil on cooling heat transfer of supercritical carbon dioxide Dang, C. et al. International Journal of Refrigeration, 2007, 30, (4), 724– 731. In this research the cooling heat transfer coefficient and pressure drop of supercritical CO2 with PAG-type lubricating oil entrained were experimentally investigated. The inner diameter of the test tubes ranged from 1 to 6 mm. The experiments were conducted at lubricating oil concentrations from 0 to 5%, pressures from 8 to 10 MPa, mass fluxes from 200 to 1200 kg m2 s1, and heat fluxes from 12 to 24 kW m1. In comparison to the oil-free condition, when lubricating oil entrainment occurred, the heat transfer coefficient decreased and the pressure drop increased. The maximum reduction in the heat transfer coefficients – about 75% – occurred in the vicinity of the pseudocritical temperature. The influence of oil was significant for a small tube diameter and a large oil concentration. From visual observation, it was confirmed that this degradation in the heat transfer was due to the formation of an oil-rich layer along the inner wall of the test tube. However, when the oil concentration exceeded 3%, no further degradation in the heat transfer coefficient could be confirmed, which implies that the oil flowing along with CO2 in the bulk region does not influence the heat transfer coefficient and the pressure drops significantly. For a large tube at a lower mass flux, no significant degradation in the heat transfer coefficient was observed until the oil concentration reached 1%. This is due to the transition of the flow

pattern from an annular-dispersed flow to a wavy flow for a large tube, with CO2 flowing on the upper side and the oil-rich layer on the lower side of the test section.

07/02071 Finite-rate evaporation and droplet drag effects in spherical flame front propagation through a liquid fuel mist Greenberg, J. B. Combustion and Flame, 2007, 148, (4), 187–197. An evolution equation for a laminar flame front propagating into an air and liquid fuel mist cloud is derived for the first time, accounting for both the finite-rate evaporation of the fuel droplets and the slip velocity between them and their host environment. The asymptotic analysis employed in developing the equation exploits the usual inverse large activation energy parameter associated with chemical reaction in the flame and a small drag parameter. It is demonstrated that, in the no-slip velocity case, increasing the vaporization Damko´ hler number can produce flame extinction, presumably due to the more intense heat loss incurred due to droplet heat absorption necessary for vaporization. Droplet drag can also induce extinction due to the longer residence time of the droplets in any locale (than if there was no slip), leading to more vaporization with greater attendant heat loss. The predicted results for droplet velocity are compared to independent experimental data from the literature with good qualitative agreement.

07/02072 Interaction of Estonian kukersite with organic solvents: a volumetric swelling and molecular simulation study Savest, N. et al. Fuel, 2007, 86, (1–2), 17–21. This article describes the swelling of Estonian kukersite and isolated kerogen in 14 organic solvents. The swelling behaviour of kerogen represented by its molecular model is atomically simulated using the general amber force field. The characteristic features of the swelling behaviour of kukersite are identified, i.e. modest swelling ratios and their significant increases in specific H-bonding solvents. The swelling of the isolated kerogen and the cohesive energy density were found to be close to those of native kukersite. For non-H-bonding solvents, the total solubility parameter value is estimated to fall between 19 and 20 MPa1/2. This fits well with the value determined analogously for other type I-II kerogens. The value of the dispersion component of the solubility parameter calculated by the atomistic molecular simulation equals 18.9  0.54 MPa1/2. Electrostatic components were found to play a minor role.

07/02073 Predicting oil and gas compositional yields via chemical structure–chemical yield modeling (CS-CYM): Part 1 – concepts and implementation Freund, H. et al. Organic Geochemistry, 2007, 38, (2), 288–305. The ability to predict accurately the thermal conversion of complex carbonaceous materials under a wide range of heating rates and temperatures is of value in both petroleum exploration and refining operations. Modelling the thermal cracking of kerogen and coal under basinal heating conditions improves the pre-drill prediction of oil and gas yields and quality, thereby ultimately lowering exploration risk. Modelling the chemical structure and reactivity of asphaltenes from petroleum residues enables prediction of coke formation and properties in refinery processes, thereby lowering operating cost. Previous compositional yield models based on laboratory yield measurements have been developed for specific materials, such as isolated coals and kerogens, but extrapolation to predict oil and gas generation during geologic burial is problematic. Furthermore, models based on a few reference carbonaceous materials may not simulate varying compositions of kerogen and residues seen in nature. A method was developed to calculate the amounts and composition of products resulting from the thermal decomposition of a solid complex carbonaceous material. This procedure provides a means of using laboratory measurements of complex carbonaceous solids to construct a representative model of its chemical structure (CS) that is then coupled with elementary reaction pathways to predict the chemical yield (CY) upon thermal decomposition. Data from elemental analysis (C, H, N, O, S), solid state 13C NMR, X-ray photoelectron spectroscopy (XPS), sulfur X-ray absorption structure spectroscopy (XANES), and pyrolysis-gas chromatography (GC) are used to constrain the construction of core molecular structures representative of the complex carbonaceous material. These core structures are expanded stochastically to describe large macromolecules (>104 cores with 106 atoms) with bulk properties that match the experimental results. Gas, liquid and solid product yields, resulting from thermal decomposition, are calculated by identifying reactive functional groups within the CS stochastic ensemble and imposing a reaction network constrained by fundamental thermodynamics and kinetics. An expulsion model is added to the decomposition model to calculate the chemical products in open and closed systems. Product yields may then be predicted under a wide range of time–temperature conditions used in rapid laboratory pyrolysis experiments, refinery processes, or geologic maturation.

Fuel and Energy Abstracts September 2007 317

02 Liquid fuels (transport, refining, quality, storage) 07/02074 Predicting oil and gas compositional yields via chemical structure–chemical yield modeling (CS-CYM): Part 2 – application under laboratory and geologic conditions Walters, C. C. et al. Organic Geochemistry, 2007, 38, (2), 306–322. The authors have developed a method for calculating from first principles the amounts and composition of products resulting from the thermal decomposition of a solid complex carbonaceous material. Advanced solid state analysis provides chemical and property measurements for kerogen that are used to construct a representative model of its chemical structure (CS). These chemical structural models are then coupled with a chemical yields (CY) model that is based primarily on free radical reaction mechanisms. The combined model, CS–CYM offers the ability to predict the thermal conversion of kerogen under a wide range of heating rates and temperature. Results from laboratory heating experiments are compared with those calculated with CS–CYM and show excellent agreement with a variety of bulk physical and chemical properties, open and closed system pyrolysis yields and product compositions, and open system kinetics. The reliability of CS– CYM in predicting the thermal reactions that occur under laboratory conditions indicates that a significant portion of the thermal reaction mechanisms and pathways that occur in nature have been captured. Hence, it is suggested that CS–CYM approach provides a better prediction of the thermal chemistry that occurs under geologic conditions than extrapolation of experimental results conducted at much higher temperature and faster heating rates where reactions, product distributions and modes of expulsion may differ significantly from basinal processes.

07/02075 Radiation effect on thermal explosion in a gas containing evaporating fuel droplets Goldfarb, I. et al. International Journal of Thermal Sciences, 2007, 46, (4), 358–370. The dynamics of thermal explosion in a fuel droplets/hot air mixture is investigated using the geometrical version of the method of integral manifolds. The results are applied to the modelling of the ignition process in diesel engines. Effects of the thermal radiation, semitransparency of droplets and oxidizer are taken into account. In contrast to the previous studies, the difference between gas temperature (responsible for convective heating of droplets) and external temperature (responsible for radiative heating of droplets) is taken into account. The dynamics of the explosion is presented in terms of the dynamics of a multi-scale, singularly perturbed system. The relevant parametric regions of this system are analysed. Explicit analytical formulae for the ignition delay in the presence of thermal radiation are derived. It is shown that the effect of thermal radiation can lead to considerable reduction (up to about 30%) of the total ignition delay time.

Transport, refining, quality, storage 07/02076 An active and selective production of gasolinerange hydrocarbons over bifunctional Co-based catalysts Ngamcharussrivichai, C. et al. Fuel, 2007, 86, (1–2), 50–59. Catalytic performance of several bifunctional cobalt-based catalysts in slurry-phase Fischer–Tropsch synthesis has been investigated at 1 MPa and 230  C. The catalysts were prepared according to the conventional impregnation method using SiO2, Al2O3, montmorillonite (K101), and various zeolites (USY, ZSM-5 and MCM-22) as a support. When an acidic support was applied, the formation of heavier hydrocarbons was retarded and the carbon number distribution was shifted to gasoline range (C4–C12). Montmorillonite loaded with Co (Co/MONT) was a good catalyst, showing higher the CO conversion than Co/SiO2 and Co/ Al2O3. MCM-22 exhibited a superior performance to other zeolitic supports. With decreasing aluminum content, the activity of Co/MCM22 catalysts was remarkably enhanced and the selectivity to methane and isoparaffins decreased. Besides the high CO conversion (55–60%), isoparaffins were produced more selectively over Co/MCM-22 (43– 53%) than Co/USY (43.5%) and Co/ZSM-5 (36%). Compared to the results under supercritical conditions, the slurry-phase conditions are more suitable for an active and selective production of gasoline-range hydrocarbons through the Fischer–Tropsch synthesis over MCM-22 supported Co catalysts.

07/02077 Characterization and activity of Mo supported catalysts for diesel deep hydrodesulphurization Duan, A. et al. Catalysis Today, 2007, 119, (1–4), 13–18. Various highly dispersed Mo-supported catalysts with various carriers were prepared for deep hydrodesulfurization of diesel. The carriers included a high surface area and large pore volume -Al2O3, two types of meso-microporous composite molecular sieves prepared by incipi-

318 Fuel and Energy Abstracts September 2007

ent-wetness impregnation method. A new mesoporous MoSiOx catalyst synthesized with in situ composite method was also studied. The hydrodesulfurization experiments were carried out in a micro-reactor over different catalysts including Mo supported series and a commercial catalyst. Spectroscopic techniques (FT-IR and UV–vis DRS) were utilized to determine the structure of MoO x species. The catalyst characterizations of BET, XRD, FT-IR, UV–vis DRS and FTIR pyridine adsorption indicated that the existences of metal active component of Mo in the catalysts were highly dispersed nano MoO3 clusters and the Mo series catalysts had high surface areas and plenty of large pores which were propitious to the diffusions of reactant and product molecules. CatNiMo exhibited the highest B/L acidity ratio and higher total concentration of Brønsted acid sites and Lewis acid sites, and its HDS activity also gave the highest in this study to produce a sulfur-free diesel, which was verified by the sulfur content in products analysed by GC–MS methods.

07/02078

Creep analysis of bolted flange joints

Nechache, A. and Bouzid, A.-H. International Journal of Pressure Vessels and Piping, 2007, 84, (3), 185–194. In the petrochemical and nuclear industries, the difficulty in assessing the effect of creep on the tightening load of bolted flanged connections is recognized. Under high temperatures, the leak tightness of bolted joints is compromised due to the loss of the bolt load as a result of creep of not only the gasket and bolt materials but also the flange material. Apart from acknowledgment of this effect, there exists no established design calculation procedure that accounts for creep. This is because the relaxation of the bolt load and the corresponding loss of the gasket contact stress are not easy to assess analytically. The main objective of the work is the development of a simple analytical solution to the creep-relaxation problem encountered in bolted flange connections of the float type. Particular emphasis is put towards relaxation caused by the flange and bolt material creep. The validation of the methodology is carefully checked against the more complex 3D numerical FE method using different size flanges. Based on the creep constants of the different joint elements (bolt, flange and gasket), the implemented analytical method is shown to predict the bolt and gasket load relaxation with reasonable accuracy. In some flange cases, up to 70% of bolt load relaxation is found with both methods depending on the flange creep material and size.

07/02079 Effect of hydrothermal treatment temperature on FCC gasoline upgrading properties of the modified nanoscale ZSM-5 catalyst Zhao, X. et al. Fuel Processing Technology, 2007, 88, (3), 237–241. Nanoscale HZSM-5 zeolite was hydrothermally treated with ammonia water at different temperatures and then loaded with La2O3 and ZnO. The parent and the modified nanoscale HZSM-5 catalysts were characterized by SEM, NH3-TPD, IR and XRF. The performance of the modified HZSM-5 catalysts for FCC gasoline upgrading was evaluated in a fixed bed reactor in the presence of hydrogen. The results indicated that the modified catalyst which was hydrothermally treated at 400  C exhibited excellent aromatization activity, isomerization activity and higher ability of reducing olefin content in FCC gasoline. Under the given reaction conditions, the olefin content in FCC gasoline could be decreased from 49.6 to 8.1 vol.%. The catalytic performance of the modified nanoscale ZSM-5 catalyst hardly changed within 300 h time on stream, and the research octane number of gasoline was preserved.

07/02080 Fischer–Tro¨ psch synthesis over Co/TiO2: effect of ethanol addition Jalama, K. et al. Fuel, 2007, 86, (1–2), 73–80. The effect of the addition of ethanol (2% and 6%) during Fischer– Tro ¨ psch (FT) synthesis has been investigated using a 10% Co/TiO2 catalyst in a stirred basket reactor (T = 220  C, P = 8 bar, H2/CO = 2). The transformation of ethanol vapour (2% and 6% in nitrogen) over the Co/TiO2 catalyst was also studied in the absence of the synthesis gas under FT reaction conditions. Ethanol was observed to be incorporated in the growing chain and was found to (i) increase the selectivity to light products, (ii) increase the olefin to paraffin ratio and (iii) significantly decrease the catalyst activity. These effects were almost completely reversed when the ethanol in the feed was removed. Thermodynamic predictions, TPR and XRD analysis have shown that cobalt metal particles were oxidized to CoO by ethanol but that rereduction to Co metal was possible when ethanol was removed from the feed stream allowing the catalyst to recover most of its initial performance, in particular when high flow rates were used.

07/02081 Investigation of low-temperature methanol synthesis in a bubble column slurry reactor with a flash column Zhao, Y. et al. Fuel Processing Technology, 2007, 88, (2), 137–142.

02 Liquid fuels (economics, business, marketing, policy) Reaction performance of a CuCr/CH3ONa catalyst for the lowtemperature methanol synthesis was examined in a bubble column slurry reactor with a flash column (BCSR/FC). The BCSR/FC was operated at 4.5  0.2 MPa/110–120  C for BCSR and 0.4  0.1 MPa/80– 90  C for FC, although fluctuation of operation parameters was larger. Syngas conversion decreased from 71.0% to 19.8% during the operation test in 100 h, which was attributed to consumption of CH3ONa and a negative effect of the emulsifier OP-10 used.

07/02082 Multi-objective optimization of fuel oil blending using the jumping gene adaptation of genetic algorithm Khosla, D. K. et al. Fuel Processing Technology, 2007, 88, (1), 51–63. Production and marketing of heavy fuel oil are an easy, effective and economical way to dispose off certain very heavy refinery streams such as short residue (available from the bottom of vacuum distillation units) and clarified liquid oil (available from the bottom of the main fractionators of fluidized-bed catalytic crackers). Certain lighter streams such as heavy cycle oil, light cycle oil (LCO) and kerosene, are added to the heavy residual stock to improve its quality in terms of fluidity, combustibility, etc., to be marketed as fuel oil. The present study aims at optimization of the fuel oil blending process to maximize profit, minimize quality give-away, maximize production, minimize use of lighter products such as LCO and kerosene, and maximize the calorific value, etc. Several multi-objective optimization problems have been formulated comprising of two and three-objective functions and solved using the elitist non-dominated sorting genetic algorithm (NSGA-II). This evolutionary technique produces a set of nondominating (equally good) Pareto optimal solutions from which the operator can choose the one that is most suitable (preferred point). Also, a fixed-length macro–macro mutation operator, inspired by jumping genes in natural genetics, has been used with NSGA-II to solve this problem. This modified algorithm leads to a significant reduction in the computational effort. Indeed, this adaptation can be of immense use in reducing the computational effort for other problems in chemical engineering.

07/02083 Static and impact crack properties of a high-strength steel welded joint Zrilic, M. et al. International Journal of Pressure Vessels and Piping, 2007, 84, (3), 139–150. In order to gain the benefits of weldable high-strength steels in pressurized equipment applications, satisfactory toughness and crack properties of the welded joint, both in the weld metal and the heataffected zone (HAZ), are required. Experimental investigations of toughness and crack resistance parameters through static and impact tests of a high-strength, low-alloy steel (HSLA) with a nominal yield strength of 700 MPa and its welded joint, were performed on Charpysized specimens, V-notched and pre-cracked, of the parent metal, weld metal and HAZ. The selected electrode produced slight undermatching and enabled the welded joints to be manufactured without cold cracks. The impact energy and its parts responsible for crack initiation and propagation were determined by toughness evaluation. Crack sensitivity, defined as the ratio of the impact energy for V-notched and for pre-cracked specimens, enabled a comparison of the homogeneous microstructure of the parent metal and the weld metal, and of the heterogeneous microstructure of the HAZ, which indicated a better crack toughness behaviour of the HAZ. The results obtained showed that the toughness and crack resistance of the weld metal were significantly lower than those of the parent metal and the HAZ. The fracture mechanics parameters, JIc integral, and plane strain fracture toughness, KIc, as well as J resistance curves expressed the degradation less.

07/02084 Ultra-deep desulfurization of coker and straightrun gas oils: effect of lowering feedstock 95% boiling point Al-Barood, A. and Stanislaus, A. Fuel Processing Technology, 2007, 88, (3), 309–315. Production of diesel fuels with ultra-low-sulfur levels by deep desulfurization of gas oil feeds has received considerable importance in the petroleum refineries in recent years. The type of the gas oil feed and its distillation temperature play a key role in the deep desulfurization process. In the present research project, the effect of lowering the 95% distillation temperature (T95) of two gas oil feeds, namely, straight-run gas oil (SRGO) and coker gas oil (CGO), on deep desulfurization to ultra-low-sulfur levels was investigated. The results showed that for both types of feeds a higher degree of desulfurization was achieved with reduction of T95 from > 360  C to < 340  C. The refractory alkyl dibenzothiophenes boiling above 320  C were present in very low concentrations in the low-boiling cuts and deep HDS to ultra-low-sulfur levels (< 50 ppm) was achieved at low severity operating conditions. Among the two feeds, the CGO that contained high nitrogen content, high concentrations of sterically hIndexred alkyl DBTs and high aromatics content (low feed saturation) was more difficult to desulfurize than SRGO.

Economics, business, marketing, policy 07/02085 A decision framework for risk management, with application to the offshore oil and gas industry Aven, T. et al. Reliability Engineering & System Safety, 2007, 92, (4), 433–448. This paper discusses a decision framework for risk management. The framework comprises the basic elements: problem definition (challenges, goals and alternatives), stakeholders, concerns that affect the consequence analyses and the value judgments related to these consequences and analyses (frame conditions and constraints), identification of which consequence analyses to execute and the execution of these, managerial review and judgement, and the decision. The framework has novel aspects on the way of classifying the decision situations and characterizing risks. The classification is based on the two dimensions, expected consequences, and uncertainties. The starting point is the offshore oil and gas industry, but our framework and discussion is to a large extent general and could also be applied in other areas. An example is outlined to illustrate the use of the framework.

07/02086 An experimental investigation and modelling of the thermodynamic properties of isobutane–compressor oil solutions: Some aspects of experimental methodology Zhelezny, P. V. et al. International Journal of Refrigeration, 2007, 30, (3), 433–445. This paper presents experimental data for the solubility, density and capillary constant for solutions of natural refrigerant isobutane with commercial mineral compressor oil Azmol over a wide range of temperatures and concentrations. Based on information for the capillary constant, the surface tension of the solutions isobutane/ Azmol is determined. The experimental data were obtained in the temperature range from 303 to 363 K and at pressures up to 1.7 MPa using static methods. The experimental data obtained for the solutions of the natural refrigerant isobutane with the commercial mineral compressor oil Azmol are sufficiently described with the help of correlations based on the theory of thermodynamic similarity. The paper reports variation of the vapour pressure, density, capillary constant and surface tension as a function of concentration for the isobutane/Azmol solutions. The enthalpy of liquid phase of the isobutane/Azmol solutions is calculated. The analysis of the behaviour of the excess thermodynamic functions is carried out. The paper examines experimental and methodical uncertainties in the investigation of thermodynamic properties of the refrigerant/oil solutions (ROS). The influence of the time taken to establish thermodynamic equilibrium in the experimental cell on the uncertainty of the experimental data for gas-saturated mixtures such as ROS is discussed. Information about the changing concentration of refrigerant in the liquid phase of the ROS and in the surface layer of the liquid phase of the ROS at increasing temperature is presented. In addition, the experimental data for the density, surface tension and refractive Index of the mineral compressor oil Azmol are reported.

07/02087 Asymmetric error correction models for the oil–gasoline price relationship Grasso, M. and Manera, M. Energy Policy, 2007, 35, (1), 156–177. The existing literature on price asymmetries does not systematically investigate the sensitivity of the empirical results to the choice of a particular econometric specification. This paper fills this gap by providing a detailed comparison of the three most popular models designed to describe asymmetric price behaviour, namely asymmetric ECM, autoregressive threshold ECM and ECM with threshold cointegration. Each model is estimated on a common monthly data set for the gasoline markets of France, Germany, Italy, Spain and UK over the period 1985–2003. All models are able to capture the temporal delay in the reaction of retail prices to changes in spot gasoline and crude oil prices, as well as some evidence of asymmetric behaviour. However, the type of market and the number of countries that are characterized by asymmetric oil–gasoline price relations vary across models. The asymmetric ECM prescribes that long-run price asymmetries are most likely to be found in the second stage of the transmission chain. Conversely, the ECM with threshold cointegration suggests that long-run price asymmetries vary across countries and markets. Shortrun price asymmetries are captured by the asymmetric ECM specification and the TAR-ECM. The latter model suggests that all European countries are likely to be affected by asymmetries at the distribution stage, while the results obtained with the asymmetric ECM are mixed.

07/02088 Development of a database for accidents and incidents in the Greek petrochemical industry Nivolianitou, Z. et al. Journal of Loss Prevention in the Process Industries, 2006, 19, (6), 630–638.

Fuel and Energy Abstracts September 2007 319

02 Liquid fuels (derived liquid fuels) This paper describes the development of a database that comprises all incidents from the Greek petrochemical industry for the period 1997– 2003. The database includes industrial incidents, accidents, operational accidents and near misses from all petrochemical sites in Greece and Cyprus. The design of the database has been conceived in a userfriendly way with additional possibilities for its further use, such as: statistical analysis of the data, calculation of safety indicators, accident reports and human factors analysis. The database allows the various participating industries to compare the analysis of indicators in their own installations with the national average, as the database comprises data from the entire Greek petrochemical industry. Special care has been given to include data from near misses as well.

07/02089 Investigation of energy and feedstock saving production of gasoline blending components free of benzene Hancso ´ k, J. et al. Fuel Processing Technology, 2007, 88, (4), 393–399. In the production of environmentally friendly and human biologically favorable blending components of engine gasolines isoparaffin fractions having low carbon number (C5–C6) are indispensable. The objective of the research work was to select a catalyst that is applicable for the isomerization of benzene-containing n-hexane fractions at low temperature (< 200  C). n-Hexane isomerizing and benzene saturating ability of a commercial Pt/Al2O3 catalyst – on which light paraffins can only be isomerized at higher temperatures (> 360  C) – and of Pt/ Al2O3/Cl catalysts (5–10% chlorine) – obtained from the previously mentioned catalyst by special pre-treating, chlorination and expedient post-treating – was investigated. n-Hexane fractions of various benzene content (0–4.6%) were used as feeds. The use of chlorinated catalyst (110–190  C reaction temperature) resulted in higher yield (by 3–7%) and increased octane number (by 2–4 units) of the practically benzenefree (< 0.01%) products compared to those produced over the presently used commercial catalysts active at medium temperatures (230–270  C). Additionally, the new process contributes to energyeconomical operation.

07/02090 Modelling the world oil market: assessment of a quarterly econometric model De´es, S. et al. Energy Policy, 2007, 35, (1), 178–191. This paper describes a structural econometric model of the world oil market that can be used to analyse oil market developments and risks. Oil demand depends on domestic economic activity and the real price of oil. Oil supply for non-OPEC producers, based on competitive behaviours, is constrained by geological and institutional conditions. Oil prices are determined by a ‘price rule’ that includes market conditions and OPEC behaviour. Policy simulations indicate that oil demand and non-OPEC supply are rather inelastic to changes in price, while OPEC decisions about quota and capacity utilization have a significant, immediate impact on oil prices.

07/02091

Progress and recent trends in biofuels

Demirbas, A. Progress in Energy and Combustion Science, 2007, 33, (1), 1–18. In this paper, the modern biomass-based transportation fuels such as fuels from Fischer–Tropsch synthesis, bioethanol, fatty acid (m)ethylester, biomethanol, and biohydrogen are briefly reviewed. Here, the term biofuel is referred to as liquid or gaseous fuels for the transport sector that are predominantly produced from biomass. There are several reasons for biofuels to be considered as relevant technologies by both developing and industrialized countries. They include energy security reasons, environmental concerns, foreign exchange savings, and socioeconomic issues related to the rural sector. The term modern biomass is generally used to describe the traditional biomass use through the efficient and clean combustion technologies and sustained supply of biomass resources, environmentally sound and competitive fuels, heat and electricity using modern conversion technologies. Modern biomass can be used for the generation of electricity and heat. Bioethanol and biodiesel as well as diesel produced from biomass by Fischer–Tropsch synthesis are the most modern biomass-based transportation fuels. Bio-ethanol is a petrol additive/substitute. It is possible that wood, straw and even household wastes may be economically converted to bio-ethanol. Bio-ethanol is derived from alcoholic fermentation of sucrose or simple sugars, which are produced from biomass by hydrolysis process. Currently crops generating starch, sugar or oil are the basis for transport fuel production. There has been renewed interest in the use of vegetable oils for making biodiesel due to its less polluting and renewable nature as against the conventional petroleum diesel fuel. Biodiesel is a renewable replacement to petroleum-based diesel. Biomass energy conversion facilities are important for obtaining bio-oil. Pyrolysis is the most important process among the thermal conversion processes of biomass. Brief summaries of the basic concepts involved in the thermochemical conversions of biomass fuels are presented. The percentage share of biomass was

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62.1% of the total renewable energy sources in 1995. The reduction of greenhouse gases pollution is the main advantage of utilizing biomass energy.

07/02092 Properties of Brazilian gasoline mixed with hydrated ethanol for flex-fuel technology Delgado, R. C. O. B. et al. Fuel Processing Technology, 2007, 88, (4), 365–368. In the present work, samples of Brazilian gasoline type C previously mixed with hydrated ethanol at concentrations of 20, 40, 60 and 80 vol.% were analysed by distillation, octane number, specific mass, pH and conductivity, in order to evaluate the physico-chemical properties for a better comprehension of the effects caused by the flex-fuel technology. The obtained results were compared with the specifications of the Ageˆncia Nacional de Petro ´ leo Ga´s Natural e Biocombustı´veis – the federal regulatory agency for monitoring of the quality of fuels in Brazil. It was observed that there exists an ideal concentration of hydrated ethanol for addition in gasoline type C in order to obtain good properties for application in the flex-fuel technology.

Derived liquid fuels 07/02093 A pre-heating vaporization technology of coal-water-slurry for the gasification process Aiuchi, K. et al. Fuel Processing Technology, 2007, 88, (4), 325–331. A pre-heating vaporization technology of coal water slurry, CWS, was developed to increase the efficiency of coal gasification with the reduction of oxygen consumption. A CWS pre-heating experimental unit having a capacity of 2.0 tons-coal/day was manufactured. After the CWS was heated to 573 K at about 10 MPa, water in CWS was continuously vaporized in a tube of which the diameter increased gradually (2–10 mm I.D.), and dry coal particles with steam were atomized and fed to a vessel. No aggregation of coal particles was observed in the atomized samples. The temperature and the pressure distributions of the fluid were calculated with empirical heat transfer and pressure drop correlations. The calculated results well corresponded to the experimental data measured in some test points. Using the calculation model, a large scale apparatus of 100 tons-coal/day was designed using KNO3 + NaNO2 + NaNO3 molten salt as a heating medium.

07/02094 fuels

Combustion fundamentals of pyrolysis oil based

Calabria, R. et al. Experimental Thermal and Fluid Science, 2007, 31, (5), 413–420. The combustion behaviour of emulsions of pyrolysis oil in commercial diesel oil was studied. The emulsions were different in terms of concentration and size of the dispersed phase. The study was carried out in a single droplet combustion chamber. The size of droplets varied between 400 mm and 1200 mm. They were suspended to a bare thermocouple and, hence, their temperature during combustion was measured. High-speed digital shadowgraphy was used to follow droplets evolution. The main features of the droplet combustion were recognized. The general combustion behaviour of emulsions is intermediate with respect to pure PO and commercial diesel oil. Emulsion droplets underwent strong swelling and microexplosion phenomena. However, under the investigated conditions, the microexplosions were ineffective in destroying droplets. The size distribution of the dispersed PO droplets in the range 3–10 mm was not effective nor for determining the overall thermal behaviour nor for the efficacy of the microexplosions. The homogeneous combustion phase resulted identical for emulsions and diesel oil despite the emulsions composition (i.e. concentration of oil, surfactant and co-surfactant, as well as the size of the oil droplets in the emulsion) and the different structure of the flame and also its time and spatial evolution.

07/02095 Electrocatalytic enhancement of methanol oxidation by graphite nanofibers with a high loading of PtRu alloy nanoparticles Park, I.-S. et al. Carbon, 2007, 45, (1), 28–33. The geometric effect of graphite nanofibres (GNFs) as a support for PtRu electrocatalysts on the oxidation of methanol for direct methanol fuel cells (DMFCs) was studied using X-ray diffraction, field emission transmission electron microscopy (FETEM) and electrochemical measurements. A high loading of 60 wt% PtRu catalyst, which is readily applicable to DMFCs, was well dispersed on GNFs. Further, the shape of the supported metal particles was affected by interactions with the GNFs. Electrochemical analysis indicated that GNFsupported PtRu catalysts resulted in an increased catalytic activity of about 100% over that of Vulcan XC-72 supported catalysts. FETEM

03 Gaseous fuels (sources, properties, recovery, treatment) data indicate that the enhanced activities result from a geometric modification of the catalyst particles by specific interactions between the GNFs and the supported PtRu nanoparticles.

07/02096 Preparation and rheological properties of oil–water–coal triplex synfuel using petroleum sulfonate as the dispersants Zhu, H. et al. Fuel Processing Technology, 2007, 88, (3), 221–225. Triplex synfuel containing light oil, water and coal was prepared using octyl phenol polyethenoxy ether (OP) nonionic surfactant as emulsifying agent and petroleum sulfonate (PS) anionic surfactant as dispersing agent. Rheological properties of triplex mixture systems were investigated and the ratio of OP to PS was also optimized. The structures of PS products and naphthalene sulfonate and formaldehyde condensation compound (NSF) that has good dispersing performance were analysed through FTIR spectrum. It was found that the dispersing performance of F# petroleum sulfonate which was sulfonated higher and contained more aromatic was the best. Furthermore it was better to be used as a kind of dispersant of triplex mixture systems. The triplex systems, with the ratio of the components of coal (C) to water (W) to oil (O) by weight was C:W:O = 63%:27%:10% and C:W:O = 65%:30%:5% were prepared when OP:PS-F# was 0.3%:0.8%. Moreover, at 25  C apparent viscosities of triplex mixture systems were 415.0 and 1060.7 mPa s1 respectively at a shear rate of 100 s1 and it could be kept stable for more than two months. Two kinds of triplex synfuels can meet the demand of industrial quality.

03 GASEOUS FUELS Sources, properties, recovery, treatment 07/02097 Cerium promoted Pd/HZSM-5 catalyst for methane combustion Shi, C. et al. Fuel, 2007, 86, (1–2), 106–112. A series of Pd/HZSM-5 (Si/Al2 = 165) catalysts without and with additives of oxides of La, Ce, Sm, Nd and Tb were prepared by the impregnation method, and characterized by XRD, Raman spectra, N2adsorption, CO-chemisorption, O2-TPD and CH4-TPR techniques. The catalysts were investigated for low-temperature CH4 combustion, and CeO2 was found to have a significant promoting effect on the activity of Pd/HZSM-5. Pd–Ce/HZSM-5 showed the best methane combustion activity and the improved thermal/hydrothermal reaction stability among tested catalysts. The characterization results of catalysts indicated that CeO2 can effectively promote the formation of crystalline PdO and weaken the bond strength of Pd–O on Pd–Ce/ HZSM-5, resulting in that Pd–Ce/HZSM-5 possessed lower temperatures for oxygen desorption and CH4 reduction than Pd/HZSM-5. This could be ascribed to the covalent property and large oxygen storage/ supplying capacity of CeO2. It is believed that more active PdO species on Pd/HZSM-5 for low-temperature methane combustion process could be effectively promoted due to the introduction of CeO2.

07/02098 Characterization of the origin of coalbed gases in southeastern Illinois Basin by compound-specific carbon and hydrogen stable isotope ratios Strapoc, D et al. Organic Geochemistry, 2007, 38, (2), 267–287. Coalbed gases and waters from exploratory and production gas wells in the southeastern Illinois Basin were sampled to assess geochemically the origin of coalbed gases, with an emphasis on the Springfield and Seelyville Coal Members that are commercially targeted for coalbed methane production in Indiana. On-line analyses of hydrocarbon gases methane to butanes (C1, C2, C3, n-C4, i-C4) and CO2 yielded gas concentrations, plus D and 13C values. The low thermal maturity of Indiana coals with vitrinite reflectance R0 0.6% is in agreement with an overwhelmingly biogenic isotopic signature of coalbed gases containing 96% methane generated via bacterial CO2-reduction. In contrast, thermogenic gas was generated in the stratigraphically equivalent coal beds in western Kentucky’s Rough Creek Graben zone where higher maturities of up to R0 0.8% were reached owing to tectonic and hydrothermal activity. No secondary biogenic methane was observed in more mature western Kentucky coal beds where greater burial depth limits the recharge of meteoric water. Biogenic and thermogenic coalbed gases represent two end-members that are compositionally and isotopically distinct. Microbial biodegradation of thermogenic C2+ hydrocarbon gases in Indiana coal beds preferentially targets C3 and introduces isotope fractionation whereby remaining C3 is enriched in deuterium and 13C.

07/02099 Halogen concentrations in pore waters and sediments of the Nankai Trough, Japan: implications for the origin of gas hydrates Muramatsu, Y. et al. Applied Geochemistry, 2007, 22, (3), 534–556. Presented here are halogen concentrations (Cl, Br and I) in pore waters and sediments from three deep cores in gas hydrate fields of the Nankai Trough area. The three cores were drilled between 1999 and 2004 in different geologic regions of the northeastern Nankai Trough hydrate zone. Iodine concentrations in all three cores increase rapidly with depth from seawater concentrations (0.00043 mmol/L) to values of up to 0.45 mmol/L. The chemical form of I was identified as I, in accordance with the anaerobic conditions in marine sediments below the SO2 reduction depth. The increase in I is accompanied by a parallel, although lesser increase in Br concentrations, while Cl concentrations are close to seawater values throughout most of the profiles. Large concentration fluctuations of the three halogens in pore waters were found close to the lower boundary of the hydrate stability zone, related to processes of formation and dissociation of hydrates in this zone. Generally low concentrations of I and Br in sediments and the lack of correlation between sediment and pore water profiles speak against derivation of I and Br from local sediments and suggest transport of halogen rich fluids into the gas hydrate fields. Differences in the concentration profiles between the three cores indicate that modes of transportation shifted from an essentially vertical pattern in a sedimentary basin location to more horizontal patterns in accretionary ridge settings. Because of the close association between organic material and I and the similarity of transport behaviour for I and CH4, the results suggest that the CH4 in the gas hydrates also was transported by aqueous fluids from older sediments into the present layers.

07/02100 Halogen systematics in the Mallik 5L-38 gas hydrate production research well, Northwest Territories, Canada: implications for the origin of gas hydrates under terrestrial permafrost conditions Tomaru, H. et al. Applied Geochemistry, 2007, 22, (3), 656–675. The authors report here halogen concentrations in pore waters and sediments collected from the Mallik 5L-38 gas hydrate production research well, a permafrost location in the Mackenzie Delta, Northwest Territories, Canada. Iodine and Br are commonly enriched in waters associated with CH4, reflecting the close association between these halogens and source organic materials. Pore waters collected from the Mallik well show I enrichment, by one order of magnitude above that of seawater, particularly in sandy layers below the gas hydrate stability zone (GHSZ). Although Cl and Br concentrations increase with depth similar to the I profile, they remain below seawater values. The increase in I concentrations observed below the GHSZ suggests that Irich fluids responsible for the accumulation of CH4 in gas hydrates are preferentially transported through the sandy permeable layers below the GHSZ. The Br and I concentrations and I/Br ratios in Mallik are considerably lower than those in marine gas hydrate locations, demonstrating a terrestrial nature for the organic materials responsible for the CH4 at the Mallik site. Halogen systematics in Mallik suggest that they are the result of mixing between seawater, freshwater and an I-rich source fluid. The comparison between I/Br ratios in pore waters and sediments speaks against the origin of the source fluids within the host formations of gas hydrates, a finding compatible with the results from a limited set of 129I/I ratios determined in pore waters, which gives a minimum age of 29 Ma for the source material, i.e. at the lower end of the age range of the host formations. The likely scenario for the gas hydrate formation in Mallik is the derivation of CH4 together with I from the terrestrial source materials in formations other than the host layers through sandy permeable layers into the present gas hydrate zones.

07/02101 Measurement of stable carbon isotope ratios of methane in ice samples Schaefer, H. and Whiticar, M. J. Organic Geochemistry, 2007, 38, (2), 216–226. Methane concentrations and carbon isotope ratios in ice samples offer an approach to study past budgets of atmospheric methane and to investigate changes in source composition or sink processes. Methane concentrations in ice samples also provide a tool for age correlation between different ice cores. Critical for the use of these parameters are measurements with sufficient accuracy and precision on small samples. To this end, a micro-extraction gas chromatography-continuous-flow isotope ratio mass spectrometry (GC-IRMS) technique was developed to extract, focus and measure the methane 13C/12C ratio (13CH4) from extremely small gas occlusions in ice (ca. 300 pmol of methane from 100 to 250 g of ice). This micro-measurement allows the time resolution (sample stratigraphic thickness) necessary in paleo-records to investigate decadal-range changes in the methane cycle coupled to abrupt warming events during the last glacial period. The accuracy (0.4%) and precision (1 = 0.32%) of the method was established by in-house ice standards and confirmed with analysis of ice from GISP2 and the

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03 Gaseous fuels (economics, business, marketing, policy) Agassiz ice cap. The 13CH4 measurements of 49.7% between 225 and 330 yr BP agree very well with previously published data. These 13CH4 ice core results indicate an unexpected 13C-enrichment of the pre-industrial atmospheric methane, compared to predictions by mass balance models.

07/02102 Natural gas formation in the western Nile delta (Eastern Mediterranean): thermogenic versus microbial Vandre´, C. et al. Organic Geochemistry, 2007, 38, (4), 523–539. The offshore part of the Nile delta is an emerging gas and condensate province and one of the most promising areas for future petroleum exploration and supply in northern Africa. While the Nile delta’s hydrocarbon potential and its geological and stratigraphic pattern has been the focus of numerous studies, the origin of its gas has been poorly studied. In order to characterize the natural gas and to determine whether microbial or thermogenic processes are the dominant generation pathways of methane, a regional geochemical study was performed on 38 test gases collected from nine Neogene western Nile delta discoveries. Main constituents of the gases are methane (89.4–99.4%) up to pentane with traces of carbon dioxide and nitrogen. Methane carbon isotopic composition ranges from 66.0% to 39.6% displaying a mixed microbial and thermogenic character for most of the gases. Microbial gas contributions range from 15% to 95%. The mixed and the more thermogenic gases are frequently accompanied by light oils and condensates (41–59  API). Calculated maturities of the thermogenic gas proportions suggest source rock maturities between 0.8% and 1.4% Ro, which are actually present in the pre-Miocene section. Evidence for microbial alteration of petroleum accumulations in the Nile delta is largely manifested in anomalously heavy isotopic compositions of both wet-gas components propane and n-butane and preferential removal of higher n-alkanes from condensates. The hydrocarbon accumulations affected by biodegradation are trapped within shallow Pliocene reservoirs (<2400 m) where present day temperatures are below 80  C. The coexistence of biodegraded thermogenic gas and condensate with dry microbial gas supports the concept that generation of secondary microbial methane by biodegradation of thermogenic hydrocarbons may occur within the Nile delta.

Transport, storage 07/02103 Efforts to harmonize gas pipeline operations with the demands of the electricity sector Costello, K. The Electricity Journal, 2006, 19, (10), 7–26. A possible future course of action is for pipelines to continue their efforts to provide new services with FERC approval. Over time, pipelines could satisfy power generators by giving them the flexibility and services they desire and for which they are willing to pay. Another possibility is that FERC will enact new rules governing regional electricity markets that would function similarly to nationwide business practices.

temperature is vital to methane storage capacity for ACF3, and adsorption storage at the temperatures below 280 K is recommended for favorite uptakes. To model ACF3, the pores are described as slitshaped with a pore size distribution that was determined by molecular simulation and the statistics integral equation. Predictions of methane adsorption, carried out at 258 and 298 K and high pressures by molecular simulation, indicate that the sample ACF3 can reach the uptake of 14.99 wt% at 4.0 MPa and 298 K, which is comparable with the best result in the literature.

07/02106

Modelling of a pressure regulator

Rami, E. C. et al. International Journal of Pressure Vessels and Piping, 2007, 84, (3), 234–243. With the increase of gas consumption and the expansion of the associated distribution network, a research program was set up to study the stability and to simulate the main characteristics of the dynamic behaviour of any type of pressure regulator. The modelling of a pressure regulating station is based on hydraulic, mechanical and valve models. The library of models is validated on one type of pressure regulator and simulations are in good agreement with measurements. The study showed that the operating conditions and installation requirements have the greatest influence on the stability of the pressure regulator. From measurements and simulations, the amplitudes of the downstream pressure are particularly sensitive to the size of the downstream volume and to upstream pressure.

07/02107 The low cost of geological assessment for underground CO2 storage: policy and economic implications Friedmann, S. J. et al. Energy Conversion and Management, 2006, 47, (13–14), 1894–1901. The costs for carbon dioxide (CO2) capture and storage (CCS) in geologic formations is estimated to be $6–75/t CO2. In the absence of a mandate to reduce greenhouse gas emissions or some other significant incentive for CCS deployment, this cost effectively limits CCS technology deployment to small niche markets and stymies the potential for further technological development through learning by doing until these disincentives for the free venting of CO2 are in place. By far, the largest current fraction of these costs is capture (including compression and dehydration), commonly estimated at $25–60/t CO2 for power plant applications, followed by CO2 transport and storage, estimated at $0–15/t CO2. Of the storage costs, only a small fraction of the cost will go to accurate geological characterization. These one time costs are probably on the order of $0.1/t CO2 or less as these costs are spread out over the many millions of tons likely to be injected into a field over many decades. Geologic assessments include information central to capacity prediction, risk estimation for the target intervals and development facilities engineering. Since assessment costs are roughly two orders of magnitude smaller than capture costs, and assessment products carry other tangible societal benefits, such as improved accuracy in fossil fuel and ground water reserves estimates, government or joint private–public funding of major assessment initiatives should underpin early policy choices regarding CO2 storage deployment and should serve as a point of entry for policy makers and regulators. Early assessment is also likely to improve the knowledge base upon which the first commercial CCS deployments will rest.

07/02104 Evaluation of the effect of corrosion defects on the structural integrity of X52 gas pipelines using the SINTAP procedure and notch theory Adib, H. et al. International Journal of Pressure Vessels and Piping, 2007, 84, (3), 123–131. The notch stress intensity factor concept and the structural integrity assessment procedure for European industry (SINTAP) structural integrity procedure are used to assess gas pipeline integrity using deterministic and probabilistic methods. These pipes have external longitudinal semi-elliptical corrosion defects. Stress concentration at a defect tip is investigated via elastic–plastic finite element method analysis. The notch stress intensity concept is implemented into the SINTAP procedure and a notch-based failure assessment diagram is proposed. The safety factor and security factor are calculated through the SINTAP basic level.

07/02105 Experimental measurements and computer simulation of methane adsorption on activated carbon fibers Shao, X. et al. Carbon, 2007, 45, (1), 188–195. Three activated carbon fibres (ACFs) with different BET specific surface areas (SSAs) were prepared. Experimental characterization and methane adsorption on the ACFs were measured by the intelligent gravimetric analyser (IGA-003, Hiden) at 258 and 298 K. Correlations proposed between the methane adsorption capacity and SSA indicate that the SSA plays an important role on storage amount at a given temperature. A detailed experimental investigation was focused on the sample ACF3 of the highest SSF of 1511 m2/g at five temperatures, from 258 to 298 K. The temperature dependence for methane adsorption amount on ACF3 at 1.8 MPa is proposed. It shows that

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Economics, business, marketing, policy 07/02108 Can deployment of renewable energy put downward pressure on natural gas prices? Wiser, R. and Bolinger, M. Energy Policy, 2007, 35, (1), 295–306. High and volatile natural gas prices have increasingly led to calls for investments in renewable energy. One line of argument is that deployment of these resources may lead to reductions in the demand for and price of natural gas. Many recent US-based modelling studies have demonstrated that this effect could provide significant consumer savings. In this article these studies are evaluated, and benchmark their findings against economic theory, other modelling results, and a limited empirical literature. It is found that many uncertainties remain regarding the absolute magnitude of this effect, and that the reduction in natural gas prices may not represent an increase in aggregate economic wealth. Nonetheless, it is concluded that many of the studies of the impact of renewable energy on natural gas prices appear to have represented this effect within reason, given current knowledge. These studies specifically suggest that a 1% reduction in US natural gas demand could lead to long-term average wellhead price reductions of 0.8–2%, and that each megawatt-hour of renewable energy may benefit natural gas consumers to the tune of at least $7.5–20.

03 Gaseous fuels (derived gaseous fuels) 07/02109 pricing

Combined natural gas and electricity network

Morais, M. S. and Marangon Lima, J. W. Electric Power Systems Research, 2007, 77, (5–6), 712–719. The introduction of competition to electricity generation and commercialization has been the main focus of many restructuring experiences around the world. The open access to the transmission network and a fair regulated tariff have been the keystones for the development of the electricity market. Parallel to the electricity industry, the natural gas business has great interaction with the electricity market in terms of fuel consumption and energy conversion. Given that the transmission and distribution monopolistic activities are very similar to the natural gas transportation through pipelines, economic regulation related to the natural gas network should be coherent with the transmission counterpart. This paper shows the application of the main wheeling charge methods, such as MW/gas-mile, invested related asset cost (IRAC) and Aumman-Shapley allocation, to both transmission and gas network. Stead-state equations are developed to adequate the various pricing methods. Some examples clarify the results, in terms of investments for thermal generation plants and end consumers, when combined pricing methods are used for transmission and gas networks. The paper also shows that the synergies between gas and electricity industry should be adequately considered, otherwise wrong economic signals are sent to the market players.

07/02110 Downstream natural gas in Europe – high hopes dashed for upstream oil and gas companies Eikeland, P. O. Energy Policy, 2007, 35, (1), 227–237. Access for independents to retail gas markets was a central concern in European policy reform efforts in the 1990s. Upstream oil and gas companies reacted with strategic intentions of forward integration. By late 2004, forward integration was still weak, however. An important explanation of the gap between announced strategic re-orientation and actual strategy implementation lies in the political failure of EU member states to dismantle market barriers to entry for independents. Variations between companies in downstream strategy implementation are explained by variations in business opportunities and internal company factors.

07/02111 Efficient industry configurations in downstream gas markets. An empirical assessment Casarin, A. A. Energy Economics, 2007, 29, (2), 312–328. This paper examines the production technology of the downstream gas industry in order to provide some useful insights into its efficient structure by looking at the optimal size of firms and the productive efficiency reasons for and against their vertical integration. The analysis is based on a restricted cost function model estimated using firm level data for Argentina and Great Britain. The findings provide evidence for the presence of vertical diseconomies between stages. Results indicate that a single transmitter is able to produce the industry’s output at lower costs for large market sizes and that several regional firms are able to operate without sacrificing scale economies if gas distribution is integrated with supply. The findings also indicate that a gas retailer experiences constant returns to scale when it supplies a large customer base. Liberalization could thus result in oligopolistic industry configurations.

07/02112

Safety distances for hydrogen filling stations

Matthijsen, A. J. C. M. and Kooi, E. S. Journal of Loss Prevention in the Process Industries, 2006, 19, (6), 719–723. In the context of spatial planning the Dutch Ministry of Housing, Spatial Planning and the Environment asked the Centre for External Safety of the National Institute for Public Health and the Environment (RIVM) to advice on safe distances pertaining to hydrogen filling stations. The RIVM made use of failure modelling and parameters for calculating the distance in detail. An imaginary hydrogen filling station for cars is used in the determination of ‘external safety’ or third party distances for the installations and the pipe work for three different sizes of hydrogen filling stations. For several failure scenarios ‘effect’ distances are calculated for car filling at 350 and 700 bar. Safe distances of filling stations from locations where people live and work appear to be similar for compressed hydrogen, gasoline/petrol and compressed natural gas. Safe distances for LPG are greater. A filling unit for hydrogen can be placed at gasoline/petrol-filling stations without increasing safety distances.

07/02113 Europe?

The security of gas supply – a critical issue for

Weisser, H. Energy Policy, 2007, 35, (1), 1–5. Gas is competing with oil for being the dominant energy source. In electricity generation gas is to play as pivotal a role as oil in transportation. The security equation of gas and electricity become unseparably interrelated. Energy disruptions have considerable influence on the national accounts far beyond the direct cost of market participants (asymmetry). The present gas supply to the EU depends

dangerously on too few sources and venues. There is a decided lack of optionality. The EU directly or through its members needs a clear proactive policy on ‘security of gas supply’ with a strong multilateral direction. The measures developed for the oil industry over the last 30 years can at least serve as a starting point for a constructive debate. When discussing security of supply dependence it is useful to clearly define the various risks one wishes to protect against. Free riders relying on alternative fuels without participating in their security systems are not permissible.

Derived gaseous fuels 07/02114 An economic and energy analysis on bio-hydrogen fuel using a gasification process Dowaki, K. et al. Renewable Energy, 2007, 32, (1), 80–94. Recently, in Japan, recycling technologies have been developed using waste biomass material. Waste biomass is traded in the waste materials market between users and a third-party, who receives a fee for processing them. This study is an environmental and economic analysis of a biomass energy system, which can produce hydrogen fuel for fuel cells (purity of 99.99%) as an example of an environmental business model. The experimental apparatus was made based on the moving-bed gasifier by the German company, DM2 Inc., and the hydrogen gas yield was measured. Finally, the economic viability of the future hydrogen business was estimated. The experimental results obtained gave the gas concentration of 57.5% in a steam/carbon ratio of 1.40 at 900  C. Assuming the plant scale of 10 t/d, the production amount of hydrogen gas would be 21.3 kg/h. Based on the law concerning waste processing in Japan, a sizeable amount of waste biomass could be expected. Therefore, if the processing fee which is paid to the group (contractor) ranges between 5.0 and 10.0 $/t, and if the whole investment cost is 6 million dollars and the depreciation period is 15 years, the biohydrogen production cost using the experimental data would be 5.75– 7.86 $/kg-H2 without receiving related subsidies. In a one-third grant proportion, the cost would become 4.60–6.72 $/kg-H2.

07/02115 Assessment of detonation hazards in high-pressure hydrogen storage from chemical sensitivity analysis Ng, H. D. et al. International Journal of Hydrogen Energy, 2007, 32, (1), 93–99. In this study, a series of detonation sensitivity analyses have been carried out to assess detonation hazards in hydrogen–air mixture. The present investigation in particular concerns with the effect of elevated initial pressure on the detonation sensitivity, which stems from the renewing interest in preventing possible explosion scenario in hydrogen economy when high-pressure hydrogen storage facilities are contaminated with air. From the steady ZND analyses based on a recently updated comprehensive kinetic mechanism of hydrogen combustion and using improved semi-empirical models, various dynamic parameters, i.e. characteristic cell size and direct initiation energy, for hydrogen–air detonations are estimated and assessed against available experimental data. Results for the hydrogen–air detonation sensitivity indicated that from a purely chemical kinetics consideration, the probability of having a detonation of hydrogen–air mixture at elevated initial pressure is not higher than in other hydrocarbon fuels at elevated initial pressure.

07/02116 Interpretation of biomass gasification yields regarding temperature intervals under nitrogen–steam atmosphere Haykiri-Acma, H. and Yaman, S. Fuel Processing Technology, 2007, 88, (4), 417–425. Gasification of some agricultural waste biomass samples (sunflower shell, pine cone, cotton refuse, and olive refuse) and colza seed was performed using a thermogravimetric analyser at temperatures up to 1273 K with a constant heating rate of 20 K/min under a dynamic nitrogen–steam atmosphere. Derivative thermogravimetric analysis profiles of the samples were derived from the non-isothermal thermogravimetric analysis data. Gasification yields of the biomass samples at temperature intervals of 473–553 K, 553–653 K, 653–773 K, 773–973 K, and 973–1173 K were investigated considering the successive stages of ‘evolution of carbon oxides’, ‘start of hydrocarbon evolution’, ‘evolution of hydrocarbons’, ‘dissociation’, and ‘evolution of hydrogen’, respectively. Although, there were some interactions between these stages, some evident relations were observed between the gasification yields in a given stage and the chemical properties of the parent biomass materials.

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03 Gaseous fuels (hydrogen generation and storage) 07/02117 Study about the kinetic processes of biomass steam gasification Dupont, C. et al. Fuel, 2007, 86, (1–2), 32–40. Modelling approaches of biomass steam gasification are investigated that take into account both chemical and physical kinetic limitations. The gas phase can be described by two independent reactions: (i) the steam reforming of CH 4, which is kinetically limited under the operating conditions (1073 < T < 1273 K, p = 1 bar), (ii) the water– gas shift reaction, which would be close to equilibrium under the operating conditions (1073 < T < 1273 K, p = 1 bar). Concerning solid, a time scale analysis of the main phenomena has been performed. For particles of 500 mm, the transformation can be seen as two successive steps: (i) pyrolysis of biomass, which is both chemically and heattransfer controlled; (ii) steam gasification of residue, which is chemically controlled.

07/02118 Syngas to iso-paraffins over Co/SiO2 combined with metal/zeolite catalysts Liu, Z.-M. et al. Fuel Processing Technology, 2007, 88, (2), 165–170. Selective production of gasoline ranged iso-paraffins from synthesis gas was performed in a consecutive dual reactor system, in which Fischer– Tropsch reaction was carried out over Co/SiO2 catalyst in the upper reactor and hydroconversion of the Fischer–Tropsch hydrocarbons occurred over precious metal/zeolite catalyst in the lower reactor. Results indicate that the product distribution of traditional Fischer– Tropsch synthesis was significantly modified and high selectivity to isoparaffins was achieved with the presence of metal/zeolite catalyst in the lower reactor. A significant effect of metals (Pt and Pd), zeolites (zeolites of  and USY), and the preparation methods (impregnation and ion exchange) of the metal/zeolite catalyst on the iso-paraffins selectivity and product distribution was clearly observed. This was explained based on the property of the metal for hydrogen spillover and the acidic and structural properties of the zeolite in the bifunctional metal/zeolite catalyst.

LNG 07/02119

Chile’s first LNG terminal

Anon., Pump Industry Analyst, 2007, (6), 2. A liquefied natural gas (LNG) regasification terminal is to be built at Quintero Bay, Chile. The project will involve the engineering, procurement and construction of a regasification and sendout system, a new marine jetty with complete ship unloading facilities, two large full containment LNG storage tanks and a smaller storage tank. The 2.5 million tonnes per annum terminal in Quintero Bay, which is approximately 110 km northwest of Santiago, will have the capacity to meet up to 40% of the country’s demand for natural gas. Operation is targeted to commence in the second quarter of 2009.

07/02120 Feasibility of transporting LNG from South-Pars gas field to potential markets Javanmardi, J. et al. Applied Thermal Engineering, 2006, 26, (16), 1812– 1819. On the basis of exporting 7.5 million tons per annum LNG from SouthPars in southern part of Iran, a two-train LNG plant is designed. The design parameters for the equipments are calculated and reported. Using a simple economical model, the production cost for transporting natural gas as LNG to some potential gas markets in the world is estimated. Evaluations indicated that based on natural gas price between $4.74  104 and $7.58  104 MJ1, the LNG product cost is obtained between $1.89  103 and $2.84  103 MJ1. This suggests that transporting natural gas in the form of LNG is cost effective.

would disperse as a heavy rather than a light gas, although the natural gas is lighter than air at normal conditions. On the other hand, the statistical treatment revealed that box-models may also give acceptable results even for the complex case of non-isothermal gas dispersion. Nevertheless, the CFX code unambiguously demonstrated considerably better accuracy.

07/02122

UK LNG terminal expansion

Anon., Pump Industry Analyst, 2007, (6), 2. The National Grid’s liquefied natural gas (LNG) import terminal at the Isle of Grain is undergoing expansion. Costing approximately US$500 million, the terminal’s capacity will increase by 700 million cubic feet per day to 2.1 billion cubic feet per day. The facility is located about 40 miles east of central London. The work includes a new jetty capable of berthing LNG carriers with capacity up to 265,000 cubic metres and with an unloading rate of 12,000 cubic metres per hour. The work scope also includes the construction of another 190,000 cubic metres’ full containment LNG storage tank and new gas processing facilities. This work is scheduled to be completed in 2010.

Hydrogen generation and storage 07/02123

A nanocontainer for the storage of hydrogen

Ye, X. et al. Carbon, 2007, 45, (2), 315–320. Molecule hydrogen is known to have a weak van der Waals potential, which makes it difficult to raise its storage efficiency for physisorption based methods. This report explores the other side of such a weak potential, the well-known compressibility of hydrogen. A (20, 0) single wall carbon nanotube based nanocontainer is designed, in which a C60 ‘peapod’ at the cap section of the nanotube serves as a molecular valve. Diffusion barriers through such a valve is examined by molecular dynamics simulations under various conditions. It is demonstrated that H2 can first be filled into the container upon compression at low temperature, and then be locked inside it after the release of external pressure. The internal pressure that can be achieved in this design is in the GPa range at room temperature, which is much higher than the typical pressure of a few hundred bar currently employed for hydrogen storage. At 2.5 GPa, the storage weight ratio approaches a promising 7.7%.

07/02124 A study of the hydrogen production from a small plasma converter Horng, R.-F. et al. Fuel, 2007, 86, (1–2), 81–89. In this paper, the hydrogen production characteristics of a purposedesigned and built small scale plasma converter for small engines was investigated. Hydrogen was produced through the reformation of ionized hydrocarbon fuel and air mixture by means of a spark discharge. The experimental results showed that a suitable size of the reaction chamber can increase the concentration of the produced hydrogen and that under a given methane supply rate, a low O2/C ratio resulted in high hydrogen production concentration as well as high hydrogen volume flow rate. As the methane supply rate was increased, however, the hydrogen concentration reduced while the hydrogen volume flow rate increased. Hydrogen concentration was also improved when the intake gas mixture resided longer in the reaction channel, although the hydrogen volume flow rate revealed an inversed trend. It was also shown that by combining an intake air swirl with an appropriate O2/C ratio and methane supply rate, both the methane conversion efficiency and the hydrogen production concentration were improved. In general, under the optimal operating condition, the plasma converter produced a maximum hydrogen concentration of 48% and a hydrogen volume flow rate of 70 mL/min.

07/02121 Simulation of Coyote series trials – Part I: CFD estimation of non-isothermal LNG releases and comparison with box-model predictions

07/02125 Cold start response of a small methanol reformer by partial oxidation reforming of hydrogen for fuel cell

Sklavounos, S. and Rigas, F. Chemical Engineering Science, 2006, 61, (5), 1434–1443. This paper deals with the computational simulation of atmospheric cloud dispersion resulting from liquefied gas spills. Experimental data were taken from the Coyote series trials that involved large-scale cryogenic natural gas releases. The data were used for checking the validity of the results obtained through the computational fluid dynamics code CFX. Moreover, using the experimental data-set of the non-isothermal gas dispersion, a comparative evaluation was performed between the code and two popular box-models (SLAB and DEGADIS) on the basis of specific statistical performance measures. The results showed that CFX approximated gas concentration histories with a reasonably good agreement and predicted correctly the behaviour of gas cloud during dispersion. In particular, it predicted that the cryogenic dense cloud produced by the flash boiling

Horng, R.-F. et al. Applied Thermal Engineering, 2006, 26, (11–12), 1115–1124. This paper experimentally investigated the cold start response of a small methanol reformer. The parameters studied were heating power, methanol supply rate, air supply rate and heat transfer loss. The aim was to vary the operating parameters for promoting rapid response of the reformer such that hydrogen was quickly produced. From the experiments, it was revealed that the most economical use of methanol from cold start was a methanol supply rate of 25.5 cm3/min under the combined setting of a heating power of 240 W, a heating temperature of 100  C and an air supply rate of 70 L/min. Under this setting, hydrogen was produced when the temperature of the catalyst outlet was approximately 100  C and hydrogen concentration reached 37.5%, equalling the stable value, at about 290  C, approximately 3 min from cold start.

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04 By-products related to fuels 07/02126 Electrochemical hydrogen production from thermochemical cycles using a proton exchange membrane electrolyzer Sivasubramanian, P. et al. International Journal of Hydrogen Energy, 2007, 32, (4), 463–468. The electrochemical step in two thermochemical cycles for hydrogen production is reported. One cycle involves the electrochemical oxidation of sulfur dioxide to sulfuric acid (both water and SO2 are reactants). The other cycle involves the oxidation of anhydrous hydrogen bromide to bromine (anhydrous HBr is the only reactant). In both cycles, protons are reduced at the cathode to produce hydrogen. The novelty of this work is that both anode reactions are carried out in the gas phase of a proton exchange membrane (PEM) electrolyser, which enhances the transport rate of reactants to the electrode surface. The HBr process achieved 2.0 A/cm2 at 1.91 V. The SO2 process reached 0.4 A/cm2, but behind this current density the cell experienced mass transfer limitations of water across the membrane. However, the voltage required to achieve 0.4 A/cm2 was 0.835 V, compared to 1.025 V for the HBr process at this current density.

07/02130 Membrane processes for the sulfur–iodine thermochemical cycle Stewart, F. F. et al. International Journal of Hydrogen Energy, 2007, 32, (4), 457–462. Removal of water from aqueous hydriodic acid (HI) by pervaporation using Nafion-1171 membranes was studied. Specifically, Nafion membranes were used to separate water from HI at concentrations from 18% to 70% and at temperatures ranging from 22 to 109 C. Initial fluxes of the more dilute acid solutions were as high as 1500 g/m2 h with a separation factor (
) of 139. Furthermore, separation factors as high as 500–700 were obtained for more concentrated samples. In general, increased temperatures yielded higher fluxes with lower separation factors and higher feed concentrations gave lower fluxes with higher separation factors. Activation energies of transport (EJ) values were calculated for lower and higher concentration HI feeds and compared to pure water pervaporation. These data suggest that the degree of protonation and mole fraction water in the feed influence transport kinetics and that boundary layer issues become more prevalent at higher HI concentrations.

07/02127 Environmental and sustainability aspects of hydrogen and fuel cell systems Dincer, I. International Journal of Energy Research, 2007, 31, (1), 29– 55. Discussed in this paper are current environmental problems, potential solutions to these problems, possible future hydrogen energy-utilization patterns for better environment and sustainable development through life cycle assessment (LCA), and how the principles of thermodynamics via exergy can be beneficially used to evaluate hydrogen and fuel cell systems and their role in sustainable development. Throughout the paper current and future perspectives of hydrogen and fuel cell systems based on exergetic, LCA and sustainability aspects development are considered. The results will likely be useful to scientists, researchers and engineers as well as policy and decision makers. Two case studies on the LCA aspects of hydrogen and fuel cell systems are presented to highlight the importance of the hydrogen and fuel cell systems and show that these can help achieve better environment and sustainability.

07/02128 Future hydrogen markets for large-scale hydrogen production systems Forsberg, C. W. International Journal of Hydrogen Energy, 2007, 32, (4), 431–439. The cost of delivered hydrogen includes production, storage, and distribution. For equal production costs, large users (>106 m3/day) will favour high-volume centralized hydrogen production technologies to avoid collection costs for hydrogen from widely distributed sources. Potential hydrogen markets were examined to identify and characterize those markets that will favor large-scale hydrogen production technologies. The two high-volume centralized hydrogen production technologies are nuclear energy and fossil energy with carbon dioxide sequestration. The potential markets for these technologies are: (1) production of liquid fuels (gasoline, diesel and jet) including liquid fuels with no net greenhouse gas emissions and, (2) peak electricity production. The development of high-volume centralized hydrogen production technologies requires an understanding of the markets to: (1) define hydrogen production requirements (purity, pressure, volumes, need for co-product oxygen, etc.); (2) define and develop technologies to use the hydrogen, and (3) create the industrial partnerships to commercialize such technologies.

07/02129 Hydrogen storage on chemically activated carbons and carbon nanomaterials at high pressures Jorda´-Beneyto, M. et al. Carbon, 2007, 45, (2), 293–303. Hydrogen adsorption measurements have been carried out at different temperatures (298 K and 77 K) and high pressure on a series of chemically activated carbons with a wide range of porosities and also on other types of carbon materials, such as activated carbon fibres, carbon nanotubes and carbon nanofibres. This paper provides a useful interpretation of hydrogen adsorption data according to the porosity of the materials and to the adsorption conditions, using the fundamentals of adsorption. At 298 K, the hydrogen adsorption capacity depends on both the micropore volume and the micropore size distribution. Values of hydrogen adsorption capacities at 298 K of 1.2 and 2.7 wt% have been obtained at 20 and 50 MPa, respectively, for a chemically activated carbon. At 77 K, hydrogen adsorption depends on the surface area and the total micropore volume of the activated carbon. Hydrogen adsorption capacity of 5.6 wt% at 4 and 77 K have been reached by a chemically activated carbon. The total hydrogen storage on the best activated carbon at 298 K is 16.7 and 37.2 g H2/l at 20 and 50 MPa, respectively (which correspond to 3.2 and 6.8 wt%, excluding the tank weight) and 38.8 g H2/l at 77 K and 4 MPa (8 wt% excluding the tank weight).

04 BY-PRODUCTS RELATED TO FUELS 07/02131 Activated carbon monolith of high thermal conductivity for adsorption processes improvement. Part B. thermal regeneration Menard, D. et al. Chemical Engineering and Processing, 2007, 46, (6), 565–572. Composite materials made of expanded natural graphite matrix in which activated carbon has been elaborated, present high thermal conductivity (up to 30 W m1 K1) compared to conventional activated carbon bed (0.15–0.5 W m1 K1). In a first part, the experimental adsorption of pure and diluted CO2 has been presented for both the composite and a commercial granular bed for comparison. In the present part, thermal regenerations of the two adsorptive beds by peripheral heating are presented. The conductive composite leads to reduced regeneration time and to the production of concentrated gaseous streams of the adsorbate. The experimental data have been used for numerical model validation which is used for the estimation of the materials performances in larger column scale.

07/02132 Activated carbon surface heterogeneity seen by parallel probing by inverse liquid chromatography at the solid/liquid interface and by gas adsorption analysis at the solid/gas interface Garnier, C. et al. Carbon, 2007, 45, (2), 240–247. The energetic surface heterogeneity of four different activated carbons was assessed by the parallel probing at the solid/liquid and solid/gas interfaces. At the solid/liquid interface a method of inverse liquid chromatography, frontal analysis by characteristic point was applied using phenylalanine in water solution as a probe molecule. At the solid/ gas interface, argon was used as a probe in the low pressure quasi equilibrium volumetry method. The treatment of the adsorption isotherms by the derivative isotherm summation procedure revealed similar adsorption energy distributions for both argon and phenylalanine. Such an agreement between both methods suggests that, at the solid/liquid interface and on the solid/gas interface, the adsorption was mainly controlled by geometric parameters and no specific interaction was observed and physisorbed water did not played a significant role in adsorption process on three from four studied carbons.

07/02133 Adsorption equilibrium of phenol onto chemically modified activated carbon F400 Can ˜ izares, P. et al. Journal of Hazardous Materials, 2006, 131, (1–3), 243–248. In this work the adsorption of phenol solutions onto activated carbon Calgon F400 has been studied. The carbon was modified by acid treatment, using soxhlet extraction with hydrochloric acid 2N for 120 cycles. The treatment did not affect significantly the surface area of the activated carbon but affected significantly the different functional groups, and thus its adsorption properties. To´ th model reproduced satisfactorily the experimental isotherm data and an adsorption enthalpy of 17.9 kJ mol1 was found, which indicates that the process is exothermic. The pH affected significantly to the adsorption process and an empirical polynomial equation was able to reproduce maximum capacity as a function of pH. The isotherms obtained at pH 3 and 7 are very similar and showed a higher adsorption capacity compared with that obtained at pH 13. The use of phosphate buffer solutions decreased the maximum phenol adsorption capacity, due to the

Fuel and Energy Abstracts September 2007 325

04 By-products related to fuels competitive adsorption between the phenol and phosphates. Finally, it was demonstrated that the acid treatment introduced chloride ions into the carbon, giving it properties of ion exchanger.

07/02134 Carbon black composites – supports of HDS catalysts Gheek, P. et al. Catalysis Today, 2007, 119, (1–4), 19–22. HDS activity of sulfided Mo (W) catalysts supported on carbon black composites (CBC) is affected by kind of functional groups present on the CBC surface. Oxidation of CBC with (NH 4)2S2O8 produce functionalities with the highest acid strength and corresponding catalyst exhibits the highest HDS activity. Sulfided W/CBC is less active in thiophene HDS than corresponding Mo counterpart. The rate of thiophene HDS over Mo/‘basic’ CBC does not depend on the method of Mo deposition.

07/02135 Carbon black oxidation in the presence of Al2O3, CeO2, and Mn oxide catalysts: an EPR study Saab, E. et al. Catalysis Today, 2007, 119, (1–4), 286–290. Carbon black oxidation in the presence of CeO2, Al2O3 and manganese oxide catalysts has been studied in tight contact conditions. In the presence of manganese based catalysts, the temperature gain is about 275  C compared to the non-catalysed carbon black oxidation. The contribution of the manganese species to enhance the reactivity of carbon black oxidation has been evaluated by EPR technique. For Mn/ Ce + CB mixtures the Mn2+ content considerably increases consequently to tight milled treatment indicating the reduction of some manganese species with higher oxidation states into Mn2+ ions. This phenomenon can be considered as the first step in the carbon black oxidation mechanism in the presence of Mn/Ce catalysts.

07/02136 Controlled preparation of Pd/AC catalysts for hydrogenation reactions Cabiac, A. et al. Carbon, 2007, 45, (1), 3–10. A commercial activated carbon was submitted to different liquid oxidizing treatments in order to create a high density of carboxylic groups on the carbonaceous surface. Characterization of the modified activated carbon shows that it is possible to generate a large range in acidic group concentration without significant change of the textural properties. This ability allows us to introduce, by ion exchange, palladium cations up to 7.3 wt%. This way of preparation, coupled to soft formaldehyde reduction, leads to highly dispersed metallic palladium catalysts. The resulting catalysts were tested in hydrogenation of cinnamaldehyde and exhibited a high hydrogenation efficiency compared to activities reported in the literature.

07/02137 Coupling a stochastic soot population balance to gas-phase chemistry using operator splitting Celnik, M. et al. Combustion and Flame, 2007, 148, (3), 158–176. The feasibility of coupling a stochastic soot algorithm to a deterministic gas-phase chemistry solver is investigated for homogeneous combusting systems. A second-order splitting technique was used to decouple the particle population and gas phase in order to solve. A numerical convergence study is presented that demonstrates convergence with splitting step size and particle count for a batch reactor and a perfectly stirred reactor. Simulation results are presented alongside experimental data for a plug flow reactor (PFR) and are compared to a method of moments simulation of a perfectly stirred reactor. Coupling of the soot and chemistry solvers is shown to converge for both systems; however, numerical instabilities present significant challenges in the PSR case. Comparison with the experimental data for a PFR showed good agreement of the soot mass and reasonable agreement of the particle size distribution. Two different soot particle models were used to simulate the PFR: a spherical particle model and a surface–volume model that takes some account of particle shape. The results for the two models are compared. Additionally, the stochastic soot solver is used to track the evolution of the C/H ratio of individual soot particles in the PFR for the first time.

07/02138 Development of surface area and pore structure for activation of anthracite coal Zondlo, J. W. and Velez, M. R. Fuel Processing Technology, 2007, 88, (4), 369–374. The use of anthracite coal as a feedstock for activated carbon is investigated. A rotating reactor was constructed to activate the coal in a carbon dioxide environment at three temperatures. The reaction was started and stopped by switching the gas atmosphere from carbon dioxide to nitrogen. The change in anthracite weight was followed over time, allowing a study of the overall kinetics of the reaction. Samples from the reactor were taken at specific time intervals and surface area was assessed. It was determined that BET and micropore surface areas were functions of conversion and activation temperature. Likewise, for each of the activation temperatures, good control of BET to micropore surface area ratios was demonstrated. Typical BET surface areas of nearly 1000 m2/g were obtained along with the ability to alter the micro-

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and meso-porous structure. Testing of these activated carbons for use in electric double layer capacitors displayed a capacitance of 140 F/g. These results are comparable to other research carbons for this application. Results on the activation of the two anthracite coal samples are reported along with details of the pore development and global kinetics of activation.

07/02139 Effects of pyrolysis temperatures on the microstructure and mechanical properties of 2D-Cf/SiC composites using polycarbosilane Jian, K. et al. Ceramics International, 2007, 33, (1), 73–76. Two-dimensional carbon fibre cloth reinforced silicon carbide (2D-Cf/ SiC) composites were fabricated with polycarbosilane (PCS) and divinylbenzene (DVB) as precursors and SiC as inert fillers. The effects of the pyrolysis temperatures in the first cycle on the microstructure and mechanical properties of Cf/SiC composites were investigated. The results showed that increasing the pyrolysis temperature of the first cycle could weaken the interfacial bonding between carbon fibre and SiC matrix. As a result, the composites fabricated with higher pyrolysis temperature exhibit better mechanical properties. When the pyrolysis temperature of the first cycle was raised from 1000  C to 1600  C, the flexural strength, shear strength and fracture toughness were elevated from 200.7 MPa, 16.8 MPa and 7.4 MPa m1/2 to 319.2 MPa, 29.8 MPa and 15.0 MPa m1/2, respectively.

07/02140 Filtration of fly ash using fluidized bed at 300–500  C Liu, K.-Y. and Wey, M.-Y. Fuel, 2007, 86, (1–2), 161–168. The filtration of the coal-burning fly ash using fluidized beds with silica sand of 770 mm under temperatures of 36, 300, 400, and 500  C was studied. The variations of the outlet concentration and particle size distribution with time were measured to evaluate the dynamic characteristics of the process. Experimental results showed that the overall collection efficiency decayed with the operation time, revealed the effect of the elutriation of fly ash on particle filtration. The collection efficiency rose when the temperature increased from 36 to 500  C. The strong attrition at high temperature released more small particles than that at room temperature, increased the concentration of the particles less than 10 mm (PM10) at high temperature. The removal efficiency of the particles in a size of 4–7 mm, not the submicron particles, is the lowest because they are most easily elutriated from fluidized beds.

07/02141 Hydrogen addition to acetylene–air laminar diffusion flames: studies on soot formation under different flow arrangements Pandey, P. et al. Combustion and Flame, 2007, 148, (4), 249–262. Axisymmetric co-flowing acetylene/air laminar diffusion flames have been experimentally investigated to study the effect of hydrogen addition on soot formation and soot morphology. An acetylene– hydrogen jet burning in co-flowing air at atmospheric pressure has been studied under different flow arrangements, i.e. premixed and with separate addition of acetylene and hydrogen. Thermophoretic sampling and analysis by transmission electron microscopy are employed for soot diagnostics. Soot microstructure, primary particle size, soot volume fraction, and fractal geometry results are reported. The effect of hydrogen addition on the temperature field is moderate (maximum increase 100 K), the effect being greater when hydrogen is premixed with acetylene. Soot volume fraction decreases with hydrogen addition. A shift was noted in the soot volume fraction peak with change in the Reynolds and Froude numbers at the burner exit. The primary soot particle diameter is in the range of 20–35 nm. Soot particles are larger in size close to the burner for the pure acetylene flame. A reverse trend is observed with hydrogen addition. The fractal dimension of the soot aggregates is about 1.7–1.8. It is unaffected by hydrogen addition and location in the flame. Soot aggregate size tends to decrease with hydrogen addition. The results of the present study on the effect of hydrogen addition on soot volume fraction and mean primary particle size are in good correlation with the results of other investigators for ethylene–, propane–, and butane–air flames, which have been described with regard to the HACA mechanism of soot nucleation and growth and enhanced soot oxidation in fuel-rich flames by increased OH radical concentration.

07/02142 Improved sooting tendency measurements for aromatic hydrocarbons and their implications for naphthalene formation pathways McEnally, C. S. and Pfefferle, L. D. Combustion and Flame, 2007, 148, (4), 210–222. Sooting tendencies have been determined for aromatic hydrocarbons using a new definition: the maximum soot volume fraction fv,max measured in a coflow methane/air nonpremixed flame whose fuel is doped with 400 ppm of the test hydrocarbon. These fv,max were converted into apparatus-independent yield sooting indices (YSIs) by the equation YSI=Cfv,max+D, where C and D are apparatus-specific

05 Nuclear fuels (scientific, technical) parameters chosen so that YSI-benzene 30 and YSI-1,2-dihydronaphthalene 100. The dopants were added to the fuel mixture with a syringe pump and fv,max was measured with laser-induced incandescence. YSI was determined for six cycloaliphatics and for 62 aromatics, which included 28 alkylbenzenes, 10 alkenylbenzenes, 10 alkynylbenzenes, 25 multiply substituted benzenes, six two-ring aromatics, and six substituted benzenes with heteroatoms in the side chains. The YSIs correlate well with literature values of threshold sooting index (TSI), which is a more traditional sooting tendency based on the height of pure-fuelled flames at the smoke point. This agreement indicates that fv,max and smoke height are equivalent measures of sooting tendency and that YSI is largely apparatus-independent. However, the YSIs have a total uncertainty of 3%, which is substantially better than the TSIs, and the number of aromatic YSIs reported here is more than double the number of aromatic TSIs in the literature. The YSIs depend strongly on molecular structure; thus they provide information about the chemical kinetic reaction mechanisms responsible for fuel decomposition and hydrocarbon growth from a broad cross section of one-ring aromatics. Important naphthalene formation pathways appear to include acetylene addition to ethynylphenyl, propargyl addition to benzyl, and methyl addition to indenyl. This last pathway is particularly significant because it converts indene quantitatively to naphthalene and because the side chains in many alkenylbenzenes and alkynylbenzenes cyclize to form five-membered rings.

07/02143 Influence of fuel ash composition on high temperature aerosol formation in fixed bed combustion of woody biomass pellets Wiinikka, H. et al. Fuel, 2007, 86, (1–2), 181–193. In this work, the influence of fuel ash composition on high temperature aerosol formation during fixed bed combustion of woody biomass (two wood pellets and one bark pellets) were investigated experimentally in a laboratory reactor and theoretically through chemical equilibrium model calculations. For all fuels, the particle mass size distribution in the PM2.5 region was bimodal, with one fine mode and one coarse mode. Early in the flame, the fine mode was dominated by particles from incomplete combustion and these particles were rapidly oxidized in the post flame zone. After the hot flame, the fine mode concentration and the particle diameter increases gradually when the temperature decreases due to condensation of vaporized inorganic matter, K, Na, S, Cl, and Zn. For two of the fuels also P could be found in the fine particles. The coarse mode consisted of carbon, refractory metals and considerable amount of alkali. Further, the initial fuel alkali concentration and the alkali to silicon ratio (K + Na)/Si influenced the amount of vaporized aerosol forming alkali matter. Finally, the present study shows that, combustion temperature and fuel ash composition is of major importance for the formation of high temperature aerosols in fixed bed combustion of woody biomass pellets.

07/02144 Preparation of modified active carbon from brown coal by ammoxidation Pietrzak, R. et al. Fuel Processing Technology, 2007, 88, (4), 409–415. The technology of obtaining active carbon enriched in nitrogen from brown coal is described. The effect of ammoxidation by a mixture of ammonia and air at the ratio 1:3 at 300 and 350  C, at each stage of the active carbon production has been tested. The amount of nitrogen introduced into the active carbon has been proved to depend on the stage at which ammoxidation was performed. Carbonization and activation with steam of the samples enriched in nitrogen have been found to lead to a significant decrease in its content and to cause an increase in the stability of the nitrogen groups. The ammoxidation of the active carbon has decreased their surface area, while the ammoxidation and high temperature of activation favour the formation of surface oxide groups of basic character.

07/02145 Properties of flash hydrated and agglomerated particles of CFB fly ashes Li, D. et al. Fuel Processing Technology, 2007, 88, (3), 215–220. The fly ash (high carbon content and high unreacted CaO) recirculation in CFB is a typical method to improve the carbon burnout efficiency and the calcium utilization ratio. While the effectiveness of it is limited by the resident time and the reactivity of the re-injected fly ash particles. In the present research, an improved fly ash recirculation method is suggested in which the CFB fly ash is mixed with water or the mixtures of additives (such as waste water of paper mill, cement, sodium silicate, and carbide slag) and water in a blender. Then, this mixture is re-injected into the combustion chamber of CFB by a sludge pump. Because the temperature in CFB is higher, the fly ash was flash hydrated. At the same time, it was dehydrated and agglomerated. The size of agglomerates is bigger than that of original particle and their attrition rate is lower. Therefore the resident time of agglomerates is much longer than that of fine fly ash particles. The absorption of SO2 is higher than that of original particles, too. This results in high carbon burnout efficiency. The hydrated lime also improves the calcium utilization.

07/02146 Quality characteristics of Greek fly ashes and potential uses Skodras, G. et al. Fuel Processing Technology, 2007, 88, (1), 77–85. The main characteristics of fly ash from Greek coal-fired boilers are presented in this paper in relation to its exploitation potential. Both fuel and fly ash samples were collected and analysed according to the ASTM Standards. Apart from the typical analyses (proximate, ultimate, ash analysis and calorific value), an ICP-AES spectrometer was used for the analysis of heavy metals in the ash. Experimental measurements in order to determine the radioactivity content of raw fuel and the fly ash were carried out as well. A representative fly ash sample from Ptolemais power plant was evaluated and tested as filler in self-compacting concrete (SCC). Ashes from the Greek brown coal are classified in type C, most of the fly ash being produced in Ptolemais of Northern Greece, while the rest in Megalopolis. Ptolemais fly ash is rich in calcium compounds, while Megalopolis fly ash contains more pyrite. Increased heavy metal concentrations are observed in the fly ash samples of Greek coal. Greek fly ash appears to have not only pozzolanic but also hydraulic behaviour. Furthermore, Greek fly ash, depending on its origin, may have relatively high natural radioactivity content, reaching in the case of Megalopolis fly ash 1 kBq kg1 of 226 Ra. The laboratory results showed that fly ashes can be a competitive substitute to conventional limestone filler material in SCC. Fly ash is mostly used in Greece in cement industry replacing cement clinker and aiming to the production of special types of Portland cements. However, a more aggressive utilization strategy should be developed, since low quantities of the total produced fly ash are currently further utilized.

07/02147 The evolution of the exhaust diesel soot adsorptive properties after NO2 exposure and according to their SOF content Muller, S. et al. Catalysis Today, 2007, 119, (1–4), 291–294. Several samples of exhaust diesel soot are investigated by inverse gas chromatography and linear solvation energy relationship modelling according to their soluble organic fraction content and their time of exposure in oxidative conditions. The results demonstrate the evolution of the adsorptive properties of the studied materials towards volatile compounds during the oxidation under NO2.

05 NUCLEAR FUELS Scientific, technical 07/02148 A new plastic correction for the stress intensity factor of an under-clad defect in a PWR vessel subjected to a pressurised thermal shock Marie, S. and Ne´de´lec, M. International Journal of Pressure Vessels and Piping, 2007, 84, (3), 159–170. For the assessment of an under-clad defect in a vessel subjected to a cold pressurised thermal shock, plasticity is considered through the amplification  of the elastic stress intensity factor KI in the ferritic part of the vessel. An important effort has been made recently by CEA to improve the analytical tools in the frame of R&D activities funded by IRSN. The current solution in the French RSE-M code has been developed from fitted finite element calculation results. A more physical solution is proposed in this paper. This takes into account two phenomena: the amplification of the elastic KI due to plasticity in the cladding and a plastic zone size correction in the ferritic part. The first correction has been established by representing the cladding plasticity by an imposed displacement on the crack faces at the interface between the cladding and the ferritic vessel. The corresponding elastic stress intensity factor is determined from the elastic plane strain asymptotic solution for the opening displacement. Plasticity in the ferritic steel is considered through a classical plastic zone size correction. The application of the solution to axisymmetric defects is first checked. The case of semi-elliptical defects is also investigated. For the correction determined at the interface between the cladding and the ferritic vessel, an amplification of the correction proposed for the deepest point is determined from a fitting of the 3D finite element calculation results. It is also shown that the proposition of RSE-M, which consists in applying the same  correction at the deepest point and the interface point is not suitable. The applicability to a thermal shock, eventually combined with an internal pressure has been verified. For the deepest point, the proposed correction leads to similar results to the RSE-M method, but presents an extended domain of validity (no limits on the crack length are imposed).

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05 Nuclear fuels (scientific, technical) 07/02149 A statistical method for passive gamma ray tomography of nuclear waste vaults Cattle, B. A. and West, R. M. Annals of Nuclear Energy, 2006, 33, (16), 1297–1308. This paper demonstrates a parameter identification problem encountered in the assay of intermediate-level nuclear waste vaults. A lumped parameter model of the vault contents is employed in which a likely geometry is assumed so as to reduce the number of unknown quantities in the resulting inverse problem. The inverse problem is tackled using Bayesian statistics, and the statistical distributions are sampled using a Markov chain Monte Carlo approach. The Bayesian approach affords flexibility in the specification of prior information: i.e. information that is known in advance of recording any measurements. Two parameterizations of the problem are considered: one involving five parameters and the other involving three parameters. It is shown that in order to obtain a satisfactory solution to the five-parameter problem a very specific type of prior information has to be specified, whereas for the three-parameter problem much less specific prior information is required. The inverse problem of identifying the model parameters in both the three-parameter and five-parameter formulations is solved with limited, but quantifiable precision.

07/02150 A two-dimensional dual-modality tomography technique for a radioactive waste separation process Cattle, B. A. and West, R. M. Annals of Nuclear Energy, 2006, 33, (14– 15), 1236–1244. The monitoring of a waste separation process in the nuclear power industry is considered. Recent advances in gamma ray emission and electrical impedance tomography mean that it is now feasible to unite these two modalities into a novel dual-modality monitoring method. This paper considers a simple model problem for the identification of a boundary between two distinct waste streams in a semi-continuous rotation separator. The simplicity of the problem affords the opportunity to demonstrate the general feasibility of the approach whilst avoiding unnecessary complications.

07/02151 Assessment of on-line burnup monitoring of pebble bed reactor fuel by passive neutron counting Su, B. et al. Progress in Nuclear Energy, 2006, 48, (7), 686–702. Due to the multi-pass fuel circulation design for pebble bed reactors, an on-line measurement system is needed to accurately assess whether a given pebble has reached its end-of-life burnup limit and thereby provide an on-line, automated go/no-go decision on fuel disposition on a pebble-by-pebble basis. Gamma spectrometry has been used for burnup determination of pebble bed reactor fuels. In this work a preliminary investigation was conducted to assess the feasibility of using passive neutron counting techniques to analyse fuel pebbles in real time to provide the speed, accuracy, and burnup range required for burnup determination. Specifically, numerical simulations were performed to study the correlation between passive neutron emission rate of an irradiated pebble and its burnup level, the detectability of passive neutron emission from an irradiated fuel pebble by commonly used neutron detectors, and these detectors’ abilities to discriminate gamma interference. The overall conclusion is that there is an acceptable correlation between burnup and passive neutron emission rate of an irradiated pebble at high-burnup levels; and if the neutron detection system is well designed, passive neutron counting can be used to provide an on-line, go/no-go decision on fuel disposition on a pebbleby-pebble basis for pebble bed reactors.

07/02152 Characterization of simulated burnup fuel by nanoindentation Kurosaki, K. et al. Journal of Nuclear Materials, 2006, 350, (3), 203– 207. A simulated burnup UO2 based fuel (150 GWd/t) was prepared by solid-state reactions. The phase equilibria of the simulated fuel were evaluated by XRD and SEM/EDX analysis. Nanoindentation tests were performed for the simulated fuel at room temperature in air. The modulus and hardness of the matrix phase and oxide precipitates that exit in the simulated fuel were directly evaluated by the nanoindentation.

07/02153 Comparison of MCB and MONTEBURNS Monte Carlo burnup codes on a one-pass deep burn Talamo, A. et al. Annals of Nuclear Energy, 2006, 33, (14–15), 1176– 1188. Numerical applications implemented on the Monte Carlo method have developed in line with the increase of computer power; nowadays, in the field of nuclear reactor physics, it is possible to perform burnup simulations in a detailed 3D geometry and a continuous energy description by the Monte Carlo method; moreover, the required computing time can be abundantly reduced by taking advantage of a computer cluster. In this paper the authors focused on comparing the results of the two major Monte Carlo burnup codes, MONTEBURNS and MCB, when they share the same MCNP geometry, nuclear data

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library, core thermal power, and they apply the same refueling and shuffling schedule. While simulating a total operation time of the gas turbine-modular helium reactor of 2100 effective full power days and a one-pass deep burn in-core fuel management schedule, it was found that the two Monte Carlo codes produce very similar results both on the criticality value of the core and the transmutation of the key actinides.

07/02154 Development of a model to predict fission product behaviour in spherical fuel elements during water ingress events van der Merwe, J. J. and Coetzee, P. P. Nuclear Engineering and Design, 2007, 237, (1), 47–53. At Pebble Bed Modular Reactor (PBMR) gaseous fission product releases from spherical fuel elements under normal conditions are calculated by the code NOBLEG. The ability of NOBLEG to calculate noble gas and halogen release under oxidizing conditions during water ingress was developed. Observations made during the water vapour injection tests performed during the irradiation experiment HFR-K6, were used to determine simple relations that can be used to predict gaseous fission product release from spherical fuel elements under oxidizing conditions caused by small water ingress events, for PBMR operational temperatures. A new model was proposed to explain peculiarities observed during the water injection tests.

07/02155 Magnetothermoelastic interactions in hollow structures of functionally graded material subjected to mechanical loads Dai, H. L. and Fu, Y. M. International Journal of Pressure Vessels and Piping, 2007, 84, (3), 132–138. This paper considers the magnetothermoelastic problem of functionally graded material (FGM) hollow structures subjected to mechanical loads. Exact solutions for stresses and perturbations of the magnetic field vector in FGM hollow cylIndexrs and FGM hollow spheres are determined using the infinitesimal theory of magnetothermoelasticity. The material stiffness, thermal expansion coefficient and magnetic permeability are assumed to obey the same simple power-law variation through the structures’ wall thickness. The aim of this research is to understand the effect of composition on magneto-thermoelastic stresses and to design optimum FGM hollow cylinders and hollow spheres.

07/02156 Neutron flux optimization in irradiation channels at NUR research reactor Meftah, B. et al. Annals of Nuclear Energy, 2006, 33, (14–15), 1164– 1175. Optimization of neutron fluxes in experimental channels is of great concern in research reactor utilization. The general approach used at the NUR research reactor for neutron flux optimization in irradiation channels is presented. The approach is essentially based upon a judicious optimization of the core configuration combined with the improvement of reflector characteristics. The method allowed the increase of thermal neutron flux for radioisotope production purposes by more than 800%. Increases of up to 60% are also observed in levels of useful fluxes available for neutron diffraction experiments (small angle neutron scattering, neutron reflectometry, etc.). Such improvements in the neutronic characteristics of the NUR reactor opened new perspectives in terms of its utilization. More particularly, it is now possible to produce at industrial scales major radio-isotopes for medicine and industry and to perform, for the first time, material testing experiments. The cost of the irradiations in the optimized configuration is generally small when compared to those performed in the old configuration and an average reduction factor of about of 10 is expected in the case of production of molybdenum-99 (isotope required for the manufacturing of technetium-99 medical kits). In addition to these important results, safety analysis studies showed that the more symmetrical nature of the core geometry leads to a more adequately balanced reactivity control system and contributes quite efficiently to the operational safety of the NUR reactor. Results of comparisons between calculations and measurements for a series of parameters of importance in reactor operation and safety showed good agreement.

07/02157 On TiN-particle fuel based helium-cooled transmutation systems Westle´n, D. and Wallenius, J. Annals of Nuclear Energy, 2006, 33, (16), 1322–1328. The authors have designed a sub-critical helium-cooled core with TiNcoated particle fuel, dedicated to the transmutation of minor actinides. The excellent neutronic properties of helium allows for a low plutonium fraction in the fuel, which yields a low reactivity swing,
k = 2600 pcm, for a burnup of 31.2%. Further the neutron spectrum is hard, limiting the buildup of Cm and Cf. The high burnup combined with a minor actinide burning rate of 355 kg/GWth year makes the present design an attractive transmutation system.

05 Nuclear fuels (economics, policy, supplies, forecasts) 07/02158 Reactivity feedback and control margins in natural uranium fueled and heavy water moderated nuclear research reactors Khan, M. J. et al. Progress in Nuclear Energy, 2006, 48, (7), 647–654. Three-dimensional neutronics analyses were performed to find the reactivity feedback coefficients and control margins under normal and presumed accidental conditions for the novel proliferation resistant, safer and economical natural uranium fueled and heavy water moderated nuclear research reactor cores. The results were compared with the reference core similar in design to National Experimental Reactor (NRX) and Canadian Indian Reactor (CIR). Standard reactor physics simulation codes WIMS-D/4 and CITATION were employed for this study. It was found that as opposed to the reference design, the new proposed cores are inherently stable as far as temperature reactivity feedback is concerned. Voids formation (loss of coolant) adds positive reactivity in all the cores. However, in the case of proposed cores, the reactivity added would be about 10% of that added in the reference core for loss of a given fraction of coolant. Moreover, as opposed to the NRX/CIR core, the shut-off rods, under the one stuck rod criterion, can shutdown and maintain the proposed cores subcritical in the accidental conditions.

07/02159 Spatial and model-order based reactor signal analysis methodology for BWR core stability evaluation Dokhane, A. et al. Annals of Nuclear Energy, 2006, 33, (16), 1329–1338. A new methodology for the boiling water reactor core stability evaluation from measured noise signals has been recently developed and adopted at the Paul Scherrer Institut (PSI). This methodology consists in a general reactor noise analysis where as much as possible information recorded during the tests is investigated prior to determining core representative stability parameters, i.e. the decay ratio (DR) and the resonance frequency, along with an associated estimate of the uncertainty range. A central part in this approach is that the evaluation of the core stability parameters is performed not only for a few but for all recorded neutron flux signals, allowing thereby the assessment of signal-related uncertainties. In addition, for each signal, three different model-order optimization methods are systematically employed to take into account the sensitivity upon the modelorder. The current methodology is then applied to the evaluation of the core stability measurements performed at the Leibstadt NPP, Switzerland, during cycles 10, 13 and 19. The results show that as the core becomes very stable, the method-related uncertainty becomes the major contributor to the overall uncertainty range while for intermediate DR values, the signal-related uncertainty becomes dominant. However, as the core stability deteriorates, the method-related and signal-related spreads have similar contributions to the overall uncertainty, and both are found to be small. The PSI methodology identifies the origin of the different contributions to the uncertainty. Furthermore, in order to assess the results obtained with the current methodology, a comparative study is for completeness carried out with respect to results from previously developed and applied procedures. The results show a good agreement between the current method and the other methods.

07/02160

Study on behavior of tritium in concrete wall

Furuichi, K. et al. Journal of Nuclear Materials, 2006, 350, (3), 246–253. It is required to understand the tritium behaviour in concrete for establishment of tritium safety technology of a fusion reactor or a tritium handling facility because the concrete wall is used as the final containment to prevent tritium release to the environment. This paper discusses about the effect of adsorption and diffusion of water and isotope exchange reaction between physically adsorbed water and chemically adsorbed water or structural water. It is known in this study that a large amount of tritium can be trapped to the concrete wall because cement paste has the nature of porous hydrophilic material.

07/02161 The development of a stress analysis code for nuclear graphite components in gas-cooled reactors Tsang, D. K. L. and Marsden, B. J. Journal of Nuclear Materials, 2006, 350, (3), 208–220. Most of the UK nuclear power reactors are gas-cooled and graphite moderated. As well as acting as a moderator the graphite also acts as a structural component providing channels for the coolant gas and control rods. For this reason the structural integrity assessments of nuclear graphite components is an essential element of reactor design. In order to perform graphite component stress analysis, the definition of the constitutive equation relating stress and strain for irradiated graphite is required. Apart from the usual elastic and thermal strains, irradiated graphite components are subject to additional strains due to fast neutron irradiation and radiolytic oxidation. In this paper a material model for nuclear graphite is presented along with an example of a stress analysis of a nuclear graphite moderator brick subject to both fast neutron irradiation and radiolytic oxidation.

07/02162 The study on the hydraulic control rod driving system in cyclical swing Zheng, Y. et al. Nuclear Engineering and Design, 2007, 237, (1), 100– 106. This paper discusses the behaviour of the hydraulic control rod driving system (HCRDS) in cyclical swing. The first generation HCRDS with the hole–hole step cylinder, the important driving component, has been applied in 5 MW nuclear heating reactors for several years and run well all along. The second generation with the chamfer-hole step cylinder has also been developed and studied. The HCRDS working principle, as well as the particular design of the hole–hole step cylinder, has been introduced in the paper. The control rod (CR) behaviour when HCDRS vacillating in certain swing and cycle has been analysed subsequently. The calculating result indicates that the CR can keep its balance in such unstable state and the operation of driving CR upwards or downwards can function properly likewise. In cyclical swing, the CR can drop down quickly and meet the reactor shut-down needs. The theoretical analysis proves the HCRDS reliable and safe, establishing basement for its further research and wide use.

07/02163 The thorium molten salt reactor: moving on from the MSBR Mathieu, L. et al. Progress in Nuclear Energy, 2006, 48, (7), 664–679. A re-evaluation of the molten salt breeder reactor (MSBR) concept has revealed problems related to its safety and to the complexity of the reprocessing considered. A reflection is carried out anew in view of finding innovative solutions leading to the thorium molten salt reactor concept. Several main constraints are established and serve as guides to parametric evaluations. These then give an understanding of the influence of important core parameters on the reactor’s operation. The aim of this paper is to discuss this vast research domain and to single out the molten salt reactor configurations that deserve further evaluation.

07/02164 Ultrasonic measurements for in-service assessment of wrought Inconel 625 cracker tubes of heavy water plants Kumar, A. et al. Journal of Nuclear Materials, 2006, 350, (3), 284–292. The degradation in mechanical properties of Inconel 625 ammonia cracker tubes occurs during the service for long duration in heavy water plants. The present study brings out the possibility of using Poisson’s ratio (derived from measurement of time of flight of ultrasonic waves) in combination with hardness measurements, as an effective nondestructive tool for assessment of in-service degradation of Inconel 625 cracker tubes and qualification of re-solution annealing heat treatment for their rejuvenation. Further, the study also indicates the feasibility of extending the life of some of the tubes beyond the presently followed 120,000 h, before they are taken up for re-solution annealing, without affecting their serviceability. However, further studies are required to identify quantitative criterion for Poisson’s ratio and hardness values, for deciding on the basis for removal of the tubes for rejuvenation.

07/02165 Verification of NETFLOW code using plant data of sodium cooled reactor and facility Mochizuki, H. Nuclear Engineering and Design, 2007, 237, (1), 87–93. The plant simulation code NETFLOW on PC applicable to the liquidmetal cooled reactors has been developed on the basis of the models developed for single-phase and two-phase light water flow systems. The functions of this code have been verified by individual tests for light water flow systems and a sodium flow system. In order to apply this code to a sodium cooled fast reactor, several extra functions were verified using the plant data obtained using 50 MW steam generators and the Monju fast breeder reactor. Finally, the turbine trip transient of the Monju was simulated and the result was compared with the measured plant data. Good agreements were obtained in these verifications. As a result of the present study, the code can be applied as an education tool for students.

Economics, policy, supplies, forecasts 07/02166 Adaptive fuzzy system for degradation study in nuclear power plants’ passive components Guimara˜es, A. C. F. et al. Progress in Nuclear Energy, 2006, 48, (7), 655–663. This paper presents a preliminary study on the use of adaptive neural fuzzy inference system (ANFIS) to determine the fragility curves in degraded nuclear power plant passive components. The goal of this approach is to allow the direct association, using a mapping of input/ output patterns, between measurable beam deflections and the structure probability of failure for a severe degradation condition. The present study consists of an artificial intelligence framework

Fuel and Energy Abstracts September 2007 329

06 Electrical power supply and utilization (scientific, technical) application considering the information obtained from an original Nuclear Regulatory Commission research program. The results indicate that the ANFIS modelling is a promising alternative to traditional approach in nuclear studies of structure degradation in passive components.

07/02167 Advanced qualification process of ANAV NPP integral dynamic models for supporting plant operation and control Revento´ s, F. et al. Nuclear Engineering and Design, 2007, 237, (1), 54– 63. Extensive technical literature exists aimed at establishing the requirements needed to qualify a nuclear power plant model. Most of this literature is focused on qualifying a model for licensing uses. Less documentation is available nowadays on the requirements needed when an integral plant model is used for supporting plant operation and control of an actual commercial facility, while fulfiling its goals of safety and competitiveness. For the last 15 years the Technical University of Catalonia has been working in this field along with Asociacio ´ n Nuclear Asco´ –Vandello` s, which is a utility that presently runs three operating PWRs. The paper develops an advanced qualification process of plant models for operation support, introduces the concept of plant configuration and explains how this activity complements other usual validation tasks.

07/02168 Determination of acceptable operating cost level of nuclear energy for Turkey’s power system Yildirim, M. and Erkan, K. Energy, 2007, 32, (2), 128–136. Generally, it is very difficult to assess the true operating cost of an electrical power unit in the countries where there is little or no operational experience. Since Turkey has no experience on operating a nuclear unit, operating costs of a nuclear unit is uncertain for use in generation expansion planning. Furthermore, there is a disagreement of whether it is cheap or not. In this study, an acceptable level of operating cost of nuclear units is determined for Turkey’s power system. It is aimed to find a numerical value for nuclear operating cost at which nuclear is able to compete with other energy sources. Seven types of units are chosen as candidate units to the power system. Mixed-integer programming is used as a mathematical model of generation expansion planning. The model consists of the cost function that minimizes the construction and operating costs and the reliability constraints. Adaptive simulated annealing genetic algorithm is used for optimization algorithm to determine the types, times, and number of candidate units which meet forecasted demand within a pre-specified reliability criterion over the planning horizon from 2006 to 2025. In the case studies, a high level of nuclear energy operating cost is taken and then the cost is gradually lowered. Optimizations are made for each level of nuclear operating costs within four different scenarios and the quantities of nuclear capacity selected by optimizations are recorded. It is determined that, nuclear energy is able to compete with other energy sources when the operating cost is less than 210$/kWh yr or 2.4 cents/kWh.

07/02169 for Fe

This study analyses the availability and reliability of a high-performance linac (linear accelerator) conceived for accelerator-driven systems. The lack of a well-established component database has been pointed out as the main issue related to the accelerator reliability assessment. The results, affected by the conservative character of the study, show a high margin for the improvement in terms of accelerator reliability and availability figures prediction. The paper outlines the viable path towards the accelerator reliability and availability enhancement process and delineates the most proper strategies. The improvement in the reliability characteristics along this path is shown as well.

07/02171 Safety culture enhancement through the implementation of IAEA guidelines Mengolini, A. and Debarberis, L. Reliability Engineering & System Safety, 2007, 92, (4), 520–529. This paper presents the methodology applied and the results achieved in adapting and implementing the International Atomic Energy Agency (IAEA) guidelines on safety culture to a research reactor as a step towards supporting its life management program. The background is presented together with the effort undertaken to develop awareness on safety culture and the enhancement programme hereafter developed. The present study shows how issues of safety culture, management awareness and commitment deserve attention and can be of fundamental relevance also for research reactors. The study presents how guidelines developed specifically for nuclear power installations can be adapted to meet the needs and peculiarities of other nuclear installations. Moreover, the difficulties met during the implementation of the guidelines are discussed and important information and lessons can be learnt for the nuclear industry in general.

07/02172 Variations of a passive safety containment for a BWR with active and passive safety systems Sato, T. and Kojima, Y. Nuclear Engineering and Design, 2007, 237, (1), 74–86. The paper presents variations of a certain passive safety containment for a near future boiling water reactor (BWR). It is tentatively named Mark S containment in the paper and uses the operating dome as the upper secondary containment vessel (USCV) to where the pressure of the primary containment vessel (PCV) can be released through the upper vent pipes. One of the merits of the Mark S containment is very low peak pressure at severe accidents without venting the containment atmosphere to the environment. Another merit is the capability to submerge the PCV and the reactor pressure vessel above the core level by flooding water from the gravity-driven cooling system pool and the upper pool. The third merit is robustness against external events such as a large commercial airplane crash owing to the reinforced concrete USCV. The Mark S containment is applicable to a large reactor that generates 1830 MW electric power. The paper presents several examples of BWRs that use the Mark S containment. In those examples active safety systems and passive safety systems function independently and constitute in-depth hybrid safety (IDHS). The concept of the IDHS is also presented in the paper.

New intermediate-energy nuclear data libraries

Duijvestijn, M. C. and Koning, A. J. Annals of Nuclear Energy, 2006, 33, (14–15), 1196–1226. New ENDF-6 formatted nuclear data libraries are presented for 54Fe, 56 Fe, 57Fe, and 58Fe, for incident neutrons and protons between 0 and 200 MeV. The main objective of this work is to provide a comprehensive and improved description of all nuclear processes in the intermediate-energy range. This is accomplished by means of computational analyses carried out with the nuclear model code TALYS. Apart from the resonance range, which the authors have adopted from the best available source in existing libraries, the nuclear data files for the less abundant iron isotopes, 54Fe, 57Fe, and 58Fe, are completely new in the whole energy range. The new data library for 56Fe is based entirely on the existing JEFF-3.0 library below 20 MeV and extended with TALYS results up to 200 MeV. The most important nuclear reaction models needed for the data files are described. A consistent method was used to store the data in ENDF-6 format, including cross sections, angular distributions, double-differential spectra, discrete and continuum photon production cross sections, and residual production (activation) cross sections including isomers. It is shown that the data present in the libraries give a good agreement with existing basic experimental data. Moreover, the authors have validated the new libraries with a shielding benchmark.

07/02170 Reliability studies of a high-power proton accelerator for accelerator-driven system applications for nuclear waste transmutation Burgazzi, L. and Pierini, P. Reliability Engineering & System Safety, 2007, 92, (4), 449–463.

330 Fuel and Energy Abstracts September 2007

06 ELECTRICAL POWER SUPPLY AND UTILIZATION Scientific, technical 07/02173 A comprehensive method for break points finding based on expert system for protection coordination in power systems Abyaneh, H. A. et al. Electric Power Systems Research, 2007, 77, (5–6), 660–672. Interconnected power systems are multi-loop structured. In such networks, the determination of settings for all overcurrent relays can be carried out in different forms and may be quite complicated. The main problem for coordination is the determination of starting points, i.e. the location of starting relays in the procedure for settings, which is referred to as break points. In this paper, a powerful approach based on expert system is applied. The rules of the expert system include network configuration, protection systems, fault levels, etc. The method is applied to two networks with different configurations, pilot

06 Electrical power supply and utilization (scientific, technical) protection and other protection systems. From the obtained results, it is reviled that the new method is efficient, accurate, comprehensive and more optimal than the previously used graph theory.

07/02174 A new look at component maintenance practices and their effect on customer, station and system reliability Kalinowski, B. and Anders, G. International Journal of Electrical Power & Energy Systems, 2006, 28, (10), 679–695. This paper introduces a new concept in the analysis of the effect of changes in maintenance policies on component, delivery point and bulk electric system reliability and associated costs. In the new approach several different analysis methods are combined, allowing for a comprehensive look at the effect of maintenance and reliability issues. This approach has been made possible by a development of a computer platform, which seamlessly links several complex computer programs. The concepts of the new approach and the implementation of the computer platform are presented in this paper. A numerical example illustrating implementation of these concepts is also presented.

07/02175 Case study of HTS resistive superconducting fault current limiter in electrical distribution systems Ye, L. and Campbell, A. M. Electric Power Systems Research, 2007, 77, (5–6), 534–539. As electric power systems grow and become more interconnected, the fault current levels increase. Superconducting fault current limiters (SFCL) can limit the prospective short-circuit currents to lower levels, so that the underrated switchgears can be operated safely. In order to introduce SFCL into the electric power system, we need a way to conveniently predict the limiting characteristics in a given situation. We have developed an electromagnetic transient program (EMTP) model of high temperature resistive type SFCL based on the electric field (E)– current density (J) characteristic of the superconductor. The SFCL in series with a circuit breaker could be practically used in electrical distribution systems. Case studies of EMTP simulations show that the SFCL cannot only limit the fault current to an acceptable value, but also reduce voltage decrease and the rise rate of the transient recovery voltage. In order to ensure the safe and proper usage of SFCL, some future considerations on the interaction between SFCL and power systems are presented as well.

07/02176 Exergy analysis of a coal-based 210 MW thermal power plant Sengupta, S. et al. International Journal of Energy Research, 2007, 31, (1), 14–28. In the present work, exergy analysis of a coal-based thermal power plant is done using the design data from a 210 MW thermal power plant under operation in India. The entire plant cycle is split up into three zones for the analysis: (1) only the turbo-generator with its inlets and outlets, (2) turbo-generator, condenser, feed pumps and the regenerative heaters, (3) the entire cycle with boiler, turbo-generator, condenser, feed pumps, regenerative heaters and the plant auxiliaries. It helps to find out the contributions of different parts of the plant towards exergy destruction. The exergy efficiency is calculated using the operating data from the plant at different conditions, namely, at different loads, different condenser pressures, with and without regenerative heaters and with different settings of the turbine governing. The load variation is studied with the data at 100, 75, 60 and 40% of full load. Effects of two different condenser pressures, i.e. 76 and 89 mmHg (abs.), are studied. Effect of regeneration on exergy efficiency is studied by successively removing the high-pressure regenerative heaters out of operation. The turbine governing system has been kept at constant pressure and sliding pressure modes to study their effects. It is observed that the major source of irreversibility in the power cycle is the boiler, which contributes to an exergy destruction of the order of 60%. Part load operation increases the irreversibilities in the cycle and the effect is more pronounced with the reduction of the load. Increase in the condenser back pressure decreases the exergy efficiency. Successive withdrawal of the high pressure heaters show a gradual increment in the exergy efficiency for the control volume excluding the boiler, while a decrease in exergy efficiency when the whole plant including the boiler is considered. Keeping the main steam pressure before the turbine control valves in sliding mode improves the exergy efficiencies in case of part load operation.

07/02177 High efficiency electric power generation: the environmental role Bee´r, J. M. Progress in Energy and Combustion Science, 2007, 33, (2), 107–134. Electric power generation system development is reviewed with special attention to plant efficiency. It is generally understood that efficiency improvement that is consistent with high plant reliability and low cost of electricity is economically beneficial, but its effect upon reduction of all plant emissions without installation of additional environmental equipment, is less well appreciated. As CO2 emission control is gaining increasing acceptance, efficiency improvement, as the only practical

tool capable of reducing CO2 emission from fossil fuel plant in the short term, has become a key concept for the choice of technology for new plant and upgrades of existing plant. Efficiency is also important for longer-term solutions of reducing CO2 emission by carbon capture and sequestration (CCS); it is essential for the underlying plants to be highly efficient so as to mitigate the energy penalty of CCS technology application. Power generating options, including coal-fired Rankine cycle steam plants with advanced steam parameters, natural gas-fired gas turbine-steam, and coal gasification combined cycle plants are discussed and compared for their efficiency, cost and operational availability. Special attention is paid to the timeline of the various technologies for their development, demonstration and commercial availability for deployment.

07/02178 Impacts of the SSSC control modes on small-signal and transient stability of a power system Castro, M. S. et al. Electric Power Systems Research, 2007, 77, (1), 1–9. In order to accomplish specific compensation objectives a static synchronous series compensator (SSSC) may be controlled by several ways. The most common control modes of the SSSC are: (1) constant voltage mode, (2) constant impedance emulation mode, and (3) constant power control mode. Moreover, to improve the dynamic performance of the system, a SSSC may be equipped with supplementary controllers, such as damping controls. Therefore, this paper investigates the impacts of different SSSC control modes on smallsignal and transient stability of a power system. The performance of different input signals to the power oscillation damping controller is also assessed. The stability analysis and the design of the SSSC controllers are based on modal analysis, non-linear simulations, pole placement technique, and time and frequency response techniques. The results obtained allow to conclude that the usage of the SSSC in the constant impedance emulation mode is the most beneficial strategy to improve both the small-signal and transient stability.

07/02179 Incorporating stress in electric power systems reliability models Zerriffi, H. et al. Energy Policy, 2007, 35, (1), 61–75. Electric power systems can be disrupted by a variety of circumstances impacting failure and recovery rates. However, conflict-induced stress, primary fuel supply disruptions, and impediments to repair have rarely been incorporated into a systematic analysis of power planning and dispatch. In this paper, the traditional Monte-Carlo reliability modelling framework is augmented to also represent primary fuel delivery and distributed generation (DG) topologies. The authors characterize five failure modes for the integrated system and compare the performance of centralized to DG systems under various levels of stress including conflict-induced stress. The findings show DG to be significantly more reliable than centralized systems and when wholeeconomy costs are considered they are also more economical. These findings are significant in power planning for areas concerned about conflict-induced stress or where other factors may impact reliability of supply to a far greater extent than has been the norm in OECD countries.

07/02180

On the size effect in PAFC grid-connected plant

Bizzarri, G. Applied Thermal Engineering, 2006, 26, (10), 1001–1007. This article is the final part of a research project aimed at exploring the potential of energy retrofit through fuel cell hybrid plants. If previous papers revealed the considerable environmental benefits in terms of primary energy saving and pollutant emission reduction that could be achieved by such a shift, they also demonstrated that these plants are feasible only when appropriate financial incentives are given. The identification of the best PAFC plant size thus represents a key target resulting in significant economic savings. Therefore, in this paper, several hybrid scenarios are investigated, taking nine hospitals of Ferrara province (Italy) as the study sample. Investigations reveal that the more the proper sizing is carried out in search of the highest environmental and energy benefits, the higher the financial returns will be. The knowledge of this size effect could be adopted as a useful design guideline and can be taken as a first criterion for the adoption of these systems. A first methodology for the proper sizing of fuel cell plants is suggested.

07/02181 On the use of continuous-wavelet transform for fault location in distribution power systems Borghetti, A. et al. International Journal of Electrical Power & Energy Systems, 2006, 28, (9), 608–617. The paper illustrates a procedure based on the continuous-wavelet transform (CWT) for the analysis of voltage transients due to line faults, and discusses its application to fault location in power distribution systems. The analysis carried out shows that correlation exists between typical frequencies of the CWT-transformed signals and specific paths in the network covered by the traveling waves originated by the fault. The paper presents a procedure for determining fault location in MV distribution systems, which exploits the above-

Fuel and Energy Abstracts September 2007 331

06 Electrical power supply and utilization (economics, policy, supplies, forecasts) mentioned correlation. The MV distribution system analysed in the paper is accurately represented by means of an EMTP model; various fault types and network characteristics are examined. The paper presents also the basic concepts of a measurement and fault location prototype system with distributed architecture.

07/02182 Optimization of a wind-power fuel-cell hybrid system in an autonomous electrical network environment Kasseris, E. et al. Renewable Energy, 2007, 32, (1), 57–79. Stability considerations associated with intermittency prevent high wind energy penetration in small electrical networks. The case of the islands of the Aegean is presented, which proposed a wind turbine(WT)–fuel-cell hybrid as a means to store wind energy and increase penetration in these islands. The effect of network restraints was, however, not included in that study. Simulation results including network restrictions prove that when network restrictions are relatively ‘strict’, hybridizing a WT using the scheme presented in the same paper will indeed increase the WT’s energy output. However, in the case of ‘lenient’ network restrictions, that hybridization scheme will in fact decrease the WT’s energy output. Moreover, the system configurations presented that paper could not achieve financial viability at current electricity prices due to high capital costs. Two alternative operating principles for the hybrid system are presented in this study. These operating principles significantly improve the hybrid system’s energy performance even under ‘lenient’ network restrictions. In some cases, these operating principles manage to yield hybrid systems that are financially viable assuming current electricity prices.

07/02183 Performance characteristics and modelling of a micro gas turbine for their integration with thermally activated cooling technologies Vidal, A. et al. International Journal of Energy Research, 2007, 31, (2), 119–134. The authors have developed a simple model of a micro gas turbine system operating at high ambient temperatures and characterized its performance with a view to integrating this system with thermally activated cooling technologies. To develop and validate this model, the authors used experimental data from the micro gas turbine test facility of the CREVER research centre. The microturbine components were modelled and the thermodynamic properties of air and combustion gases were estimated using a commercial process simulator. Important information such as net output power, microturbine fuel consumption and exhaust gas mass flow rate can be obtained with the empirical correlations developed in this study. This information can be useful for design exhaust gas fired absorption chillers.

The operating point of a photovoltaic generator that is connected to a load is determined by the intersection point of its characteristic curves. In general, this point is not the same as the generator’s maximum power point. This difference means losses in the system performance. DC/DC converters together with maximum power point tracking systems are used to avoid these losses. Different algorithms have been proposed for maximum power point tracking. Nevertheless, the choice of the configuration of the right converter has not been studied so widely, although this choice, as demonstrated in this work, has an important influence in the optimum performance of the photovoltaic system. In this article, the authors conduct a study of the three basic topologies of DC/DC converters with resistive load connected to photovoltaic modules. This article demonstrates that there is a limitation in the system’s performance according to the type of converter used. Two fundamental conclusions are derived from this study: (1) the buck–boost DC/DC converter topology is the only one which allows the follow-up of the PV module maximum power point regardless of temperature, irradiance and connected load and (2) the connection of a buck–boost DC/DC converter in a photovoltaic facility to the panel output could be a good practice to improve performance.

07/02187 Transient changes in the power output from the concentration difference cell (dialytic battery) between seawater and river water Suda, F. et al. Energy, 2007, 32, (2), 165–173. Experimental study on the concentration difference cell between seawater and river water (dialytic battery) has been made with special attention to the transient change in the power output. The cell consists of 59 compartments made with 29 ion-exchange membrane pairs, each of which has an effective area of 80 cm2 per sheet. It has been found that the voltage drop across the load decreases exponentially with two different short and long time constants, of which values are about 50 and 800 s, respectively. Accordingly the power also decreased to about one fourth (from 259 to 68.9 mW/m2 pair) after sufficient time passed. These transient behaviours have been successfully interpreted by the capacitor-type equivalent circuit model. From comparisons between the experimental and the model results, values of the internal resistance and two kinds of capacitor were determined, of which values were 114 , 1.35 and 66.4 F, respectively. It was suggested that the short and long time constants came from charge double layers formed at the cathode and the anode, respectively. Measurements of potential difference between saline water compartments in the case with and without external current by reference electrodes showed that voltage losses occurred due to the concentration polarization near the ion-exchange membranes and the activation polarization at the electrode surfaces.

07/02184 State enumeration technique combined with a labeling bus set approach for reliability evaluation of substation configuration in power systems Lu, J. et al. Electric Power Systems Research, 2007, 77, (5–6), 401–406. The paper presents a network state enumeration technique combined with a labeling bus set approach for reliability evaluation of substation configuration in power systems. The presented method is easy to handle dependent failures, multiple failure modes and multiple states of components. Another merit is that network failure states enumerated are mutually exclusive and therefore avoid complex calculations associated with union and intersections which have to be conducted in the minimum cut set method. The basic procedure of the labelling bus set approach for identifying a network failure state is explained using a substation configuration with protection action and operational switching. An example of a substation layout is given to demonstrate effectiveness of the proposed method.

07/02185 The design and cost analysis of a portable PEMFC UPS system Chang, H.-P. et al. International Journal of Hydrogen Energy, 2007, 32, (3), 316–322. This paper describes the development, assembly, and test of a portable PEMFC UPS system (CSIST-50–01). CSIST-50–01 is a fuel cell power generator with a dc/dc converter to supply a clean, stable, and high quality power at 20 Vdc. Under dry H2/air operating condition, the peak power output is about 80 W at 20 V, and maximum system efficiency is about 30% at 60 W. CSIST-50–01 could function as an uninterruptible power supply (UPS) to be a power generator to prevent electronic devices from power interruption. Performance evaluation proves that CSIST-50–01 has fast power responses. CSIST-50–01 costs US$2739–2779, which could be reduced by mass production. Finally, the system characteristics and specifications are compared with other similar systems such as PowerPEM1PS-250 (PlugPower), and A-500 (Phoenixtec power).

07/02186 Theoretical assessment of the maximum power point tracking efficiency of photovoltaic facilities with different converter topologies Enrique, J. M. et al. Solar Energy, 2007, 81, (1), 31–38.

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Economics, policy, supplies, forecasts 07/02188 A comparison of Nash equilibria analysis and agent-based modelling for power markets Krause, T. et al. International Journal of Electrical Power & Energy Systems, 2006, 28, (9), 599–607. In this paper, Nash equilibria analysis and agent-based modelling are compared for assessing the market dynamics of network-constrained pool markets. Power suppliers submit their bids to the market place in order to maximize their payoffs, where reinforcement learning is applied as a behavioural agent model. The market clearing mechanism is based on the locational marginal pricing scheme. Simulations are carried out on a benchmark power system. The authors show how the evolution of the agent-based approach relates to the existence of a unique Nash equilibrium or multiple equilibria in the system. Additionally, the parameter sensitivity of the results is discussed.

07/02189 A proposal for investment recovery of FACTS devices in deregulated electricity markets Mithulananthan, N. and Acharya, N. Electric Power Systems Research, 2007, 77, (5–6), 695–703. The paper presents a methodology to quantify the benefits, in terms of monetary values, of FACTS devices when used in deregulated electricity market for congestion management. The proposed methodology is used in the proposal for investment recovery of FACTS devices. Despite the long history of development and mature technology, the practical installations of FACTS devices are still limited. The main reasons for few installations are high investment cost and lack of viable measures to quantify the long list of benefits offered by FACTS device. In this respect, the methodology proposed in the paper provides a promising solution. The proposed methodology is based on establishing pricing schemes with and without FACTS devices using OPF formulation. The volume of market with FACTS devices and the increase in surplus due to them forms the basis of quantifying

06 Electrical power supply and utilization (economics, policy, supplies, forecasts) their benefits. The pricing scheme does not destroy the incentive effect in short run and also makes possible the provision of merchant FACTS. The proposed concept was tested and validated with TCSC in five-bus test system. Result shows that, when TCSC is used to relieve congestion in the system and the investment on TCSC can be recovered.

07/02190 An economic evaluation for an autonomous Indexpendent network of distributed energy resources Zoka, Y. et al. Electric Power Systems Research, 2007, 77, (7), 831–838. This paper proposes a method for the economic evaluation of an autonomous Indexpendent network of distributed energy resources. There are existing proposals for such networks; the system that we are proposing and analysing in this study is called microgrid. Microgrid is a new framework of power delivery system that is formed by small, modular generation systems connected to each other to create a small autonomous grid. This paper estimates the total costs to consumers in a microgrid with optimized operation of distributed generators and energy storage systems. This estimation includes not only installation and operation costs but also the additional expenses to construct the microgrid itself. In addition, power interruption costs are also taken into account to consider the reliability enhancement created by the microgrid. The paper attempts to determine whether or not it is economical for consumers to form this kind of autonomous independent network.

07/02191 An empirical analysis of electricity consumption in Cyprus Zachariadis, T. and Pashourtidou, N. Energy Economics, 2007, 29, (2), 183–198. The paper presents the first empirical analysis of electricity consumption in Cyprus. Using annual data from 1960 to 2004, the authors have examined electricity use in the residential and the services sectors, which are the fastest-growing electricity consumers in the island, and its interaction with income, prices and the weather. The analysis was performed with the aid of time series analysis techniques such as unit root tests with and without a structural break in levels, cointegration tests, vector error correction models, Granger causality tests and impulse response functions. Results show long-term elasticities of electricity use above unity for income, and of the order of 0.3 to 0.4 for prices. In the short-term electricity consumption is rather inelastic, mostly affected by weather fluctuations. Granger causality tests confirm exogeneity of electricity prices and bidirectional causality between residential electricity consumption and private income. The commercial sector is less elastic and reverts faster to equilibrium than the residential sector. Despite the relatively small sample size, results reported here are quite robust and can be used for forecasts and policy analyses.

07/02192

Asset management techniques

Schneider, J. et al. International Journal of Electrical Power & Energy Systems, 2006, 28, (9), 643–654. Deregulation and an increasing competition in electricity markets urge energy suppliers to optimize the utilization of their equipment, focusing on technical and cost-effective aspects. As a respond to these requirements utilities introduce methods formerly used by investment managers or insurance companies. The article describes the usage of these methods, particularly with regard to asset management and risk management within electrical grids. The essential information needed to set up an appropriate asset management system and differences between asset management systems in transmission and distribution systems are discussed. The bulk of costs in electrical grids can be found in costs for maintenance and capital depreciation. A comprehensive approach for an asset management in transmission systems thus focuses on the ‘life-cycle costs’ of the individual equipment. The objective of the life management process is the optimal utilization of the remaining life time regarding a given reliability of service and a constant distribution of costs for reinvestment and maintenance ensuring a suitable return. In distribution systems the high number of components would require an enormous effort for the consideration of single individuals. Therefore statistical approaches have been used successfully in practical applications. Newest insights gained by a German research project on asset management systems in distribution grids give an outlook to future developments.

07/02193 Component criticality importance measures for the power industry Espiritu, J. F. et al. Electric Power Systems Research, 2007, 77, (5–6), 407–420. New reliability importance measures have been developed for the power industry to be applied for electricity transmission systems (ETS). Reliability criticality measures are useful metrics to rank components regarding their impact on system performance. Criticality measures serve as useful tools to prioritize reliability improvement activities, identify weak-links in the system and many other uses. These proposed measures pertain to the outage rate of the system and component

instead of the probability of failure or survival for a defined mission time. Outage rate is the best suited and appropriate output variable to evaluate the importance of the components in the electricity distribution system. The ETS is the component of the bulk transmission system to provide electricity to large municipalities, large industrial customers and the retail distribution system. The ETS is composed mainly of components such as lines, transformers, breakers and buses. All these components are interconnected with the aim of transporting electrical energy from the bulk transmission system to various load points. The new criticality measures are demonstrated on some commonly used electrical configurations, such as, breaker-and-ahalf, breaker-and-a-third and the dual element spot network for ETS.

07/02194 pricing

Deregulated model and locational marginal

Sood, Y. R. et al. Electric Power Systems Research, 2007, 77, (5–6), 574–582. This paper presents a generalized optimal model that dispatches the pool in combination with privately negotiated bilateral and multilateral contracts while maximizing social benefit has been proposed. This model determines the locational marginal pricing based on marginal cost theory. It also determines the size of non-firm transactions as well as pool demand and generations. Both firms as well as non-firm transactions are considered in this model. The proposed model has been applied to IEEE-30 bus test system. In this test system different types of transactions are added for analysis of the proposed model.

07/02195 Economic theory and the application of incentive contracts to procure operating reserves Wang, L. et al. Electric Power Systems Research, 2007, 77, (5–6), 518– 526. The ancillary services market plays an important role in the operation of an electricity market, especially for achieving a high level of reliability. Among all ancillary services, operating reserve is an important research focus, with the attention mainly on the optional procurement and pricing methods. These methods differ in many aspects, including the objective, allocation of risks, and feasibility. In this paper, a new approach is proposed to analyse the users’ reserve procurement problem and a novel reserve trade mechanism is developed between electricity users and the retailer of the market. First, the differences between the procurement of operating reserve in decentralized and centralized ways are analysed. The comparison of the equilibrium solutions reveals that the centralized procurement that results in a systemic optimal solution is better than the decentralized procurement that results in a Nash equilibrium solution. Furthermore, an incentive contract based on a principal-agent model, that is able to induce a systemic optimality as well as a Pareto equilibrium and manage risks at the same time is designed. The proposed model is equitable and beneficial to all participants. An example is served to illustrate the features of the model and the methodology.

07/02196

Electricity rationing and public response

Souza, L. R. and Soares, L. J. Energy Economics, 2007, 29, (2), 296– 311. This paper studies the electricity load demand behaviour during the 2001 rationing period, which was implemented because of the Brazilian energy crisis. The hourly data refers to a utility situated in the southeast of the country. The model proposed by Soares and Souza is used, making use of generalized long memory to model the seasonal behaviour of the load. The rationing period is shown to have imposed a structural break in the series, decreasing the load at about 20%. Even so, the forecast accuracy is decreased only marginally, and the forecasts rapidly readapt to the new situation. The structural break, as well as the forecast errors from this model, also permits verifying the public response to pieces of information released regarding the crisis.

07/02197 Encouraging the implementation of small renewable electricity CDM projects: an economic analysis of different options Del Rı´o, P. Renewable and Sustainable Energy Reviews, 2007, 11, (7), 1361–1387. Apart from contributing to the mitigation of GHG emissions, the deployment of renewable electricity clean development mechanism (RE-CDM) projects may provide substantial local economic, social and environmental sustainability benefits to host countries. However, in spite of these advantages, a wide array of barriers prevents the realization of these projects. They compete with other CDM options which lead to cheaper GHG emissions reductions but which do not provide as much opportunities for sustainable development in developing countries. Taking into account that, in contrast to GHG benefits, sustainability benefits are not valued in the market place and that article 12 of the Kyoto Protocol envisages two objectives for the CDM (cost-effective emissions reductions and contribution to sustainability), this market mechanism might be leading to a ‘market failure’ in RE-CDM projects. This paper explores the different barriers

Fuel and Energy Abstracts September 2007 333

06 Electrical power supply and utilization (economics, policy, supplies, forecasts) affecting the implementation of RE-CDM projects and proposes and analyses several policies and measures that could be implemented to encourage their deployment by tackling those obstacles.

07/02198 Evaluation of existing cooling systems for reducing cooling power consumption Hatamipour, M. S. et al. Energy and Buildings, 2007, 39, (1), 105–112. This work was designed to estimate the cooling load power consumption during the summer in the hot and humid areas of Iran. The actual electrical energy consumption for cooling systems of some typical buildings with various applications (three residential home buildings, two industrial plant buildings, a trade centre with 38 shops, three public sectors and a city hospital) in a hot and humid region in South of Iran was recorded during the peak load period of the year (July–August). The records were used for estimating the total power consumption of the cooling systems in this region. According to this estimation, which was confirmed by the regional electrical power distribution office, the cooling systems power consumption in this region accounted for more than 60% of the total power consumption during the peak load period of the year. A computer program was developed for simulating the effect of various parameters on cooling load of the buildings in hot and humid regions. According to the simulation results, use of double glazed windows, light coloured walls and roofs, and insulated walls and roofs can reduce the cooling load of the buildings more than 40%.

07/02199 Extended ARMA models for estimating price developments on day-ahead electricity markets Swider, D. J. and Weber, C. Electric Power Systems Research, 2007, 77, (5–6), 583–593. In this paper extended models for estimating price developments on electricity markets are presented. The models consider deviations from the normality hypothesis of the prices. Based on an ARMA model combination with GARCH, Gaussian-mixture and switching-regime approaches are comparatively discussed. The comparison is based on historic electricity prices of the spot and two reserve markets in Germany. It is shown that the proposed extended models lead to significantly improved representations of the considered stochastic price processes. It is inferred that these models may be preferred for estimating price developments on electricity markets.

07/02200

Hourly electricity prices in day-ahead markets

Huisman, R. et al. Energy Economics, 2007, 29, (2), 240–248. This paper focuses on the characteristics of hourly electricity prices in day-ahead markets. In these markets, quotes for day-ahead delivery of electricity are submitted simultaneously for all hours in the next day. The same information set is used for quoting all hours of the day. The dynamics of hourly electricity prices does not behave as a time series process. Instead, these prices should be treated as a panel in which the prices of 24 cross-sectional hours vary from day to day. This paper introduces a panel model for hourly electricity prices in day-ahead markets and examines their characteristics. The results show that hourly electricity prices exhibit hourly specific mean-reversion and that they oscillate around an hourly specific mean price level. Furthermore, a block structured cross-sectional correlation pattern between the hours is apparent.

07/02201 Impacts of lighting density on heating and cooling loads in different climates in China Lam, J. C et al. Energy Conversion and Management, 2006, 47, (13–14), 1942–1953. Changes in lighting load density affect not only energy use for electric lighting but also energy requirements for space heating and cooling. In general, a reduction in electric energy use would tend to increase space heating during the winter months and lower the cooling requirement in the summer. The implications for total building energy use, however, would vary, depending on the building and building services designs, its operation and the prevailing climates. This paper presents an analysis of the interactions between lighting and space heating/cooling loads in office buildings in the five major climatic zones – severe cold, cold, hot summer and cold winter, mild, and hot summer and warm winter – in China through building energy simulation using DOE-2.1E.

07/02202 Integrating reliability, availability, maintainability and supportability with risk analysis for improved operation of the Afam thermal power-station Eti, M. C. et al. Applied Energy, 2007, 84, (2), 202–221. The ability to improve continually is desirable. In recent years, the reliabilities of power plants have become increasingly important issues in most developed and developing countries. Reliability, availability, maintainability and supportability (RAMS), as well as risk analysis, have become big issues in the power industries. Major causes of customer dissatisfaction often result from unexpected failures, which have led to unanticipated costs in the Afam thermal power-station. However, with proper integration of RAMS and risk analysis in each maintenance process in the Afam thermal power-station, the frequency

334 Fuel and Energy Abstracts September 2007

of failures can be reduced and their consequences diminished. Taking experiences from the developed world, an approach for the integration of RAMS and risk analysis can be developed as a guide in maintenance policies for the Afam thermal power station. This paper discusses the applications of failure mode effect analysis, failure mode effect and criticality analysis, feedback information, supportive systems and risk analysis, in order to reduce the frequency of failures and maintenance costs.

07/02203 systems

Integration of stochastic generation in power

Papaefthymiou, G. et al. International Journal of Electrical Power & Energy Systems, 2006, 28, (9), 655–667. Stochastic generation, i.e. electrical power production by an uncontrolled primary energy source, is expected to play an important role in future power systems. A new power system structure is created due to the large-scale implementation of this small-scale, distributed, nondispatchable generation; the ‘horizontally-operated’ system. Modelling methodologies that can deal with the operational uncertainty introduced by these power units should be used for analysing the impact of this generation to the system. In this contribution, the principles for this modelling are presented, based on the decoupling of the single stochastic generator behaviour (marginal distribution-stochastic unit capacity) from the concurrent behaviour of the stochastic generators (stochastic dependence structure-stochastic system dispatch). Subsequently, the stochastic bounds methodology is applied to model the extreme power contribution of the stochastic generation to the system, based on two new sampling concepts (comonotonicity–countermonotonicity). The application of this methodology to the power system leads to the definition of clusters of positively correlated stochastic generators and the combination of different clusters based on the sampling concepts. The stochastic decomposition and clustering concepts presented in this contribution provide the basis for the application of new uncertainty analysis techniques for the modelling of stochastic generation in power systems.

07/02204 Monte Carlo based unit commitment procedures for the deregulated market environment Granelli, G. P. et al. International Journal of Electrical Power & Energy Systems, 2006, 28, (10), 712–722. The unit commitment problem, originally conceived in the framework of short term operation of vertically integrated utilities, needs a thorough re-examination in the light of the ongoing transition towards the open electricity market environment. In this work the problem is re-formulated to adapt unit commitment to the viewpoint of a generation company (GENCO) which is no longer bound to satisfy its load, but is willing to maximize its profits. Moreover, with reference to the present day situation in many countries, the presence of a GENCO (the former monopolist) which is in the position of exerting the market power, requires a careful analysis to be carried out considering the different perspectives of a price taker and of the price maker GENCO. Unit commitment is thus shown to lead to a couple of distinct, yet slightly different problems. The unavoidable uncertainties in load profile and price behaviour over the time period of interest are also taken into account by means of a Monte Carlo simulation. Both the forecasted loads and prices are handled as random variables with a normal multivariate distribution. The correlation between the random input variables corresponding to successive hours of the day was considered by carrying out a statistical analysis of actual load and price data. The whole procedure was tested making use of reasonable approximations of the actual data of the thermal generation units available to come actual GENCOs operating in Italy.

07/02205

Option value of electricity demand response

Sezgen, O. et al. Energy, 2007, 32, (2), 108–119. As electricity markets deregulate and energy tariffs increasingly expose customers to commodity price volatility, it is difficult for energy consumers to assess the economic value of investments in technologies that manage electricity demand in response to changing energy prices. The key uncertainties in evaluating the economics of demand–response technologies are the level and volatility of future wholesale energy prices. In this paper, the authors demonstrate that financial engineering methodologies originally developed for pricing equity and commodity derivatives (e.g. futures, swaps, options) can be used to estimate the value of demand-response technologies. The authors also adapt models used to value energy options and assets to value three common demand–response strategies: load curtailment, load shifting or displacement, and short-term fuel substitution, specifically distributed generation. These option models represent an improvement to traditional discounted cash flow methods for assessing the relative merits of demand-side technology investments in restructured electricity markets.

07 Steam raising (boiler operation/design) 07/02206 Pricing of monthly forward contracts in the Nord Pool market Kristiansen, T. Energy Policy, 2007, 35, (1), 307–316. This paper investigates whether the pricing of forward contracts in the Nord Pool market is efficient. Monthly forward contracts were introduced in the Nord Pool market in 2003. Likewise, quarterly contracts that will replace seasonal contracts were introduced in 2004. For a transition period these contracts together with the pre-existing seasonal and yearly contracts constitute the forward market. In an efficient forward market the price of a seasonal forward contract should equal the time-weighted average of the underlying monthly forward contracts. In this paper, historic forward price information is used to evaluate whether this relationship holds true and find that there are inefficiencies in the pricing.

07/02207 Renewable energy resources for electricity generation in Sudan Omer, A. M. Renewable and Sustainable Energy Reviews, 2007, 11, (7), 1481–1497. Electricity reaches only about 30% of Sudan’s more than 40 million population; this mainly in urban areas. Hence, a major problem for rural people is the inadequate supply of power for lighting, heating, cooking, cooling, water pumping, radio or TV communications and security services. Petroleum product supplies, including diesel, kerosene and LPG are irregular and often subject to sudden price increases. Because of the inadequate supply of these fuels, women trek great distances into the forest to collect fuelwood, charcoal and biomass residues from animal and agriculture, account for more than half of total energy consumption. Most of this is utilized for cooking and heating water in rural and semi urban areas and by the urban poor. It is a need to provide alternative renewable energy sources to enhance women’s participation in, and benefit from development. Household energy was the first energy sector that paid explicit attention to women and their energy needs. The contribution of women to environmental policy is largely ignored. Decision-making and policy formulation at all environmental levels, i.e. conservation, protection and rehabilitation and environmental management are more or less a male preserve. Women have been involved in promotion of appropriate energy technologies, primarily for rural population over the past 15 years. This article highlights the experience of working with rural people in seeking solutions for community energy needs through renewable environmentally friendly energy technologies.

07/02208 Turkey

Residential electricity demand dynamics in

Halicioglu, F. Energy Economics, 2007, 29, (2), 199–210. This article provides fresh empirical evidences for the income and price elasticies of the residential energy demand both in the short-run and long-run for Turkey over the period 1968–2005, using the bounds testing procedure to cointegration. The computed elasticities of income and price are consistent with the previous studies and, as expected, the long-run elasticities are greater than the short-run elasticities. An augmented form of Granger causality analysis is implemented among residential electricity, income, price and urbanization. In the long-run, causality runs interactively through the error-correction term from income, price and urbanization to residential energy but the short-run causality tests are inconclusive The parameter stability of the short-run as well as long-run coefficients in the residential energy demand function are tested. The results of these tests display a stable pattern.

07/02210 Robust searching hybrid differential evolution method for optimal reactive power planning in large-scale distribution systems Chang, C.-F. et al. Electric Power Systems Research, 2007, 77, (5–6), 430–437. A robust searching hybrid differential evolution (RSHDE) method which can be used to solve the optimization problem of large-scale integer nonlinear systems is proposed. Two new schemes, the multidirection search scheme and the search space reduction scheme, are embedded into the HDE. These two schemes are used to enhance the search ability before performing the initialization step of the solution process. Without these two schemes, the HDE is awkward in finding an efficient search direction in large-scale systems because of applying a random search method. In this study, the RSHDE is applied to solve the capacitor placement problem in distribution systems. Variousscales distribution systems are employed to demonstrate the application and verify the effectiveness of the proposed method. Moreover, the previous DE, HDE, simulated annealing and genetic algorithms methods are also applied to the same example systems for the purpose of comparison.

07/02211

Spatial peak-load pricing

Soledad Arellano, M. and Serra, P. Energy Economics, 2007, 29, (2), 228–239. This article extends the traditional electricity peak-load pricing model to include transmission costs. In the context of a two-node, twotechnology electric power system, where suppliers face inelastic demand, it is shown that when the marginal plant is located at the energy-importing centre, generators located away from that centre should pay the marginal capacity transmission cost; otherwise, consumers should bear this cost through capacity payments. Since electric power transmission is a natural monopoly, marginal-cost pricing does not fully cover costs. The authors propose distributing the revenue deficit among users in proportion to the surplus they derive from the service priced at marginal cost.

07/02212 Supply security and short-run capacity markets for electricity Creti, A. and Fabra, N. Energy Economics, 2007, 29, (2), 259–276. The creation of electricity markets has raised the fundamental question as to whether markets create the right incentives for the provision of the reserves needed to maintain supply security in the short-run, or whether some form of regulation is required. In some states in the US, electricity distributors have been made responsible for providing such reserves by contracting capacity in excess of their forecasted peak demand. The so-called installed capacity markets provide one means of contracting reserves, and are the subject of this paper. Under monopoly as well as under perfect competition, the authors identify firms’ short-run opportunity costs of committing resources in the capacity market and the costs of inducing full capacity commitment. The long-run investment problem is not considered. From a welfare viewpoint, the authors also compare the desirability of providing reserves either through capacity markets or through the demand side (i.e. power curtailments). At the optimum, capacity obligations equal peak demand (plus expected outages) and the capacity deficiency rate (which serves as a price cap) is set at firms’ opportunity costs of providing full capacity commitment.

07 STEAM RAISING 07/02209 Revision of the underfrequency load-shedding scheme of the Slovenian power system Tomsˇicˇ, T. et al. Electric Power Systems Research, 2007, 77, (5–6), 494– 500. The main motivation for the study presented in this paper was the numerous blackouts that occurred in 2003. After the Italian blackout, which almost caused a collapse of the Slovenian power system as well, it became clear that some automatic procedures, with underfrequency load-shedding being one of the most important ones, need to be thoroughly revised. The paper studies three different load-shedding schemes. Two of them use the frequency decline gradient, which is currently not implemented in the Slovenian power system. The first two schemes have fixed maximal amount of load to be shed, while the third one sheds more loads if the frequency gradient is greater, which makes this scheme successful also in those case where the first two fail due to insufficient load-shedding. This is application of known techniques to a specific case of finding the best load-shedding scheme in Slovenian power system to avoid blackout. The simulations were performed on a detailed model of the Slovenian power system using the software package EUROSTAG. The proposed underfrequency relays’ settings conform to the UCTE Operation handbook.

Boiler operation/design 07/02213 Experimental investigation of flow-induced vibration in PFBR steam generator sector model Thirumalai, M. et al. International Journal of Energy Science and Technology, 2007, 3, (1), 88–108. The 500 Mwe prototype fast breeder reactor (PFBR) is under construction at Kalpakkam. It is a liquid metal sodium-cooled pooltype fast reactor with all primary components located inside a sodium pool. Fission heat is transferred to a secondary sodium system in an intermediate heat exchanger, which is in turn transferred to water in a steam general (SG). The PFBR-SG is a vertical shell and tube-type heat exchanger with sodium in its shell side and water in the tube side. Flow-induced vibration experiments were carried out in a water test loop on a 60-degree sector model to validate the design and also to qualify the component for plant operation.

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08 Combustion (burners, combustion systems) 07/02214 Field corrosion tests for a low chromium steel carried out at superheater area of a utility boiler with three coals containing different chlorine contents Li, L. et al. Fuel Processing Technology, 2007, 88, (4), 387–392. Field corrosion tests for a low chromium steel were carried out at a superheater area of a 100 MW pulverized coal-fired boiler for various times up to 500 h, when three coals having different chlorine contents were combusted. The low chromium steel had obvious metal loss due to corrosion, and comparison of the metal loss and corrosion scale structure was made among the three coals in respect to chlorine contents as well as other elements affecting its corrosion. Corrosion scales of the low chromium steel had a general two-layer structure: an inner layer containing iron, chromium, oxygen and sulfur, and an outer layer made of porous iron oxide and fly ash particles. Distinct molten phase formation, which is an indication of severe corrosion, was observed for the coal containing only the middle high chlorine, and it initiated in the outer layer of the corrosion scales.

in the flue gas have been measured with a flue gas analyser, and the black smoke emitted from the chimney has been screened with charge couple device (CCD) video camera. Power 2# coal, sized at 5–25 mm, has been fired in the fixed-grate model. The secondary air has been used to enhance the turbulence in the furnace after the numerical simulation. The results of experiments show that the emission of the black smoke at the time of ignition of the coal at ambient temperature is more serious than that of restart of the combustion after the temporary flameout for the case of the temperature; the secondary air is helpful for reducing the black smoke emission for enhancing the intensity of the turbulence in the furnace; selection of coal particle size is necessary, the smaller the size of the coal is, the more serious the black smoke emission is, and the effect of reducing the black smoke emission with the secondary air is more evident with smaller-size coal. The industrial test has been employed to study the effect of the air demand. It indicates that rational stoichiometric air/fuel ratio is helpful for reducing the black smoke emission in the restart of the combustion after the temporary flameout.

07/02215 Long-term creep deformation characteristics of advanced ferritic steels for USC power plants Yoshizawa, M. and Igarashi, M. International Journal of Pressure Vessels and Piping, 2007, 84, (1–2), 37–43. Creep rupture and deformation behaviour of T122-type steels with different matrix phases such as
0 (martensite) and
+ (martensite and delta-ferrite) at different stress levels has been studied using creep testing and a detailed FE-STEM microscopy. Long-term creep rupture strength of the dual phase steel is found to be lower than that expected from the short-term creep testing. Fine grain microstructure enhances the creep deformation of the dual phase steel at lower stress region, but is not the major factor on the degradation. Decrease in fine MX and unequal distribution of MX in the ferrite matrix are found to be the major causes of the strength degradation in the dual phase steel with the higher Cr content. It is thus concluded that the heterogeneous creep deformation is much more pronounced at lower stress level in the dual phase steel, which is due to inhomogeneous microstructure consisting of
+ phase matrix and the relevant heterogeneous distribution of fine precipitates such as MX and M23C6 in the -ferrite matrix and near the interface between /.

07/02216 Multi-period steam turbine network optimisation. Part I: simulation based regression models and an evolutionary algorithm for finding D-optimal designs Tveit, T.-M. and Fogelholm, C.-J. Applied Thermal Engineering, 2006, 26, (10), 993–1000. In this work, a methodology for building multi-period optimization model of steam turbine network is presented. The optimization model can estimate and evaluate the effect of changes to the thermal energy demand of processes. The subject is divided into two parts. In part I, a method for finding regression models for steam turbine networks using a simulation model and an evolutionary algorithm for finding Doptimal designs is presented. In part II the method presented in part I is used to develop and solve a multi-period MINLP model of a steam turbine network in a utility system. There are two major problems that are addressed in part I. First, the evolutionary algorithm for finding Doptimal design is applied to try to determine which values should be simulated in order to generate the data for the regression model. Second, a theoretical model of steam turbine performance is used to model the feasible operation of the steam turbine. This is necessary to be able to make an efficient evolutionary algorithm for finding Doptimal designs. The use of regression models makes it possible to build optimization models of utility systems that are compact and transparent. There is a natural trade-off between the flexibility of a model and the accuracy. The major drawback of the methodology, is that the models developed must be considered ad hoc-models, and are not as flexible compared to models where all the process units are modelled in full detail. An advantage of the methodology developed in this work is that it gives more possibilities of finding an acceptable simplification of the optimization problem, as the methodology is not bound by a certain set of thermodynamic rules or specific mathematical form of the relations in the models. Part II demonstrates how the methodology can be applied when building a multi-period optimization model to estimate and evaluate how changes to the processes will affect the utility system.

07/02217 The black smoke control in a chain-grate stokerfired boiler at the time of ignition and restart of the combustion Wang, Q. C. and Luo, Y. H. International Journal of Energy Research, 2006, 30, (15), 1363–1376. The black smoke is always emitted from the chimney in the chain-grate stoker-fired boiler at the time of ignition at ambient temperature and restart of the combustion after temporary flameout in China. The purpose of the work is to reduce the black smoke emission. A laboratory fixed-grate model has been used to simulate the combustion of coal in chain-grate stoker-fired boiler. The CO and O2 concentration

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08 COMBUSTION Burners, combustion systems 07/02218 SrTiO3

Catalytic combustion of soot over alkali doped

Bialobok, B. et al. Catalysis Today, 2007, 119, (1–4), 278–285. The effect of introduction of alkalis (Me Li, K, Cs) into SrTiO3 on the physico-chemical properties of resulted materials and their catalytic activity in soot combustion was studied. Two groups of SrTiO3 based perovskites were prepared: substituted in A-position of the structure (Sr1  xMexTiO3, x = 0.05–0.2) and impregnated with the same amount of alkali metals. Prepared materials exhibit low specific surface area and perovskite structure, only these ones impregnated with the highest amount of Cs (K) show weak XRD signals of Me2O. TPD-O2 experiments show bimodal profiles of O2 desorption curves with maximums corresponding to individual step of alkali nitrates thermal decomposition. It is supposed that second peak of O2 desorption from impregnated SrTiO3 can be related to reversible decomposition of MeNO3. XPS shows that surface of SrTiO3 substituted with K (Cs) is much richer in these elements than the surface of impregnated one. Prepared materials lower the temperature of soot ignition from 530 (inert) to 470  C for SrTiO3 and to 302–303  C for Sr0.8K0.2TiO3 and Sr0.8K0.2TiO3, respectively. Substituted materials are more active in soot combustion than impregnated ones. A mechanism explaining effect of alkali metals nitrate addition to SrTiO3 on its catalytic activity in soot combustion is proposed.

07/02219 Characteristics of flamelets in spray flames formed in a laminar counterflow Watanabe, H. et al. Combustion and Flame, 2007, 148, (4), 234–248. A two-dimensional numerical simulation of a spray flame formed in a laminar counterflow is presented, and the flamelet characteristics are studied in detail. The effects of strain rate, equivalence ratio, and droplet size are examined in terms of mixture fraction and scalar dissipation rate. n-Decane (C10H22) is used as a liquid spray fuel, and the droplet motion is calculated by the Lagrangian method without the parcel model. A one-step global reaction is employed for the combustion reaction model. The results show that there appear large differences in the trends of gaseous temperature and mass fractions of chemical species in the mixture fraction space between the spray flame and the gaseous diffusion flame. The gas temperature in the spray flame is much higher than that in the gaseous diffusion flame. This is due to the much lower scalar dissipation rate and the coexistence of premixed and diffusion-limited combustion in the spray flame. For the spray flames, gas temperature and mass fractions of chemical species are not unique functions of the mixture fraction scalar dissipation rate. This is because the production rate of the mixture fraction, namely evaporation rate of the droplets, in the upstream region is not in proportion to its transport-diffusion rate in the downstream region. The behaviour shows marked differences as the strain rate decreases, the equivalence ratio increases, or the droplet size decreases.

07/02220 Effect of raw material composition in woody biomass pellets on combustion characteristics Rhe´n, C. et al. Biomass and Bioenergy, 2007, 31, (1), 66–72.

08 Combustion (burners, combustion systems) Char yield, char combustion time and char combustion rate of pellets made from different tree parts of Norway spruce and industrially made stem wood pellets of Norway spruce and Scots pine were studied. The pellets were incinerated in a laboratory scale oven at various temperatures, gas flows and oxygen concentrations. It was found that the combustion time for a single pellet mostly depended on the raw material composition and to a minor extent on the density. Pellets made of bark had up to a 50% longer char combustion time compared to that of stem wood pellets, due to differences in char yield. Industrially made stem wood pellets of pine and spruce sawdust were found to have small differences in combustion characteristics. The variations in combustion characteristics of pellets are discussed in relation to composition of raw material.

07/02221 Energy balance analysis for Erdemir blast furnace number one Ertem, M. E. and Gu ¨ rgen, S. Applied Thermal Engineering, 2006, 26, (11–12), 1139–1148. Eregli Iron and Steel Works (Erdemir) began its activities on May 15, 1965 with an annual production capacity of 450,000 tons and has made important contributions to the Turkish economy ever since. Today, with a total amount of crude steel production exceeding three million tons, it is the largest integrated iron and steel factory and the sole producer of flat steel in the country. Erdemir produces hot and cold rolled coils, zinc, tin, and chromium plated steel. There are two blast furnaces in Erdemir. The blast furnace No. 1, Ayse, , started operations in 1965. Having been modernized three times in the years 1971, 1977, and 1986, it has been re-lined (the renewal of refractory bricks) in the year 1998. The diameter of its reservoir is 8.99 m with a working volume of 1505.0 m3. The daily production capacity is 3000 tons amounting to 1,065,000 tons annually tons. The blast furnace No. 2, Zu ¨ beyde, started its operations in 1978. It has been modernized twice in the years 1987 and 1995 and has been re-lined in October 2000. It is of top pressure type and has oxygen injection. The diameter of its reservoir is 9.70 m with the working volume being 1707.7 m3. The daily production capacity is 4000 tons with the annual being 1,420,000 tons. The iron production process consumes 50% of the total energy and comprises a significant portion of total costs in the integrated steel works. Iron (Fe) production is made by the reduction of hematite (Fe2O3) and magnetite (Fe3O2) with coke in the blast furnace. This can be analysed as two separate areas, namely the furnace and stoves. The necessary carbon and high temperature required by the reduction process makes the furnaces an energy balance centre. In this study, the limits of the blast furnace no. 1 in Erdemir have been chosen as the control volume in which the stoves have not been included. By the identification of the energy sources that move in and out of the control volume, the energy output sources have been fractioned and categorized. For the implementation of the method, also known as the balance analysis has been chosen and the model presented in the ‘Japanese steel making handbook’ has been taken as a reference.

07/02222 particles

Modelling thermal degradation of woody fuel

Benkoussas, B. et al. International Journal of Thermal Sciences, 2007, 46, (4), 319–327. A model for thermal degradation of woody fuel particles is developed. It includes drying, pyrolysis, and char oxidation processes. The model is first applied to assess the validity of the thermally thin pyrolysis assumption commonly used in wildfire behaviour models. For a given external radiant heat flux, the particle size at which transition between thermally-thin and thermally-thick pyrolysis regimes occurs is evaluated by comparing the pyrolysis times computed for both regimes. It is found that, for a given flux, the particle size above which the thermally thin assumption is questionable, is independent on the moisture content and on the particle surface-area-to-volume ratio. This means that the transition characteristic lengths for spheres, cylinders and slabs are related by: Lcr=Lcr,slab=Lcr,cyl/2=Lcr,sph/3. A Biot number based on the particle surface-area-to-volume ratio, p can then be defined as Bi="wQext/wp
T. Results show that the thermally-thin regime can be defined by Bi<0.1 whatever the particle shape. They reveal that the traditional thermally thin pyrolysis assumption is not suitable to model wildland fire behaviour. For thin particles responsible for fire spread pyrolysis is kinetically controlled while it is controlled by heat diffusion for large particles. Secondly, the model is applied to the combustion of firebrands. Model results are found in good agreement with available experimental data.

07/02223 Multiple cool flames in static, unstirred reactors under reduced-gravity and terrestrial conditions Pearlman, H. Combustion and Flame, 2007, 148, (4), 280–284. Multiple cool flames have been observed experimentally in a static, unstirred reactor at reduced gravity in an equimolar n-butane–oxygen premixture diluted with helium. These are the first observations of sustained cool flame oscillations in a static reactor when transport is governed by diffusive fluxes of heat and species. To date, only single

cool flames have been reported at reduced gravity, while oscillatory cool flames have long been observed in static reactors at terrestrial conditions. The results suggest that enhanced conduction heat transfer can provide the required heat loss to sustain cool flame oscillations.

07/02224 Probe sampling measurements and modeling of nitric oxide formation in ethane + air flames Dyakov, I. V. et al. Fuel, 2007, 86, (1–2), 98–105. Burning velocity and probe sampling measurements of the concentrations of O2, CO2, CO and NO in the post-flame zone of ethane + air flames are reported. The heat flux method was used for stabilization of laminar, premixed, non-stretched flames on a perforated plate burner at 1 atm. Axial profiles of the concentrations of the major species were used to assess interaction of the flame with the burner surface and conversion of the sampling gases in the probe. Tests performed with the probes of different inlet diameters showed negligible CO–CO 2 and NO–NO2 conversion within the experimental accuracy. Two kinetic models, the GRI-mech. 3.0 and in-house modified detailed reaction mechanism, were tested. Both kinetic mechanisms accurately reproduce laminar burning velocities and concentrations of the major species, CO, CO2 and O2, in these flames. Numerical predictions of the concentrations of NO in a post-flame zone of lean and stoichiometric flames are in good agreement with experiment when downstream heat losses to the environment were taken into account. The GRI-mech. 3.0 over-predicts the [NO] by about 30 ppm at the equivalence ratio of 1.4. The predictions of the in-house mechanism in rich flames are closer to the experimental data with an under-prediction of about 14 ppm. The influence of the assumed temperature gradient downstream the flame front on the calculated flame structure was also assessed.

07/02225 Solid-state synthesis and spark plasma sintering of submicron BaYxZr1xO3x/2 (x = 0, 0.08 and 0.16) ceramics Anselmi-Tamburini, U. et al. Journal of the European Ceramic Society, 2006, 26, (12), 2313–2318. Fine powders (particle size of 100–200 nm) of BaYxZr1xO3x/2 (x = 0, 0.08, 0.16) were produced by solid-state reaction at 1000–1050  C using nanocrystalline ZrO2 and BaCO3 raw materials. The powders were densified by means of the spark plasma sintering process resulting in dense and homogeneous submicron microstructures. Near full density ceramics with grain size < 300 nm were obtained by sintering at 1600  C for 1–5 min.

07/02226 Surface properties of carbons obtained from hexachlorobenzene and hexachloroethane by combustion synthesis Cudzilo, S. et al. Carbon, 2007, 45, (1), 103–109. The paper describes the combustion synthesis of carbon materials from hexachloroethane (C2Cl6), hexachlorobenzene (C6Cl6), and a mixture of these compounds. The chemical composition (elemental analysis), structural composition (XRD, Raman spectroscopy), microstructure (SEM), surface physicochemical properties (low-temperature nitrogen adsorption, XPS, FTIR) and electrochemical behaviour (cyclic voltammetry) of the solid reaction products were investigated. Their unique structural and surface properties depend on the chemical composition of the starting compounds. The properties of the carbon samples tested are much like those of carbon black, but the material from hexachloroethane exhibits the most distinctly amorphous features. In contrast, the adsorptive properties (porous structure) of the sample obtained from hexachlorobenzene tend to resemble those of activated carbon.

07/02227 The simplest method for calculating energy output and Gurney velocity of explosives Keshavarz, M. H. and Semnani, A. Journal of Hazardous Materials, 2006, 131, (1–3), 1–5. Two correlations are introduced for calculating Gurney velocity as a useful parameter for thermochemical estimation of explosive energy output. For CaHbNcOd explosives, only the chemical composition of high explosive as well as its condensed or estimated gas phase heat of formation, which later is calculated by group additivity rules, is needed for calculating Gurney velocity. The introduced simple correlations in the present work may be applied to any explosive that contains the elements of carbon, hydrogen, nitrogen and oxygen with no difficulties at any loading density. There is no need to use any assumed decomposition reaction in present work. Gurney velocity are calculated for different pure and explosive formulations and compared with measured Gurney velocity at specified loading density. The results show that the agreement is good for present method as compared to previous correlations.

07/02228 Toward an understanding of the stabilization mechanisms of lifted turbulent jet flames: experiments Lyons, K. M. Progress in Energy and Combustion Science, 2007, 33, (2), 211–231.

Fuel and Energy Abstracts September 2007 337

09 Process heating, power and incineration (energy applications in industry) This review discusses recent progress in understanding turbulent, lifted hydrocarbon jet flames and the conditions under which they stabilize. The viewpoint is from that of the empiricist, focusing on experimental results and the physically based theories that have emerged from their interpretations, as well as from the theoretically founded notions that have been supported. Pertinent concepts from laminar lifted flame stabilization studies are introduced at the onset. Classification in broad categories of the types of turbulent lifted flame theories is then presented. Experiments are discussed which support the importance of a variety of effects, including partial premixing, edge-flames, local extinction, streamline divergence and large-scale structures. This discussion details which of the categories of theories are supported by particular experiments, comments on the experimental results themselves and their salient contributions. Overall conclusions on the state of the field are drawn and future directions for research are also discussed.

Fire safety 07/02229 Effects of thin-layer boilover on flame geometry and dynamics in large hydrocarbon pool fires Ferrero, F. et al. Fuel Processing Technology, 2007, 88, (3), 227–235. This work aims to estimate the effects of thin-layer boilover on flame geometry and dynamics. A series of large scale experiments (in pools ranging from 1.5 to 6 m in diameter) were performed using gasoline and diesel as fuel. As expected, only diesel showed evidence of this phenomenon. This article presents a summary of the results obtained for flame height, tilt and pulsation. Flame height increases during water ebullition, though the increase is no longer detectable when wind speed exceeds certain values. Correlations previously presented in the literature to predict flame length and tilt were modified in order to fit the results obtained during thin-layer boilover. However, the influence on flame tilt is not as great and the equations for the stationary period seem suitable for the entire fire. Results of flame pulsation during the stationary period fill the gap in the literature for fires between 1.5 and 6 m and fit previous correlations. On the other hand, during ebullition, the flame pulsates faster, as air entrainment is greater and, as one would expect, this effect decreases with pool size. A new equation for estimating pulsation frequency during boilover is proposed.

07/02230 Experimental studies on time-dependent size distributions of smoke particles of standard test fires Xie, Q. et al. Building and Environment, 2007, 42, (2), 640–646. The time-dependent size distributions of smoke particles are measured by SMPS spectrometer as experiments go on, respectively, for four standard fires, i.e. TF2, TF3, TF4 and TF5. The results suggest that, for the TF4, the normalized number distributions of smoke aerosol be best fitted with lognormal functions and little time-dependency be shown throughout the experiments. It is also indicated that the best fitting curves of the normalized number distributions of smoke particles change from the so-called under-lognormal fittings to over-lognormal fittings for the TF2, TF3 and TF5, as time moves. In addition, a common changing trend of the size distribution curves can be drawn for the three standard fires. Namely, the curves mainly drift toward larger diameters of smoke particles and the peaks of the curves keep increasing as time goes by for each standard test fire.

09 PROCESS HEATING, POWER AND INCINERATION Energy applications in industry 07/02231 A review and assessment of the energy utilization efficiency in the Turkish industrial sector using energy and exergy analysis method Utlu, Z. and Hepbasli, A. Renewable and Sustainable Energy Reviews, 2007, 11, (7), 1438–1459. Exergy has been seen a key component for a sustainable society, and in the recent years exergy analysis has been widely used in the design, simulation and performance evaluation of thermal and thermo

338 Fuel and Energy Abstracts September 2007

chemical systems. A particular thermo dynamical system is the society of a country, while the energy utilization of a country can be assessed using exergy analysis to gain insights into its efficiency and potential for improvements. Energy and exergy utilization efficiencies in the Turkish industrial sector (TIS) over the period from 1990 to 2003 are reviewed and evaluated in this study. Energy and exergy analyses are performed for eight industrial modes, namely iron–steel, chemical–petrochemical, petrochemical–feedstock, cement, fertilizer, sugar, non-metal industry, other industry, while in the analysis the actual data are used. Sectoral energy and exergy analyses are conducted to study the variations of energy and exergy efficiencies for each subsector throughout the years studied, and these heating and overall energy and exergy efficiencies are compared for the eight subsectors. The chemical and petrochemical subsector, and the iron and steel subsector appear to be the most energy and exergy efficient sectors, respectively. The energy utilization efficiencies for the Turkish overall industrial sector range from 63.45% to 70.11%, while the exergy utilization efficiencies vary from 29.72% to 33.23% in the analysed years. Exergetic improvement potential for this sector is also determined to be 681 PJ in 2003, with an average increase rate of 9.5% annually for the analysed years. It may be concluded that the methodology used in this study is practical and useful for analysing sectoral and subsectoral energy and exergy utilization to determine how efficient energy and exergy are used in the sector studied. It is also expected that this study will be helpful in developing highly applicable and productive planning for energy policies.

07/02232 sites

A risk severity Index for industrial plants and

Planas, E. et al. Journal of Hazardous Materials, 2006, 130, (3), 242– 250. A risk index (risk severity index, S) has been devised to allow the assessment of the risk level originated by a given installation or site over the affected zone. A set of threshold levels for thermal radiation, toxic concentration and overpressure, together with the probabilities and frequencies associated to critical events and their effects have been the basis for calculating the values of S. A computer tool has been designed to perform a quick calculation of the diverse risk severity indexes (for a critical event, for a dangerous phenomenon, for a type of effect and for the whole installation) and to plot a map of the risk severity levels around the site. The methodology has been applied to diverse test cases and it has proved to be useful for risk assessment, for comparative studies and for land use planning.

07/02233

Endoreversible four-reservoir chemical pump

Xia, D. et al. Applied Energy, 2007, 84, (1), 56–65. A new cyclic model for the behaviour of a four-reservoir endoreversible chemical pump is proposed. The optimal relation between the coefficient of performance and the rate of energy pumping is derived by using finite-time thermodynamics or thermodynamic optimization. The optimal times of the four mass-transfer processes are also obtained. Moreover, the effects of the cyclic parameters on the coefficient of performance and the rate of energy pumping are studied by detailed numerical examples.

07/02234 process

Exergy analysis of industrial pasta drying

Ozgener, L. and Ozgener, O. International Journal of Energy Research, 2006, 30, (15), 1323–1335. This study presents an energy and exergy modelling of the industrial final macaroni (pasta) drying process for its system analysis, performance evaluation and optimization. Using actual system data, a performance assessment of the industrial macaroni drying process through energy and exergy destructions in the overall system is quantified and illustrated using energy and exergy flow diagrams. The total energy rate input to system is 316.25 kW. The evaporation rate is 72 kg h1 (0.03 kg s1) and energy consumption rate is found as 4.38 kW for 1 kg water evaporation from product. Humidity product rate is 792 kg h1 (0.22 kg s1) and energy consumption rate is found about 0.4 kW for 1 kg short cut pasta product. The energy efficiencies of the pasta drying process and the overall system are found to be as 7.55–77.09% and 68.63%. The exergy efficiency of pasta drying process is obtained to be as 72.98–82.15%. For the actual system that is presented the system exergy efficiency vary between 41.90 and 70.94%.

07/02235 High-performance dispersant of coal–water slurry synthesized from wheat straw alkali lignin Zhou, M. et al. Fuel Processing Technology, 2007, 88, (4), 375–382. Environmental concerns have stimulated interest in utilizing plantderived materials in various industrial fields. The main objective of the present study was to synthesize a new type of high-performance lignin series dispersant of coal–water slurry (CWS) from wheat straw alkali lignin (WAL), and determine the affecting factors in the reaction and the application performance for CWS preparation. The experimental results showed that the inherent viscosity and the sulfonic group content of the modified wheat straw alkali lignin (MSL) are the key

09 Process heating, power and incineration (energy applications in industry) factors affecting its dispersing effect for CWS. In the reaction, the reactant mass concentration and the sulfonating agent amount were changed to obtain the MSL with different inherent viscosities and sulfonic group contents, and the MSL with intermediate inherent viscosity (6.0 ml/g) and higher sulfonic group content (1.80 mmol g1) was found to have excellent dispersing effect for CWS. The MSL obtained from optimized process was used as dispersant for CWS preparation, the studies of the properties of CWS showed that MSL has similar dispersing effect with naphtalenesulfonate–formaldehyde condensate, and far better dispersing effect than lignosulfonate. Recently this kind of new dispersant has been applied in several power plants in China.

07/02236 Mathematical modelling of straw combustion in a 38 MWe power plant furnace and effect of operating conditions Yang, Y. B. et al. Fuel, 2007, 86, (1–2), 129–142. As one of the most easily accessible renewable energy resources, straw can be burned to provide electricity and heat to local communities. In this paper, mathematical modelling methods have been employed to simulate the operation of a 38 MWe straw-burning power plant to obtain detailed information on the flow and combustion characteristics in the furnace and to predict the effect on plant performance of variation in operating conditions. The predicted data are compared to measurements in terms of burning time, furnace temperature, flue gas emissions (including NOx), carbon content in the ash and overall combustion efficiency. It is concluded that straw burning on the grate is locally sub-stoichiometric and most of the NO is formed in the downstream combustion chamber and radiation shaft; auxiliary gas burners are responsible for the uneven distribution of temperature and gas flow at the furnace exit; and fuel moisture content is limited to below 25% to prevent excessive CO emission without compromising the plant performance. The current work greatly helps to understand the operating characteristics of large-scale straw-burning plants.

07/02237 Novel hybrid separation processes based on pervaporation for THF recovery Koczka, K. et al. Chemical Engineering and Processing, 2007, 46, (3), 239–246. Design of novel hybrid processes is performed for the industrial recovery of tetrahydrofuran (THF) from two different highly non-ideal mixtures. The novel hybrid processes combine the advantages of batch and/or continuous distillations, extractive distillation, and pervaporation for efficient separation of highly non-ideal mixtures. Pervaporation, used for the final dewatering of the THF, is the last step in the separation technologies and carried out with available industrial technology (Sulzer Chemtech GmbH, Batch pervaporation BP models, PERVAP1 2210 membrane type). It is necessary, however, to design a proper pre-separation process of the mixture to be pervaporated and coordinate its operation with the pervaporation unit. Since methanol is also present in one of the mixtures, its behaviour during pervaporation is also investigated. It shows that since the methanol is able to permeate the membrane, it should be separated in the pre-separation process. The vapour–liquid equilibrium data indicate that with extractive distillation it becomes possible to break the THF–methanol azeotrope and the appropriate application of pervaporation makes the further reduction of the recovery costs possible. The total annual costs of the novel hybrid separation processes range between 10.3 and 54% of that of the old technology based on chemical dewatering. The THF loss decreases to the 7.5 and 17% of that of the old technology and shows that pervaporation is also a powerful tool for the application of the principles of the sustainable development and consumption.

07/02238 Production of macroporous ceramics from fibres dispersed mortars (FDM) Maschio, S. et al. Ceramics International, 2007, 33, (1), 1–7. The authors examined the production of macroporous monolithic ceramic from mortars prepared using aluminate cements, one or two different types of alumina powders, superfluidificant, water and polyurethane fibres. Some relevant parameters for the preparation process of the mortar are: (i) the weight ratio between cement powder and water, (ii) the weight ratio between superfluidificant and cement powder and (iii) that between superfluidificant and water. Thirty-six percent is the upper limit is 36% for the volumetric content of the fibres that can be introduced into the mortar without leading to a material that breaks up by handling after the successive thermal cycle. The thermal cycle that may be used in order to avoid the spontaneous break-up of the material during the sintering treatment was also optimized. Materials containing fine and coarse particles of alumina powders exhibit extended ruptures probably dependent on the thermal stresses that grow on cooling after the sintering process, whereas in materials containing only fine alumina powders the presence of ruptures is more limited so that the fired materials have a sufficient strength and can be handled without a particular care. The ageing time at the maximum temperature plays an important role on the

microstructure of the sintered material since it has been seen that after 2 h at 1250  C the residual porosity seems to be completely closed and the large grain size shows the presence of structures which can be due to the presence of aluminates.

07/02239 Reactivation of limestone sorbents in FBC for SO2 capture Anthony, E. J. et al. Progress in Energy and Combustion Science, 2007, 33, (2), 171–210. Fluidized bed combustion (FBC) has the considerable advantage of being capable of burning high-sulfur fuels while achieving in situ sulfur capture by means of limestone addition. Unfortunately the efficiency of this process is limited, and limestone utilization in the range of 30–45% is not uncommon. In consequence, improving limestone utilization has long been an aim of FBC research. The principal directions this research has taken are the use of water (as liquid or vapour) to reactivate the spent sorbent, or mixing of chemical additives with the limestone to improve its utilization. Despite research stretching over the entire history of FBC combustion, there are still no working commercial applications of reactivation technology noted in the open literature. It is the aim of this paper to present some of the more important research undertaken in this field and to explore the major knowledge gaps that still exist in the area of sorbent reactivation.

07/02240 Simulation and exergy-method analysis of an industrial refrigeration cycle used in NGL recovery units Mehrpooya, M. et al. International Journal of Energy Research, 2006, 30, (15), 1336–1351. The behaviour of an industrial refrigeration cycle with refrigerant propane has been investigated by the exergy method. A natural gas liquid recovery unit with its refrigeration cycle has been simulated to prepare the exergy analysis. Using a typical actual work input value; the exergetic efficiency of the refrigeration cycle is determined to be 26.51% indicating a great potential for improvements. The obtained simulation results reveal that the exergetic efficiencies of the air cooler(s) and chilling sections get the lowest rank among the other compartments of refrigeration cycle. Refrigeration calculations have been carried out through the analysis of T–S and P–H diagrams where coefficient of performance (COP) was obtained as 1.8. The novelty of this article include the suggestions for increasing efficiencies, along with the discussion about the reasons for deviation from ideal cycles and also the effect and sensitivity analysis of pressure drops on the coefficient of performance of the cycle.

07/02241 Solvent effect on microstructure of yttria-stabilized zirconia (YSZ) particles in solvothermal synthesis Hua, Z. et al. Journal of the European Ceramic Society, 2006, 26, (12), 2257–2264. Using methanol or methanol/2-propanol mixtures as reaction media, yttria-stabilized zirconia (YSZ) particles were synthesized with a solvothermal route. The particles were characterized with X-ray diffractometry (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), laser diffraction technique, and nitrogen adsorption isotherms. Results indicated that cubic/tetragonal YSZ nanocrystals with crystal size lower than 5 nm were obtained and the crystal size depends on solvent composition, reaction temperature and reaction time. For the same reaction temperature and reaction time, the solvent composition also controls YSZ crystal agglomeration behaviour. According to the DLVO theory and analysis of experimental results, the solvent effect on microstructures of YSZ particles in solvothermal synthesis has been discussed. In addition, the mechanism of particle microstructure evolution during solvothermal synthesis has been suggested.

07/02242 Wind tunnel simulation of exhaust recirculation in an air-cooling system at a large power plant Gu, Z. et al. International Journal of Thermal Sciences, 2007, 46, (3), 308–317. The recirculation of hot exhaust air and its dependence on wind direction was investigated as a cause of reduced efficiency in an aircooled condenser (ACC). A method of simulating exhaust air recirculation at an ACC platform using a wind tunnel is presented, and applied to a proposed ACC addition at an existing power plant. It was found that wind speed and the height of an ACC platform have a significant impact on recirculation. Wind direction was also found to be significant, due to the interference of the buildings adjacent to the ACC platform. The mechanisms that cause recirculation are presented and analysed, and the characteristics of the recirculating flow are described. It was found that when considering additions to existing power plants, the distance of the new ACC and power plant from the original buildings and structures has only a minor effect on the recirculation of the added ACC platform. Wind tunnel simulation is recommended in the initial design stage of new or renovated power plants with ACC systems to minimize exhaust recirculation.

Fuel and Energy Abstracts September 2007 339

10 Space heating and cooling/heat pumps

10 SPACE HEATING AND COOLING/HEAT PUMPS 07/02243 A consolidated calcium chloride-expanded graphite compound for use in sorption refrigeration systems Oliveira, R. G. and Wang, R. Z. Carbon, 2007, 45, (2), 390–396. A consolidated composite reactive bed for refrigeration sorption systems made from expanded graphite powder impregnated with CaCl2 was produced and tested. The composite material was compressed under a pressure of 10 MPa to enhance its heat transfer properties. Experimental results showed that this material could incorporate 0.90 kg of NH3 per kg of salt and that the agglomeration phenomenon was avoided. The blocks with apparent density of 0.56 g cm3 and 35% of expanded graphite ensured a good refrigerant mass transfer with a negligible pressure drop between the inner and outer part of the blocks. However, the heat transfer still need some improvements, as the temperature difference inside the blocks could reach 15  C during the decomposition phase. The average specific cooling power during the synthesis phase was 306 and 194 W per kg of salt at the average evaporation temperatures of 2.7 and 18.3  C, respectively. The calculated coefficient of performance under different generation temperatures and global conversions ranged from 0.28 to 0.46, and it was not very sensitive to the increase of the generation temperature.

07/02244 A new heat pump desiccant dehumidifier for supermarket application Lazzarin, R. M. and Castellotti, F. Energy and Buildings, 2007, 39, (1), 59–65. Recently a new equipment for dehumidification was put onto the market. It is a self-regenerating liquid desiccant cooling system able to dehumidify, heating or cooling the ambient air by an electric heat pump that is a part of the equipment. Its operation is here studied in a supermarket application where air temperature and relative humidity play a very important role and the air-conditioning becomes necessary not only to assure a suitable thermal comfort, but also to make the refrigerated display cabinets operate properly. In this paper possible energy savings, compared to a traditional mechanical dehumidification, are evaluated by means of a numerical model that simulates a typical Italian supermarket.

07/02245 A stochastic method to generate bin weather data in Nanjing, China Zhou, J. et al. Energy Conversion and Management, 2006, 47, (13–14), 1843–1850. The bin method, as one of the well-known and simple steady state methods used to predict heating and cooling energy consumption of buildings, requires reliable and detailed bin data. Since the long-term hourly temperature records are not available in China, there is a lack of bin weather data for study and use. In order to keep the bin method practical in China, a stochastic model using only the daily maximum and minimum temperatures to generate bin weather data was established and tested by applying one year of measured hourly ambient temperature data in Nanjing, China. By comparison with the measured values, the bin weather data generated by the model shows adequate accuracy. This stochastic model can be used to estimate the bin weather data in areas, especially in China, where the long term hourly temperature records are missing or not available.

07/02246 A techno-economic comparison of groundcoupled and air-coupled heat pump system for space cooling Esen, H. et al. Building and Environment, 2007, 42, (5), 1955–1965. This paper reports a techno-economic comparison between a groundcoupled heat pump (GCHP) system and an air-coupled heat pump (ACHP) system. The systems connected to a test room in Firat University, Elazig (38.41 N, 39.14 E), Turkey, were designed and constructed for space cooling. The performances of the GCHP and the ACHP system were experimentally determined. The experimental results were obtained from June to September in cooling season of 2004. The average cooling performance coefficients (COPsys) of the GCHP system for horizontal ground heat exchanger (HGHE) in the different trenches, at 1 and 2 m depths, were obtained to be 3.85 and 4.26, respectively and the COPsys of the ACHP system was determined to be 3.17. The test results indicate that system parameters can have an important effect on performance, and that GCHP systems are economically preferable to ACHP systems for the purpose of space cooling.

07/02247 A theoretical study of a novel regenerative ejector refrigeration cycle Yu, J. and Li, Y. International Journal of Refrigeration, 2007, 30, (3), 464–470.

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There has been a demand for developments of the ejector refrigeration systems using low grade thermal energy, such as solar energy and waste heat. In this paper, a novel regenerative ejector refrigeration cycle was described, which uses an auxiliary jet pump and a conventional regenerator to enhance the performance of the novel cycle. The theoretical analysis on the performance characteristics was carried out for the novel cycle with the refrigerant R141b. Compared with the conventional cycle, the simulation results show that the coefficient of performance (COP) of the novel cycle increases, respectively, by from 9.3 to 12.1% when generating temperature is in a range of 80–160  C, the condensing temperature is in a range of 35–45  C and the evaporating temperature is fixed at 10  C. Especially due to the enhanced regeneration with increasing the pump outlet pressure, the improvement of COP of the novel cycle is approached to 17.8% compared with that in the conventional cycle under the operating condition that generating temperature is 100  C, condensing temperature is 40  C and evaporating temperature is 10  C. Therefore, the characteristics of the novel cycle performance show its promise in using low grade thermal energy for the ejector refrigeration system.

07/02248 A two-factor method for appraising building renovation and energy efficiency improvement projects Martinaitis, V. et al. Energy Policy, 2007, 35, (1), 192–201. The renovation of residential buildings usually involves a variety of measures aiming at reducing energy and building maintenance bills, increasing safety and market value, and improving comfort and aesthetics. A significant number of project appraisal methods in current use – such as calculations of payback time, net present value, internal rate of return or cost of conserved energy (CCE) – only quantify energy efficiency gains. These approaches are relatively easy to use, but offer a distorted view of complex modernization projects. On the other hand, various methods using multiple criteria take a much wider perspective but are usually time-consuming, based on sometimes uncertain assumptions and require sophisticated tools. A ‘two-factor’ appraisal method offers a compromise between these two approaches. The main idea of the method is to separate investments into those related to energy efficiency improvements, and those related to building renovation. Costs and benefits of complex measures, which both influence energy consumption and improve building constructions, are separated by using a building rehabilitation coefficient. The CCE is used for the appraisal of energy efficiency investments, while investments in building renovation are appraised using standard tools for the assessment of investments in maintenance, repair and rehabilitation.

07/02249 Adaptive control design for VSC-HVDC systems based on backstepping method Ruan, S.-Y. et al. Electric Power Systems Research, 2007, 77, (5–6), 559–565. An adaptive control design is proposed to improve dynamic performances of voltage source converter high voltage direct current (VSCHVDC) systems. The adaptive controller design for nonlinear characteristics of VSC-HVDC systems, which is based on backstepping method, considers parameters uncertainties. For an original high-order system, the final control laws can be derived step by step through suitable Lyapunov functions. Thus, the design process is not complex. The effectiveness of the proposed adaptive controllers is demonstrated through digital simulation studies on a VSC-HVDC power system, using the PSCAD/EMTDC software package. The simulation results show that the controllers contribute significantly toward improving the dynamic behaviour of the VSC-HVDC system under a wide range of operating conditions.

07/02250 An experimental system for advanced heating, ventilating and air conditioning (HVAC) control Anderson, M. et al. Energy and Buildings, 2007, 39, (2), 136–147. While having the potential to significantly improve heating, ventilating and air conditioning (HVAC) system performance, advanced (e.g. optimal, robust and various forms of adaptive) controllers have yet to be incorporated into commercial systems. Controllers consisting of distributed proportional-integral (PI) control loops continue to dominate commercial HVAC systems. Investigation into advanced HVAC controllers has largely been limited to proposals and simulations, with few controllers being tested on physical systems. While simulation can be insightful, the only true means for verifying the performance provided by HVAC controllers is by actually using them to control an HVAC system. The construction and modelling of an experimental system for testing advanced HVAC controllers, is the focus of this article. A simple HVAC system, intended for controlling the temperature and flow rate of the discharge air, was built using standard components. While only a portion of an overall HVAC system, it is representative of a typical hot water to air heating system. In this article, a single integrated environment is created that is used for data acquisition, controller design, simulation, and closed loop

10 Space heating and cooling/heat pumps controller implementation and testing. This environment provides the power and flexibility needed for rapid prototyping of various controllers and control design methodologies.

07/02251 Analysis of design approaches to improve the comfort level of a small glazed-envelope building during summer Kim, K. et al. Solar Energy, 2007, 81, (1), 39–51. An architect applies glazing to a building envelope to express an expansiveness and hi-tech quality through transparency. However, in small over-glazed buildings, the glazed envelopes often lead to an inadequate comfort level in summer, when much cooling energy is needed to improve the comfort level and occupants are forced to avoid the use of glazed envelopes. This paper presents the results of comfort survey and measurements on the indoor environment of an architecturally significant small glazed-envelope building that has received many awards for its architectural design quality, and analyses design approaches to improve the comfort level of its occupants. During the late summer of 2002, the comfort survey was conducted, polling responses from 57 office workers, while simultaneously measuring air/ surface temperatures and daylight factors. Numerical simulations were performed to investigate 13 design approaches for the improvement of the comfort level. From the temperature/daylight factor measurements, the indoor air temperature did not maintain the set-point temperature of 24.0  C even with the operation of the air-conditioning system. When using the roller shades, the intensities of illumination and luminance on each measured desk surface were unevenly distributed from 650 Lux and 51 cd/m2 to 6291 Lux and 310 cd/m2. From the survey, office workers suffered thermal discomfort and uncomfortable glare from high or non-uniform brightness distributions in the working areas. From the numerical analyses using computer simulations, the doubleskin envelopes with the sufficient intermediate space and shading devices were suggested to improve the comfort level.

07/02252 Analysis of enthalpy change with/without a heat pipe heat exchanger in a tropical air conditioning system Yao, Y. H. International Journal of Energy Research, 2006, 30, (15), 1251–1263. In an earlier paper, the baseline performance characteristics of the eight-row wickless heat pipe heat exchanger (HPHX) were established for it being used in a vertical configuration under tropical climate conditions. The present paper covers the tests and simulation conducted on the same experimental HVAC system without the HPHX installed, thereby determining the enthalpy change for the air passing through the chilled water coil (CWC) alone (i.e. without the pre-cooling or reheating effect of the HPHX). These experimental results, in comparison with those already obtained, would also allow an examination of how the reheat recovery with the eight-row HPHX installed was influenced by the same key inlet parameters. The final results show that the enthalpy change with a HPHX installed for all cases examined are significantly higher than enthalpy change without a HPHX installed, demonstrating that the cooling capability of the CWC was enhanced by the HPHX.

07/02253 Annual performance of liquid desiccant based independent humidity control HVAC system Liu, X. et al. Applied Thermal Engineering, 2006, 26, (11–12), 1198– 1207. Based on a new type of sprayed liquid desiccant total heat recovery device, this paper presents the working principle of a liquid desiccant system combined refrigeration/heat grid system with the independent humidity control (IHC) strategy, in which the liquid desiccant system operates annually instead of only in the summer and removes the entire latent load and part of the sensible load. Electrical coefficient of performance (ECOP) and thermal coefficient of performance (TCOP) are adopted here to evaluate the performance of the IHC system. Reduced primary energy and operating cost differences of the IHC system and the conventional HVAC system are analysed based on annual hour-by-hour simulation results for the Beijing climate. It is shown that (1) in summer, when the average latent load covers 30%, the average ECOP and TCOP of the IHC system are 6.7 and 6.8, primary energy consumption and operating cost are 78% and 75%, respectively, of the conventional HVAC system; and (2) in winter when average latent load covers 10%, the average TCOP of the IHC system is 1.34, primary energy consumption and operating cost are 62% and 57%, respectively, compared with the conventional system.

07/02254 Annual thermal performance of greenhouse with an earth–air heat exchanger: an experimental validation Tiwari, G. N. et al. Renewable Energy, 2006, 31, (15), 2432–2446. In this paper the thermal model given by Ghoshal and Tiwari has been validated by round-the-year experimental work at IIT Delhi, New Delhi (28 350 N, 77 120 E), India. The correlation coefficient and root-meansquare percentage deviation have been computed for each month for validation of the thermal model. The values are 0.99% and 4.24% for

the greenhouse temperature with an earth–air heat exchanger (EAHE) in the month of January. Statistical analysis shows that there is fair agreement between predicted and experimental values. An effort has also been made to optimize the working hours of an EAHE to obtain maximum heating/cooling potential. The non-operational hours of an EAHE are 252 and 279 for February and March months, respectively. The maximum value of heating potential (11.55 MJ) and cooling potential (18.87 MJ) has been found during off sunshine (8 pm–8 am) hours and peak sunshine hours (8 am–8 pm), for a typical day in the month of January and June.

07/02255 Application of a heat pipe heat exchanger to dehumidification enhancement in a HVAC system for tropical climates – a baseline performance characteristics study Yau, Y. H. International Journal of Thermal Sciences, 2007, 46, (2), 164–171. In Malaysia, humidity control is a common problem in built environments in tropical hot and humid climates as it is an important aspect of the maintenance of comfortable and healthy conditions within a controlled airspace. An eight-row thermosyphon-based heat pipe heat exchanger (HPHX) for tropical building HVAC systems was studied experimentally. This research was an investigation into how the sensible heat ratio (SHR) of the eight-row HPHX was influenced by each of three key parameters of the inlet air state, namely, dry-bulb temperature, relative humidity and air velocity. On the basis of this study, it is recommended that tropical HVAC systems should be installed with heat pipe heat exchangers for dehumidification enhancement.

07/02256 Characteristics of condensing and evaporating heat transfer using hydrocarbon refrigerants Lee, H.-S. et al. Applied Thermal Engineering, 2006, 26, (10), 1054– 1062. This paper discusses the heat transfer characteristics of R-290 (propane), R-600a (iso-butane) and R-1270 (propylene) as an environment-friendly refrigerant and R-22 as a HCFCs refrigerant for condensing and evaporating. An experiment was performed for a conventional vapour compression type heat pump system. The test section was a horizontal double-pipe heat exchanger. A tube diameter of 12.70 mm with 1.315 mm wall thickness was used for this experiment. The experimental results show that the local condensing heat transfer coefficients of hydrocarbon refrigerants were higher than those of R22. The average condensing heat transfer coefficient for R-1270 was a maximum value and for R-22 was a minimum value among the refrigerant tested. The experimental results of comparing the condensing heat transfer coefficients agreed satisfactorily to the referenced simulation data such as the Cavallini–Zecchin’s correlation for all refrigerants. The local evaporating heat transfer coefficients of hydrocarbon refrigerants were higher to those of R-22. The average evaporating heat transfer coefficient increased with the increase of mass velocity. The results show that the evaporating heat transfer coefficients in hydrocarbon refrigerants were higher than that of R-22. The experimental results for all the refrigerants in general agreed with Kandlikar’s correlation for the evaporating heat transfer.

07/02257 Climatic potential for passive cooling of buildings by night-time ventilation in Europe Artmann, N. et al., Applied Energy, 2007, 84, (2), 187–201. Due to an overall trend towards less heating and more cooling demands in buildings in many European countries over the last few decades, passive cooling by night-time ventilation is seen as a promising technique, particularly for commercial buildings in the moderate or cold climates of Central, Eastern and Northern Europe. The basic concept involves cooling the building structure overnight in order to provide a heat sink that is available during the occupancy period. In this study, the potential for passive cooling of buildings by night-time ventilation was evaluated by analysing climatic data, without considering any building-specific parameters. An approach for calculating degree–hours based on a variable building temperature – within a standardized range of thermal comfort – is presented and applied to climatic data of 259 stations all over Europe. The results show a high potential for night-time ventilative cooling over the whole of Northern Europe and still significant potential in Central, Eastern and even some regions of Southern Europe. However, due to the inherent stochastic properties of weather patterns, a series of warmer nights can occur at some locations, where passive cooling by night-time ventilation alone might not be sufficient to guarantee thermal comfort.

07/02258 Combination technique for improving natural convection cooling in electronics Florio, L. A. and Harnoy, A. International Journal of Thermal Sciences, 2007, 46, (1), 76–92.

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10 Space heating and cooling/heat pumps The combination of an appropriately placed cross-flow opening and a strategically positioned transversely vibrating plate is proposed as a means of augmenting pure natural convection in a vertical channel. This method is intended to provide a more efficient, reliable, and consumer conscious alternative to conventional techniques for lower power dissipating devices where standard natural convection cooling proves insufficient. Two-dimensional numerical simulations are employed to investigate this combination method using models consisting of a vertical channel containing two rectangular heat sources which are attached to a vertical mounting board, as well as a transversely oscillating plate and a cross-flow opening in the mounting board area between the two heat sources. Varied parameters and geometric configurations are studied. The results indicate the combined effects of the vibrating plate and the opening flow have the potential to cause significant improvement in the thermal conditions over pure natural convection. As much as a 70% improvement in the local heat transfer coefficient from that for a system with a board opening but without a vibrating plate was attained.

07/02259 Condensate retention on a louver-fin-and-tube air cooling coil Xu, X. et al. International Journal of Refrigeration, 2007, 30, (3), 409– 417. This paper presents a study of condensate retention on a louvre-finand-tube air cooling coil, which is commonly used in air-conditioning systems. Compared to previously related work focusing on the influence of condensate retention on the heat and mass transfer between air and a cooling coil, the present study emphasizes the impacts of operating parameters on condensate retention on a cooling coil. A new method to describe the steady-state condensation has been suggested and a new mathematical model to represent the force balance of retained condensate developed. The mass of condensate retained has been measured experimentally under various operating conditions of a direct expansion air cooling and dehumidification system. The influences of air dry-bulb temperature, moisture content and Reynolds Number on condensate retention are discussed. The model developed relates the mass of condensate retained to condensing rate, and is successful in predicting the trends of condensate retention under normal operating conditions for air cooling applications.

07/02260 Constructal multi-scale design of compact microtube heat sinks and heat exchangers Muzychka, Y. S. International Journal of Thermal Sciences, 2007, 46, (3), 245–252. A constructal multi-scale design approach is examined for micro-tube heat sinks and heat exchangers. Heat transfer per unit volume is increased by considering the use of additional micro-tubes placed in the intersticial regions of a circular tube array. Three constructs are considered in the proposed analysis. As the system complexity increases, the heat transfer rate increases, and exceeds the theoretical value for a volume of similar size, composed of parallel plates. Approximate solutions for the diameter of the principal construct are obtained for each case using Bejan’s intersection of asymptotes method. Exact analytical methods are applied to determine the relative increase in heat dissipation per unit volume as compared with systems containing parallel plates.

07/02261 Determinants of residential space heating expenditures in Germany Rehdanz, K. Energy Economics, 2007, 29, (2), 167–182. The authors first examine the determinants of household expenditures on space heating and hot water supply in Germany. A number of socioeconomic characteristics of households are included along with building characteristics. The analysis covers information on more than 12,000 households in Germany for the years 1998 and 2003. The analysis continues by investigating whether different kinds of households are affected differently by increases in energy prices. Households in owner-occupied properties are less affected compared to those in rented accommodation, this could be because owners are more likely to have installed energy-efficient heating and hot water supply systems and landlords have less of an incentive to improve the conditions of their rented accommodations. An energy policy targeting especially the latter group might benefit not only households in rented accommodation, but might also increase energy-efficiency and reduce greenhouse gas emissions as well.

07/02262 Determination of optimum insulation thickness for building walls with respect to various fuels and climate zones in Turkey Bolattu ¨ rk, A. Applied Thermal Engineering, 2006, 26, (11–12), 1301– 1309. In Turkey, heat loss from buildings is one of the primary sources of energy waste since no or little insulation is used in existing and new buildings. Therefore, considerable energy savings can be obtained by

342 Fuel and Energy Abstracts September 2007

using proper thickness of insulation in buildings. Given the significant climatic variations that exist in different parts of Turkey, 16 cities from four climate zones of Turkey are selected for analysis and optimum insulation thicknesses, energy savings, and payback periods are calculated. The annual heating requirements of buildings in different climates zones were obtained by means of the heating degree-days concept. The optimization is based on life-cycle cost analysis. Five different fuels; coal, natural gas, fuel oil, liquefied petroleum gas, and electricity, and as an insulation material polystyrene are considered. The results show that optimum insulation thicknesses vary between 2 and 17 cm, energy savings between 22% and 79%, and payback periods between 1.3 and 4.5 years depending on the city and the type of fuel.

07/02263 Development and validation of online models with parameter estimation for a building zone with VAV system Wen, J. and Smith, T. F. Energy and Buildings, 2007, 39, (1), 13–22. The energy consumption by building heating, ventilating, and air conditioning (HVAC) systems has evoked increasing attention to promote energy efficient control and operation of HVAC systems. Application of advanced control and operation strategies requires robust online system models. In this study, online models with parameter estimation for a building zone with a variable air volume system, which is one of the most common HVAC systems, are developed and validated using experimental data. Building zone temperature and zone entering air flow are modelled based on physical rules and only the measurements that are commonly available in a commercial building are used. Various validation experiments were performed using a real-building test facility to examine the prediction accuracies for system outputs. Using the online system models with parameter estimation, the prediction errors for all validation experiments are less than 0.28  C for temperature outputs, and less than 84.9 m3/h for air flow outputs. The online models can be further used for local and supervisory control, as well as fault detection applications.

07/02264 Economic benefits of improved condenser features for air-cooled chillers serving an air-conditioned hotel Yu, F. W. and Chan, K. T. Applied Thermal Engineering, 2006, 26, (10), 1063–1073. Air-cooled chillers can take up around one-fourth of the total electricity consumption of an air-conditioned building. This paper evaluates the potential electricity cost savings of these chillers with improved condenser features of condensing temperature control, evaporative pre-coolers and variable speed condenser fans. A validated model for an air-cooled screw chiller was used to ascertain how the individual and mixed features influence the annual electricity consumption of chillers operating for the cooling load profile of a hotel. With regard to a chiller plant with a 15-year lifespan, the life cycle electricity cost savings are estimated at between HK$2,291,247 and 8,320,732, depending on the features used. The simple payback of the features could range from 1.07 to 3.32 years. These findings show how chiller manufacturers and building owners can profit from implementing energy efficient technologies for air-cooled chillers.

07/02265 Effect of heat conduction through the fins of a microchannel serpentine gas cooler of transcritical CO2 system Park, C. Y. and Hrnjak, P. International Journal of Refrigeration, 2007, 30, (3), 389–397. This paper presents results of an experimental study to investigate the effect of conduction through the fins on the capacity of a serpentine gas cooler. The gas cooler was a part of a transcritical CO2 system which was operated in A/C mode. The capacity of the gas cooler was carefully measured in the chamber that simulated the outdoor condition with the original heat exchanger. In order to experimentally validate the conduction effect on the capacity, some sections of the fins, where the conduction was most significant, were cut by electrical discharge machining. The capacity of the heat exchanger, after cutting fins, was measured in the same chamber at nearly identical test conditions as before cutting. Gas cooler capacity was improved up to 3.9% by cutting the fins, and temperature difference between refrigerant exit and air inlet for the gas cooler was reduced by 0.9–1.5  C. The maximum uncertainty in the capacity measurements was 2.5% and the accuracy of temperature measurements was 0.1  C. It was shown by system simulation that system COP could be improved by 5% by eliminating this severe conduction effect, as was done in this experiment. The tube surface temperature at some points of the gas cooler was measured and infrared images were taken to show the conduction effect before and after cutting fins.

07/02266 Effect of propeller type swirl generators on the entropy generation and efficiency of heat exchangers Kurtbas, , I. et al. International Journal of Thermal Sciences, 2007, 46, (3), 300–307.

10 Space heating and cooling/heat pumps In this study, the effects of propeller-type turbulators located in the inner pipe of co-axial heat exchanger were investigated on entropy generation rate (Ns) and exergy loss rate (E*). Propeller-type turbulators have blade angles () of 10 , 20 and 40 , also at each angle the propellers have diameter (Db) of 48 mm, 50 mm and 52 mm. These turbulators were mounted in the inner pipe by different distances (Lt). According to the flow observation experiments, maximum decaying distance of swirl flow was found as 30 cm. The experiments were performed with different distances of turbulators. In this system, heat transfer, entropy generation rate and exergy loss rate were investigated. Then, the effects of angle, diameter and number of the blades on the heat transfer, entropy generation rate and exergy loss rate was investigated and compared with each other for different values of the Reynolds number, from 104 to 3104, and Prandtl number equal to 0.71. It was seen that Nusselt number and exergy loss rate approximately increased from 95 to 354 and 0.04 to 0.2 depending on blade angle, interturbulator distance and propeller diameter for 104  Re<3104. Efficiency of the heat exchanger changed at between 0.17 to 0.72 levels.

As a high-efficiency air-conditioning scheme, the variable refrigerant flow (VRF) air-conditioning system is finding its way in office buildings. However, there is no well-known energy simulation software available so far which can be used for the energy analysis of VRF. Based on the generic dynamic building energy simulation environment, EnergyPlus, a new VRF module is developed and the energy usage of the VRF system is investigated. This paper compares the energy consumption of the VRF system with that of two conventional airconditioning systems, namely, variable air volume (VAV) system as well as fan-coil plus fresh air (FPFA) system. A generic office building is used to accommodate the different types of heating, ventilating, and air-conditioning (HVAC) systems. The work focuses on the energy consumption of the VRF system in the office buildings and helps the designer’s evaluation and decision-making on the HVAC systems in the early stages of building design. Simulation results show that the energysaving potentials of the VRF system are expected to achieve 22.2% and 11.7%, compared with the VAV system and the FPFA system, respectively. Energy-usage breakdown for the end-users in various systems is also presented.

07/02267 Effect of throat diameters of the ejector on the performance of the refrigeration cycle using a two-phase ejector as an expansion device

07/02271 Exergy-based ecological optimization for a generalized irreversible Carnot heat-pump

Chaiwongsa, P. and Wongwises, S. International Journal of Refrigeration, 2007, 30, (4), 601–608. This paper is a part in a series that reports on the experimental study of the performance of the two-phase ejector expansion refrigeration cycle. In the present study, three two-phase ejectors are used as an expansion device in the refrigeration cycle. The effects of throat diameter of the motive nozzle, on the coefficient of performance, primary mass flow rate of the refrigerant, secondary mass flow rate of the refrigerant, recirculation ratio, average evaporator pressure, compressor pressure ratio, discharge temperature and cooling capacity, which have never before appeared in open literature, are presented. The effects of the heat sink and heat source temperatures on the system performance are also discussed.

07/02268 Energy and exergy performance of residential heating systems with separate mechanical ventilation Zmeureanu, R. and Wu, X. Y. Energy, 2007, 32, (3), 187–195. The paper brings new evidence on the impact of separate mechanical ventilation system on the annual energy and exergy performance of several design alternatives of residential heating systems, when they are designed for a house in Montreal. Mathematical models of residential heating, ventilation and domestic hot water (HVAC–DHW) systems, which are needed for this purpose, are developed and furthermore implemented in the engineering equation solver environment. The coefficient of performance and the exergy efficiency are estimated as well as the entropy generation and exergy destruction of the overall system. The equivalent greenhouse gas emissions due to the on-site and off-site use of primary energy sources are also estimated. The addition of a mechanical ventilation system with heat recovery to any HVAC– DHW system discussed in the paper increases the energy efficiency; however, it decreases the exergy efficiency, which indicates a potential long-term damaging impact on the natural environment. Therefore, the use of a separate mechanical ventilation system in a house should be considered with caution, and recommended only when other means for controlling the indoor air quality cannot be applied.

07/02269 Energy efficient building design using sensitivity analysis – a case study de Almeida Ferreira Tavares, P. F. and de Oliveira Gomes Martins, A. M. Energy and Buildings, 2007, 39, (1), 23–31. A case-study of a public building is presented as an example of the adequacy of timely analyses of building performance, based on a preliminary architectural design. The final design of the case-study building benefited of the thorough analysis performed at this early stage, the main motivation being the willingness of a town government of an intelligent design, leading to a sustainable town-hall building, in a town in the centre region of Portugal. A virtuous combination of a receptive building owner and a multidisciplinary design team, allowed a systematic methodology to be used, providing the opportunity for the consideration of several options for each class of constructive element and the possibility of choosing among the options for each case, based on quantitative results on the expected performance of the building. The options were created and analysed with the help of the VisualDOETM building simulation tool, aiming at a comfortable and energy efficient building. Several parameters were used for enabling the sensitivity analyses, namely relating to wall structure and materials, window frames, HVAC system, etc.

07/02270 Energy simulation in the variable refrigerant flow air-conditioning system under cooling conditions Zhou, Y. P. et al. Energy and Buildings, 2007, 39, (2), 212–220.

Chen, L. et al. Applied Energy, 2007, 84, (1), 78–88. The optimal exergy-based ecological performance of a Newton’s law generalized irreversible Carnot heat-pump, with losses due to heatresistance, heat leak and internal irreversibility, is derived by taking into account an ecological optimization criterion as the objective function. This consists of maximizing a function representing the best compromise between the exergy-output rate and exergy-loss rate (i.e. entropy-production rate) of the heat-pump. Numerical examples are given to show the effects of heat leakage and internal irreversibility on the optimal performance of the generalized irreversible heat-pump.

07/02272 Experimental analysis of the scroll compressor performances varying its speed Aprea, C. et al. Applied Thermal Engineering, 2006, 26, (10), 983–992. Referring to a vapour compression plant able to operate both as water chiller and heat pump, the aim of this paper is to evaluate experimentally the energy saving obtainable varying the scroll compressor speed to control the refrigeration capacity instead of the classical thermostatic control. The compressor speed is continuously controlled by means of a fuzzy algorithm regulating an inverter located on the electric line supplying the compressor motor. On the contrary the control by thermostat imposes on/off cycles on the compressor that works at the nominal frequency of 50 Hz. In particular, the performances of a vapour compression experimental plant, generally used in industrial processing or conditioning plants where a supply of refrigerated and reheated water is required, are studied. The experimental plant is made up of an hermetic scroll compressor, a plate-type water heat exchanger inserted in a water tank, a finned tube air heat exchanger, two thermostatic expansion valves that have substituted the classical capillaries not suitable for fast load variations. The use of a scroll compressor allows to have a compressor electric motor supply current frequency even of 15 Hz in comparison with the semi-hermetic reciprocating compressor that for frequency values under 30 Hz presents considerable vibrations and noise increase together with the lubrication troubles due to the splash system. For different working conditions a significant energy saving on average equal to about 20% has been obtained adopting a scroll compressor speed control algorithm, based on the fuzzy logic, in comparison with the classical thermostatic control. Moreover, in this paper the aim has been to determine also experimentally the optimum frequency, corresponding to a definite heating (cooling) load, to be imposed to a compressor electric motor by means of an inverter to obtain the highest energy saving.

07/02273 Experimental and numerical study on charging processes of an ice-on-coil thermal energy storage system Erek, A. and Ezan, M. A. International Journal of Energy Research, 2007, 31, (2), 158–176. In this study, an external melt ice-on-coil thermal storage was studied and tested over various inlet conditions of secondary fluid – glycol solution – flow rate and temperature in charging process. Experiments were conducted to investigate the effect of inlet conditions of secondary fluid and validate the numerical model predictions on iceon-coil thermal energy storage system. The total thermal storage energy and the heat transfer rate in the system were investigated in the range of 101 min1 V  60 l min1. A new numerical model based on temperature transforming method for phase change material (PCM) described by Faghri was developed to solve the problem of the system consisting of governing equations for the heat transfer fluid, pipe wall and PCM. Numerical simulations were performed to investigate the effect of working conditions of secondary fluid and these were compared with the experimental results. The numerical results verified

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10 Space heating and cooling/heat pumps with experimental investigation show that the stored energy rises with increasing flow rate a decreasing tendency. It is also observed that the inlet temperature of the fluid has more influence on energy storage quantity than flow rate.

07/02274 Experimental investigation of a liquid desiccant system for solar cooling and dehumidification Gommed, K. and Grossman, G. Solar Energy, 2007, 81, (1), 131–138. Growing demand for air conditioning in recent years has caused a significant increase in demand for primary energy resources. Solarpowered cooling is one of the environmentally-friendly techniques which may help alleviate the problem. A promising solar cooling method is through the use of a liquid desiccant system, where humidity is absorbed directly from the process air by direct contact with the desiccant. The desiccant is then regenerated, again in direct contact with an external air stream, by solar heat at relatively low temperatures. The liquid desiccant system has many potential advantages over other solar air conditioning systems and can provide a promising alternative to absorption or to solid desiccant systems. Earlier work by the authors included theoretical simulations and preliminary experiments on the key components of the liquid desiccant system. The objective of the present study has been to construct a prototype system based on the knowledge gained, to monitor its performance, identify problems and carry out preliminary design optimization. A 16 kWt system was installed at the Energy Engineering Center at the Technion, in the Mediterranean city of Haifa. The system comprises a dehumidifier and a regenerator with their associated components operating together to dehumidify the fresh (ambient) air supply to a group of offices on the top floor of the building. LiCl-water is employed as the working fluid. The system is coupled to a solar collector field and employs two methods of storage – hot water and desiccant solution in the regenerated state. The performance of the system was monitored for five summer months under varying operating conditions. The paper describes the operation of the experimental system and presents the measured data and the calculated performance parameters.

07/02275 Experimental microchannel heat sink performance studies using nanofluids Chein, R. and Chuang, J. International Journal of Thermal Sciences, 2007, 46, (1), 57–66. In this study, microchannel heat sink (MCHS) performance using nanofluids as coolants is addressed. First a simple theoretical analysis was carried out that indicated more energy and lower MCHS wall temperature could be obtained under the assumption that heat transfer could be enhanced by the presence of nanoparticles. Experiments were then performed to verify the theoretical predictions. A silicon MCHS was made and CuO–H2O mixtures without a dispersion agent were used as the coolants. The CuO particle volume fraction was in the range of 0.2 to 0.4%. It was found that nanofluid-cooled MCHS could absorb more energy than water-cooled MCHS when the flow rate was low. For high flow rates, the heat transfer was dominated by the volume flow rate and nanoparticles did not contribute to the extra heat absorption. The measured MCHS wall temperature variations agreed with the theoretical prediction for low flow rate. For high flow rate, the measured MCHS wall temperatures did not completely agree with the theoretical prediction due to the particle agglomeration and deposition. It was also found that raising the nanofluid bulk temperature could prevent the particles from being agglomerated into larger scale particle clusters. The experimental result also indicated that only slightly increase in pressure drop due to the presence of nanoparticles in MCHS operation.

07/02276 Experimental study on an absorption refrigeration system at low temperatures He, Y. and Chen, G. International Journal of Thermal Sciences, 2007, 46, (3), 294–299. The heat-driven auto-cascade absorption refrigeration cycle can be used at low temperatures, and a novel auto-cascade absorption refrigeration system is proposed to gain better performances with a refrigerating temperature as low as 50  C. The new system uses a mixture of R23 + R32 + R134a/DMF as its working pair and its characteristic study is carried out under different operational conditions. It has successfully obtained a refrigerating temperature of 47.2  C under the generating temperature of 163  C. This refrigerating temperature is far lower than that of a traditional absorption refrigeration system with the same working pair, and it is also lower than that of an auto-cascade absorption refrigeration system using R32 + R134a/DMF as its working pair. From the experimental results, it is clearly seen that this new system shows a rapider lowering rate of refrigerating temperature than that of an auto-cascade absorption refrigeration system using R23 + R134a/DMF as its working pair. The results of experimental analyses imply that this new absorption refrigeration system can be used in the deep-freezing as low as 50  C by utilizing low-potential thermal power. Its potential of

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industrial application might be greater than that of an auto-cascade absorption refrigeration system using R23 + R134a/DMF as its working pair in the future.

07/02277 Extension of the applicable range of the implicit curve-fitting method for refrigerant thermodynamic properties to critical pressure Guo, L. D. et al. International Journal of Refrigeration, 2007, 30, (3), 418–432. The method of implicit curve-fitting and explicit-calculation has been used for fast and stable calculations of thermodynamic properties of subcritical refrigerants. In order to extend that method to the critical pressure, a method of sectional implicit curve-fitting and explicitcalculation for refrigerant thermodynamic properties is introduced in this paper. The whole data range is divided into several subsections. The requirements on the continuity of thermodynamic properties and the first order derivative of thermodynamic properties in the intersection points of subsections are indicated, and the methods to meet the requirements are presented. Quadric equations are constructed instead of curve-fitting when no data can be given. With the source data obtained from REFPROP 7.1, explicit fast calculation formulae for thermodynamic properties of R410A, covering the saturated temperature of 213.15–344.51 K and superheat of 0–65 K, are given as an example. The calculation speeds of the formulae of R410A are more than 7000 times faster than those of REFPROP 7.1 while the total mean relative deviation of the fast calculation formulae from REFPROP 7.1 is only 0.04%.

07/02278 Family design of scroll compressors with optimization Tseng, C.-H. and Chang, Y.-C. Applied Thermal Engineering, 2006, 26, (10), 1074–1086. This paper proposes a systematic design method for developing a family of scroll-type compressor (STC). Except of using the general design optimization model includes multi-variable, direct search, inequality constraints, both interactive session and discrete variable design optimization skills have also been employed in this study. A practical design case on the 5200–9800 W capacity range of the STC family using R22 refrigerant has been implemented, and to achieve a common share percentage of 80% for the major components of this STC series plus a coefficient of performance based on electrical power input (COPel) of over 3.02 for each specified capacity of this family. Comparisons between calculated and measured results show that the maximum deviation of cooling capacity and COPel are below 2.53% and 1.69%, respectively.

07/02279 Field experiments on natural energy utilization in a residential house with a double skin fac˛ade system Xu, L. and Ojima, T. Building and Environment, 2007, 42, (5), 2014– 2023. Energy consumption in the residential and commercial sector accounts for over 25% of the total in Japan. With the information technology revolution and the improving requirement for indoor air environment, energy consumption for household air conditioning is increasing. In this research, a double skin facade is proposed for a two-storey house in Kitakyushu of Japan. The stack effect in the double skin space during the summer, the greenhouse effect during the winter and the availability for free air-conditioning during the autumn have been studied. The temperature distribution, thermal performance in the double skin space and its impact on air-conditioning load in rooms have been measured. Results show that the double skin facade leads to about 10–15% energy saving for cooling in the peak of summer because of heat exhausted by natural ventilation, 20–30% energy for heating in winter because of the greenhouse effect, and the temperature adjustment is quite large with the different operation mode of the double skin system during the intermediate seasons. Therefore the double skin system is proved to be effective in energy conservation in residential buildings.

07/02280

Greenhouse effect in double-skin facade

Gratia, E. and De Herde, A. Energy and Buildings, 2007, 39, (2), 199– 211. In these last years, a great deal of interest has been devoted to doubleskin facades due to the advantages claimed by this technology (in terms of energy saving in the cold season, high-tech image, protection from external noise and wind loads). One of the great characteristics of the double-skin facade is the greenhouse effect. The factors are identified that influence the greenhouse effect. The identified parameters are solar radiation level, orientation and shading devices use, opaque wall/ window proportion of the interior facade, wind speed, colour of shading devices and of interior facade, depth of the cavity of the double-skin, glazing type in the interior facade and openings in the double-skin. The authors analyse the impact of these parameters

10 Space heating and cooling/heat pumps on the mean air temperature evolution in the cavity. After that analyse, the article answers the question: is greenhouse effect favourable? The answer is moderate according to the double-skin orientation.

07/02281 Heat transfer analysis of ground heat exchangers with inclined boreholes Cui, P. et al. Applied Thermal Engineering, 2006, 26, (11–12), 1169– 1175. Consisting of closed-loop of pipes buried in boreholes, ground heat exchangers (GHEs) are devised for extraction or injection of thermal energy from/into the ground. Evolved from the vertical borehole systems, the configuration of inclined boreholes is considered in order to reduce the land plots required to install the GHEs in densely populated areas. A transient three-dimensional heat conduction model has been established and solved analytically to describe the temperature response in the ground caused by a single inclined line source. Heat transfer in the GHEs with multiple boreholes is then studied by superimposition of the temperature excesses resulted from individual boreholes. On this basis, two kinds of representative temperature responses on the borehole wall are defined and discussed. The thermal interference between inclined boreholes is compared with that between vertical ones. The analyses can provide a basic and useful tool for the design and thermal simulation of the GHEs with inclined boreholes.

07/02282 Impact of adaptive comfort criteria and heat waves on optimal building thermal mass control Henze, G. P. et al. Energy and Buildings, 2007, 39, (2), 221–235. This article investigates building thermal mass control of commercial buildings to reduce utility costs with a particular emphasis on the individual impacts of both adaptive comfort criteria and of heat waves. Recent changes in international standards on thermal comfort for indoor environments allow for adaptation to the weather development as manifested in comfort criteria prEN 15251.2005 and NPR-CR 1752.2005 relative to the non-adaptive comfort criterion ISO 7730.2003. Furthermore, since extreme weather patterns tend to occur more frequently, even in moderate climate zones, it is of interest how a building’s passive thermal storage inventory responds to prolonged heat waves. The individual and compounded effects of adaptive comfort criteria and heat waves on the conventional and optimal operation of a prototypical office building are investigated for the particularly hot month of August 2003 in Freiburg, Germany. It is found that operating commercial buildings using adaptive comfort criteria strongly reduces total cooling loads and associated building systems energy consumption under conventional and building thermal mass control. In the case of conventional control, total operating cost reductions follow the cooling loads reductions closely. Conversely, the use of adaptive comfort criteria under optimal building thermal mass control leads to both lower and slightly higher absolute operating costs compared to the optimal costs for the non-adaptive ISO 7730. While heat waves strongly affect the peak cooling loads under both conventional and optimal building thermal mass control, total cooling loads, building energy consumption and costs are only weakly affected for both control modes. Passive cooling under cost-optimal control, while achieving significant total cost reductions of up to 13%, is associated with total energy penalties on the order of 1–3% relative to conventional nighttime setup control. Thus, building thermal mass control defends its cost saving potential under optimal control in the presence of adaptive comfort criteria and heat waves.

07/02283 Improving cooling efficiency of dry-cooling towers under cross-wind conditions by using wind-break methods Zhai, Z. and Fu, S. Applied Thermal Engineering, 2006, 26, (10), 1008– 1017. Cross-wind can significantly reduce cooling efficiency of natural-draft dry-cooling towers. This paper investigates solutions that may improve cooling performance of cooling towers in windy days, with particular interest in wind-break methods in and around towers. The study explores a realistic scenario with two cooling towers in-tandem arranged under cross-wind conditions. Both experimental and numerical approaches were employed to optimize the wind-break measures. The results show that wind-break walls placed at the lateral sides of cooling towers perpendicular to the cross-wind is a straightforward and effective method, which can recover about 50% of the reduced cooling capacity. The study analyses the relationship between the cooling efficiency recovery and the size of wind-break walls, indicating an optimal scale of wind-break walls.

07/02284 Investigation on incomplete condensation of nonazeotropic working fluids in high temperature heat pumps Pan, G. and Li, Z. Energy Conversion and Management, 2006, 47, (13– 14), 1884–1893. In order to improve high temperature heat pumps (HTHP), firstly, after theoretical analysis is conducted about the heat transfer of nonazeotropic working fluids in the condenser, the possibility of

incomplete condensation of non-azeotropic working fluids in the condenser of a HTHP is presented. Secondly, an experimental plan is designed to study the phenomenon, and many working conditions experiments (flow rate, temperature and frequency are changed) are done on a water-to-water heat pump unit. Finally, the incomplete condensation is found, and some relationships are presented between the phenomenon and the parameters, which are helpful to improve the control strategy of the HTHP.

07/02285 Living in cold homes after heating improvements: evidence from Warm-Front, England’s Home Energy Efficiency scheme Critchley, R. et al. Applied Energy, 2007, 84, (2), 147–158. This paper investigated explanatory factors for persistent cold temperatures in homes which have received heating improvements. Data were analysed from a national survey of dwellings and households (in England occupied by low-income residents) that had received heating improvements or repairs under the Warm Front Scheme. Over the winters of 2001–02 and 2002–03, householders recorded living room and main bedroom temperatures in a diary. Entries were examined for 888 households, which had received high level heating interventions. Two hundred and twenty-two households were identified as occupying cold homes, with mean bedroom temperature below 16  C or mean living room temperatures below 18  C. Binary logistic regression was used to model dwelling and household features and then occupants’ behaviour and attitudes in the ‘cold homes’ sub-set compared with the remainder of the high intervention group. Seventy-nine supplementary, structured telephone interviews explored reasons given for lower temperatures. Using graphical and tabular methods, householders preferring cooler homes were distinguished from those who felt constrained in some way. It was found that cold homes predominate in pre-1930 properties where the householder remains dissatisfied with the heating system despite major improvements funded by Warm Front. Residents of cold homes are less likely to have long-standing illness or disability, but more likely to experience anxiety or depression. A small sample of telephone interviews reveals those preferring lower temperatures for health or other reasons, report less anxiety and depression than those with limited control over their home environment. Their ‘thermal resistance’ to higher temperatures challenges orthodox definitions of comfort and fuel poverty.

07/02286 Measurements of indoor thermal environment and energy analysis in a large space building in typical seasons Huang, C. et al. Building and Environment, 2007, 42, (5), 1869–1877. Shanghai International Gymnastics Stadium is the selected object for site-measurement. The site-measurements have been carried out during summer, winter, and the transitional seasons. Their indoor thermal environments were controlled by continuous air-conditioning, intermittent air-conditioning and natural ventilation, respectively. The site-measurement includes outdoor environment (the weather conditions and peripheral hallway), indoor air temperature distribution (the occupant zone temperature, radial temperature near upper openings and the vertical temperature distributions, etc.), and the heat balance of air-conditioning system, etc. It is found that temperature stratification in winter with air-conditioning is most obvious. The maximum difference of vertical temperature is 15  C in winter. The second largest one is 12  C in summer, and less than 2  C in the transitional season. The results of measurements indicate that it is different in the characteristics on energy saving of upper openings during the different seasons. With heat balance measurements, it is discovered that the roof load and ventilated and infiltrated load account for larger percentages in terms of cooling and heating load. In this paper, many discussions on the results of site measurements show some characteristics and regulations of indoor thermal environment in large space building.

07/02287 Optimization of two-stage transcritical carbon dioxide heat pump cycles Agrawal, N. et al. International Journal of Thermal Sciences, 2007, 46, (2), 180–187. Optimization studies of two-stage transcritical carbon dioxide heat pump cycles, incorporating options such as flash gas bypass, flash intercooling and compressor intercooling, are presented based on cycle simulation. Sub-critical and super-critical thermodynamic and transport properties of carbon dioxide coded and then integrated with the simulation code for further analyses. Results exhibit improvement in performance by adopting optimal operating conditions. The optimum interstage pressure, thus obtained, deviate from the classical estimate of geometric mean of gas cooler and evaporator pressure. It is observed that the flash gas bypass system yields the best performance among the three two stage cycles analysed. Internal heat exchanger effectiveness and compressor isentropic efficiency shows marginal influence on the system performance. Internal heat exchanger effectiveness shows marginal influence on the system performance while compressor

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10 Space heating and cooling/heat pumps isentropic efficiency shows an about 10% variation in COP. However, optimum gas cooler pressure and optimum intermediate pressure are only marginally affected. Based on the cycle simulations, correlations of optimum gas cooler pressure and inter-stage pressure in terms of gas cooler temperature and evaporator temperature are obtained. This would be useful as a guideline in design of such systems.

07/02288 Performance investigation of transcritical carbon dioxide two-stage compression cycle with expander Yang, J. L. et al. Energy, 2007, 32, (3), 237–245. The trend toward the energy efficiency improvement for transcritical carbon dioxide refrigeration cycles has led to the development of the two-stage compression process. Three different variations of transcritical carbon dioxide two-stage compression cycles with expanders are investigated by using thermodynamics analysis. They are the two-stage compression at optimal intermediate pressure (TCOP) cycle, two-stage compression with expander driving high-pressure stage (TCDH) cycle and two-stage compression with expander driving low-pressure stage (TCDL) cycle, respectively. The performance of the TCOP cycle and the single-stage compression with expander (SCE) cycle is mainly discussed and compared for a wide operating condition. It is found that the COP and exergy efficiency of the TCOP cycle are on average 9% higher than those of the SCE cycle. At given design points, the COP of the TCDH cycle outperforms the other options, showing 11.32%, 9.65% and 0.72% performance improvement over the TCDL cycle, SCE cycle and the TCOP cycle, respectively. If design and structure are also taken into account, the TCDH cycle is a feasible option since the expander and the auxiliary compressor are integrated into one unit; thus, the transfer loss and leakage loss can be decreased greatly. The key problem is to adopt some measures that control the operating conditions to avoid deviating from the design point.

07/02289 Performance of EN ISO 13790 utilisation factor heat demand calculation method in a cold climate Jokisalo, J. and Kurnitski, J. Energy and Buildings, 2007, 39, (2), 236– 247. The applicability of the utilization factor method EN ISO 13790 is studied in modern Finnish buildings in the cold climate of Finland. The heat-demand results of EN ISO 13790 are compared against a validated dynamic simulation tool. It is shown that, with the default values of the numerical parameters of the utilization factor, EN ISO 13790 gives in Finnish conditions as much as 46% higher or 59% lower heat demand of the building compared to the simulation tool, depending on the type of the building and its thermal inertia. The results of EN ISO 13790 can be calibrated for the residential buildings with the correct selection of the numerical parameters for Finnish conditions. With the new values of the parameters, the results are in good agreement in most cases; however, the maximum difference between the methods remained 29% for highly insulated residential buildings. For office buildings, heat demand was strongly underestimated in all the cases by the monthly method EN ISO 13790 regardless of the values of the parameters. The results of the study indicate that the monthly method EN ISO 13790 with new determined numerical parameters is reasonably applicable for residential buildings, but not applicable for office buildings. Therefore, the other methods of prEN 13790, i.e. simple hourly or detailed simulation methods, should be used for office buildings.

07/02290 Performance of thermostatic and electronic valves controlling the compressor capacity Aprea, C. et al. International Journal of Energy Research, 2006, 30, (15), 1313–1322. The performance of the energy consumption of an electronic valve and a classical thermostatic valve has been compared when these expansion valves are adopted in a vapour compression plant subjected to a cold store. The main aim is to verify experimentally which type of expansion valve would be preferable from energy point of view when a classical thermostat or a fuzzy logic algorithm are used as the control system for the refrigeration capacity. The fuzzy logic-based control is able to modulate continuously the compressor speed through an inverter. The results show that with a fuzzy algorithm, the thermostatic expansion valve allows an energy saving of about 8% in comparison with the electronic valve. When on–off control is used, the electric energy consumption obtained both with the electronic valve and with the thermostatic valve is comparable.

07/02291 Performance optimization of irreversible refrigerators based on a new thermo-ecological criterion Ust, Y. and Sahin, B. International Journal of Refrigeration, 2007, 30, (3), 527–534. A performance analysis and optimization based on a new thermoecological optimization criterion has been carried out for refrigerators. The ecological objective function is defined as the ratio of the cooling load to the loss rate of availability (or entropy generation rate). The

346 Fuel and Energy Abstracts September 2007

maximum of the ecological performance criterion and the corresponding optimal conditions have been derived analytically. The optimum performance parameters which maximize the objective function have been investigated and the effects of irreversibility parameters on the general and optimal performances are discussed detailed. The obtained results may provide a general theoretical tool for the ecological design of refrigerators.

07/02292 Performance optimization of quantum Brayton refrigeration cycle working with spin systems He, J. et al. Applied Energy, 2007, 84, (2), 176–186. The new model of a quantum refrigeration cycle composed of two adiabatic and two isomagnetic field processes is established. The working substance in the cycle consists of many non-interacting spin1/2 systems. The performance of the cycle is investigated, based on the quantum master equation and semi-group approach. The general expressions of several important performance parameters, such as the coefficient of performance, cooling rate and power input, are given. It is found that the coefficient of performance of this cycle is a close analogue of the classical Carnot-cycle. Some performance characteristic curves relating the cooling rate, the coefficient of performance and power input are plotted. Further, for high temperatures, the optimal relations between the cooling rate and the coefficient of performance are analysed in detail.

07/02293 Second-law-based performance evaluation of cooling towers and evaporative heat exchangers Qureshi, B. A. and Zubair, S. M. International Journal of Thermal Sciences, 2007, 46, (2), 188–198. This paper presents thermodynamic analysis of counter flow wet cooling towers and evaporative heat exchangers using both the first and second laws of thermodynamics. A parametric study is carried out to determine the variation of second-law efficiency as well as exergy destruction as a function of various input parameters such as inlet wet bulb temperature. Irreversible losses are determined by applying an exergy balance on each of the systems investigated. In this regard, an engineering equation solver program, with built-in functions for most thermodynamic and transport properties, is used. The concept of total exergy as the sum of thermomechanical and chemical parts is employed in calculating the flow exergies for air and water vapour mixtures. For the different input variables investigated, efficiencies were, almost always, seen to increase or decrease monotonically. It was noticed that an increase in the inlet wet bulb temperature invariably increases the second-law efficiency of all the heat exchangers. Also, it is shown that Bejan’s definition of second-law efficiency is not limited in evaluating performance. Furthermore, it is understood that the variation in the dead state does not significantly affect the overall efficiency of the system.

07/02294 Sizing room air conditioners used in sleeping environments in the subtropics Lin, Z. and Deng, S. Energy Conversion and Management, 2006, 47, (13–14), 1851–1856. In the subtropics, room air conditioners (RACs) have been widely used to maintain an appropriate indoor thermal environment not only at day but also at night for sleeping. However, currently RACs are often sized by rules of thumb that are based on the applications and practices of air conditioning during daytime operating periods. A method of sizing RACs used in sleeping environments has been developed in this paper. The sizing of RACs used in sleeping environments in the subtropics should not be based on the peak load that occurs at the beginning of a night air conditioning process, but preferably on 70–80% of the peak load for better indoor thermal comfort and higher energy efficiency.

07/02295 Temperature and energy performance of refrigerated retail display and commercial catering cabinets under test conditions Evans, J. A. et al. International Journal of Refrigeration, 2007, 30, (3), 398–408. An analysis of the performance of well freezers, chest freezers, frozen and chilled door cabinets (solid or glass door) and open-fronted chilled cabinets under EN441 test conditions demonstrated that maximum temperatures in cabinets were generally in the most exposed (to ambient) areas and that minimum temperatures were located in the least exposed areas. Detailed positions of maximum and minimum temperature varied between cabinet types. In chest freezers 95% of the maximum temperature positions were located in the top layer and 95% of the minimum temperature positions were located in the middle layer of the cabinets. In full-door frozen cabinets the maximum temperature position was in the majority of cases on the top shelf (64%) with most maximum packs being at the front of the top shelf (53%). In the chilled full-door cabinets 94% of the maximum temperature packs were situated at the front of the cabinet. In open-fronted cabinets the majority of maximum temperature packs (97%) were located at the front of the cabinet, the largest number (60%) being at the front

10 Space heating and cooling/heat pumps of the base of the cabinet. In well cabinets the majority of maximum temperature packs (81%) were located in the top layer of the cabinet and the majority (91%) of minimum temperature packs were located in the bottom of the cabinet. Large differences in energy consumed by cabinets of similar size and temperature performance were found indicating that large reductions in energy and CO2 emissions could be achieved by selection of the most efficient cabinets.

07/02296 Temperature and time-sharing running combination control strategy of two-circuit cycle refrigerator–freezer with parallel evaporators Lu, Z. and Ding, G. Applied Thermal Engineering, 2006, 26, (11–12), 1208–1217. A two-circuit cycle refrigerator/freezer (RF) with parallel evaporators is more efficient than a single-loop RF and a bypass two-circuit cycle RF, and its cost is less than that of a dual-loop RF with two compressors. The existing control strategies for this kind of RFs are only based on the temperature control with freezer compartment (FZC) prior to fresh food compartment (FFC) or FFC prior to FZC. When a lot of foods are put into FFC or FZC at a time, the compartment temperatures will go up very high and the food will be damaged. In order to solve this problem, the combination control strategy based on both the temperature control and the time-sharing running control is put forward in this paper. The rules to determine the maximum set on-time of FFC loop and that of FZC loop are presented based on theoretically analyses. The new control strategy is validated in a two-circuit cycle RF with parallel evaporators, and the compartment temperature fluctuations can be controlled within rational ranges under the conditions that a lot of food is put into FFC or FZC at a time, or the ambient temperature is very high. The daily energy consumption of the tested RF with the new control strategy is about 0.99% larger than that with the existed control strategies, which may be caused by the frequent shifts between FZC loop and FFC loop.

07/02297 The dynamic storage capacity of a periodically heated slab Cossali, G. E. International Journal of Thermal Sciences, 2007, 46, (4), 342–348. The well-known problem of evaluating the dynamic heat storage capacity of a 1D slab is analysed extending the results to the more general case of periodic excitation profiles of any form. Equations in time and frequency domain to calculate the storage capacity are obtained and applied to some cases, showing that harmonic heating is not the most efficient way to store energy in finite and semi-infinite slabs. Quantitative comparisons show that, for slab of finite thickness, intermittent heating may yield up to 40% more heat storage capacity (and up to 52% for semi-infinite slab) than harmonic heating.

07/02298 The impact of evaporator fouling and filtration on the performance of packaged air conditioners Yang, L. et al. International Journal of Refrigeration, 2007, 30, (3), 506– 514. The goal of the study presented in this paper was to evaluate the impact of different filter types on the performance of three typical packaged air conditioners under both clean and fouled conditions. In a companion paper, combinations of six different levels of filtration and four different coils were tested under clean and fouled conditions. From the tests, it was found that fouling has a relatively small impact on air-side effective heat transfer coefficient, but can have a large impact on coil pressure drop. Data from the experimental study were used in developing simulation models for the three packaged air conditioners. Simulations show that the equipment cooling capacity is reduced with fouling primarily because of a decrease in air flow due to the increased pressure drop. In most cases, EER (energy efficiency ratio) was reduced with fouling primarily due to increased fan power. However, the changes in EER were relatively small, in the range of 1– 10%. Equipment having low efficiency filters had higher EER after fouling than equipment with high efficiency filters, because high efficiency filters result in significantly higher pressure drops than low efficiency filters. The impact of the evaporator side fan efficiency was found to be significant. The energy penalty associated with high efficiency filters was reduced greatly when fan efficiency increased. Although high efficiency filters cause higher energy penalties they provide considerably better air quality. The quantity of dust passing through the coil with an MERV14 filter was approximately 30 times less than the dust passing the coil with an MERV4 filter. This difference was doubled when the MERV14 filter was compared to a case with no filter in place.

07/02299 The importance of the ammonia purification process in ammonia–water absorption systems Ferna´ndez-Seara, J. and Sieres, J. Energy Conversion and Management, 2006, 47, (13–14), 1975–1987.

Practical experience in working with ammonia–water absorption systems shows that the ammonia purification process is a crucial issue in order to obtain an efficient and reliable system. In this paper, the detrimental effects of the residual water content in the vapour refrigerant are described and quantified based on the system design variables that determine the effectiveness of the purification process. The study has been performed considering a single stage system with a distillation column with complete condensation. The ammonia purification effectiveness of the column is analysed in terms of the efficiencies in the stripping and rectifying sections and the reflux ratio. By varying the efficiencies from 0 to 1, systems with neither the rectifying nor stripping section, with either the rectifying or stripping section, or with both sections can be considered. The impact of the ammonia purification process on the absorption system performance is studied based on the column efficiencies and reflux ratio; and its effects on refrigerant concentration, system COP, system pressures and main system mass flow rates and concentrations are analysed. When the highest efficiency rectifying sections are used a combination of generation temperature and reflux ratio which leads to optimum COP values is found. The analysis covers different operating conditions with air and water cooled systems from refrigeration to air conditioning applications by changing the evaporation temperature. The importance of rectification in each kind of application is evaluated.

07/02300 design

The London heat island and building cooling

Kolokotroni, M. et al. Solar Energy, 2007, 81, (1), 102–110. London’s urban heat island increases the mean air temperature, which affects the demand for heating and cooling buildings. Measured air temperature data have been used as input to a building energy simulation computer program to assess the heating and cooling load of a typical air-conditioned office building positioned at 24 different locations within the London heat island. It is found that the urban cooling load is up to 25% higher than the rural load over the year, and the annual heating load is reduced by 22%. The effect of raised temperature and urban context are assessed separately, and the sensitivity of the net impact to the internal gains in a building is determined. For the estimation of peak cooling demand, hourly temperature corrections are proposed based on radial distance from London’s centre to be applied to standard published temperatures for the region. For more detailed investigations over the cooling season a range of models is available. These are reviewed in this paper and the authors describe preliminary results of an artificial neural network model that predicts location specific hourly temperatures for London, taking into account radial distance from central London, hourly air temperature measured at the meteorological station and associated synoptic weather data.

07/02301 Tracer testing of the geothermal heat exchanger at Soultz-sous-Foreˆ ts (France) between 2000 and 2005 Sanjuan, B. et al. Geothermics, 2006, 35, (5–6), 622–653. Inter-well tracer tests were conducted at the Soultz-sous-Foreˆts (France) site of the European hot dry rock program at less than 3900 m depth before the year 2000, and at about 5000 m depth in the period 2000–2005. The paper discusses the results and conclusions drawn from tracer tests performed in 2000–2005 during hydraulic stimulation operations and a short-term circulation test in wells GPK2, GPK-3 and GPK-4. The tracer tests were conducted using organic compounds such as Na-benzoate, 1,5-, 2,7-, 1,6- and 2,6-naphthalene disulfonate, and fluorescein. These studies indicated that the tracers behaved conservatively during a long period (at least 5 months for fluorescein and up to 4 years for Na-benzoate and 1,5-nds) under the harsh conditions of the Soultz reservoir (up to 200  C and high fluid salinity). Combined with the monitoring of conservative species such as dissolved chloride, the tracer tests allowed us to estimate the fractions of native geothermal brine and injected fresh water in the fluids discharged during the short-term production tests. These tests consistently indicated that only low amounts of the injected fresh water were recovered and that the proportion of native brine was relatively high in the produced fluids. It was estimated that more than 750,000 m3 of native brine mixed with approximately 142,000 m3 of fresh water that had been injected since 2000. The mean natural flux for the native brine was estimated at about 1–1.2 m3/h. The tracer tests gave evidence of a fast and relatively direct hydraulic connection between GPK-3 and GPK-2 (short loop) but also indicated the existence of another larger and slower hydraulic connection between the wells (large loop). Hydrodynamic characteristics (mean transfer time, swept volume, tracer recovery, and mean fluid velocity) were estimated for both circulation loops. The hydraulic connection between GPK-3 and GPK-4 appeared to be poor. Differences observed between experimental and modelled data at the end of the fluorescein-recovery curves suggest the existence of another quasi-infinite loop connecting both GPK-2 and GPK-4 to GPK-3.

Fuel and Energy Abstracts September 2007 347

11 Engines (power generation and propulsion, electrical vehicles) 07/02302 Use of microencapsulated PCM in concrete walls for energy savings Cabeza, L. F. et al. Energy and Buildings, 2007, 39, (2), 113–119. This paper studies a new innovative concrete with phase change materials (PCM) on thermal aspects. The final objective is to develop a product that would achieve important energy savings in buildings. The work here presented is the construction and experimental installation of two real size concrete cubicles to study the effect of the inclusion of a PCM with a melting point of 26  C. The cubicles were constructed in the locality of Puigverd of Lleida (Spain). The results of this study show the energy storage in the walls by encapsulating PCMs and the comparison with conventional concrete without PCMs leading to an improved thermal inertia as well as lower inner temperatures.

07/02303 Wind tunnel experiments modelling the thermal effects within the vicinity of a single block building with leeward wall heating Richards, K. et al. Journal of Wind Engineering and Industrial Aerodynamics, 2006, 94, (8), 621–636. A wind tunnel model aiming to simulate the thermal effects within the vicinity of a building with leeward wall heating was set up. The work was conducted within the scope of the European ATREUS project in which micro-scale numerical models were used to obtain data concerning the microclimatic conditions within the vicinity of buildings. This data was then used as input data for generating typical weather data required as input for building and heating, ventilation and airconditioning (HVAC) system models in order to study the energy budgets of buildings and assess the performance of air-conditioning systems. However, it was first necessary to validate these microscale numerical models for a simplified case under different thermal conditions. A series of wind tunnel experiments were conducted in which the mean velocity and temperature field within the vicinity of a single block building (a cube) with leeward wall heating were measured. The ratio of Grashof number to the square of Reynolds number, Gr/Re2 was used to model thermal effects within the vicinity of the model, but some compromises were needed in order to obtain a practical model while at the same time fulfilling the objectives of the task set. Conditions representative of mixed and forced convection were modelled. Results showed some degree of flow modification within the recirculation region of the model for both Gr/Re20.9 and 1.6, the recirculation length in both cases being shortened when compared to the non-heated case. The velocity field influenced the temperature distribution within the recirculation region. There was a rapid temperature drop away from the surface, with the temperature distribution reaching near ambient conditions within one model height downstream of the heated face for Gr/Re21.6. In spite of the restrictions applied to the physical model, the technique applied showed very good stability and repeatability during the entire measurement campaign producing a reliable data set for the validation of the microscale numerical models.

11 ENGINES Power generation and propulsion, electrical vehicles 07/02304 engines

07/02305 Characterization of the flow field and stratification effects of fuel spray in a visualization engine using DPIV and entropy analysis Lee, K. H. and Lee, C. H. Experimental Thermal and Fluid Science, 2007, 77, (7), 579–592. The objective of this study was to analyse the spray characteristics according to the injection duration under ambient pressure conditions and the injection timing in the visualization engine. In order to investigate spray behaviour, the spray velocity is obtained through the PIV method a useful optical diagnostics technology and the vorticity calculated from the spray velocity component. These results elucidated the relationship between vorticity and entropy which plays an important role in the diffusion process for early injection and the stratification process for late injection cases. In addition, the homogeneous diffusion rate of spray was quantified using the entropy analysis based on Boltzmann’s statistical thermodynamics. Using these methods, it was found that the homogeneous mixture distribution is more effective as a momentum dissipation of surrounding air than that of the spray concentration to increase the injection timing. It is found that the homogenous diffusion rate increased as the injection timing moved to the early intake stroke process, and BTDC 60 was the most efficient injection timing for the stratified mixture formation during the compression stroke.

07/02306 Control of c-dump converters fed switched reluctance motor on an automotive application Lee, T.-W. et al. Electric Power Systems Research, 2007, 77, (7), 804– 812. This paper deals with the analysis of switched reluctance motor drives for different drive circuit topologies used in automobiles. Therefore, the authors attempt to improve the weaknesses associated with the asymmetric bridge converter in the limited internal environment of automotive application. Two kinds of c-dump converters are tested in terms of dump capacitor voltage, speed response according to the variation of advance angle and efficiency for the radiator cooling-fan drive of an automobile. They enable more economical and efficient converter topology for automobile industries. This paper describes the performance characteristics of 12 V–250 W–3000 rpm SRM drives for automobiles. Computer simulation and experiment results are then presented to verify the performance of the two kinds of c-dump converters.

07/02307 Corrosion behavior of biodiesel from seed oils of Indian origin on diesel engine parts Kaul, S. et al. Fuel Processing Technology, 2007, 88, (3), 303–307. Environmental factors and depleting reserves of crude oil are becoming the main driving force in the quest for cleaner and alternate fuels. In India, adoption of Euro III and Euro IV equivalent emission norms are under consideration. The Euro III emission norms have already been implemented in seven mega cities and would be implemented in the rest of the country by the year 2010. This will lead to drastic reduction in sulfur content and increase in cetane number, which in turn will adversely affect the lubricity characteristics of the diesel fuel. However, the use of biodiesel will improve the lubricity and cetane number requirements particularly for ultra low sulfur diesel. Studies for the synthesis and characterization of biodiesel from non-edible oils like Jatropha curcas, Pongamia glabra (Karanja), Madhuca indica (Mahua) and Salvadora oleoides (Pilu) have already been carried out in our laborotary. Corrosion characteristics of biodiesel are important for long term durability of engine parts, and very little information is available on this aspect. The studies were therefore taken up to assess the corrosion of synthesized biodiesel from the above mentioned nonedible oils. Using long duration static immersion test method corrosion studies on engine parts like piston metal and piston liner were carried out with neat diesel procured from one of the Indian refinery and biodiesel synthesised from these non-edible oils. Biodiesel from Salvadora showed marked corrosion on both metal parts of diesel engine whereas biodiesel from other oils showed little or/no corrosion as compared to neat diesel.

A concise wall temperature model for DI diesel

Torregrosa, A. et al. Applied Thermal Engineering, 2006, 26, (11–12), 1320–1327. A concise resistor model for wall temperature prediction in diesel engines with piston cooling is presented here. The model uses the instantaneous in-cylinder pressure and some usually measured operational parameters to predict the temperature of the structural elements of the engine. The resistor model was adjusted by means of temperature measurements in the cylinder head, the liner and the piston. For each model parameter, an expression as a function of the engine geometry, operational parameters and material properties was derived to make the model applicable to other similar engines. The model predicts well the cylinder head, liner and piston temperature and is sensitive to variations of operational parameters such as the start of injection, coolant and oil temperature and engine speed and load.

348 Fuel and Energy Abstracts September 2007

07/02308 Design of a prototype ocean current turbine – part I: mathematical modeling and dynamics simulation VanZwieten, J. et al. Ocean Engineering, 2006, 33, (11–12), 1485–1521. The ‘C-Plane’ is a submerged variable depth ocean current turbine that is tethered to the sea floor and uses sustained ocean currents to produce electricity. As part of the development of a 301th scale physical model of the C-Plane, a mathematical model and dynamics simulation of the prototype was developed and is presented in this paper. This three-dimensional mathematical model represents the C-Plane as a rigid body with moveable control surfaces that is moored with three linear elastic cable elements. Gravitational, buoyancy, hydrodynamic, cable, gyroscopic, and inertial forces are included and a PC-based dynamics simulation is created. The simulation demonstrates that the C-Plane is stable and capable of changing depth in all expected operating conditions. The C-Plane prototype can fly level from a height

11 Engines (power generation and propulsion, electrical vehicles) of 3 to 6 m using the configuration suggested in this paper. The maximum ascent rates of the C-Plane with a water speed of 0.3 m/s are 0.015 m/s when the pitch is fixed at 0 and 0.030 m/s when the pitch is fixed at 4 . The maximum descent rates of the C-Plane are 0.018 m/s when the pitch is held at 0 and 0.031 m/s if the pitch is held at 4 .

07/02309 Design of a prototype ocean current turbine – part II: flight control system VanZwieten, J. et al. Ocean Engineering, 2006, 33, (11–12), 1522–1551. 1 This paper presents and compares control strategies for the 30 -scale C-Plane prototype, an ocean current turbine under development at FAU. The C-Plane is a hydrodynamic platform that is tethered to the sea floor and uses sustained ocean currents to produce electricity. This turbine uses its wingtips and canard to control its depth and orientation so that it can maximize energy production while flying in a temporally and spatially varying current. Three different control systems are developed and compared in this paper using the mathematical model and dynamics simulation developed in the companion paper. These control approaches each use three sub-modes of operation (ascending, descending, and steady) and are the MIXED PID/BANG BANg (MPID), Mixed LQR/PID/Bang Bang, and Mixed LQG/PID/Bang Bang control approaches. All three controllers are effective and were to control the C-Plane under expected operating conditions. The MPID controller proved to be slightly more effective and robust.

07/02310 Effect of ageing on microstructure changes in EB-PVD manufactured standard PYSZ top coat of thermal barrier coatings Renteria, A. F. and Saruhan, B. Journal of the European Ceramic Society, 2006, 26, (12), 2249–2255. The ceramic top coat of thermal barrier coatings (TBC) manufactured by electron beam-physical vapour deposition process is a crucial part of a system which protects the high pressure turbine blades of aero engines and stationary gas turbines. Under service conditions, turbine blades are exposed to temperatures above 1100  C, typically with shortterm peaks. Ceramic top coat has a unique microstructure made up of individual primary columns, growing in a preferred crystal direction. This columnar growth produces an inter-columnar spacing exhibiting a weak bonding between the neighbouring columns, and providing the TBCs with high strain tolerance. Rotation of the substrates during vapour phase deposition produces an additional intra-columnar closed porosity, causes formation of a feather-like sub-columnar structure at the periphery of each primary column due to over-shadowing, increasing total porosity and thus contributing to low thermal conductivity of the material. On thermal exposure during service, both inter- and intra-columnar porosity decrease as a result of sintering induced surface area reduction. The driving force for this process is the decrease in surface energy. As a result, thermal conductivity increases due to the alteration of the porosity distribution, size and morphology. The in-plane strain tolerance decreases after the primary columns sinter together to form bridges at the contact points. These are two important factors that affect the performance of the entire system. Thus, analysis of the involvement of each pore family (feather-arm, intra- and inter-columnar pores) in thermal insulating capabilities of yttria stabilized zirconia TBC may provide a guideline for engine manufacturers in designing more efficient coatings with optimized thermal properties, in all probability solely by controlled adjustment of the process parameters. This work reports the thermal-induced microstructural changes in terms of total porosity at EB-PVD produced top coats before and after annealing at 900, 1000, 1100, 1200, 1300 and 1400  C for 1 h, as well as at 1100  C for 20 min, 1 h, 3 h, 10 h and 100 h. For the analysis of the changes in pore surface area, methods such as SANS (small angle neutron scattering) and BET (Brunauer–Emmett–Teller) were applied. Alteration of surface area with time and temperature commonly gives an indication of the type of diffusion mechanism. Hence, kinetic and the activation energy of the mechanism are calculated and determined with the help of the data obtained by SANS and BET-analysis. Due to the presence of a large number of nano-sized closed porosity in the coatings, SANS measurements were crucial to distinguish those from the remaining open porosity. A mean porosity representative for pores smaller than 180 nm is obtained by interaction of neutrons diffracting parallel to the primary column axis.

07/02311 Effect of rotation on leading edge region film cooling of a gas turbine blade with three rows of film cooling holes Ahn, J. et al. International Journal of Heat and Mass Transfer, 2007, 50, (1–2), 15–25. Effect of rotation on detailed film cooling effectiveness distributions in the leading edge region of a gas turbine blade with three showerhead rows of radial-angle holes were measured using the pressure sensitive paint technique. Tests were conducted on the first-stage rotor blade of a three-stage axial turbine at three rotational speeds. The effect of the blowing ratio was also studied. The Reynolds number based on the

axial chord length and the exit velocity was 200,000 and the total to exit pressure ratio was 1.12 for the first-stage rotor blade. The corresponding rotor blade inlet and exit Mach number was 0.1 and 0.3, respectively. The film cooling effectiveness distributions were presented along with the discussions on the influences of rotational speed, blowing ratio, and vortices around the leading edge region. Results showed that different rotation speeds significantly change the film cooling traces with the average film cooling effectiveness in the leading edge region increasing with blowing ratio.

07/02312 Improved direct torque control for induction motor drives with rapid prototyping system Kennel, P. et al. Energy Conversion and Management, 2006, 47, (13–14), 1999–2010. Direct torque control (DTC) is an AC drives control method especially designed to provide fast and robust responses, but they usually behave like hysteresis controllers. Consequently, there are similar problems like non-constant switching frequencies and high torque ripple, especially when operation conditions result in low switching frequencies. In this paper, the basic concept of DTC will be improved by modifying the classical method. Problems that arise when using standard DTC methods are explained, and improvements are derived to overcome these problems. Two theoretical approaches are verified and compared with standard DTC by measurements and experiments. The proposed methods provide a constant switching frequency and solve the starting problem without dither signal. Further results are a reduction of torque pulsations as well as a new method for stator flux estimation. Experimental results of the new DTC method obtained by an experimental rapid prototype system for drives are presented.

07/02313 Measurement of nitric oxide concentration in a spark-ignition engine using degenerate four-wave mixing Stevens, R. et al. Combustion and Flame, 2007, 148, (4), 223–233. The measurement of in-cylinder, combustion-generated nitric oxide using degenerate four-wave mixing (DFWM) in a firing, methanefueled research engine is reported. An optical arrangement for producing DFWM in the forward geometry is described that results in reliable signal generation with excellent signal-to-noise ratio from the skip-fired engine. DFWM signals from temperature-insensitive lines were used to infer variations in NO concentration at the end of the expansion stroke at exhaust valve opening. The variation in NO concentration inferred from the DFWM signals was measured as a function of equivalence ratio and ignition timing indicated by peak pressure values. These measurements using DFWM were compared to measurements using line-of-sight optical absorption and a chemiluminescence exhaust gas analyser. Good agreement was found for all three measurements. The results demonstrate the potential for DFWM to make quantitative spatially and temporally resolved measurements in a firing spark-ignition engine.

07/02314 On-line efficiency optimization of a synchronous reluctance motor Lubin, T. et al. Electric Power Systems Research, 2007, 77, (5–6), 484– 493. This paper deals with an on-line optimum-efficiency control of a synchronous reluctance motor drive. The input power minimization control is implemented with a search controller using Fibonacci search algorithm. It searches the optimal reference value of the d-axis stator current for which the input power is minimum. The input power is calculated from the measured dc-bus current and dc-bus voltage of the inverter. A rotor-oriented vector control of the synchronous reluctance machine with the optimization efficiency controller is achieved with a DSP board. Experimental results are presented to validate the proposed control methods. It is shown that stability problems can appear during the search process.

07/02315 On-road and laboratory evaluation of combustion aerosols – Part 1: Summary of diesel engine results Kittelson, D. B. et al. Journal of Aerosol Science, 2006, 37, (8), 913–930. The objective was to characterize diesel exhaust aerosols on road and to duplicate the results in the laboratory without altering the physical characteristics of the nuclei mode. On-road emissions from four, heavyduty diesel truck engines were measured. The same engines were reevaluated in the manufacturers’ laboratories. For highway cruise and acceleration conditions, all engines produced bimodal size distributions with the nuclei mode ranging in size from 6 to 11 nm and the accumulation mode from 52 to 62 nm. On-road size distribution measurements nearly always showed a nuclei mode while laboratory measurements showed a nuclei mode under many, but not all conditions. Laboratory studies showed that nuclei mode particles consisted mainly of heavy hydrocarbons. More than 97% of the volume of 12 and 30 nm particles disappeared on heating to 400  C. The volatility resembled that of C24–C32 n-alkanes implying a significant contribution from lubricating oil.

Fuel and Energy Abstracts September 2007 349

11 Engines (hybrid engine systems) 07/02316 On-road and laboratory evaluation of combustion aerosols – Part 2: summary of spark ignition engine results Kittelson, D. B. et al. Journal of Aerosol Science, 2006, 37, (8), 931–949. The primary objective was to characterize exhaust aerosols from a small group of in-use, light-duty, spark ignition (SI) vehicles operated on-road, and on a chassis dynamometer. A significant particle signature above background was not measured at highway cruise condition. Number emissions were much higher during acceleration, at high-speed cruise, and during cold–cold starts. Group average fuelspecific number emissions range from 3.91014 to 1.01017 particles/kg of fuel. Cold–cold start temperatures, driving cycles and vehicular condition influence SI emissions. Elemental carbon was a major contributor to mass emissions measured in chassis dynamometer Unified Driving Cycle (UDC) tests averaging 64% and 34% of the mass emissions for cold–cold and hot start cycles, respectively. Average ratios of cold–cold to hot start emissions were 3.3, 7.6, and 22 for CPC number, filter mass and SMPS volume, respectively. Apportionment results showed that on a weekly weighted basis and on weekdays, the majority of observed particle number was attributed to heavy-duty diesel traffic. Weekend production of particles was attributable to light-duty automobiles. On a per vehicle basis, heavy-duty vehicles produced substantially greater number concentrations. On a fuelspecific basis, heavy-duty vehicles produce slightly higher concentrations of particles than light-duty vehicles. The relative contribution of light-duty vehicles to particle number emissions increased as particle size decreased, for the smallest particles apportioned number emissions were 1.31016 and 7.11015 particles/kg of fuel for heavy-duty and light-duty vehicles, respectively. Comparison of on-road chase and apportionment results with chassis dynamometer tests in a certification type facility suggests that the latter may underestimate real-world number emissions.

07/02317 Potential of regenerative gas-turbine systems with high fogging compression Kim, K. H. and Perez-Blanco, H. Applied Energy, 2007, 84, (1), 16–28. The study of evaporatively cooled cycles is of interest because of the prospect of enhanced efficiencies and conceptual simplicity that can lead to low capital costs. This work focuses on a cycle that relies on continuous cooling of the air under compression, followed by recuperation of residual exhaust heat, combustion and expansion. Ideal gases are modelled, with realistic values of efficiencies, air-to-fuel ratios and turbine-inlet temperatures. As the amount of water injected in the compressor increases, the efficiency of the cycle peaks at progressively higher pressure-ratios. The pressure ratio and the recuperator effectiveness are important parameters for cycle efficiency. Compared to a dry cycle with no recuperation with a pressure ratio of 25, the efficiency can increase from 45% to 51.5% and the specific work from 410 kJ/kg to 680 kJ/kg when compression cooling and recuperation are implemented.

07/02318 The effects of ethanol–unleaded gasoline blends and ignition timing on engine performance and exhaust emissions Topgu ¨ l, T. et al. Renewable Energy, 2006, 31, (15), 2534–2542. In this study, the effects of using unleaded gasoline (E0) and unleaded gasoline–ethanol blends (E10, E20 E40 and E60) on engine performance and exhaust emissions have been experimentally investigated. The investigation was conducted on a Hydra single-cylinder, four-stroke, spark ignition engine. The experiments were performed by varying the compression ratio (8:1, 9:1 and 10:1) and ignition timing at a constant speed of 2000 rpm at wide open throttle (WOT). The experimental results showed that blending unleaded gasoline with ethanol slightly increased the brake torque and decreased carbon monoxide (CO) and hydrocarbon (HC) emissions. It was also found that blending with ethanol allows increasing the compression ratio without knock occurrence.

07/02319 Thermodynamic performance assessment of an indirect intercooled reheat regenerative gas turbine cycle with inlet air cooling and evaporative aftercooling of the compressor discharge Khaliq, A. and Choudhary, K. International Journal of Energy Research, 2006, 30, (15), 1295–1312. This study provides a computational analysis to investigate the effects of cycle pressure ratio, turbine inlet temperature (TIT), and ambient relative humidity () on the thermodynamic performance of an indirect intercooled reheat regenerative gas turbine cycle with indirect evaporative cooling of the inlet air and evaporative aftercooling of the compressor discharge. Combined first- and second-law analysis indicates that the exergy destruction in various components of gas turbine cycles is significantly affected by compressor pressure ratio and turbine inlet temperature, and is not at all affected by ambient relative humidity. It also indicates that the maximum exergy is destroyed in the combustion chamber; which represents over 60% of the total exergy destruction in the overall system. The net work output, first-law

350 Fuel and Energy Abstracts September 2007

efficiency, and the second-law efficiency of the cycle significantly varies with the change in the pressure ratio, turbine inlet temperature and ambient relative humidity. Results clearly shows that performance evaluation based on first-law analysis alone is not adequate, and hence more meaningful evaluation must include second law analysis. Decision makers should find the methodology contained in this paper useful in the comparison and selection of gas turbine systems.

07/02320 Transient performance of a single-phase self-regulated self-excited induction generator using a three-phase machine Mahato, S. N. et al. Electric Power Systems Research, 2007, 77, (7), 839–850. This paper presents the transient behaviour of a three-phase star connected self-excited induction generator using three capacitors connected in series and parallel with a single-phase load. The voltage regulation of this generator is very small due to the effect of three capacitors. The dynamic model of the above generator has been developed based on stationary reference frame d–q-axes theory incorporating the effect of cross-saturation. The steady-state model of the scheme has also been developed. The simulated results of both the transient analysis for the different dynamic conditions, such as initiation of self-excitation, load perturbation and short-circuit and the steady-state analysis are compared with the experimental results. Both the simulated and experimental results are in close agreement with each other.

Hybrid engine systems 07/02321 Dynamic delivery analysis of adsorptive natural gas storages at room temperature Ridha, F. N. et al. Fuel Processing Technology, 2007, 88, (4), 349–357. This work analyses the performance of adsorptive natural gas (ANG) storage during dynamic discharge phase at room temperature. Various aspects of the dynamic system were studied, however, emphasis was given to the delivery capacity of the storage cylIndexr since it is the absolute measure of ANG storage system viability. The results demonstrated that activated carbons have better delivery capacities than molecular sieve zeolite and silica gel in spite of their higher thermal instability. Dynamic delivery capacities were found to be related inversely to discharge rate as a subsequent of further thermal instability. Increase in discharge rate from 1 to 5 L min1 resulted in the severest reduction in steady state delivery capacity, represented by a net factor between 7.6 and 12.1% taking the total delivery capacity as a reference. This range is dependent on the adsorbent type and properties. However, no hydrodynamic hindrances were observed in spite of these adsorbents were in powder form. Non-methane hydrocarbon gases have potential impacts on all types of delivery capacities within a reduction factor of 19.4% for natural gas containing 14.98 and 14.54 vol.% of ethane and propane discharged at 1 L min1. Such behaviour appears to be mainly governed by the deactivation degree of the adsorbent with heavier hydrocarbon molecules.

07/02322 Ethanol–electric propulsion as a sustainable technological alternative for urban buses in Brazil Sampaio, M. R. et al. Renewable and Sustainable Energy Reviews, 2007, 11, (7), 1514–1529. The option of fitting electric motors to vehicles that are more efficient and quieter than internal combustion engines has been hampered considerably, looking only at the use of conventional batteries supplying electricity. This is basically due to low gravimetric and volumetric energy densities of these devices that result in shorter autonomy, in addition to more weight and less usable space in the vehicle. An alternative that could make electric motors more attractive for vehicular applications by replacing batteries as the main electricity source is the fuel cell. Hydrogen is the main fuel used in these cells, but the hydrogen storage systems developed so far are heavier and bulkier than their equivalent for conventional liquid fuels such as diesel, gasoline and alcohol, despite heavier energy densities compared to batteries. This paper reviews technological aspects of fuel cells, the main storage systems for hydrogen and other energy sources, data on fuel use and the types of vehicles most commonly used in the Brazilian road transportation sector, followed by an overview of the insertion of hybrid ethanol–electric buses in Brazil.

07/02323 Experimental investigation of control of NOx emissions in biodiesel-fueled compression ignition engine Agarwal, D. et al. Renewable Energy, 2006, 31, (14), 2356–2369. Biodiesel is an alternative fuel consisting of the alkyl esters of fatty acids from vegetable oils or animal fats. Vegetable oils are produced from numerous oil seed crops (edible and non-edible), e.g. rapeseed

12 Refractories/ceramics (properties, production, applications) oil, linseed oil, rice bran oil, soybean oil, etc. Research has shown that biodiesel-fueled engines produce less carbon monoxide (CO), unburned hydrocarbon (HC), and particulate emissions compared to mineral diesel fuel but higher NOx emissions. Exhaust gas recirculation (EGR) is effective to reduce NOx from diesel engines because it lowers the flame temperature and the oxygen concentration in the combustion chamber. However, EGR results in higher particulate matter (PM) emissions. Thus, the drawback of higher NOx emissions while using biodiesel may be overcome by employing EGR. The objective of current research work is to investigate the usage of biodiesel and EGR simultaneously in order to reduce the emissions of all regulated pollutants from diesel engines. A two-cylinder, air-cooled, constant speed direct injection diesel engine was used for experiments. HCs, NOx, CO, and opacity of the exhaust gas were measured to estimate the emissions. Various engine performance parameters such as thermal efficiency, brake specific fuel consumption (BSFC), and brake specific energy consumption (BSEC), etc. were calculated from the acquired data. Application of EGR with biodiesel blends resulted in reductions in NOx emissions without any significant penalty in PM emissions or BSEC.

07/02324 The effect of rapeseed oil methyl ester on direct injection diesel engine performance and exhaust emissions Labeckas, G. and Slavinskas, S. Energy Conversion and Management, 2006, 47, (13–14), 1954–1967. This article presents the comparative bench testing results of a fourstroke, four-cylinder, direct injection, unmodified, naturally aspirated diesel engine when operating on neat RME and its 5%, 10%, 20% and 35% blends with diesel fuel. The purpose of this research is to examine the effects of RME inclusion in diesel fuel on the brake specific fuel consumption (bsfc) of a high speed diesel engine, its brake thermal efficiency, emission composition changes and smoke opacity of the exhausts. The brake specific fuel consumption at maximum torque (273.5 g/kW h) and rated power (281 g/kW h) for RME is higher by 18.7% and 23.2% relative to Diesel fuel. It is difficult to determine the RME concentration in Diesel fuel that could be recognized as equally good for all loads and speeds. The maximum brake thermal efficiency varies from 0.356 to 0.398 for RME and from 0.373 to 0.383 for Diesel fuel. The highest fuel energy content-based economy (9.36–9.61 MJ/ kW h) is achieved during operation on blend B10, whereas the lowest ones belong to B35 and neat RME. The maximum NOx emissions increase proportionally with the mass percent of oxygen in the biofuel and engine speed, reaching the highest values at the speed of 2000 min1, the highest being 2132 ppm value for the B35 blend and 2107 ppm for RME. The carbon monoxide, CO, emissions and visible smoke emerging from the biodiesel over all load and speed ranges are lower by up to 51.6% and 13.5% to 60.3%, respectively. The carbon dioxide, CO2, emissions along with the fuel consumption and gas temperature, are slightly higher for the B20 and B35 blends and neat RME. The emissions of unburned hydrocarbons, HC, for all biofuels are low, ranging at 5–21 ppm levels.

07/02325 The use of boron for thermochemical storage and distribution of solar energy Abu-Hamed, T. et al. Solar Energy, 2007, 81, (1), 93–101. Boron has been proposed as a candidate for hydrogen production. In this study a process is described in which boron is used as a means to store and transport solar energy from a production site to motor vehicles, where it is used to generate hydrogen and heat. The proposed multi-step fuel cycle includes no carbon as a reducing agent and, therefore, no release of CO2 to the atmosphere. This process is safe, mostly involving harmless materials and well-understood technologies. It eliminates the distribution, storage, and pumping of hydrogen at the refueling station, and diminishes the amount of hydrogen stored on the vehicle to a minimum. It is shown that the boron reaction with water, performed on-board of a vehicle, has high hydrogen storage capacity based on both volume and mass, compared with other candidate technologies. An energy balance of the entire process predicts that the overall efficiency of converting solar energy to work by the vehicle engine can be about 11%.

Transport battery development 07/02326 CO selective oxidation in hydrogen-rich gas over platinum catalysts Ren, S. and Hong, X. Fuel Processing Technology, 2007, 88, (4), 383– 386. The kinetics of CO oxidation in hydrogen-rich gas on Pt/mordenite (Pt/ MD) or Pt/Al2O3 were investigated over a wide range of CO (0.4– 1.8%) and O2 concentrations (0.26–1.14%). The integral flow

measurements showed that both the catalysts that could remove CO from 1% to ppm-level Pt/MD had a wider operation temperature range than Pt/Al2O3, especially towards lower temperatures.

07/02327 Deposited RuO2–IrO2/Pt electrocatalyst for the regenerative fuel cell Zhang, Y. et al. International Journal of Hydrogen Energy, 2007, 32, (3), 400–404. A bifunctional RuO2–IrO2/Pt electrocatalyst for the unitized regenerative fuel cell (URFC) was synthesized by colloid deposition and characterized by analytical methods like TEM, XRD, etc. The result reveals that RuO2–IrO2 was well dispersed and deposited on the surface of Pt black. With deposited RuO2–IrO2/Pt as the catalyst of oxygen electrode, the performance of fuel cell/water electrolysis of unitized regenerative fuel cell (URFC) was studied in detail. URFC with deposited RuO2–IrO2/Pt shows better performance than that of URFC with mixed RuO2–IrO2/Pt catalyst. Cyclic performance of URFC with deposited RuO2–IrO2/Pt is very stable during 10 cyclic tests.

07/02328 Granulation of nano-scale Ni(OH)2 cathode materials for high power Ni-MH batteries He, X. et al. Energy Conversion and Management, 2006, 47, (13–14), 1879–1883. Nano-scale -Ni(OH)2 and Co(OH)2 were prepared by controlled crystallization, mixed by ball milling and granulated to form about 5 mm spherical grains by spray drying granulation. The granulation significantly enhanced the electrochemical performance of nano-scale Ni(OH)2, probably because of good size matching between the active material and the electric conductor. The granulated grains of nanoscale Ni(OH)2 presented high performance at high discharge C-rate, and its specific capacity at 10 C exceeded that of conventional spherical micro-scale Ni(OH)2 at 3 C. The granulated nano-scale -Ni(OH)2 is a promising cathode active material for high power Ni-MH batteries.

12 REFRACTORIES/ CERAMICS Properties, production, applications 07/02329 Effective thermal conductivity of expanded graphite–CaCl2 composite adsorbent for chemical adsorption chillers Wang, K. et al. Energy Conversion and Management, 2006, 47, (13–14), 1902–1912. This paper presents experimental data on the thermal conductivity for three types of adsorbent, namely, pure CaCl2 powder, simple composite adsorbent and consolidated composite adsorbent. The thermal conductivities were measured by the ‘hot wire method’ at a fixed pressure and temperature under an ammonia atmosphere. Effective thermal conductivities of the expanded graphite– CaCl2  nNH3 (n = 2, 4, 8) consolidated composite adsorbent are in the range of 7.05–9.2 W m1 K 1, which are significant higher values than those of the powders bed of 0.3–0.4 W m 1 K 1. The obtained results show that the composite adsorbent thermal conductivity  has a strong dependence on the bulk density, the weight fraction of expanded graphite and the ammoniated state of CaCl2.

07/02330 Effects of gamma irradiation on optical and structural properties of PbO–Bi2O3–B2O3 glasses Sharma, G. et al. Radiation Physics and Chemistry, 2006, 75, (9), 959– 966. Optical and structural properties of xPbO2xBi2O3 (1–3x)B2O3 glasses of different composition have been studied using UV-VIS and FTIR spectroscopic techniques. Effects of gamma radiations on glass network and structural units have been studied by irradiating glass samples with a 60Co radioisotope to the overall dose of 2.5 kGy. It is shown that irradiation causes compaction of the borate network by breaking the bonds between trigonal elements, which leads to a decrease in the optical band gap energy. Changes in the atomic structure before and after the irradiation are observed and explained.

07/02331 Elastic properties of gallium substituted Bi (Pb)2212 superconducting system at 300 K Solunke, M. B. et al. Ceramics International, 2007, 33, (1), 21–26.

Fuel and Energy Abstracts September 2007 351

12 Refractories/ceramics (properties, production, applications) The elastic behaviour of Bi1.7xGaxPb0.3Sr2Ca1Cu2Oy (x = 0.0–0.3) superconducting system has been studied using ultrasonic pulse transmission technique at 1 MHz (300 K). The values of Young’s modulus, rigidity modulus, longitudinal modulus, bulk modulus, Poisson’s ratio and Debye temperature of the specimens are computed from longitudinal and shear wave velocities and corrected to zero porosity. The strength of interatomic bonding is found to increase on gallium substitution, in consistency with Al-substituted Bi (Pb)-2223 system. The applicability of the heterogeneous metal mixture rule for estimating elastic constants and critical temperature has been tested, and agreement with the experimental results validates the method used.

07/02332 Electrical properties of (Na2O)35.7(RE2O3)7.2(SiO2)57.1 (RE = Y, Sm, Gd, Dy, Ho, Er and Yb) glasses and ceramics Nakayama, S. et al. Journal of the European Ceramic Society, 2006, 26, (9), 1605–1610. Fifteen kinds of sodium rare earth silicate glasses and ceramics with (Na2O) 35.7(RE2O3)7.2(SiO2)57.1 (RE = Y, Sm, Gd, Dy, Ho, Er and Yb) composition were synthesized from a mixture of Na2CO3, RE2O3 and SiO2. The densities of the glasses were in fairly good agreement with the theoretical densities and were 0.2–0.41 g cm3 larger than those of the polycrystalline ceramics. The conductivities of the glasses are 1–2 orders lower than those of the ceramics and the highest electrical conductivity was achieved for the Yb ceramic sample with the smallest ion radius of RE3+. The electromotive force, EMF, of the potentiometric CO2 gas sensors using (Na2O)35.7(Y2O3)7.2(SiO2)57.1 glass and ceramic increased linearly with an increase in the logarithm of CO2 partial pressure, in accordance with Nernst’s law. It was suggested from the slope of Nernst’s equation that the two electron-transfer reaction associated with the carbon dioxide molecule takes place at the detection electrode above 450  C.

07/02333 Energy and visual comfort performance of electrochromic windows with overhangs Lee, E. S. and Tavil, A. Building and Environment, 2007, 42, (6), 2439– 2449. DOE-2 building energy simulations were conducted to determine whether electrochromic (EC) windows could significantly improve visual comfort without eroding energy-efficiency benefits. EC windows were combined with overhangs since opaque overhangs provide protection from direct sun which EC windows are unable to do alone. The window wall was divided into an upper and lower aperture so that various combinations of overhang position and control strategies could be considered. The overhang was positioned either at the top of the upper window aperture or between the upper and lower apertures. Overhang depth was varied. EC control strategies were fully bleached at all times, modulated based on incident vertical solar radiation limits, or modulated to meet the design work plane illuminance with daylight. The EC performance was compared to a state-of-the-art spectrally selective low-e window with the same divided window wall, window size, and overhang as the EC configuration. The reference window was also combined with an interior shade, which was manually deployed to control glare and direct sun. Both systems had the same daylighting control system to dim the electric lighting. Results were given for south-facing private offices in a typical commercial building. In hot and cold climates such as Houston and Chicago, EC windows with overhangs can significantly reduce the average annual daylight glare index (DGI) and deliver significant annual energy use savings if the window area is large. Total primary annual energy use was increased by 2–5% for moderate-area windows in either climate but decreased by 10% in Chicago and 5% in Houston for large-area windows. Peak electric demand can be reduced by 7–8% for moderate-area windows and by 14–16% for large-area windows in either climate. Energy and peak demand reductions can be significantly greater if the reference case does not have exterior shading or state-of-the-art static glass.

07/02334 Hydrogen production by water dissociation using mixed conducting dense ceramic membranes Balachandran, U. et al. International Journal of Hydrogen Energy, 2007, 32, (4), 451–456. Significant amounts of hydrogen or oxygen can be generated at moderate temperatures (500–900  C) if a mixed-conducting (i.e. electron- and ion-conducting) membrane is used to remove either oxygen or hydrogen as it is generated. The authors demonstrated this in a previous study using cermet (i.e. ceramic–metal composite) membranes composed of an oxygen ion conductor, Gd-doped CeO 2 (CGO), and an electronic conductor, Ni. The study shows several ways to increase the hydrogen production rate by water dissociation with mixed-conducting membranes. Producing CGO/Ni membranes with a finer microstructure enlarged the triple-phase-boundary area, and increased the hydrogen production rate to 10 cm3 (STP)/min-cm2. Using a single-phase, mixed-conducting membranes [SrFeCo0.5Ox (SFC2)] also produced higher hydrogen production rates, relative to dual-phase cermet membranes.

352 Fuel and Energy Abstracts September 2007

07/02335 Impedance spectroscopy studies on Fe3+ ion modified PLZT ceramics Dutta, S. et al. Ceramics International, 2007, 33, (1), 13–20. Polycrystalline Fe3+-modified lanthanum-modified lead zirconate titanate (PLZT) Pb0.92 (La0.1Fe0.9)0.08(Zr0.60Ti0.40)0.98O3 (PLFZT) was prepared by high temperature solid-state reaction. Preliminary room temperature X-ray study confirms the formation of single-phase compounds in a tetragonal crystal system. The electrical behaviour (complex impedance Z*, complex permittivity "*, complex modulus M*) of the PLFZT system has been studied by non-destructive complex impedance spectroscopy (CIS). Grain and grain boundary conduction is observed from complex impedance spectrum at high temperatures (650 K and above) by the appearance of two semicircular arcs. The Cole–Cole plots of permittivity spectrum consisted of a circular arc followed by a semicircular spur indicate that the dielectric phenomenon of PLFZT is due to conductive grain boundaries. This is quite different in nature from Debye type mono dispersive phenomenon. The temperature variation of real permittivity gives evidence of the ferroelectric phase transition as well as of the relaxation behaviour. The presence of non-Debye type multiple relaxations has been confirmed by complex modulus analysis.

07/02336 Influence of additives on microstructural changes in nitride bonded SiC refractories Nourbakhsh, A. A. et al. Journal of the European Ceramic Society, 2006, 26, (9), 1737–1741. In this study the microstructural development of nitride-bonded SiC refractories is reported in presence of Al2O3 and MgO. The samples were prepared by mixing, shaping and firing at 1450–1600  C in a controlled atmosphere furnace. Phase analysis, microscopic observation and mechanical evaluation were taken as criteria for microstructural evolution. The strength of samples doped with alumina was initially increased and then decreased at higher amount of alumina additions while the addition of magnesia decreased the strength. These phenomena could be attributed to microstructural evolution and mainly to liquid phase formation and grain morphology. It was found that the additives such as Al2O3 and MgO could modify the microstructure and influence the mechanical behaviour.

07/02337 Influence of glass curtain walls on the building thermal energy consumption under Tunisian climatic conditions: the case of administrative buildings Bouden, C. Renewable Energy, 2007, 32, (1), 141–156. The glass curtain walls have been recently introduced in Tunisia; they are seen as a new fashion and are highly appreciated by some for their pleasing aesthetics. The objective of this paper is to investigate whether the glass curtain walls are appropriate for the Tunisian local climate and context and if it is so, to give recommendations concerning the kind of glass to be used. A TRNSYS simulation was conducted on a typical administrative building. The investigation concerns only the building heating and cooling load. The building was split in five thermal zones; for each thermal zone, all the windows have the same orientation. The single zone model TYPE19 of TRNSYS was used to model each thermal zone. An additional convection heat transfer between the different thermal zones of the building was modelled according to the Brown and Solvason law. This particular law was used because it has been validated in the Tunisian context by Bouden. It was assumed that the glass curtain wall would only be implemented on the main building facade; this is why it was simulated with different glazing sizes and glass types. The other facades remain unchanged. The results of this simulation have shown that, in relation to space heating, the glass curtain wall can be very interesting in the Tunisian context if the orientation as well as the kind of glazing are carefully selected.

07/02338 Low emittance coatings and the thermal performance of vacuum glazing Fang, Y. et al. Solar Energy, 2007, 81, (1), 8–12. The thermal performances of vacuum glazings employing coatings with emittance between 0.02 and 0.16 were simulated using a threedimensional finite volume model. Physical samples of vacuum glazings with hard and soft coatings with emittance of 0.04, 0.12 and 0.16 were fabricated and their thermal performance characterized experimentally using a guarded hot box calorimeter. Good agreement was found between experimental and theoretical thermal performances for both a vacuum glazing with a soft coating (emittance 0.04) and those with hard coatings (emittance 0.12 and 0.16). Simulations showed that for a low value of emittance (e.g. 0.02), the use of two low-emittance coatings gives limited improvement in thermal performance of the glazing system. The use of a single high performance low-emittance coating in a vacuum glazing has been shown to provide excellent performance.

07/02339 Microstructural development in cubic silicon carbide during irradiation at elevated temperatures Katoh, Y. et al. Journal of Nuclear Materials, 2006, 351, (1–3), 228–240.

13 Alternative energy supplies (biofuels and bioconversion energy) Microstructural development in chemically vapour-deposited (CVD) high-purity beta-SiC during neutron and self-ion irradiation at elevated temperatures was studied. The CVD SiC samples were examined by transmission electron microscopy following neutron irradiation to 4.5– 7.7  1025 n/m2 (E > 0.1 MeV) at 300 and 800  C and 5.1 MeV Si2+ ion irradiation up to 200 dpa at 600–1400  C. The evolution of various irradiation-produced defects including black spot defects, dislocation loops, network dislocations, and cavities was characterized as a function of irradiation temperature and fluence. It was demonstrated that the black spot defects and small dislocation loops continue to dominate at relatively low temperatures (<800  C), whereas they grow into Frank faulted loops and finally develop into dislocation networks at a higher temperature (1400  C). Substantial cavity formation on grain boundaries and stacking faults was confirmed after ion irradiation at 1400  C. These observations were discussed in relation with the known irradiation phenomena in SiC, such as low temperature swelling and cavity swelling.

results show that the composite thick films containing sol–gel derived Ba0.80Sr0.20TiO3 and Pb0.82La0.18TiO3 perovskite phases have been fabricated by using the PbO–B 2O3 glass as a sintering aid. Compared to conventional sintering at 1200  C, high densification of the composite thick films is achieved at temperature as low as 800  C by the ‘wetting’ and ‘infiltration’ of the liquid phase on the particles. The homogenization of the BST and PLT perovskite phase in the composite thick films is evitable by controlling the sintering temperature and time. The formation of the small amount of pyrochlore phase in composite thick films sintered at 800  C is resulted from both the volatilization of PbO and the interaction between the PLT and PbO–B2O3 glass. The relative dielectric properties of the composite thick films exhibit good temperature-stable behaviour, and the variation of the relative dielectric constant is less than 10% in the temperature range 0–300  C.

07/02340 New porous silicon carbide composite reinforced by intact high-strength carbon fibres

13 ALTERNATIVE ENERGY SUPPLIES

Mentz, J. et al. Journal of the European Ceramic Society, 2006, 26, (9), 1715–1724. A novel processing method to produce a carbon-fibre-reinforced silicon carbide (C/SiC) is presented and the mechanical properties are evaluated. The low-cost process yields a reaction bonded silicon carbide matrix but avoids efficiently reactive damage of the carbon fibres. Thus, the C/SiC-material shows a fibre-dominated behaviour due to high fibre strength and matrix porosity. The characteristics and mechanical properties of this C/SiC are highlighted. The discussion deals with the particular mechanical characteristics of porous-matrix materials relating to similar materials investigated hitherto.

07/02341 Optimization of the ceramization process for the production of three-dimensional biomorphic porous SiC ceramics by chemical vapor infiltration (CVI) Streitwieser, D. A. et al. Journal of the European Ceramic Society, 2006, 26, (12), 2381–2387. The ceramization process for the preparation of three-dimensional (3D) biomorphic porous SiC ceramics by chemical vapour infiltration (CVI) with methyltrichlorosilane/hydrogen mixture has been optimized in this work. As a first step, two alternative ceramization routes have been compared with each other with regard to composition, morphology and bending strength of the resulting ceramics using flat samples. Optimal ceramization route was found to be a three-step process including carbonization of the paper preforms, followed by chemical vapour infiltration with stoichiometric SiC layers and a final oxidation step, in which the residual carbon from the template (Cb) is burnt out of the ceramics. Based on these results 3D honeycomb structures have been ceramized. Prior to these experiments, a computational fluid dynamics simulation of the gas flow in the reactor and through the honeycomb structure has been performed with the software STAR-CD. As a result, homogeneously infiltrated threedimensional structured SiC ceramics could be produced.

07/02342 Re-investigation of synthesis of BaTiO3 by conventional solid-state reaction and oxalate coprecipitation route for piezoelectric applications Simon-Seveyrat, L. et al. Ceramics International, 2007, 33, (1), 35–40. The formation of barium titanate powder by solid-state reaction and oxalate coprecipitation route is re-investigated by differential thermal analysis–thermo-gravimetry (DTA–TG) thermal analysis and high temperature X-ray diffraction (XRD). The temperature formation of the perovskite phase is lower for the chemical way than for the solid state one, and no intermediate product is detected. The obtained powder leads to ceramics with high dielectric and piezoelectric properties. For example the room temperature piezoelectric d33 coefficient is 260 pC/N (higher than the values usually published in the literature) and it shows a good stability under electrical solicitations. These properties make BaTiO3 (BT) a lead-free high performance material for piezoelectric applications.

07/02343 The structures and dielectric properties of Ba0.80Sr0.20TiO3/Pb0.82La0.18TiO3 composite thick films with addition of PbO–B2O3 glass Wu, R. et al. Journal of the European Ceramic Society, 2006, 26, (9), 1611–1617. Sol–gel derived Ba0.80Sr0.20TiO3 (BST) and Pb0.82La0.18TiO3 (PLT) powders and a low-melting PbO–B2O3 glass powder were mixed to prepare paste. The composite thick films (40 mm) were fabricated by screen-printing the paste onto the Al2O3 substrates with screen-printed silver bottom electrode and then sintered at the low temperature 650– 800  C, respectively. X-ray diffraction (XRD), transmission microscope (TEM), scanning electron microscope (SEM) and an impedance analyser were used to analyse the structures, microstructures and dielectric properties of the powders and the composite thick films. The

Biofuels and bioconversion energy 07/02344 A study on the intercepted insolation as a function of slope and azimuth of the surface Gopinathan, K. K. et al. Energy, 2007, 32, (3), 213–220. Monthly average daily global radiation on surfaces tilted towards the equator and also inclined at various azimuth angels are estimated for three locations in the Southern African region from reported global and diffuse radiation on a horizontal surface. The anisotropic model suggested by Hay is used in obtaining daily radiation at various slopes and orientations. Total annual radiation data are also computed for various tilt and azimuth angles and optimum tilt and azimuth angels corresponding to maximum insolation are obtained for winter, summer and annual collection. The optimum tilt and orientation reported here show some variation from those reported earlier by other investigators and the results are discussed.

07/02345 Adsorption of hydrogen sulphide (H2S) by activated carbons derived from oil-palm shell Guo, J. et al. Carbon, 2007, 45, (2), 330–336. Adsorption of hydrogen sulfide (H 2S) onto activated carbons derived from oil palm shell, an abundant solid waste from palm oil processing mills, by thermal or chemical activation method was investigated in this paper. Dynamic adsorption in a fixed bed configuration showed that the palm-shell activated carbons prepared by chemical activation (KOH or H2SO4 impregnation) performed better than the palm-shell activated carbon by thermal activation and a coconut-shell-based commercial activated carbon. Static equilibrium adsorption studies confirmed this experimental result. An intra-particle Knudsen diffusion model based on a Freundlich isotherm was developed for predicting the amount of H2S adsorbed. Desorption tests at the same temperature as adsorption (298 K) and at an elevated temperature (473 K) were carried out to confirm the occurrence of chemisorption and oxidation of H2S on the activated carbon. Surface chemistries of the palm-shell activated carbons were characterized by Fourier transform infrared spectroscopy and Boehm titration. It was found that uptaking H2S onto the palm-shell activated carbons was due to different mechanisms, e.g. physisorption, chemisorption and/or H2S oxidation, depending on the activation agent and activation method.

07/02346 Artificial neural networks used for the prediction of the cetane number of biodiesel Ramadhas, A. S. et al. Renewable Energy, 2006, 31, (15), 2524–2533. Cetane number (CN) is one of the most significant properties to specify the ignition quality of any fuel for internal combustion engines. The CN of biodiesel varies widely in the range of 48–67 depending upon various parameters including the oil processing technology and climatic conditions where the feedstock (vegetable oil) is collected. Determination of the CN of a fuel by an experimental procedure is a tedious job for the upcoming biodiesel production industry. The fatty acid composition of base oil predominantly affects the CN of the biodiesel produced from it. This paper discusses the currently available CN estimation techniques and the necessity of accurate prediction of CN of biodiesel. Artificial Neural Network (ANN) models are developed to predict the CN of any biodiesel. The present paper deals with the application of multi-layer feed forward, radial base, generalized regression and recurrent network models for the prediction of CN. The fatty acid compositions of biodiesel and the experimental CNs are

Fuel and Energy Abstracts September 2007 353

13 Alternative energy supplies (biofuels and bioconversion energy) used to train the networks. The parameters that affect the development of the model are also discussed. ANN predicted CNs are found to be in agreement with the experimental CNs. Hence, the ANN models developed can be used reliably for the prediction of CN of biodiesel.

07/02347 Availability of logging residues and potential for electricity production and carbon displacement in the USA

and particulate. This review focuses on performance and emission of biodiesel in CI engines, combustion analysis, wear performance on long-term engine usage, and economic feasibility.

07/02350 Enhancing sulphur self-retention by building-in CaO in straw–bitumen pellets

Gan, J. and Smith, C. T. Biomass and Bioenergy, 2006, 30, (12), 1011– 1020. This study assessed the abundance and regional distribution of logging residues and their potential for electricity generation and CO2 emission displacement in the USA. Based on the 1997 Forest Inventory and Analysis data, a 70% residue recovery rate, and a minimum viable power plant capacity of 10 MW, annually recoverable logging residues in the USA were estimated at 13.9 million dry t from growing stock and 36.2 million dry t from both growing stock and other sources. Most logging residues were located in the eastern USA; the Southeast and South Central regions accounted for approximately two-thirds of the national total from growing stock and about 50% of that from both growing stock and other sources. The recoverable residues from both growing stock and other sources could generate 67.4 TWh electricity annually. This would displace 17.6 million t carbon emitted from coal-fuelled power plants (about 3% of total carbon emissions from the US electricity sector in 1997) at a cost ranging from US$60 to 80 t1 C.

Okasha, F. Fuel Processing Technology, 2007, 88, (4), 401–408. Combined straw–bitumen pellets have been proposed as an alternative fuel. An interesting finding is the potentiality of straw ash constituents to retain sulfur as bitumen that has relatively high sulfur content. The aim of the present work is to enhance sulfur self-retention to directly meet the environmental regulations by building-in CaO in the pellet instead of feeding sorbent separately. CaO powder has been mixed with the pellet constituents during production processes. An experimental study has been carried out to investigate the effectiveness of built-in CaO to retain sulfur. Two experimental facilities have been utilized. A fluidized bed combustor of 100 mm ID is used to perform batch tests, whereas a pre-pilot scale combustor of 300 mm ID is used for continuous operation. The obtained results demonstrate that building-in CaO is a very efficient technique for retaining sulfur. A major portion of sulfur is retained within the pellet throughout the entire burning period, in particular, during char burning stage. After being a completely burned pellet the remaining ashes work as a very efficient sorbent within the combustor. Typically, at built-in Ca/S = 0.75, SO 2 is reduced to about 65 ppm corresponding to 96% sulfur retention efficiency.

07/02348 Biodiesel production from heterotrophic microalgal oil

07/02351 Flow properties of biodiesel fuel blends at low temperatures

Miao, X. and Wu, Q. Bioresource Technology, 2006, 97, (6), 841–846. The present study introduced an integrated method for the production of biodiesel from microalgal oil. Heterotrophic growth of Chlorella protothecoides resulted in the accumulation of high lipid content (55%) in cells. Large amount of microalgal oil was efficiently extracted from these heterotrophic cells by using n-hexane. Biodiesel comparable to conventional diesel was obtained from heterotrophic microalgal oil by acidic transesterification. The best process combination was 100% catalyst quantity (based on oil weight) with 56:1 molar ratio of methanol to oil at temperature of 30  C, which reduced product specific gravity from an initial value of 0.912 to a final value of 0.8637 in about 4 h of reaction time. The results suggested that the new process, which combined bioengineering and transesterification, was a feasible and effective method for the production of high quality biodiesel from microalgal oil.

Joshi, R. M. and Pegg, M. J. Fuel, 2007, 86, (1–2), 143–151. The dynamic viscosities of biodiesel derived from ethyl esters of fish oil, no. 2 diesel fuel, and their blends were measured from 298 K down to their respective pour points. Blends of B80 (80 vol.% biodiesel– 20 vol.% no. 2 diesel), B60, B40 and B20 were investigated. All the viscosity measurements were made with a Bohlin VOR Rheometer. Cloud point and pour point measurements were made according to ASTM standards. Arrhenius equations were used to predict the viscosities of the pure Biodiesel (B100), no. 2 diesel fuel (B0) and the biodiesel blends (B80, B60, B40, and B20) as a function of temperature. The predicted viscosities agreed well with measured values. An empirical equation for calculating the dynamic viscosity of these blends as a function of both temperature and blend has been developed. Furthermore, based on the kinematic viscosity and density measurements of B100 up to 573 K from an earlier study, an empirical equation for predicting the dynamic viscosity of pure biodiesel for temperatures from 277 K to 573 K is given. Empirical equations for predicting the cloud and pour point for a given blend give values in good agreement with experiments. The dynamic viscosity of biodiesel and its blends increases as temperature decreases and shows Newtonian behaviour down to the pour point. Dynamic viscosity, cloud point and pour point decreases with an increase in concentration of no. 2 diesel in the blend.

07/02349 Biofuels (alcohols and biodiesel) applications as fuels for internal combustion engines Agarwal, A. K. Progress in Energy and Combustion Science, 2007, 33, (3), 233–271. The increasing industrialization and motorization of the world has led to a steep rise for the demand of petroleum-based fuels. Petroleumbased fuels are obtained from limited reserves. These finite reserves are highly concentrated in certain regions of the world. Therefore, those countries not having these resources are facing energy/foreign exchange crisis, mainly due to the import of crude petroleum. Hence, it is necessary to look for alternative fuels that can be produced from resources available locally within the country such as alcohol, biodiesel, vegetable oils etc. This paper reviews the production, characterization and current statuses of vegetable oil and biodiesel as well as the experimental research work carried out in various countries. This paper touches upon well-to-wheel greenhouse gas emissions, well-to-wheel efficiencies, fuel versatility, infrastructure, availability, economics, engine performance and emissions, effect on wear, lubricating oil, etc. Ethanol is also an attractive alternative fuel because it is a renewable bio-based resource and it is oxygenated, thereby providing the potential to reduce particulate emissions in compression-ignition engines. In this review, the properties and specifications of ethanol blended with diesel and gasoline fuel are also discussed. Special emphasis is placed on the factors critical to the potential commercial use of these blends. The effect of the fuel on engine performance and emissions [SI as well as compression ignition (CI) engines], and material compatibility is also considered. Biodiesel is methyl or ethyl ester of fatty acid made from virgin or used vegetable oils (both edible and non-edible) and animal fat. The main resources for biodiesel production can be non-edible oils obtained from plant species such as Jatropha curcas (Ratanjyot), Pongamia pinnata (Karanj), Calophyllum inophyllum (Nagchampa), Hevca brasiliensis (Rubber), etc. Biodiesel can be blended in any proportion with mineral diesel to create a biodiesel blend or can be used in its pure form. Just like petroleum diesel, biodiesel operates in compression ignition (diesel) engine, and essentially require very little or no engine modifications because biodiesel has properties similar to mineral diesel. It can be stored just like mineral diesel and hence does not require separate infrastructure. The use of biodiesel in conventional diesel engines result in substantial reduction in emission of unburned hydrocarbons, carbon monoxide

354 Fuel and Energy Abstracts September 2007

07/02352 Influence of particle size on the analytical and chemical properties of two energy crops Bridgeman, T. G. et al. Fuel, 2007, 86, (1–2), 60–72. Two energy crops (switchgrass and reed canary grass) have been processed using ball mills and divided into two size fractions (<90 mm and 90–600 mm) and analysed using an array of analytical techniques including proximate and ultimate analysis, metal analysis, calorific value determination, and plant component analysis (cellulose, lignin and hemicellulose contents). The results indicate that smaller particles of the two grasses have a significantly higher concentration of inorganic matter and moisture content than larger particles. In contrast the larger size fractions had a higher carbon content, and lower nitrogen content, with a resulting higher calorific value. The volatile content was also higher in the larger size fraction. The composition of the organic content varied between the two size fractions, most noticeable was the difference in cellulose concentration which was approximately 50% higher in the >90 mm sample. Two laboratory scale techniques, thermogravimetric analysis (TGA) and pyrolysis–GC–MS (py–GC– MS), were used to study the significance of these differences in thermal conversion. In py–GC–MS of reed canary grass, and switchgrass to a lesser extent, the amounts of cellulose and lignin decomposition products were higher for the larger particle size fraction. The differences in cellulose contents were also apparent from the TGA studies, where different mass losses were seen in the cellulose decomposition region of the two size fractions. From the results of these two techniques it was concluded that the differences in ash, and therefore catalytic metal contents, between the two size fractions, resulted in lower pyrolysis temperatures, lower char combustion temperatures, and higher yields of catalytic pyrolysis decomposition products for the smaller size fractions. The implications of the results are discussed in terms of the bio-oil quality in fast pyrolysis and the predicted behaviour of the ash in combustion. It is suggested that pre-

13 Alternative energy supplies (geothermal energy) treatment by milling is one route that might be used routinely as a feedstock quality improvement strategy in integrated biomass conversion processes.

direct contribution to new tree growth. The success of this model system will provide guidance for the application of similar techniques in field experiments.

07/02353 Performance optimization of two-staged gasification system for woody biomass

07/02357 Tracing N, K, Mg and Ca released from decomposing biomass to new tree growth. Part II: a model system simulating root decomposition on clearfell sites

Wang, Y. et al. Fuel Processing Technology, 2007, 88, (3), 243–250. The performance of a small-scale two-staged gasification system is reported. In this system wood chips are gasified with a fixed bed gasifier and then tar in the produced gas is reformed in a non-catalytic reformer, finally the production gas is used to generate electricity. In this system, the gasifying agents are high temperature air and steam supplied into the gasifier and the reformer. This paper reports on optimum gasification air ratio (defined as the ratio of the oxygen mole supplied into the gasifier to the oxygen mole required for complete combustion of biomass), reforming air ratio (defined as the ratio of the oxygen mole supplied in the reformer to the oxygen mole required for the complete combustion of biomass) and steam ratio (defined as the ratio of the steam mole supplied into the gasifier to the carbon mole in biomass supplied into the gasifier) for producing required gas supplied into a dual-fueled diesel engine. The results showed that, under optimum conditions, the higher heating value of the reformed gas was 3.9 MJ/m3N; the cold gas efficiency (defined as the ratio of HHV reformed gas  reformed gas flow rate to HHV biomass  biomass feed rate) of the gasification system was 66%, and the gross thermal efficiency of the overall system was 27%.

07/02354 Structural analysis of bio-oils from sub-and supercritical water liquefaction of woody biomass Qian, Y. et al. Energy, 2007, 32, (3), 196–202. Woody biomass was liquefied by water in an autoclave in the reaction temperature range of 280–420  C with sodium carbonate as the catalyst. The experimental results show that the yield of the main liquefaction product (heavy oil) was significantly influenced by the process conditions. The maximum yield of heavy oil was obtained at reaction temperature 380  C. The heavy oils obtained at different reaction temperature were analysed by Fourier transform infrared spectroscopy and gas chromatography/mass spectrometry. The analytical results show the heavy oil is complex compound that contain hydrocarbon, aldehyde, ketone, hydroxybenzene and ester.

07/02355 The effect of heating rate on yields and compositions of oil products from esparto pyrolysis Debdoubi, A. et al. International Journal of Energy Research, 2006, 30, (15), 1243–1250. Recently, much research has been focused on liquid oil from biomass pyrolysis, which is considered as an alternative to conventional fossil fuels. This paper studies the effect of heating rate on both the yields and the chemical composition of the oil product obtained from pyrolysis of esparto, which is the most important biomass in Morocco. The pyrolysis experiments of esparto was performed in a fixed bed reactor under argon atmosphere with different heating rate: 50, 150 and 250 C min1. The maximum conversion of esparto in oil of pyrolysis was obtained with fast pyrolysis 68.5% at 550 C. The FT-IR and 1H NMR anaysis showed that the oil of pyrolysis formed principally by aliphatic compound. The analysis elemental showed that the H/C ratio increase and O/C decrease as the heating rate increase. The PCV improved slightly from 33.5 to 34.8 MJ kg1. The oil obtained with higher heating rate has chemical properties similar to diesel that can be used with an economic and environmental advantage.

07/02356 Tracing N, K, Mg and Ca released from decomposing biomass to new tree growth. Part I: a model system simulating harvest residue decomposition on conventionally harvested clearfell sites Weatherall, A. et al. Biomass and Bioenergy, 2006, 30, (12), 1053–1059. It is necessary to assess the effects of removing nutrient-rich harvest residues (brash) from clearfell sites because there is a growing market for this brash as bioenergy. The aim of this study was to use stable isotope techniques in a model system to trace nutrients released by decomposing brash. Labelled biomass was obtained by growing Sitka spruce [Picea sitchensis (Bong.) Carr.] seedlings with a generous or poor nutrient supply containing elevated 15N, 41K, 26Mg, and 44Ca. This biomass was used in two subsequent studies. In this study (Part I of II), the above-ground biomass was harvested and placed on soil in a pot containing a newly planted seedling. Soils from two forests, Ae and Teindland, of contrasting nutritional status were used. A full destructive harvest was undertaken after one growing season. Enriched 15 N, 41K, 26Mg, and 44Ca were recovered in the new seedlings. The percentage contribution from labelled biomass to new tree growth was small, but discernible. The N contribution from labelled biomass to new trees was greater in Ae soil, but the base cation contribution was greater in Teindland soil. Results are discussed with reference to the initial nutrient concentrations of each soil. The elevated 15N, 41K, 26Mg and 44Ca in new seedlings indicate that nutrients in brash can make a

Weatherall, A. et al. Biomass and Bioenergy, 2006, 30, (12), 1060–1066. The decomposing roots of harvested trees are a potential source of nutrients for new trees on both conventional and whole-tree harvested clearfell sites. Roots contain significant reservoirs of nutrients, but little is known about the magnitude and rate of their release. The aim of this study was to use stable isotope techniques in a model system to trace nutrients released by decomposing roots. Labelled biomass was obtained by growing Sitka spruce [Picea sitchensis (Bong.) Carr.] seedlings with a generous or poor nutrient supply containing elevated 15 N, 41K, 26Mg and 44Ca. Labelled trees were re-potted in sand and in two contrasting soils types to remove them from the enriched isotope supply. After re-potting, the labelled above-ground biomass was harvested, removed and used in a separate study described previously (part I of II). In the study described here (part II of II), new Sitka spruce seedlings were planted alongside the labelled root systems. A full destructive harvest was undertaken after one growing season. Enriched 15 N, 41K, 26Mg, and 44Ca were recovered in the new seedlings in both sand and soils. The elevated amounts of 15N, 41K, 26Mg and 44Ca recovered in new seedlings indicate that nutrients released from decomposing roots can make a direct contribution to the growth of new trees on restock sites. The success of this model system will provide guidance for the application of similar techniques in field experiments.

07/02358 biomass

Zn(II) biosorption properties of Botrytis cinerea

Tunali, S. and Akar, T. Journal of Hazardous Materials, 2006, 131, (1–3), 137–145. The study was aimed of determining the Zn(II) sorption performance of Botrytis cinerea (B. cinerea) biomass as a new biosorbent. Heat inactivated biomass was used in the determination of optimum conditions. The rate and extent of accumulation were effected by pH, contact time and initial zinc ion concentrations. The uptake capacity of B. cinerea was increased by chemical and physical pretreatment of the cells when compared with the native biomass. The maximum removal of Zn(II) at pH 5.0–6.0 was found to be 12.98  0.9623 mg g1 at initial Zn(II) ion concentration of 100 mg l1 by heat inactivated biomass. Freundlich and Langmuir isotherm models were used to evaluate the data and regression constants were derived. The biosorbent was regenerated using 10 mM HCl solution, with up to 98% recovery and reused five times in biosorption–desorption cycles successivelly. Competitive biosorption experiments were performed with zinc in the presence of copper, cadmium and nickel ions simultaneously. The nature of the possible cell–metal ions interactions was also evaluated by chemical and instrumental analysis including infrared spectroscopy, scanning electron microscopy and X-ray energy dispersion analysis.

Geothermal energy 07/02359 A comparative study on exergetic assessment of two ground-source (geothermal) heat pump systems for residential applications Akpinar, E. K. and Hepbasli, A. Building and Environment, 2007, 42, (5), 2004–2013. Ground source heat pumps (GSHPs), also known as geothermal heat pumps, have been widely used for years in developed countries due to their higher energy utilization efficiencies than those of both conventional heating and cooling systems. However, they have been applied to the Turkish residential buildings since 1997. This study deals with the exergetic performance evaluation of two types of GSHP systems installed in Turkey based on the actual operational data. The fist one is a GSHP system designed and constructed for investigating geothermal resources with low temperatures, while the second one is a GSHP system with a vertical ground heat exchanger. In the analysis, four balance (mass, energy, entropy and exergy) equations are applied to the two GSHP systems considered for modelling purposes in a tabulated form. Exergy (second law) efficiency values for both systems are given, while exergy destructions in each of the system components are determined to assess their individual performances by presenting the potential for improvements. It may be concluded that the exergetic evaluation method presented here may be applied to other GSHP systems worldwide as a useful tool, which is a way to sustainable development.

Fuel and Energy Abstracts September 2007 355

13 Alternative energy supplies (geothermal energy) 07/02360 A new contribution to the finite line-source model for geothermal boreholes Lamarche, L. and Beauchamp, B. Energy and Buildings, 2007, 39, (2), 188–198. Heat transfer around vertical ground heat exchangers is a common problem for the design and simulation of ground-coupled heat pump systems. Most models are based on step response of the heat transfer rate, and the superposition principle allows the final solution to be in the form of the convolution of these contributions. The step response is thus a very important tool. Some authors propose numerical tabulated values while others propose analytical solutions for purely radial problem as well as axisymmetric problems. In this paper, the authors propose a new analytical model that yields results very similar to the tabulated numerical ones proposed in the literature. Analytical modelling offers better flexibility for a parameterized design.

07/02361 A simple procedure to size active solar heating schemes for low-energy building design Cuadros, F. et al. Energy and Buildings, 2007, 39, (1), 96–104. The energy consumption of a building depends on the thermal demand and on the mean performance of the system. Apart from passive solar indoor climate control techniques, it is also possible to reduce conventional energy consumption of a building, even bringing it close to zero by installing solar heating. Hence, better knowledge of these techniques and of how they can be implemented in a simple but effective way will further progress towards more energy efficient buildings. The present work describes a straightforward procedure – applicable in any part of the world – to estimate the climate variables, to compare the efficiencies of solar heat collectors, and to size certain installations for domestic hot water, radiant flooring, or heating of buildings. The values of the climate variables – the monthly means of the daily values of solar radiation, maximum and minimum temperatures, and number of hours of sun – are determined from data available in the FAO’s CLIMWAT database. Even though the calculation process uses approximate values for the variables involved rather than taking their dynamic evolution into account, it is fairly precise, giving results that are comparable to other more sophisticated and less easy to handle procedures such as the worldwide known f-CHART, TRNSYS, ISOFOTON and CENSOLAR computation programs. The predictive validity of the procedure has also been tested by comparing the results with those obtained experimentally via a solar heat collector installed on the roof of a building in the city of Badajoz. It is believed that the procedure together with the computation program, will be of great use to builders and architects, since it allows a solar installation to be rapidly sized for applications in active solar heating schemes for building design.

07/02362 Classification of geothermal resources in Turkey by exergy analysis Etemoglu, A. B. and Can, M. Renewable and Sustainable Energy Reviews, 2007, 11, (7), 1596–1606. The investigations have been directed to technology development in the usage of natural resources as a result of increase in the world energy demand associated with environmental factors. It has also sparked interest in the scientific community to take a closer look at the energy conversion devices and develop the new techniques to better utilize the existing limited sources. Geothermal resources have a great importance for the energy potential in Turkey. Exergy of a system is the capability of doing work and exergy values of geothermal resources are the strongest criterion for determining the system efficiency. In this study, geothermal resources in Turkey have been classified based on specific exergy rates (SER). The computed results of exergy analysis can be used as a tool for evaluating the characteristics of resources, and the optimum application area of geothermal resources can also be defined.

07/02363 Discrepancies in brine density databases at geothermal conditions Champel, B. Geothermics, 2006, 35, (5–6), 600–606. The study is aimed at evaluating the influence of brine density data on the assessment of pumping requirements for geothermal installations. Five databases were compiled and compared, based on an evaluation of buoyancy effect in a producing well at the site of the Soultz-sous-Foreˆts EGS/HDR project. The results show large discrepancies between the different references, which lead to severe inaccuracies in the evaluation of the buoyancy effect, and thus of the pumping requirements. It is therefore recommended that care be taken when using such databases, in particular when determining the size of the pumping systems. It is also recommended that new measurements of brine densities be carried out, focussing specifically on geothermal conditions.

07/02364 Geothermal cooling through enhancement of the natural heat sink effect – proof of concept Thompson, J. A. et al. Experimental Thermal and Fluid Science, 2007, 77, (7), 551–558.

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Underground railway system usage is growing throughout the developing world and in many cities the underground railway is the most commonly used form of public transport. The intense service provided on these systems generates substantial quantities of rejected heat energy. This energy can significantly increase air temperatures within the trains and tunnels. When coupled to high ambient temperatures this can lead to passenger discomfort and health issues. Conventional air conditioning systems have been used in some modern underground railway installations but their operation has had limitations and leads to highly energy intensive solutions. Conventional air conditioning often cannot be included in older systems through heat rejection and spatial problems. Sustainable cooling systems could reduce the overall system energy usage and provide an acceptable environment for passengers. These could include energy management methods such as reduced train velocity, low weight carriages as well as sustainable cooling technologies that have been introduced from modern building services engineering such as Groundwater and geothermal cooling. Geothermal cooling has not been investigated with respect to underground railways currently and this paper is aimed at investigating this concept. A calibrated laboratory experiment is described that investigates the conductive heat transfer in an underground railway like environment. The experiment is run with and without modification to the thermal topography of the test rig. The experiment is run under both steady state and transient conditions to explore fully the potential for geothermal cooling. The experiment shows that the same level of heat energy can be transported across a vastly reduced temperature difference. This will enhance the thermal comfort provision and allow greater levels of heat energy to be moved without compromising the tunnel temperature.

07/02365

HDR economic modelling: HDRec software

Heidinger, P. et al. Geothermics, 2006, 35, (5–6), 683–710. Hot dry rock economic (HDRec) is a cost-benefit analysis program for geothermal projects that combines economic aspects with the technical characteristics of the surface installations and the hydrogeological and thermal properties of the subsurface. Investment and operation costs are evaluated and related to the revenues gained from electricity sales. The program also accounts for discounted cash flows when determining the characteristic financial parameters, as well as the time dependency of operation costs, and the reduction in income ensuing from decreasing reservoir temperatures. It is also possible to factor in the expense incurred for maintenance or refurbishment during production, as well as the cost of dismantling the system when exploitation ends. A simple tax model is also incorporated in the economic calculations. The characteristic financial parameters can be referenced to the start of exploration, or to the beginning and end of commercial energy production. A description is given of the workflow of the HDRec program, followed by an example of its application to a dataset representing conditions in the Upper Rhine Valley of France and Germany. The paper also provides a sensitivity analysis of the influence of the parasitic power demand of pumps and of different subsurface heat exchange areas between boreholes. Finally, a scenario is proposed for optimizing the economic performance of the system using the latest information on the characteristics of the Soultz-sous-Foreˆts reservoir.

07/02366 Influence of water–rock interactions on fracture permeability of the deep reservoir at Soultz-sous-Foreˆ ts, France Andre´, L. et al. Geothermics, 2006, 35, (5–6), 507–531. Circulation of geothermal fluids through granitic fractured reservoirs leads to chemical reactions, modifying the porosity and permeability of the rock mass. FRACHEM, a thermo-hydraulic-chemical coupled computer code, was developed specifically to predict changes in the geothermal reservoir of the Soultz-sous-Foreˆts enhanced geothermal system located in Alsace, France. This code can simulate fluid–rock interactions and determine the dissolution/precipitation reactions of eight minerals in the Soultz granite (i.e. carbonates, pyrite, silicates and aluminosilicates). Numerical simulation results of long-term fluid circulation through the 5000-m deep Soultz reservoir are comparable to those determined for the shallow reservoir and confirm the role played by carbonates in the evolution of reservoir porosity and permeability. Moreover, experiments with FRACHEM in simulating short-term fluid flow during hydraulic and/or chemical stimulations have demonstrated that the code could prove an efficient tool in reservoir engineering and management.

07/02367 Modeling and performance evaluation of ground source (geothermal) heat pump systems Ozgener, O. and Hepbasli, A. Energy and Buildings, 2007, 39, (1), 66– 75. This study deals with the energetic and exergetic modelling of ground source heat pump (GSHP) systems for the system analysis and performance assessment. The analysis covers two various GSHPs, namely a solar assisted vertical GSHP and horizontal GSHP. The performances of both GSHP systems are evaluated using energy and

13 Alternative energy supplies (solar energy) exergy analysis method based on the experimental data. Energy and exergy specifications are also presented in tables. Some thermodynamic parameters, such as fuel depletion ratio, relative irreversibility, productivity lack and exergetic factor, are investigated for both systems. The results obtained are discussed in terms of energetic and exergetic aspects. The values for COPHP ranged from 3.12 to 3.64, while those for COPsys varied between 2.72 and 3.43. The exergy efficiency peak values for both whole systems on a product/fuel basis were in the range of 80.7% and 86.13%. It is expected that the model presented here would be beneficial to everyone dealing with the design, simulation and testing of GSHP systems.

07/02368 The potential of the use of dense fluids for initiating hydraulic stimulation Me´gel, T. et al. Geothermics, 2006, 35, (5–6), 589–599. To improve preferentially the permeability of fractures in the deepest parts of a geothermal reservoir, a dense fluid may be injected during the very first phase of a hydraulic stimulation test. To initiate such a permeability-enhancement process in the 5000 m deep reservoir of the European enhanced geothermal system project at Soultz-sous-Foreˆts, France, a concentrated NaCl brine was injected. The effects of this injection were estimated using measured hydraulic and microseismic data. Two tasks associated with hydraulic stimulation have been shown to be important for this purpose: (1) determination of the failure pressures of the various fractures intersecting the open-hole section under stimulation, and (2) calculation of the transient hydraulic pressure profile in the borehole. Using the numerical borehole code HEX-B, the transient pressure profiles during stimulation of wells GPK2 (June 2000) and GPK3 (May 2003) were calculated on the basis of measured wellhead data. A comparison of the temporal history of near-borehole microseismic events during the GPK2 test and downhole pressure development in the open-hole sections of this borehole indicated that use of a dense brine helped stimulate the bottom part of this well. The corresponding analysis for the GPK3 test showed that the failure pressure of the fractures in the bottom part of the wellbore was never exceeded when injecting the dense brine. It can, therefore, be assumed that the brine had no effect on the fractures in GPK3.

07/02369 Use of a hydrogeochemical approach in determining hydraulic connection between porous heat reservoirs in Kaifeng area, Henan, China Lin, X. et al. Applied Geochemistry, 2007, 22, (2), 276–288. In this paper a case study of hydraulic connectivity in a 300–1600 m deep, low temperature, sedimentary geothermal system in Kaifeng area, Henan province, China is presented. Based on lithologic data from 52 geothermal wells and chemical data on geothermal water (GW) from six depth-specific and representative wells, the system was chemically grouped into two main hot reservoirs (300–1300 m and 1300–1600 m deep), which were in turn, divided into six sub-reservoirs (SRs). Data on stable isotope (2H and 18O) ratios, radioactive isotope (14C) radiation in conjunction with computation of mineral–fluid chemical equilibria were used to establish the recharge source (a mountainous region in the southwestern part of Zhengzhou, 60 km away); evaluate groundwater age which varied with well depth from 15630  310 a to 24970  330 a; and assess the chemical equilibrium state within the system. The results of different analysis did not suggest an obvious hydraulic connection between the two main hot reservoirs. The location of the recharge zone and the geohydrologic characteristics of the study area demonstrate that the GW utilized from the system is mainly derived from confined waters of meteoric origin.

Solar energy 07/02370 A new formulation for solar irradiation and sunshine duration estimation S ˛ ahin, A. D. International Journal of Energy Research, 2007, 31, (2), 109–118. In solar engineering and atmospheric sciences solar irradiation and sunshine duration estimations are very important for different problems. Classical approaches that based on Angstro¨ m equation for estimating global solar irradiation in terms of sunshine duration are abundant in the literature. Most of them include linear and lesser extent slightly nonlinear relationships between these two variables. Parameters are determined invariably by the least squares technique leading to regression lines or curves as models. None of these models provides within year variations in the parameters and they are all very rigid in applications yielding single global solar irradiation estimation for a given data set. In this paper, relation between extraterrestrial variables (length of day and solar irradiation) ratio and terrestrial variables (measured sunshine duration and solar irradiation) ratio is taken into account. This is a novel approach and has no restrictive

assumptions. Decreasing amount of extraterrestrial variables ratio can be evaluated by subtracting measured terrestrial variables ratio (sunshine duration/total solar irradiation) from theoretical variables ratio. Differences between these ratios give atmospheric effects on length of day and extraterrestrial solar irradiation. The differences are represented by a parameter which helps to estimate easily the seasonal average parameter values without the application of the least square method. The main idea of this paper is to suggest not only a novel but also a practical formulation for solar irradiation and sunshine duration estimations. Its application is presented for three stations in Turkey and it is seen that better estimations are evaluated by proposed method than Angstro ¨ m method.

07/02371 A parametric study on the thermal performance of cross-corrugated solar air collectors Lin, W. et al. Applied Thermal Engineering, 2006, 26, (10), 1043–1053. A comprehensive parametric study has been carried out in this paper on the thermal performance of cross-corrugated solar air collectors. These collectors consists of a wavelike absorbing plate and a wavelike bottom plate which are crosswise positioned to form the air flow channel. Two types of these collectors are considered. For the Type 1 collector, the wavelike shape of the absorbing plate is along the flow direction and that of the bottom plate is perpendicular to the flow direction, while for the Type 2 collector it is the wavelike shape of the bottom plate that is along the flow direction and that of the absorbing plate is perpendicular to the flow direction. The aim of the use of the cross-corrugated absorbing plate and bottom plate is to enhance the turbulence and the heat transfer rate inside the air flow channel which are crucial to the improvement of efficiencies of solar air collectors. To quantify the achievable improvements with the cross-corrugated absorbing and bottom plates, a flat-plate solar air collector which has both a flat absorbing plate and a flat bottom plate, is also considered. The thermal performance of these three types of solar air collector are analysed and compared under various configurations and operating conditions. The results show that although the thermal performance of the Type 2 collector is just slightly superior to that of the Type 1 collector both of these cross-corrugated solar air collectors have a significantly superior thermal performance to that of the flat-plate one. It is also found that to achieve a higher collector efficiency, it is essential to construct the collectors having slender configurations along the air flow direction, to maintain a small mean gap between the absorbing plate and bottom plate, to use selected coatings on the absorbing plate and glass cover, to maintain a higher air mass flow rate, and to operate the collectors with the inlet fluid temperature close to that of the ambient fluid.

07/02372 A sensitivity study of a hybrid photovoltaic/ thermal water-heating system with natural circulation Ji, J. et al. Applied Energy, 2007, 84, (2), 222–237. A flat-box aluminium-alloy photovoltaic and water-heating system designed for natural circulation was constructed. The hybrid photovoltaic/thermal (PV/T) collector was an integration of single-crystalline silicon cells into a solar thermal collector. The product was able to generate electricity and hot water simultaneously. Outdoor tests on an improved prototype were conducted in a moderate climate zone. Then dynamic simulation runs, using a validated numerical model, were performed. These included sensitivity tests with variations of the system water mass, PV cell covering factor, and front glazing transmissivity. The test results showed that the characteristic daily primary-energy saving could reach up to 65% for this system with a PV cell covering factor 0.63 and front glazing transmissivity of 0.83, when the hot water load per unit heat-collecting area exceeded 80 kg/m2. The simulated results indicated that the higher the PV cell covering factor and the glazing transmissivity, the better the overall system performance. The effects were quantified.

07/02373 A simulation study on the operating performance of a solar–air source heat pump water heater Xu, G. et al. Applied Thermal Engineering, 2006, 26, (11–12), 1257– 1265. A simulation study on the operating performance of a new type of solar–air source heat pump water heater (SAS-HPWH) has been presented. The SAS-HPWH used a specially designed flat-plate heat collector/evaporator with spiral-finned tubes to obtain energy from both solar irradiation and ambient air for hot water heating. Using the meteorological data in Nanjing, China, the simulation results based on 150 L water heating capacity showed that such a SAS-HPWH can heat water up to 55  C efficiently under various weather conditions all year around. In this simulation study, the influences of solar radiation, ambient temperature and compressor capacity on the performance of the SAS-HPWH were analysed. In order to improve the overall operating performance, the use of a variable-capacity compressor has been proposed.

Fuel and Energy Abstracts September 2007 357

13 Alternative energy supplies (solar energy) 07/02374 Buoyancy induced heat transfer and fluid flow inside a tilted wavy solar collector Varol, Y. and Oztop, H. F. Building and Environment, 2007, 42, (5), 2062–2071. Natural convection heat transfer and fluid flow were investigated inside a wavy walled and inclined solar collector, numerically. Flat ceiling was considered as cover (cold temperature) of solar collector and wavy wall as absorber (hot temperature). CFDRC commercial code was used to solve laminar-governing equations of natural convection. Working fluid was considered as air with Pr=0.71 inside the collector. Parameters that affect the flow and temperature field are Rayleigh number, inclination angle, aspect ratio, and wavelength. Flow and temperature fields were presented by streamlines and isotherms. Local and mean Nusselt numbers were calculated. Results indicate that heat transfer is increased with increasing Rayleigh number and aspect ratio, and is decreased with increasing wavelength.

07/02375 Comparative study of various correlations in estimating hourly diffuse fraction of global solar radiation Jacovides, C. P. et al. Renewable Energy, 2006, 31, (15), 2492–2504. Proper design and performance predictions of solar energy systems require accurate information on the availability of solar radiation. The diffuse-to-global solar radiation correlation, originally developed by Liu and Jordan, has been extensively used as the technique providing accurate results, although it is latitude dependent. Thus, in the present study, empirical correlations of this type were developed to establish a relationship between the hourly diffuse fraction (kd) and the hourly clearness Index (kt) using hourly global and diffuse irradiation measurements on a horizontal surface performed at Athalassa, Cyprus. The proposed correlations were compared against 10 models available in the literature in terms of widely used statistical indicators. From this analysis, it can be concluded that the proposed yearly correlation predicts diffuse values accurately, whereas all candidate models examined appear to be location-independent for diffuse irradiation predictions.

07/02376 Daylighting provided by horizontal openings using the illumination vector Navarro, J. and Sendra, J. J. Renewable Energy, 2006, 31, (15), 2513– 2523. Stemming from the expressions of the illumination vector provided by vertical openings at any point of the interior space, this article proposes and solves the equivalent expressions for openings in horizontal planes, thus completing the expressions of Navarro and offering algorithms which give the value of the illumination vector for CIE skies at any point of the interior space and for any size of window whether vertical or horizontal.

07/02377 Design and construction of a two-axis Sun tracking system for parabolic trough collector (PTC) efficiency improvement Bakos, G. C. Renewable Energy, 2006, 31, (15), 2411–2421. An experimental study was performed to investigate the effect of using a continuous operation two-axes tracking on the solar energy collected. The collected energy was measured and compared with that on a fixed surface tilted at 40 towards the South. The results indicate that the measured collected solar energy on the moving surface was significantly larger (up to 46.46%) compared with the fixed surface. The proposed two-axis Sun tracking system was characterized by a fairly simple and low-cost electromechanical set-up with low maintenance requirements and ease on installation and operation.

07/02378 Design and testing of a separate-type lighting system using solar energy and cold-cathode fluorescent lamps Yang, J.-P. and Hsiao, H.-C. Applied Energy, 2007, 84, (1), 99–115. This paper presents a solar-powered lighting system, using coldcathode fluorescent lamps (CCFLs), with its battery-charging circuit and lamp-ignition circuit being separated so that its solar panels can be installed at any distance deemed necessary away from the lighting site in order to receive the maximum solar energy available. This system adopts the maximum-power point tracking method to control the power output of the solar panels and uses the zero-voltage switching DC–DC converter, as the charging circuit, to increase the panels’ power generation efficiency and the charging circuit’s conversion efficiency. The electronic ballast circuit for the CCFL is constructed with a half-bridge inverter, a resonant inductor, and a Rosen-type piezoelectric transformer, which forms a piezoelectric resonant-type inverter: to simplify the circuitry and to improve the power conversion efficiency, the ballast circuit is designed to directly step up the battery voltage in igniting the lamp. It was also established the transmissionparameter model for the piezoelectric resonant-type inverter to provide the base for the electric-power circuit design. The experimental

358 Fuel and Energy Abstracts September 2007

results indicate that the proposed system possesses some advantages, such as greater energy efficiency, circuitry simplicity, and so on, and is suitable for night lighting in house yards, parks and advertising panels.

07/02379 Development and applications of solar-based thermoelectric technologies Xi, H. et al. Renewable and Sustainable Energy Reviews, 2007, 11, (5), 923–936. This paper presents a survey of solar-based driven thermoelectric technologies and their applications. A brief analysis of the environmental problems related to the use of conventional technologies and energy sources is presented and the benefits offered by thermoelectric technologies and renewable energy systems are outlined. The development history of solar-based thermoelectric technologies is introduced together with the discussion of the existing drawbacks of current systems. Typical applications of the solar-driven thermoelectric refrigeration and the solar-driven thermoelectric power generation are presented in order to show to the reader the extent of their applicability. The application areas described in this paper show that solar-driven thermoelectric technologies could be used in a wide variety of fields. They are attractive technologies that not only can serve the needs for refrigeration, air-conditioning applications and power generation, but also can meet demand for energy conservation and environment protection.

07/02380 Development of a low-cost dish solar concentrator and its application in zeolite desorption Palavras, I. and Bakos, G. C. Renewable Energy, 2006, 31, (15), 2422– 2431. This paper deals with the development and performance characteristics of a low-cost dish solar concentrator and its application in zeolite desorption. The dish solar concentrator consists of an old damaged satellite dish, purchased from a scrap yard, and a polymer mirror film used as reflecting surface. The proposed concentrator is connected to a sun-tracking system which is based on an electronic circuit that processes the input signals from a set of sensors and drives the dish actuator. The solar thermal energy application to adsorption technology (with the sorption pair water/zeolite) is simulated using the ‘icequick’ device manufactured by Zeo-Tech GmbH. Samples from two types of zeolites were initially brought to saturation condition and then mounted on the focal point of the dish solar concentrator in order to be regenerated. Experimental results are presented and useful conclusions are drawn.

07/02381

Drying of hot chilli using solar tunnel drier

Hossain, M. A. and Bala, B. K. Solar Energy, 2007, 81, (1), 85–92. A mixed mode type forced convection solar tunnel drier was used to dry hot red and green chillies under the tropical weather conditions of Bangladesh. The drier consisted of transparent plastic covered flatplate collector and a drying tunnel connected in series to supply hot air directly into the drying tunnel using two fans operated by a photovoltaic module. The drier had a loading capacity of 80 kg of fresh chillies. Moisture content of red chilli was reduced from 2.85 to 0.05 kg kg1 (db) in 20 h in solar tunnel drier and it took 32 h to reduce the moisture content to 0.09 and 0.40 kg kg1 (db) in improved and conventional sun drying methods, respectively. In case of green chilli, about 0.06 kg kg1 (db) moisture content was obtained from an initial moisture content of 7.6 kg kg1 (db) in 22 h in solar tunnel drier and 35 h to reach the moisture content to 0.10 and 0.70 kg kg1 (db) in improved and conventional sun drying methods, respectively. The use of a solar tunnel drier and blanching of sample led to a considerable reduction in drying time and dried products of better quality in terms of colour and pungency in comparison to products dried under the sun. The solar tunnel drier and blanching of chilli are recommended for drying of both red and green chillies.

07/02382 Enhancement of natural ventilation rate and attic heat gain reduction of roof solar collector using radiant barrier Puangsombut, W. et al. Building and Environment, 2007, 42, (6), 2218– 2226. Presented in this paper are the experimental results on natural ventilation flow rate enhancement and attic heat gain reduction of a roof solar collector equipped with a radiant barrier (RB). Investigation was conducted using an open-ended inclined rectangular channel with an RB. The RB was used on the lower plate while the upper plate was heated with constant heat flux intensity. The channel dimensions are 1.50.700.19 m. The slope of the channel was fixed at 30 from horizontal plane. Four heat flux (190.5, 285.7, 380.9 and 476.2 W m2) and five air gap space (3, 5, 7, 9 and 11 cm) were considered. Data analysis was made to determine the free convection heat transfer coefficient and induced airflow rate using two dimensionless parameters, namely, Nusselt number (Nu) and Reynolds number (Re). The Nu and Re were correlated as a function of Ra sin 30 and channel aspect ratio defined as the ratio of air gap space to the channel length.

13 Alternative energy supplies (solar energy) The relations obtained were as follows: Nu=0.371(Ra sin 30)0.2223 (S/ L)0.0469 and Re = 191.68 (Ra sin 30)0.1213 (S/L)0.085. When compared to a conventional roof solar configuration with gypsum board on the lower part, it was observed that the use of RB increased convective heat transfer and airflow rate by about 40–50%, thereby increasing heat transfer reduction through the lower plate by about 50%. The developed correlations are useful for the design of such open-ended channels like the roof solar collector for passive ventilation of houses.

temperature rise and useful heat delivered. Results indicate promising thermal performance of UTC in this temperature band, offering itself as an attractive alternate to glazed solar collectors for drying of food products. The results of the model have been used to develop nomograms, which can be a valuable tool for a collector designer in optimizing the design and thermal performance of UTC. It also enables the prediction of the absolute thermal performance of a UTC under a given set of conditions.

07/02383

07/02387 Modelling and experimental verification of the operating current of mono-crystalline photovoltaic modules using four- and five-parameter models

Estimating thermal stress in BIPV modules

Konttinen, P. et al. International Journal of Energy Research, 2006, 30, (15), 1264–1277. The thermal stress on building-integrated photovoltaic modules (BIPV) in Espoo, Finland, was studied with field-testing of amorphous silicon modules. Based on these results, the thermal stress at two other European locations (Paris and Lisbon) was estimated. The estimation procedure entailed thermal modelling of heat transfer in the facade with meteorological data as input. The results indicate that the thermal stress on BIPV modules in Lisbon is, in this case, approximately 50% higher that in Espoo and between 80 and 200% higher than in Paris, depending on the activation energy of the degradation process. The difference in stress between a BIPV module and a free-standing module in Espoo was 50–200%.

07/02384 Experimental investigation of a solar adsorption chiller used for grain depot cooling Luo, H. L. et al. Applied Thermal Engineering, 2006, 26, (11–12), 1218– 1225. The solar cooling technology is attractive since cooling load of building is roughly in phase with solar energy availability. In this study, a solar adsorption chiller was built and tested with aim of developing an alternative refrigeration system used for grain cooling storage. This solar adsorption chiller consists of four subsystems, namely, a solar water heating unit with 49.4 m2 solar collecting area, a silica gel–water adsorption chiller, a cooling tower and a fan coil unit. In order to achieve continuous refrigeration, two adsorption units are operated out-of-phase with mass recovery cycle in the adsorption chiller. Field test results show that, under the climatic conditions of daily solar radiation being about 16–21 MJ/m2, this solar adsorption chiller can furnish 14–22  C chilled air with an average cooling output ranging from about 3.2–4.4 kW, its daily solar cooling COP (coefficient of performance) is about 0.1–0.13.

07/02385 Hydrogen/methanol production by sulfur–iodine thermochemical cycle powered by combined solar/fossil energy Giaconia, A. et al. International Journal of Hydrogen Energy, 2007, 32, (4), 469–481. Hydrogen production from water using the sulfur–iodine (S–I) thermochemical cycle, powered by combined solar and fossil heat sources, has been investigated. This combined energy supply was conceived in order to operate the chemical process continuously: a solar concentrator plant with a large-scale heat storage supplies thermal load for services at medium temperatures (< 550 C), while a fossil fuel furnace provides heat load at higher temperatures. Additionally, a methanol production plant fed with the carbon oxides generated from fossil fuel combustion was included. Since the sulfuric acid concentration/decomposition section is interfaced to both the fossil furnace and the solar plant, it was studied more exhaustively. Results obtained show that the major part of the total energy demand (ca. 70%) is renewable. An industrial scale plant with hydrogen capacity of ca. 26,000 tons/year coupled with a 267 MWth solar plant was considered, and the specific cost of the produced hydrogen and methanol determined.

07/02386 Mathematical modeling and thermal performance analysis of unglazed transpired solar collectors Leon, M. A. and Kumar, S. Solar Energy, 2007, 81, (1), 62–75. Unglazed transpired collectors or UTC (also known as perforated collectors) are a relatively new development in solar collector technology, introduced in the early nineties for ventilation air heating. These collectors are used in several large buildings in Canada, USA and Europe, effecting considerable savings in energy and heating costs. Transpired collectors are a potential replacement for glazed flat plate collectors. This paper presents the details of a mathematical model for UTC using heat transfer expressions for the collector components, and empirical relations for estimating the various heat transfer coefficients. It predicts the thermal performance of unglazed transpired solar collectors over a wide range of design and operating conditions. Results of the model were analysed to predict the effects of key parameters on the performance of a UTC for a delivery air temperature of 45–55  C for drying applications. The parametric studies were carried out by varying the porosity, airflow rate, solar radiation, and solar absorptivity/thermal emissivity, and then finding their influence on collector efficiency, heat exchange effectiveness, air

Celik, A. N. and Acikgoz, N. Applied Energy, 2007, 84, (1), 1–15. This article presents the modelling and experimental verification of the operating current of a 120 W of mono-crystalline photovoltaic module using four- and five-parameter analytical models. The southern part of Turkey, where the experimental system is mounted, is particularly well suited to photovoltaic installations. The operating current of the photovoltaic module, calculated from the models, is validated based on a series of experimental measurements. As well as the current and voltage of the photovoltaic module, the environmental variables such as ambient temperature and solar irradiance were measured and used for validation of the operating current. The photovoltaic cell models considered in this article are drawn from the equivalent electrical circuit that includes light-generated current, diode reverse saturation current, and series and shunt resistances. The simplified fourparameter model assumes the shunt resistance as infinite and thus neglects it. After determining the model parameters, the operating current is calculated using both models and compared to the measured current produced by the photovoltaic module. It is shown that the complete five-parameter model predicts the operating current better than the simplified four-parameter model, especially around solar noon, when most of the power is produced.

07/02388 Modelling and performances of a deep-freezing process using low-grade solar heat Le Pierre`s, N. et al. Energy, 2007, 32, (2), 154–164. A solar deep-freezing process has been designed. It aims at cooling down a cold box to about 20  C, using simple flat plate solar collectors operating at 70  C. This original process involves two cascaded thermochemical systems based on the BaCl2/ammonia reaction. Its working mode is discontinuous as it alternates between a regeneration mode during daytime and a cold production mode during nighttime. A global dynamic model involving the various system components allows the simulation of the process; it predicts the evolution of the components temperatures and the rates of chemical reactions of the system. It also allows the dimensioning of the system components to maintain a 500 l cold box at 20  C during the six sunniest months of the year under typical Mediterranean weather conditions and provide over 80% of the total yearly cooling needs of this box. This requires a solar collector area of 5.8 m2 and 39 kg of reactive salt. The predicted coefficient of performance (COP) is about 0.1 over the year, and the net solar COP, taking into account the collector efficiencies, is 0.05.

07/02389 Numerical simulation of the limiting efficiency of the graded bandgap solar cell Rafat, N. H. et al. Renewable Energy, 2007, 32, (1), 21–34. The limiting efficiency of the compositionally graded bandgap solar cell is calculated using a 1-D numerical simulator. The simulator calculates the limiting efficiency by solving the coupled semiconductor equations, namely, Poisson’s equation, the current continuity equations, together with the Boltzmann photon equation, rather than the detailed balance equations that are usually used in such calculations. The non-avoidable radiative and Auger bulk losses are the only losses considered in the calculations. The effect of photon recycling on the cell’s parameters is included in the calculations of radiative recombination rates. The authors verified numerically that bandgap grading, under optimum profile, increases the limiting efficiency of the solar cell, over the previously published values. The effect of the bandgap grading on desensitizing the surface of the cell is discussed.

07/02390

Performance analysis of solar ethanol distillation

Vorayos, N. et al. Renewable Energy, 2006, 31, (15), 2543–2554. Continuous solar ethanol distillation systems having flat-plate and evacuated heat pipe solar collectors are constructed to study their performances and economic viability. The mathematical model of each main component is carried out and the system simulation is developed. The simulated outputs express a reasonable agreement with the experimental results within 14% accuracy. From the simulation, start up with 10% alcohol concentration, the production cost of 80% alcohol concentration from the distillation system of which the yield at 12,500 l/ year is evaluated. With the economic analysis, the results show that the use of solar distillation systems appear to be economical compared to the conventional distillation system using fuel oil as heat source. The minimum production cost of the system is 0.39 US$/l.

Fuel and Energy Abstracts September 2007 359

13 Alternative energy supplies (wind energy) 07/02391 Thailand

PV hybrid systems for rural electrification in

Phuangpornpitak, N. and Kumar, S. Renewable and Sustainable Energy Reviews, 2007, 11, (7), 1530–1543. Photovoltaic (PV) hybrid systems can make a positive contribution to the sustainability of rural communities in developing countries that do not have access to electricity grid. Integration of solar photovoltaic system with diesel generator for remote and rural areas would assist in expanding the electricity access in the tropical region. A survey of PV hybrid system in Thailand during the last decade regarding to status of technology, performance in terms of technical and economic aspects, and their prospects has been presented in this paper.

07/02392

Solar chimney and building ventilation

Harris, D. J. and Helwig, N. Applied Energy, 2007, 84, (2), 135–146. This study is concerned with the design of a solar chimney to induce ventilation in a building. CFD modelling techniques were used to assess the impacts of inclination angle, double glazing and lowemissivity finishes on the induced ventilation rate. It was found that for a south-facing chimney, an inclination angle of 67.5 from the horizontal was optimum for the location chosen, giving 11% greater efficiency than the vertical chimney, and that a 10% higher efficiency was obtained by using a low-emissivity wall surface.

07/02393 Solar home system electrification as a viable technology option for Africa’s development Wamukonya, N. Energy Policy, 2007, 35, (1), 6–14. This paper is based on a review of the effectiveness of solar home systems (SHS) in Africa in meeting users expectations on a service based analytical approach. Various projects have deployed SHS on the promise that they are cost-effective, can meet end-user demands, have ability to alleviate poverty, can save time and reduce emissions. However, a close review of the actual cost of these systems given the services they provide indicates most of the promises remain unmet and hence questions the wisdom of using public funds to support the system at the expense of more appropriate technologies.

07/02394 The regeneration of silica gel desiccant by air from a solar heater with a compound parabolic concentrator Pramuang, S. and Exell, R. H. B. Renewable Energy, 2007, 32, (1), 173– 182. The regeneration of silica gel desiccant by a solar air heater for use in an air-conditioning system has been investigated. The hot air is produced by a compound parabolic concentrator (CPC) collector, which has aperture and receiver areas 1.44 and 0.48 m2, respectively. The regeneration temperature can be started at 40  C. The regeneration rate and the regeneration efficiency were greatly affected by the solar radiation, but depended only slightly on the different initial moisture contents of silica gel and the number of silica gel beds. The regeneration of silica gel provided by the CPC collector is suitable for a tropical climate where the diffuse solar radiation is high all the year round.

07/02395 Water production from air using multi-shelves solar glass pyramid system Kabeel, A. E. Renewable Energy, 2007, 32, (1), 157–172. The capability of the glass pyramid shape with a multi-shelf solar system to extract water from humid air is explored. Two pyramids were used with different types of beds on the shelves. The beds are saturated with 30% concentrated calcium chloride solution. The pyramid sides were opened at night to allow the bed saturated with moist air and closed during the day to extract the moisture from the bed by solar radiation. The bed in the first pyramid was made of saw wood while it is made of only cloth in the second pyramid with the same dimensions. The system was experimentally investigated at different climatic conditions to study the effect of pyramid shape on the absorption and regeneration processes. Preliminary results have shown that the cloths bed absorbs more solution (9 kg) as compared to the saw wood bed (8 kg). Adopting this approach produces 2.5 L/day m2. The use of the pyramid shape with four glass surfaces and multi-shelves enhances the produced water by 90–95% compared with solar desiccant/collector system with horizontal and corrugated beds. Results also show that the clothes bed has higher productivity than that of saw wood bed by about 5%. This is due mainly to the greater carrying solution at the onset of the experimental work. The obtained results may help in designing more efficient system.

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Wind energy 07/02396 A novel optimization sizing model for hybrid solar-wind power generation system Yang, H. et al. Solar Energy, 2007, 81, (1), 76–84. This paper develops the hybrid solar-wind system optimization sizing (HSWSO) model, to optimize the capacity sizes of different components of hybrid solar-wind power generation systems employing a battery bank. The HSWSO model consists of three parts: the model of the hybrid system, the model of loss of power supply probability and the model of the levelized cost of energy. The flow chart of the HSWSO model is also illustrated. With the incorporated HSWSO model, the sizing optimization of hybrid solar-wind power generation systems can be achieved technically and economically according to the system reliability requirements. A case study is reported to show the importance of the HSWSO model for sizing the capacities of wind turbines, PV panel and battery banks of a hybrid solar-wind renewable energy system.

07/02397 Analysis of a fuel cell micro-grid with a small-scale wind turbine generator Obara, S. International Journal of Hydrogen Energy, 2007, 32, (3), 323– 336. If electric power is supplied using an independent micro-grid connected to renewable energy, it can flexibly match the energy demand characteristics of a local area. And an independent micro-grid is expected to be effective in cutting greenhouse gas discharge and energy costs, as well as in eliminating the need for an emergency power supply system. Since the output of renewable energy is unstable, other energy equipment needs to cover the stability of output. Thus, the operating conditions of an independent micro-grid that supplies power with natural power sources and fuel cells are investigated. The operation conditions of a fuel-cell independent micro-grid with wind power generation were investigated by numerical analysis. Step loads and an apartment house power load model were analysed using the dynamic characteristics of a fuel cell obtained from experiments. The output of wind power generation and fuel cells is controlled by proportional-integral control of an independent micro-grid for rapid power demand change.

07/02398 Assessment of wind-forcing impact on a global wind-wave model using the TOPEX altimeter Feng, H. et al. Ocean Engineering, 2006, 33, (11–12), 1431–1461. The study presents assessment of an operational wave model (Wavewatch III), focusing upon the model sensitivity to wind-forcing products. Four wind fields are used to drive the model, including the NCEP/NCAR reanalysis and three other products that assimilate various satellite wind measurements having high spatial resolution, including the QuikSCAT scatterometer. Three wave field statistics: significant wave height, mean zero-crossing wave period, and mean square slope are compared with collocated TOPEX altimeter derivatives to gauge the relative skill of differing wind-forced model runs, as well as to demonstrate an extended use of the altimeter beyond simply supplying wave height for wave model validation and assimilation. Results suggest that model output is critically sensitive to choice of the wind field product. Higher spatial resolution in the wind fields does lead to improved agreement for the higher-order wave statistics.

07/02399 Characteristics of the UK wind resource: long-term patterns and relationship to electricity demand Sinden, G. Energy Policy, 2007, 35, (1), 112–127. The ability of wind power to reliably contribute energy to electricity networks is directly related to the characteristics of the wind resource. An analysis of the characteristics of the wind power resource of the United Kingdom has been carried out, based on modelling of hourly observed wind speed data from 66 onshore weather recording sites for the period 1970–2003. Patterns of wind power availability are presented, with the data demonstrating that the output from largescale wind power development in the UK has distinct patterns of monthly and hourly variability. The extent and frequency of high and low wind power events is assessed, and wind power data are matched with electricity demand data to examine the relationship between wind power output and electricity demand. It is demonstrated that wind power output in the UK has a weak, positive correlation to current electricity demand patterns; during peak demand periods, the capacity factor of wind power in the UK is around 30% higher than the annual average capacity factor. Comments on the relevance of these findings to modelling the impact of wind-generated electricity on existing electricity networks are given.

13 Alternative energy supplies (wind energy) 07/02400 Combining hydro-generation and wind energy. Biddings and operation on electricity spot markets

07/02404 On the aerodynamics of variable-geometry oval-trajectory Darrieus wind turbines

Angarita, J. M. and Usaola, J. G. Electric Power Systems Research, 2007, 77, (5–6), 393–400. Wind generation is growing rapidly in all the world, especially in Europe. The power produced by this kind of generation is difficult to predict and the predictions are not very accurate. In most systems these imbalances are costly. These penalties reduce the revenue for the wind generation company (WGENCOs). An option to solve this problem would be to work together with another agent. In this paper, a combined strategy for bidding and operating in a power exchange is presented. It considers the combination of a WGENCO and a hydrogeneration company (HGENCO). The mathematical formulation for the optimal bids and for the optimal operation is presented, as well as results from realistic cases.

Ponta, F. L. et al. Renewable Energy, 2007, 32, (1), 35–56. A new computational model for the aerodynamics of vertical-axis wind turbines is introduced. It is based on the double-multiple streamtube concept and it incorporates the capacity of dealing with rotors whose blades follow oval-trajectories at variable setting-angles. The authors applied this model to the study of the aerodynamics of an innovative concept in extra-large wind-power plants: the VGOT (variablegeometry oval-trajectory) Darrieus wind turbine. Due to the especial geometric characteristics of the VGOT Darrieus, it was necessary to propose three new non-dimensional parameters to quantify its performance under different wind-conditions: the equivalent power coefficient, the equivalent solidity coefficient and the trajectory efficiency. The authors show some numerical results testing several rotor configurations working under different wind scenarios.

07/02401 Computer simulation of atmospheric flows over real forests for wind energy resource evaluation

07/02405 PSCAD/EMTDC-based simulation of wind power generation system

da Costa, J. C. L. et al. Journal of Wind Engineering and Industrial Aerodynamics, 2006, 94, (8), 603–620. The increased number of wind parks and the shortage of ideal sites have forced us to consider the possibility of installing wind farms in the vicinity of or within forests. Measured wind data at two potential wind farm sites, in Scotland and in France, were used for appraisal of a computer model of the wind flow over forested regions, where the trees are mimicked by momentum sinks. The results of the Scottish case were an improvement over previous computer simulations without the canopy model, and showed the difficulties of comparing detailed threedimensional computer simulations with field data point measurements. In case of the French site, agreement was excellent between mean velocity field measurements at seven heights above the ground, between 40 and 100 m, and computer results. It was found that the presence of the canopy could increase the turbulence levels by almost two orders of magnitude, when compared to the results obtained without the canopy model.

07/02402 Controllable and affordable utility-scale electricity from intermittent wind resources and compressed air energy storage Cavallo, A. Energy, 2007, 32, (2), 120–127. World wind energy resources are substantial, and in many areas, such as the US and northern Europe, could in theory supply all of the electricity demand. However, the remote or challenging location (i.e. offshore) and especially the intermittent character of the wind resources present formidable barriers to utilization on the scale required by a modern industrial economy. All of these technical challenges can be overcome. Long distance transmission is well understood, while offshore wind technology is being developed rapidly. Intermittent wind power can be transformed to a controllable power source with hybrid wind/compressed air energy storage systems. The cost of electricity from such hybrid systems (including transmission) is affordable, and comparable to what users in some modern industrial economies already pay for electricity. This approach to intermittent energy integration has many advantages compared to the current strategy of forcing utilities to cope with supply uncertainty and transmission costs. Above all, it places intermittent wind on an equal technical footing with every other generation technology, including nuclear power, its most important long-term competitor.

07/02403 Feasibility study of wind farms: a case study for Izmir, Turkey Ozerdem, B. et al. Journal of Wind Engineering and Industrial Aerodynamics, 2006, 94, (10), 725–743. Wind is one of the world’s fastest growing renewable energy sources. The rapid growth in wind power is a result of improvements accomplished in technology. This paper presents the technical and economical feasibility of wind farms. The method is applied to a potential wind farm site located in Izmir, Turkey. The site is considered on technical and economical parameters for the complete plant and its running costs. For technical consideration wind speed, prevailing wind direction, and temperature measurements are performed. For economical consideration, three different scenarios namely, autoproducer, autoproducer group, and independent power producer (IPP) cases, are investigated and compared with respect to net present value, internal rate of return (IRR), and pay back period criteria. The study indicates the costs of generated energy by wind turbines with different characteristics as a function of the installed capacity. It is concluded that, the larger the installed capacity, the smaller the generating cost per kWh. The generating cost was calculated as low as 2.68 US cent/ kWh for the IPP scenario. The profitability analysis also shows that, larger installed capacity with larger rated power wind turbines present higher IRR of the investment. The sensitivity analysis backs up the findings.

Han, S. G. et al. Renewable Energy, 2007, 32, (1), 105–117. This paper proposes a novel simulation method of wind power generation system (WPGS) using PSCAD/EMTDC. The pitch control-based rotation speed control scheme of turbine under variable wind speed is implemented. For the purpose of achieving effective and user-friendly simulation method for utility interactive (grid connected) WPGS, real weather condition-based WPGS simulation (RW–WPGS) is performed using PSCAD/EMTDC. It is not easy, in general, to consider the RW conditions in the WPGS simulation using the EMTP or PSPICE type of simulators. External parameters of the RW conditions, however, are necessary to improve the simulation accuracy. The components modelling of wind turbine system is also studied and the real weather conditions are introduced by the interface method of a non-linear external parameter of the PSCAD/EMTDC. The outcomes of the simulation demonstrate the effectiveness of the proposed simulation scheme.

07/02406 Renewable energy credit driven wind power growth for system reliability Karki, R. Electric Power Systems Research, 2007, 77, (7), 797–803. Environmental concerns over electric power generation from conventional sources has led to widespread public support for renewable energy sources. Governments throughout the world have responded by providing various forms of financial incentives to promote power generation from renewable energy sources. The rapid growth of wind power since the last decade has primarily been driven by governmental subsidies. Long-term growth of wind power should, however, be driven by sustainable market mechanisms. A potential solution is to recognize monetary values to the environmental benefits from renewable energy sources, and to specify targets for their growth. The environmental benefits from wind sources can be leveraged to allow market competition of these sources with the less costly conventional generating sources. A probabilistic method to evaluate the impact of renewable energy credit and wind penetration level on the cost and adequacy of power generating systems is presented in this paper. The technique incorporates reliability and economic analyses and is applied to a published test system to illustrate the results and their influence on key system variables. The paper provides useful information to system planners and policy makers on wind energy application in electric power systems.

07/02407 Simulating price patterns for tradable green certificates to promote electricity generation from wind Ford, A. et al. Energy Policy, 2007, 35, (1), 91–111. This article uses computer simulation to anticipate the price dynamics in a market for tradable green certificates. These markets have been used in Europe to promote generation of electricity from renewable resources like wind. Similar markets have been proposed in the United States of America where the certificates are called renewable energy credits. The certificates are issued to the generating companies for each megawatt-hour of renewable electricity generation. The companies may sell the certificates in a market, and the revenues from certificate sales provide an extra incentive to invest in new generating capacity. Proponents argue that this market-based incentive can be designed to support government mandates for a growing fraction of electricity generation from renewable sources. In the USA, these mandates are set by the states and are known as renewable portfolio standards. The authors simulate the price dynamics of a market designed to support an aggressive mandate for wind generation in the northwestern USA. The simulations show that the certificate price climbs rapidly to the cap in the early years after the market opens. Investors then react to these high prices with construction of new wind capacity. After a few years, wind generation meets, and then exceeds the requirement. It is shown that this pattern appears again and again when the simulations are repeated with wide variations in the estimates of behavioural parameters. The authors use the model to study the

Fuel and Energy Abstracts September 2007 361

13 Alternative energy supplies (others, including economics) impact of different trading strategies by the wind companies and by the distribution companies. The authors also study the simulated market response if the USA adopts the carbon allowance market envisioned in the Climate Stewardship Act. The article concludes with recommendations for policy makers involved in TGC market design.

07/02408 Urban energy generation: influence of micro-wind turbine output on electricity consumption in buildings Bahaj, A. S. et al. Energy and Buildings, 2007, 39, (2), 154–165. Small-scale wind turbines installed within the built environment is classified as microgeneration technology. Such turbines may soon become a commercial reality in the UK as a result of both advancements in technology and new financial incentives provided by the government. In addition, microgeneration technologies, especially those with appreciable resource, have the potential to reduce built environment related CO2 emissions coupled with reductions in consumers’ electricity costs. In many cases payback on capital investment is within the lifetime of the device. Micro-wind turbines installed in certain areas in the UK will fit within such criteria. The work presented here addresses modelling of such installations around the UK and presents a methodology to assess the suitability and the economic viability of micro-wind turbines for domestic dwellings. A modelling tool ‘m-Wind’ has been developed specifically for studying both energy yields and the payback periods for micro-wind turbines. mWind predicts wind turbine performance prior to installation according to specific power curves either defined by turbine manufacturers or the user. Numerical consideration of wind speed data at specific UK sites was used to estimate energy yields and the results are projected to real electricity demand data from monitored dwellings in the UK. The results show that it is possible to predict with a good degree of accuracy the expected financial payback period for a typical domestic dwelling. Furthermore, the paper postulates that micro-wind technology could have the potential to make a significant impact upon domestic electricity generation when located at the windiest sites in the UK. The likelihood of a proliferation of these turbines in the urban or suburban environment is low but at coastal or inland high elevation sites the technology appears to have a promising future.

07/02409 Wind power implementation: the nature of public attitudes. Equity and fairness instead of ‘backyard motives’ Wolsink, M. Renewable and Sustainable Energy Reviews, 2007, 11, (6), 1188–1207. Public attitudes anywhere in Europe show moderate to strong support for the implementation of renewable energy. Nevertheless, planning wind power developments appears to be a complicated matter in most countries. The problems that have to be dealt with during decision making processes on the siting of wind turbines are usually referred to as mere ‘communication problems’. However, public attitudes towards wind power are fundamentally different from attitudes towards wind farms. This ‘gap’ causes misunderstandings about the nature of public support for renewables. In particular where planners easily assume support for renewables can be generated by information campaigns emphasizing the environmental benefits, whereas opposition to renewable energy schemes can be explained by a selfish ‘not in my backyard’ attitude. Both explanations used by planners, authorities and, unfortunately, by many scholars, are falsified. Furthermore, policies that still take this ‘common knowledge’ for granted can have negative consequences for the implementation rates of renewables. Visual evaluation of the impact of wind power on landscape values is by far the dominant factor in explaining why some are opposed to wind power and others are supporting it. Moreover, feelings about equity and fairness appear the determinants of ‘backyard’ motives, instead of selfishness.

Others, including economics 07/02410 A bottom-up assessment and review of global bio-energy potentials to 2050 Smeets, E. M. W. et al. Progress in Energy and Combustion Science, 2007, 33, (1), 56–106. In this article, a model for estimating bioenergy production potentials in 2050, called the Quickscan model, is presented. In addition, a review of existing studies is carried out, using results from the Quickscan model as a starting point. The Quickscan model uses a bottom-up approach and its development is based on an evaluation of data and studies on relevant factors such as population growth, per capita food consumption and the efficiency of food production. Three types of biomass energy sources are included: dedicated bioenergy crops, agricultural and forestry residues and waste, and forest growth. The bioenergy potential in a region is limited by various factors, such as the

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demand for food, industrial roundwood, traditional woodfuel, and the need to maintain existing forests for the protection of biodiversity. Special attention is given to the technical potential to reduce the area of land needed for food production by increasing the efficiency of food production. Thus, only the surplus area of agricultural land is included as a source for bioenergy crop production. A reference scenario was composed to analyse the demand for food. Four levels of advancement of agricultural technology in the year 2050 were assumed that vary with respect to the efficiency of food production. Results indicated that the application of very efficient agricultural systems combined with the geographic optimization of land use patterns could reduce the area of land needed to cover the global food demand in 2050 by as much as 72% of the present area. A key factor was the area of land suitable for crop production, but that is presently used for permanent grazing. Another key factor is the efficiency of the production of animal products. The bioenergy potential on surplus agricultural land (i.e. land not needed for the production of food and feed) equaled 215– 1272 EJ yr1, depending on the level of advancement of agricultural technology. The bulk of this potential is found in South America and Caribbean (47–221 EJ yr1), sub-Saharan Africa (31–317 EJ yr1) and the CIS and Baltic States (45–199 EJ yr1). Also Oceania and North America had considerable potentials: 20–174 and 38–102 EJ yr1, respectively. However, realization of these (technical) potentials requires significant increases in the efficiency of food production, whereby the most robust potential is found in the C.I.S. and Baltic States and East Europe. Existing scenario studies indicated that such increases in productivity may be unrealistically high, although these studies generally excluded the impact of large scale bioenergy crop production. The global potential of bioenergy production from agricultural and forestry residues and wastes was calculated to be 76– 96 EJ yr1 in the year 2050. The potential of bioenergy production from surplus forest growth (forest growth not required for the production of industrial roundwood and traditional woodfuel) was calculated to be 74 EJ yr1 in the year 2050.

07/02411 A novel method for producing hydrogen based on the Ca–Br cycle Simpson, M. F. et al. International Journal of Hydrogen Energy, 2007, 32, (4), 505–509. The Ca–Br cycle is a promising method for efficiently producing hydrogen from water; however, it suffers from limitations inherent to gas–solid reactions. The cycle depends on the repeatable transformation of calcium bromide to calcium oxide and back to calcium bromide. The use of pure solids for these reactions would lead to rapid particle degradation and slow reaction kinetics. To circumvent these problems, a new reactor concept based on molten calcium bromide with dissolved calcium oxide has been proposed and developed. Preliminary experimental results indicate that the solubility of calcium oxide in calcium bromide at 800  C is at least 1.2 wt%, a level that is expected to be high enough to make the proposed process work as designed. Early attempts to hydrolyse molten calcium bromide indicated that solid calcium oxide formation may inhibit reactivity, and thus injection of the moisture into the salt must be optimized.

07/02412 Comparison between the kinetics of devolatilisation of forestry and agricultural wastes from the middle-south regions of Spain Lapuerta, M. et al. Biomass and Bioenergy, 2006, 30, (12), 13–19. Flexibility in the supply of biomass to the energy conversion facility, as a function of the seasonal availability, is considered as one of the keys to guarantee their continuous operation and the yield of the investments. The kinetics of devolatilization of the two most typical biomass wastes in the middle-south regions of Spain, wastes from pruning of pine and olive trees, were studied using thermogravimetric analysis, in order to evaluate their use in combination as an energy feedstock throughout the year. A kinetic devolatilization model was fitted to the experimental results and the kinetic parameters were obtained. Although slightly different behaviour was found between different categories of the same sample (large branches, small branches and needles or leaves), the differences between pine and olive wastes were not significant, which indicates that they can be combined for use in combustion or gasification systems.

07/02413 Construction materials development in sulfur– iodine thermochemical water-splitting process for hydrogen production Wong, B. et al. International Journal of Hydrogen Energy, 2007, 32, (4), 497–504. The sulfur iodine water splitting cycle for hydrogen production consists of three coupled chemical reactions, which includes the generation and decomposition of HI. The HIx environment is extremely corrosive and the severity increases with temperature. Immersion coupon corrosion screening tests were performed on materials selected from four classes of corrosion resistant materials: refractory metal, reactive metal,

13 Alternative energy supplies (others, including economics) superalloys and ceramics. Of the materials tested, only Ta and Nb-based refractory metals and ceramic mullite can tolerate the extreme HIx environment. Severe pitting and dissolution was observed in two different reactive metal zirconium. A nickel based superalloy, C-276, also showed severe dissolution in HIx solution. The materials that showed good corrosion behaviour will undergo further longterm immersion testing in order to assess performance. In addition, Cring, U-bend and DCB test samples fabricated from qualified materials will alos be tested under stress corrosion conditions in order to investigate their crack initiation and growth properties.

07/02414 Deriving efficient policy portfolios promoting sustainable energy systems – case studies applying invert simulation tool Kranzl, L. et al. Renewable Energy, 2006, 31, (15), 2393–2410. Within recent years, energy policies have imposed a number of targets at European and national level for rational use of energy, renewable energy sources and related CO2 reductions. As a result, many varied policy instruments are currently implemented and hence the question arises: how can these instruments be designed in a way to reach the maximum policy target with the minimum public money spent? The objective of this paper is to derive a methodology for obtaining efficient policy portfolios promoting sustainable energy systems depending on the policy target and show corresponding results from case studies in Austria, Germany and Poland. The investigations were carried out by application of Invert simulation tool, a computer model developed for simulating the impacts of various promotion schemes for renewable and efficient energy systems. With this tool, the CO2 reductions and related public expenses have been calculated for various policy mixes. In the building-related energy sector, it turned out that in all investigated regions support schemes for supply side measures are the most cost-efficient instruments. However, their potential is restricted and for achieving higher levels of CO2 reduction, promotion of demand side measures is indispensable. The paper shows that for a comprehensive comparison of policy portfolios, there are always two dimensions to be considered: efficiency and effectiveness. The more effective, i.e. the higher the implementation rate of a scheme, the more essential becomes the efficiency criteria.

07/02415 Energy trade-offs between intensive biomass utilization, site productivity loss, and ameliorative treatments in loblolly pine plantations Scott, D. A. and Dean, T. J. Biomass and Bioenergy, 2006, 30, (12), 1001–1010. Loblolly pine plantations are the most important source of forest products in the US and the slash remaining after conventional harvest represents a significant potential source of bioenergy. However, slash removal in intensive harvests might, under some circumstances, reduce site productivity by reducing soil organic matter and associated nutrients. Two complimentary studies in the Gulf Coastal Plain of the southeastern US were designed to test whether harvest intensity (level of biomass removal) could have a negative long-term impact on site productivity. Harvesting tree crowns in addition to the merchantable bole had a negative impact (18%) on pine biomass accumulation by age 7–10 years on 15 of 19 research blocks. Sites at risk of harvestinduced reductions in productivity were relatively unproductive prior to harvest and had low soil phosphorus (P) concentrations. Intensive harvesting, fertilization, and chemical control of non-crop vegetation were all energy efficient; the additional biomass energy gained through these practices was two-orders of magnitude greater than the energy needed to conduct the activities. Harvest of slash for bioenergy in the Gulf Coastal Plain of the southeastern US has the potential to reduce productivity on infertile soils, but fertilization has the potential to restore and even improve productivity on those sites in an energyefficient way.

07/02416 Flowsheet study of the thermochemical water-splitting iodine–sulfur process for effective hydrogen production Kasahara, S. et al. International Journal of Hydrogen Energy, 2007, 32, (4), 489–496. The Japan Atomic Energy Agency (JAEA) is performing research and development on the thermochemical water-splitting iodine–sulfur (IS) process for hydrogen production with the use of heat (temperatures close to 1000  C) from a nuclear reactor process plant. Such temperatures can be supplied by a high temperature gas-cooled reactor process. JAEA’s activity covers the control of the process for continuous hydrogen production, processing procedures for hydrogen iodide (HI) decomposition, and a preliminary screening of corrosion resistant process materials. The present status of the research and development program is reported herein, with particular attention to flowsheet studies of the process using membranes for the HI processing.

07/02417 From biomass to electricity through integrated gasification/SOFC system-optimization and energy balance Athanasiou, C. et al. International Journal of Hydrogen Energy, 2007, 32, (3), 337–342. In this paper the integrated process of biomass gasification and a solid oxide fuel cell was studied in terms of thermodynamics. The study is based on an ongoing project intending to develop an innovative sustainable technology with high efficiency. According to some assumptions, the energy balance revealed that the process can be auto-thermal. Furthermore, and due to the utilization of the hydrogen content of steam utilized in the reforming stage, the overall efficiencies to electrical power could reach very high levels.

07/02418 Green electricity market development: lessons from Europe and the US Gan, L. et al. Energy Policy, 2007, 35, (1), 144–155. This study compares the development and implementation of green electricity policies in Germany, the Netherlands, Sweden, and the United States, a set of countries applying a range of policy instruments to encourage electricity from renewable energy sources. A general tendency is identified that policies shift emphasis from R&D stimulation towards dissemination and market application of renewable energy technologies. It is argued that in light of the long term nature of policy goals on energy security, mitigation of climate change, and environmental protection, the applied range of policy instruments may be lacking in providing incentives for the long term development of new technologies. Clarifying policy objectives would allow careful selection of policy instruments, including support for R&D. Improved capacity building for policy implementation is also important.

07/02419 Nanometallic fuels for transportation: a well-to-wheels analysis Utgikar, V. P. et al. International Journal of Energy Research, 2007, 31, (1), 99–108. Nanometallic iron and aluminium, along with hydrogen and electricity, are among the proposed alternatives to the petroleum-based fuels for future transportation. The advantages of the metallic fuels appear to be high volumetric energy densities and zero greenhouse gas emissions during the operation of the vehicle. However, nanometallic fuels do not exist in nature, and a well-to-wheel analysis of the fuel manufactureutilization system is required to quantify the energy consumption and assess the true environmental impact of the proposed alternative. The three-component nanometallic fuel system consisting of a metal production process, a nanoparticle formulation process and the metal combustion process is analysed in this paper. The energy balance and the environmental impact are estimated for nanometallic iron and aluminium based systems. The sustainability of once-through systems that do not involve recycle of combustion products is questionable because of resource limitations. A viable system for satisfying the transportation fuel demands will involve the reduction and recycle of the combustion products. A comparison of these nanometallic fuels with gasoline and hydrogen indicates that nanometallic fuels are the least efficient, with primary energy consumption greater than 11 MJ km1 compared to 0.625 MJ km1 for gasoline and 8.6 MJ km1 for hydrogen. The nanometallic fuels will also have the most severe impact of the three, with CO2-equivalent emissions of 13.44 billion tons year1 for iron and 21.1 billion tons year1 for aluminium as compared to approximately 0.8 billion tons year1 for gasoline. These emissions from nanometallic fuels are at least an order-of-magnitude higher than those for gasoline and hydrogen. The results of the analysis emphasize the need for well-to-wheel assessment for determining the true impact of technologies proposed as replacements for the current technologies.

07/02420 Opportunities and impediments to the expansion of forest bioenergy in Australia Raison, R. J. Biomass and Bioenergy, 2006, 30, (12), 1021–1024. There are significant opportunities for expansion of a forest bioenergy industry in Australia based on distributed electricity generation and production of liquid fuels (ethanol and bio-oil). If the large amounts of forest residues already available annually could be utilized, this would deliver useful greenhouse benefits, assist regeneration of new forests that have increased environmental values, and benefit silvicultural management. Creation of new forests in low rainfall environments for both environmental and commercial reasons will also provide residues in the future that could be used for energy production, thus enhancing overall viability of such ventures. Currently, there are several serious impediments to realizing the potential. These include: (a) large reserves of accessible coal, and low cost of electricity generated in coal-fired power plants; (b) uncertain greenhouse and renewable energy policy (specifically that relating to implementation of the mandated renewable energy target); (c) lack of proven efficient smallscale technology to enable distributed electricity generation that would reduce transportation costs for delivery of biofuels; (d) controversy over the sustainable use of native forest residues for renewable energy

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13 Alternative energy supplies (others, including economics) generation; (e) lack of markets for environmental credits (carbon, salinity, biodiversity) and; (f) lack of efficient processes for producing ethanol from wood, inadequate commercial products from lignin, and the need for further development before diesel engines can be run on bio-oil for stationary power generation and transport. In Australia, apart from the use of firewood for domestic heating, forest bioenergy has developed only to a very limited extent, despite the existence of significant opportunities. A major impediment to expansion is lack of public acceptance and support, especially for the use of native forest residues that are the main available biomass source. A concerted effort at several levels is needed to address this issue.

07/02421 Optimum utilization of renewable energy sources in a remote area Akella, A. K. et al. Renewable and Sustainable Energy Reviews, 2007, 11, (5), 894–908. Energy is supplied in the form of electricity, heat or fuels and an energy supply system must guarantee sustainable energy supplies, production and distribution of energy. Such system based on renewable energy can be utilized as integrated renewable energy system (IRES), which can satisfy the energy needs of an area in appropriate and sustainable manner. For renewable energy based rural electrification of remote areas, the IRES can be modelled and optimized for meeting the energy needs. For the purpose, the Jaunpur block of Uttaranchal state of India has been selected as remote area. On the basis of field data, the resource potential and energy demand has been estimated. The total load is 808 MWh/yr and total available resources are 807 MWh/yr, whereas %age contribution of each resources are MHP 15.88% (128166), solar 2.77% (22363), wind 1.89% (15251) and biomass energy 79.46% (641384) kWh/yr. The model has been optimized using LINDO software 6.10 version. The results indicated that the optimized model has been found to the best choice for meeting the energy needs of the area. Renewable energy sources can contribute to the total energy demands as 16.81% (115465), solar 2.27% (15588), wind 1.78% (12201) and biomass energy 79.14% (543546) kWh/yr for the fulfillment of 687 MWh/yr at the 15% reduced level of 808 MWh/yr load. The results further indicated that optimized IRES can provide a feasible solution in terms of energy fulfillments in the range of EPDF from 1.0 to 0.75 because below 0.75 EPDF (0.50–0.25) the deficit start and so that model becomes non-feasible solution. The EPDF is electric power delivery factor and also called optimizing power factor and is maximum equal to 1. The paper reports the results of optimization of IRES models of the study area of Zone 4 of Jaunpur block of Uttaranchal state.

07/02422 Performance evaluation of hybrid PV/thermal water/air heating system: a parametric study Tiwari, A. and Sodha, M. S. Renewable Energy, 2006, 31, (15), 2460– 2474. In this paper, a thermal model of an integrated photovoltaic and thermal solar (IPVTS) water/air heating system has been developed. An analytical expression for the temperature of solar cell and water and an overall thermal efficiency of IPVTS system have been derived as a function of climatic and design parameters. Numerical computations have been carried out for composite climate of New Delhi for parametric studies. Four configurations, namely (a) unglazed with tedlar (UGT), (b) glazed with tedlar (GT), (c) unglazed without tedlar (UGWT) and (d) glazed without tedlar (GWT) have been considered. Comparison of the IPVTS system with water and air heater has also been carried out. It is found that the characteristic daily efficiency of IPVTS system with water is higher than with air for all configurations except GWT. It is also observed that an overall thermal efficiency of IPVTS system for summer and winter conditions is about 65% and 77%, respectively.

07/02423 Performance evaluation of photovoltaic– thermosyphon system for subtropical climate application Chow, T. T. et al. Solar Energy, 2007, 81, (1), 123–130. The rapid development and sales volume of photovoltaic (PV) modules has created a promising business environment in the foreseeable future. However, the current electricity cost from PV is still several times higher than from the conventional power generation. One way to shorten the payback period is to bring in the hybrid photovoltaic– thermal (PVT) technology, which multiplies the energy outputs from the same collector surface area. In this paper, the performance evaluation of a new water-type PVT collector system is presented. The thermal collection making use of the thermosyphon principle eliminates the expense of pumping power. Experimental rigs were successfully built. A dynamic simulation model of the PVT collector system was developed and validated by the experimental measurements, together with two other similar models developed for PV module and solar hot-water collector. These were then used to predict the energy outputs and the payback periods for their applications in the subtropical climate, with Hong Kong as an example. The numerical results show that a payback period of 12 years for the PVT collector

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system is comparable to the side-by-side system, and is much shorter than the plain PV application. This is a great encouragement in marketing the PVT technology.

07/02424 Productivity and costs of slash bundling in Nordic conditions Ka¨rha¨, K. and Vartiama¨ki, T. Biomass and Bioenergy, 2006, 30, (12), 1043–1052. The number of slash bundlers and the volume of slash bundling have been rapidly increasing during the last few years in Finland. However, no comprehensive time or follow-up studies have been carried out on slash bundling technology in Finland or in any other country. Metsa¨teho Oy carried out studies on the productivity and costs of slash bundling in different Nordic recovering conditions. The study methods included both time and follow-up studies. Data were collected during the summer and winter period primarily in Norway spruce (Picea abies L. Karst.) dominated clear cutting sites. The bundling techniques performed by different types of bundler (Fiberpac 370, Timberjack 1490D, Pika RS 2000, Valmet WoodPac) were studied. The average productivity of slash bundling was 18.1 bundles per operating (E15, including delays shorter than 14 min) hour with the Timberjack 1490D and Fiberpac 370 bundlers in the follow-up study. The operator of the slash bundler had the greatest effect on the productivity of bundling. The prerequisite for increased bundling volumes is a reduction in the costs of the most expensive sub-stage of the bundling supply chain, i.e. bundling itself. This requires improved recovery conditions at bundling sites, increased bundling productivity, larger sized bundles, and the execution of bundling operations in two work shifts using an efficient bundler and effective operator working methods. Implementation of these development measures will bring the bundling supply chain up to a speed that makes it the most competitive supply chain for forest chips in terms of total supply costs for long-distance transportation distances of more than 60 km.

07/02425 Real options valuation of US federal renewable energy research, development, demonstration, and deployment Siddiqui, A. S. et al. Energy Policy, 2007, 35, (1), 265–279. Benefits analysis of US Federal government research, development, demonstration, and deployment (RD3) programmes for renewable energy (RE) technology improvement typically employs a deterministic forecast of the cost and performance of renewable and non-renewable fuels. The benefits estimate for the programme derives from the difference between two forecasts, with and without the RD3 programme in place. Three deficiencies of this approach are that it ignores: (1) uncertainty in the cost of non-renewable energy (NRE); (2) the possibility of adjustment to the RD 3 effort commensurate with the evolving state of the world; and (3) the underlying technical risk associated with RD3. In this paper, an intuitive approach to determining the option value of RE RD3 is developed. This approach seeks to tackle the first two deficiencies noted above by providing an estimate via a compound real option of an RE RD3 programme in a future with uncertain NRE costs. A binomial lattice reveals the economic intuition underlying the decision-making process, while a numerical example illustrates the option components embedded in a simplified representation of current US Federal RE RD3.

07/02426 Review of augmentation of energy needs using renewable energy sources in India Varun, and Singal, S. K. Renewable and Sustainable Energy Reviews, 2007, 11, (7), 1607–1615. The paper reviews energy demand and the potential of renewable energy sources in India and its prospects for development in a costeffective and sustainable manner.

07/02427 Solubility correlation and phase behaviors of carbon dioxide and lubricant oil mixtures Yokozeki, A. Applied Energy, 2007, 84, (2), 159–175. Recently, carbon dioxide is being considered as one of the promising environmentally friendly refrigerants, and extensive studies on the ‘trans-critical’ vapour-compression cycle using CO2 have been undertaken both experimentally and theoretically. In the vapour compression cycle, lubricant oils are always required, and thus thermophysical properties of lubricant and refrigerant mixtures must be well understood. Currently, the lubricants of choice are polyalkylene glycol (PAG) or polyol ester (POE) oils. Several experimental solubility data for these oils have been published, but those experimental data have not been analysed yet theoretically (or with thermodynamic equations). In this report, the authors have investigated the phase behaviour (or solubility) of CO2 + PAG and POE mixtures, correlating experimental solubility data with the equation-of-state (EOS) model. Observed data have been successfully correlated with the present EOS, which is used for predicting the general phase behaviour for mixtures of CO2 with these lubricant oils.

14 Fuel science and technology (fundamental science, analysis, instrumentation) 07/02428

Spatial mapping of renewable energy potential

Ramachandra, T. V. and Shruthi, B. V. Renewable and Sustainable Energy Reviews, 2007, 11, (7), 1460–1480. An energy resource that is renewed by nature and whose supply is not affected by the rate of consumption is often termed as renewable energy. The need to search for renewable, alternate and non-polluting sources of energy assumes top priority for self-reliance in the regional energy supply. This demands an estimation of available energy resources spatially to evolve better management strategies for ensuring sustainability of resources. The spatial mapping of availability and demand of energy resources would help in the integrated regional energy planning through an appropriate energy supply–demand matching. This paper discusses the application of geographical information system (GIS) to map the renewable energy potential talukwise in Karnataka State, India. Taluk is an administrative division in the federal set-up in India to implement developmental programmes like dissemination of biogas, improved stoves, etc. Hence, this paper focuses talukwise mapping of renewable energy (solar, wind, bioenergy and small hydroenergy) potential for Karnataka using GIS. GIS helps in spatial and temporal analyses of the resources and demand and also aids as Decision Support System while implementing location-specific renewable energy technologies. Regions suitable for tapping solar energy are mapped based on global solar radiation data, which provides a picture of the potential. Coastal taluks in Uttara Kannada have higher global solar radiation during summer (6.31 kWh/m 2), monsoon (4.16 kWh/m2) and winter (5.48 kWh/m2). Mapping of regions suitable for tapping wind energy has been done based on wind velocity data, and it shows that Chikkodi taluk, Belgaum district, has higher potential during summer (6.06 m/s), monsoon (8.27 m/s) and winter (5.19 m/s). Mysore district has the maximum number of small hydropower plants with a capacity of 36 MW. Talukwise computation of bioenergy availability from agricultural residue, forest, horticulture, plantation and livestock indicates that Channagiri taluk in Shimoga district yields maximum bioenergy. The bioenergy status analysis shows that Siddapur taluk in Uttara Kannada district has the highest bioenergy status of 2.004 (ratio of bioresource availability and demand).

07/02429 Stability of supported platinum sulfuric acid decomposition catalysts for use in thermochemical water splitting cycles Ginosar, D. M. et al. International Journal of Hydrogen Energy, 2007, 32, (4), 482–488. The activity and stability of several metal oxide supported platinum catalysts were explored for the sulfuric acid decomposition reaction. The acid decomposition reaction is common to several sulfur based thermochemical water splitting cycles. Reactions were carried out using a feed of concentrated liquid sulfuric acid (96 wt%) at atmospheric pressure at temperatures between 800 and 850 C and a weight hour space velocity of 52 g acid/g catalyst/h. Reactions were run at high space velocities such that variations in kinetics were not masked by surplus catalyst. The influence of exposure to reaction conditions was explored for three catalysts; 0.1–0.2 wt% Pt supported on alumina, zirconia and titania. The higher surface area Pt/Al2O3 and Pt/ZrO2 catalysts had the highest activity but deactivated rapidly. A low surface area Pt/TiO2 catalyst had good stability in short term tests, but slowly lost activity for over 200 h of continuous operation.

07/02430 Three utilization patterns of the renovated Moste hydro power plant on an electricity market of power and ancillary services Bregar, Z. Electric Power Systems Research, 2007, 77, (3–4), 252–258. In addition to electricity, most hydro power plants can offer also the ancillary services: secondary and tertiary control reserve. On emerging electricity markets the need for these additional services is becoming more and more important, recognized and also paid. However, for each plant, there is some interdependence among those options. The same plant cannot provide maximal peaking electricity, maximal secondary control reserve as well as maximal tertiary control reserve at the same time. The generation capabilities of the plant must thus be partitioned properly among those options so as to achieve some overall goal (e.g. the maximum of revenue, etc.). This article briefly presents those options for the renovated Moste cascade on the upper Sava river near Bled in Slovenia. A small but effective mixed integer linear programme has been used.

14 FUEL SCIENCE AND TECHNOLOGY Fundamental science, analysis, instrumentation 07/02431 A comparative study of approaches to direct methanol fuel cells modelling Oliveira, V. B. et al. International Journal of Hydrogen Energy, 2007, 32, (3), 415–424. Fuel cell modelling has received much attention over the past decade in an attempt to better understand the phenomena occurring within the cell. Mathematical models and simulation are needed as tools for design optimization of fuel cells, stacks and fuel cell power systems. Analytical, semi-empirical and mechanistic models for direct methanol fuel cells (DMFC) are reviewed. Effective models were until now developed describing the fundamental electrochemical and transport phenomena taking place in the cell. More research is required to develop models that can account for the two-phase flows occurring in the anode and cathode of the DMFC. The merits and demerits of the models are presented. Selected models of different categories are implemented and discussed. Finally, one of the selected simplified models is proposed as a computer-aided tool for real-time system level DMFC calculations.

07/02432 A cross-property relation between the tensile modulus and the thermal conductivity of porous materials Pabst, W. and Gregorova´, E. Ceramics International, 2007, 33, (1), 9– 12. Elastic moduli and thermal conductivity are key properties determining a material’s response to mechanical deformations and temperature gradients. Although in the case of heterogeneous materials the effective properties are uniquely determined by the material’s microstructure, in the case of porous materials, due to the large difference in the phase properties, it is usually not possible to predict the porosity dependence of any of these properties based on volume fraction information alone. Thus, for real-world materials experimental measurement is often considered to be the only feasible way to obtain a reliable porosity dependence for the property in question. The authors show, however, that for isotropic materials either the relative tensile modulus Er or the relative thermal conductivity kr can be calculated from the other via the cross-property relation 3 ln Er=4 ln kr, as soon as one of them has been measured.

07/02433 A fuzzy logic based fault classification approach using current samples only Mahanty, R. N. and Dutta Gupta, P. B. Electric Power Systems Research, 2007, 77, (5–6), 501–507. An approach for classification of transmission line faults is presented. The approach is based on fuzzy logic and requires the consideration of the samples of three phase currents at one end of transmission line. To illustrate the effectiveness of the proposed approach extensive simulation studies, using EMTP and MATLAB, have been carried out for different types of fault considering wide variations in the operating conditions.

07/02434 A general theory for the construction of best-fit correlation equations for multi-dimensioned numerical data Moore, S. E. and Moffat, D. G. International Journal of Pressure Vessels and Piping, 2007, 84, (3), 256–264. A general theory for the construction of best-fit correlation equations for multi-dimensioned sets of numerical data is presented. This new theory is based on the mathematics of n-dimensional surfaces and goodness-of-fit statistics. It is shown that orthogonal best-fit analytical trend lines for each of the independent parameters of the data can be used to construct an overall best-fit correlation equation that satisfies both physical boundary conditions and best-of-fit statistical measurements. Application of the theory is illustrated by fitting a threeparameter set of numerical finite-element maximum-stress data obtained earlier for pressure vessel nozzles and/or piping system branch connections.

07/02435 A new algorithm for evaluation of the simplified gamma-ray shielding formulas Guseinov, I. I. et al. Progress in Nuclear Energy, 2006, 48, (7), 680–685. New analytical formulas for the construction of the gamma-ray shielding formulas for a plane, a disk, a cylindrical or a spherical surface (volume) sources are proposed depending on the functional of

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14 Fuel science and technology (fundamental science, analysis, instrumentation) the binomial coefficients. Numerical stability and optimization of such analytical relations become more important with increasing degree and order. Some numerical results are presented for significant mapping examples and they are briefly discussed. The computation results are compared with those of previously published studies. Using the derived expressions the gamma-ray shielding formulas can be evaluated most efficiently and accurately for mt = 0, 1, 2.

07/02436 A new trajectory sensitivity approach for computations of critical parameters Fang, D. Z. and Qin, Y.-F. Electric Power Systems Research, 2007, 77, (3–4), 303–307. An approach is proposed to assess critical parameters in power system through an evaluation of trajectory sensitivity factors, such as fault critical clearing time (CCT), stability limit generation of generator. Firstly, new formulations for analysis of trajectory sensitivity with respect to fault clearing time are developed. And then, an approach to map the trajectory sensitivity to a sensitivity factor of minimum corrected kinetic energy to fault clearing time is introduced. Directed by the sensitivity factor, CCTs of contingencies are evaluated through an iterative process. It is the advantage that the CCT approach can be used for power systems represented by complex models. Combined with
sensitivity, similar technique can be used to compute generation limit of generators. Case studies for both CCT and generation limit assessments are performed on the 10-generator New England test system to verify the effectiveness and accuracy of the approach.

07/02437 A numerical study on the heat-transfer characteristics of an array of alternating horizontal or vertical oval cross-section pipes placed in a cross stream Chen, W.-L. International Journal of Refrigeration, 2007, 30, (3), 454– 463. In this paper, a numerical study on the flow of an array of alternating horizontal or vertical oval cross-section pipes placed in a cross stream, resembling that encountered in a real cross-flow heat exchanger, is presented. The results include temperature contours and velocity vectors on the surface of the pipe and at several selected cross-sections, the local and sectional averaged Nusselt number distributions, and the overall Nusselt number variations versus the internal and external flow Reynolds numbers. The computation shows that the wall temperature varies dramatically along both the circumferential and the axial directions of the pipe, and is far different from a constant wall temperature distribution assumed in most previous studies. In general, the portion of the pipe with external wall facing forwards the cross-flow stream has lower temperature and higher local heat-transfer rate than the portion with wall facing backwards the cross-flow stream. At the maximum external flow Reynolds number, Re = 40, considered in this paper, the magnitude of pipe’s overall Nusselt number is about onesixth the magnitude of that calculated based on the ideal constant wall temperature assumption.

07/02438 A parametric model for predicting wind-induced pressures on low-rise vertical surfaces in shielded environments Sharag-Eldin, A. et al. Solar Energy, 2007, 81, (1), 52–61. This paper describes the development of a parametric mathematical model to predict wind-induced surface pressures on exterior vertical wall surfaces on a single model block in shielded environments. The first phase of the project focused on the development of a parametric model to determine the average pressure coefficients on exterior building surfaces shielded by a single windward obstruction model block. A pressure modification coefficient was defined to estimate the shielding effect based on the angular relationship between, the shielding block and the surface for which average pressure is to be computed, and the wind direction. The second phase involved expanding the scope of the prediction model to account for the various arrangement possibilities of the shielding blocks relative to the surfaces under investigation. The predicted pressure modification coefficient may be used to estimate average pressure coefficients taking into account the indoor velocity coefficients, surface porosity, window design, and interior partition types. The prediction model considers the effect of multiple shielding blocks, and the gaps between them on a vertical surface relative to wind direction. Wind tunnel verification of the model showed robust estimation of surface pressures in complex urban configurations.

07/02439 A study of the effect of heat source location in a ventilated room using multiple regression analysis Cho, Y. and Awbi, H. B. Building and Environment, 2007, 42, (5), 2072– 2082. Multiple regression analysis is a statistical technique that allows the prediction of a dependent variable from more than one independent variable and also the determination of influential independent variables. Using experimental data, in this study the multiple regression analysis is applied to predict the room mean velocity and determine the

366 Fuel and Energy Abstracts September 2007

most influencing parameters on the velocity. More than 120 experiments for four different heat source locations were carried out in a test chamber with a high level wall mounted air supply terminal at air change rates 3–6 ach. The influence of the environmental parameters such as supply air momentum, room heat load, Archimedes number and local temperature ratio, were examined by two methods: a simple regression analysis incorporated into scatter matrix plots and multiple stepwise regression analysis. It is concluded that, when a heat source is located along the jet centre line, the supply momentum mainly influences the room mean velocity regardless of the plume strength. However, when the heat source is located outside the jet region, the local temperature ratio (the inverse of the local heat removal effectiveness) is a major influencing parameter.

07/02440 An adaptive single pole autoreclosure based on zero sequence power Elkalashy, N. I. et al. Electric Power Systems Research, 2007, 77, (5–6), 438–446. In this paper, a novel adaptive single pole autoreclosure is introduced. This reclosure is based on monitoring the fundamental component of the zero sequence instantaneous power to detect the extinction instant of the arc in its secondary period. Thus, adaptive closing instant can be achieved. The concept of reclosure is validated via typical examples of transmission line exposed to ground arcing fault. Effects of fault location and load flow on the accuracy of the technique are examined. Discriminatory zones of the secondary arc period in the zero sequence power domains are determined. A proposed threshold for the reclosing instant is introduced and examined. Validation of the proposed algorithm is verified via digital signal processing experimental test set-up. The test results corroborate the efficacy of proposed technique.

07/02441 An emergency power system control based on the multi-stage fuzzy based procedure Abou El-Ela, A. A. et al. Electric Power Systems Research, 2007, 77, (5–6), 421–429. This paper proposes a multi-stage procedure to overcome the effects of different emergency conditions using multi-objective fuzzy linear programming (MFLP) technique. Comparison studies between two linear fuzzy models, triangular and trapezoidal models, are performed to obtain the best membership model for modelling power system variables. Also, this paper presents multi-modes of fired fuzzy linguistic rules inside the security regions for different constrained power dispatch controller centres. The optimal preventive control actions from power generation and transmission line power flows are prepared using MFLP technique. This preparation helps the system operator to face any emergency conditions without making a corrective control action, while, all system constraints are kept within their permissible limits. The results show the capability of the proposed procedure to remove different emergency condition effects.

07/02442 Application of the heat-balance integral to an inverse Stefan problem Ren, H.-S. International Journal of Thermal Sciences, 2007, 46, (2), 118–127. Most phase change process controls are concerned with the inverse Stefan problem. In this paper, the heat-balance integral method is applied effectively to analyse the one-region and two-region inverse Stefan problems in Cartesian and spherical coordinates. It is shown that if the movement of the phase change boundary is specified arbitrarily the present technique to predict both the temperature and its gradient at the fixed boundary is simple and accurate. As numerical illustrations, the one-dimensional inward solidification problem in Cartesian and spherical coordinates are solved and discussed in detail when the movement of the phase change interface is specified as a power function. The accuracy of these approximate solutions, based on the heat-balance integral method, is demonstrated satisfyingly by comparison with the available exact and/or numerical solutions for the one-region and the two-region problems.

07/02443 Calculations on fission gas behaviour in the high burnup structure Blair, P. et al. Journal of Nuclear Materials, 2006, 350, (3), 232–239. The behaviour of fission gas in high burnup fuel during steady-state and transient conditions is of special interest for safety reasons. Despite this, mechanistic models that reflect the fission gas transport processes and reliably predict the evolution of the remaining fission gas in the high burnup structure (HBS) are largely missing today. The authors start to address this problem by developing a one-dimensional, mass balance model and apply it to LWR UO2 fuel at the moderate temperatures found in the rim region. They also examine the quantity of gas remaining in the HBS fuel matrix at steady state and compare it with experimental values. The current model reproduces the 0.2 wt% observed xenon concentration under certain conditions, namely fast

14 Fuel science and technology (fundamental science, analysis, instrumentation) grain boundary diffusion and an effective volume diffusion coefficient. A sensitivity analysis is also conducted for the model parameters, the relative importance for which is not well established a priori.

07/02444 Computation of the time-averaged temperature fields and energy fluxes in a thermally isolated thermoacoustic stack at low acoustic Mach numbers Piccolo, A. and Pistone, G. International Journal of Thermal Sciences, 2007, 46, (3), 235–244. A simplified calculus model to investigate on the transverse heat transport near the edges of a thermally isolated thermoacoustic stack in the low acoustic Mach number regime is presented. The proposed methodology relies on the well-known results of the classical linear thermoacoustic theory, which are implemented into an energy balance calculus-scheme through a finite difference technique. Details of the time-averaged temperature and heat flux density distributions along a pore cross-section of the stack are given. It is shown that a net heat exchange between the fluid and the solid walls takes place only near the edges of the stack plates, at distances from the ends not exceeding the peak-to-peak particle displacement amplitude. The structure of the mean temperature field within a stack plate is also investigated; this last results not uniform near its terminations giving rise to a smaller temperature difference between the plate extremities than that predicted by the standard linear theory. This result, when compared with experimental measurements available in literature, suggests that thermal effects localized at the stack edges may play an important role as sources of the deviations found between linear theory predictions and experiments at low and moderate Mach numbers.

07/02445 Density of organic binary mixtures from equilibrium measurements Jelinek, M. et al. International Journal of Refrigeration, 2007, 30, (3), 471–481. A reduction model for equilibrium measurements data (pressure– temperature–weight data) was developed. The model allows indirect measurements of the refrigerant concentration at the liquid and the gas phases and the solution density. The reduction model was validated by both comparing the obtained pressure–temperature–concentration relation at equilibrium conditions and solution densities with experimentally direct measurements carried out by Kriebel and Loffler (up to 80  C) and by us (up to 120  C) over a wide range of pressure and temperature.

07/02446 Evaluation of effect of hydrogen on toughness of Zircaloy-2 by instrumented drop weight impact testing Viswanathan, U. K. et al. Journal of Nuclear Materials, 2006, 350, (3), 310–319. Hydride-assisted degradation in fracture toughness of Zircaloy-2 was evaluated by carrying out instrumented drop-weight tests on curved Charpy specimens fabricated from virgin pressure tube. Samples were charged to 60 ppm and 225 ppm hydrogen. Ductile-to-brittle-transition behaviour was exhibited by as-received and hydrided samples. The onset of ductile-to-brittle-transition was at about 130  C for hydrided samples, irrespective of their hydrogen content. Dynamic fracture toughness (KID) was estimated based on linear elastic fracture mechanics (LEFM) approach. For fractures occurring after general yielding, the fracture toughness was derived based on equivalent energy criterion. Results are supplemented with fractography. This simple procedure of impact testing appears to be promising for monitoring service-induced degradation in fracture toughness of pressure tubes.

07/02447 Fingerprinting petroporphyrin structures with vibrational spectroscopy. Part 7: calculations using density functional theory of the molecular structures and structure-sensitive vibrational modes of type II nickel(II) cycloalkanoporphyrins Czader, A. and Czernuszewicz, R. S. Organic Geochemistry, 2007, 38, (2), 250–266. The authors report density functional theory (DFT) calculations at the B3LYP/6–31G(d) level on nickel(II) complexes of the geochemically significant cycloalkanoporphyrins, Ni(CAP5–7), that contain a five-, six-, or seven-membered alicyclic ring (E) fused to the pyrrole- and methine bridge aromatic carbon atoms. The structure of each Ni(CAP) is optimized, with no symmetry constraints, by considering different orientations of the peripheral ethyl groups. The ground state structures demonstrate that the shortening of the nickel–nitrogen bonds is accommodated by out-of-plane ruffling of the porphinato skeleton, in good agreement with the experimental data available. The results reveal Ni(CAP5) to be slightly ruffled, with an angle between the planes of opposite pyrrole rings of 7.7 , but Ni(CAP6) and Ni(CAP7) have a severe ruffling of the macrocycle, with the corresponding angle of respectively 35.1 and 39.7 . The DFT and scaled quantum mechanical force-field method (DFT–SQM) have been used to calculate the vibrational frequencies of Ni(CAP5–7) in the gas phase. The trends in the DFT–SQM vibrational shifts of the porphyrin

structure-sensitive modes (1400–1700 cm1) upon varying the length of the meso,-alkano chain are analysed and compared with those observed previously by us for the solution resonance Raman spectra of Ni(CAP5–7). The authors are able to verify by theory that the observed frequency downshifts with ring E size are driven by the increasing out-of-plane ruffling distortion.

07/02448 Forecasting systems reliability based on support vector regression with genetic algorithms Chen, K.-Y. et al. Reliability Engineering & System Safety, 2007, 92, (4), 423–432. This study applies a novel neural-network technique, support vector regression (SVR), to forecast reliability in engine systems. The aim of this study is to examine the feasibility of SVR in systems reliability prediction by comparing it with the existing neural-network approaches and the autoregressive integrated moving average (ARIMA) model. To build an effective SVR model, SVR’s parameters must be set carefully. This study proposes a novel approach, known as GA-SVR, which searches for SVR’s optimal parameters using real-value genetic algorithms, and then adopts the optimal parameters to construct the SVR models. A real reliability data for 40 suits of turbochargers were employed as the data set. The experimental results demonstrate that SVR outperforms the existing neural-network approaches and the traditional ARIMA models based on the normalized root mean square error and mean absolute percentage error.

07/02449 Gas–solid turbulent flow and heat transfer with collision effect in a vertical pipe Saffar-Avval, M. et al. International Journal of Thermal Sciences, 2007, 46, (1), 67–75. A turbulent gas–solid suspension upward flow in a vertical pipe is simulated numerically using Eulerian–Lagrangian approach. Particle– particle and particle–wall collisions are simulated based on deterministic approach. The influence of particle collisions on the particle concentration, mean temperature and fluctuating velocities are investigated. Numerical results are presented for different values of loading ratios. The profiles of particle concentration, mean velocity and temperature are shown to be flatter by considering inter-particle collisions, while this effect on the gas mean velocity and temperature is not significant. It is demonstrated that the effect of inter-particle collisions have a dramatic influence on the particle fluctuation velocity. It is shown that the profiles of particle concentration and particle velocity are flattened due to inter-particle collisions and this effect becomes more pronounced with increasing loading ratio. Also, the attenuation of turbulence by inter-particle collisions in the core region of the pipe is increased by increasing loading ratio.

07/02450 General deconvolution of thin-target and thick-target Bremsstrahlung spectra to determine electron energy distributions Lamoureux, M. and Charles, P. Radiation Physics and Chemistry, 2006, 75, (10), 1220–1231. Electron energy distributions have been determined from thin-target Bremsstrahlung for many years. For thick-target Bremsstrahlung however, even the simple diagnostic that immediately gives the distribution from the second derivative of the emissivity has been established only recently. For cases when the underlying assumptions are unjustified, further deconvolutions are proposed: a matrix inversion method involving a functions basis, and an iterative method that is more general and stable. Both methods could also be applied to thintarget Bremsstrahlung.

07/02451 Generalised scattering imaging laser technique for 2-D characterization of non-isothermal sprays Calabria, R. and Massoli, P. Experimental Thermal and Fluid Science, 2007, 31, (5), 445–451. Optical techniques based on the properties of the scattered light are widely utilized to study liquid fluid sprays. However, these techniques generally require the knowledge of the optical properties of the liquid forming the droplets. This limits their use in the study of sprays in nonisothermal regime where unknown variations of the optical properties occur. In this paper the application of the generalized scattering technique, GSI, to the characterization of spray droplets in isothermal, evaporating and burning regimes is discussed. GSI is a two-dimensional imaging technique able to measure the size of droplets with a maximum uncertainty of 4%, even if no information is given on the properties of the fluid. The method is based on a peculiar experimental configuration where the imaging system is set in out of focus condition. The peculiar string-shape of the images allows the application of GSI to moderate dense spray with a droplet concentration as high as several thousands droplets per cubic centimeter. This technique being not sensitive to the refractive index of droplets is particularly prone for studying sprays in combustion. By using the GSI method, the evaporation and combustion of isopropyl alcohol droplets was successfully studied and the relative rates determined.

Fuel and Energy Abstracts September 2007 367

14 Fuel science and technology (fundamental science, analysis, instrumentation) 07/02452 Heat-conduction optimization based on constructal theory Wu, W. et al. Applied Energy, 2007, 84, (1), 39–47. An analysis of the ‘tree-like network’ construct method is presented. The high effective-conduction channel distribution has been optimized, without the premise that the new-order assembly construct must be assembled by the optimized last-order construct. The ‘tree-like network’ construct method is faultiness. A more optimal construct is obtained, and when the thermal conductivities and the proportion of the two heat-conduction materials are constants, the limit of the minimum-heat resistance is derived.

07/02453 High explosive simulation using multi-material formulations Alia, A. and Souli, M. Applied Thermal Engineering, 2006, 26, (10), 1032–1042. The accurate numerical simulation of air-blast is an industrial concern. Because the experimental investigation of these fast transient events is expensive and time-consuming, several numerical approaches of air explosion are carried out. In this paper, an air-blast simulation is described using Eulerian multi-material formulation. In order to validate the numerical approach and prove its ability for high-pressure wave propagation, comparison of two examples with experimental results is performed. Both simulations lead to the same prediction for the pressure time history. Good agreement between the test results and the predicted pressure response is achieved.

07/02454 Impact of interconnection photovoltaic/wind system with utility on their reliability using a fuzzy scheme El-Tamaly, H. H. and Elbaset Mohammed, A. A. Renewable Energy, 2006, 31, (15), 2475–2491. Reliability analysis has been considered as an important step in any system design process. A reliable electrical power system means a system that has sufficient power to feed the load demand during a certain period or, in other words, has small loss of load probability (LOLP). LOLP is defined as an expected fraction of load not met by its power needs from electrical power system during its lifetime. Photovoltaic (PV)/wind energy system (WES) hybrid electric power system (PV/WES HEPS) differs considerably from the utility grid (UG) in its performance and operating characteristics. With the interconnection of PV/WES as a HEPS into the UG, the fluctuating nature of the energy produced by these systems has a different effect on the overall system reliability than that of the fluctuating nature of energy produced by UG. Therefore, this paper presents a complete study, from reliability point of view, to determine the impact of interconnecting PV/WES HEPS into UG. Four different configurations of PV/WES/UG have been investigated and a comparative study between these four different configurations has been carried out. The overall system is divided into three subsystems, containing the UG, PV and WES. The generation capacity outage table has been built for each configuration of these subsystems. These capacity outage tables of UG, PV/UG, WES/UG and PV/WES/UG are calculated and updated to incorporate their fluctuating energy production. This paper also presents a fuzzy logic technique to calculate and assess the reliability Index for each HEPS configuration under study.

07/02455 Indirect matrix converter drives for unity displacement factor and minimum switching losses Kwak, S. et al. Electric Power Systems Research, 2007, 77, (5–6), 447– 454. With sinusoidal input currents and no dc-link capacitor, a matrix converter offers remarkable advantages over other alternatives in applications requiring improved utility interaction and critical weight/ volume reduction. Lately, indirect matrix converter topologies have also been investigated, leading to possibility of reduced switch number and multi-drive applications. However, due to off-line input current regulation of the converters, the input displacement factor varies with LC input filters and load conditions. This fact results in non-unity displacement factor and increased reactive power flow. In this paper, a novel on-line input current control strategy is proposed based on a closed-loop control in the synchronous reference frame. The approach allows Indexpendent control of two input current components (active and reactive), yielding zero reactive components. In addition, this paper specifies a relationship of input current phase angle and switching losses in semiconductors. Based on the specification, it is proved that the indirect matrix converter has minimum switching losses with the input currents in phase with the input voltages. Thus, the proposed control algorithm yields minimum switching losses and no reactive power flow. The feasibility of the proposed technique has been verified in the paper.

07/02456 Interior-point based algorithms for the solution of optimal power flow problems Capitanescu, F. et al. Electric Power Systems Research, 2007, 77, (5–6), 508–517.

368 Fuel and Energy Abstracts September 2007

Interior-point method is a very appealing approach to the optimal power flow (OPF) problem mainly due to its speed of convergence and ease of handling inequality constraints. This paper analyses the ability of three interior-point based algorithms, namely the pure primal-dual, the predictor–corrector and the multiple centrality corrections, to solve various classical OPF problems: minimization of overall generation cost, minimization of active power losses, maximization of power system loadability and minimization of the amount of load curtailment. These OPF variants have been formulated using a rectangular model for the (complex) voltages. Numerical results on three test systems of 60, 118 and 300 buses are reported.

07/02457 Lattice Boltzmann method applied to the laminar natural convection in an enclosure with a heat-generating cylinder conducting body Jami, M. et al. International Journal of Thermal Sciences, 2007, 46, (1), 38–47. In this paper, a numerical investigation of laminar convective flows in a differentially heated, square enclosure with a heat-conducting cylinder at its centre, is carried out. The flow and the temperature are computed using respectively the lattice Boltzmann equation and finite-difference with suitable coupling to take natural convection into account. The investigation is performed for Pr=0.71, Rayleigh numbers of Ra=103– 106 and temperature-difference ratio of
T*=0–50. The average hot and cold walls Nusselt numbers, the flow and temperature fields are presented and discussed. For a constant Ra, the average Nusselt number at the hot and cold walls (Nuh and Nuc) vary linearly with
T*: Nuh decreases with
T* while Nuc increases with
T*.

07/02458 Line protection based on the differential equation algorithm using mutual coupling Garcı´a-Gracia, M. et al. Electric Power Systems Research, 2007, 77, (5– 6), 566–573. The application of the distance protection for distribution systems is increasingly more frequent. However, the distance relaying algorithms employed are designed for single lines without considering mutual coupling between parallel lines. Mutual coupling affects the accuracy of the results. In this work, the behaviour of the conventional differential equation algorithm (DEA) is analysed for its accuracy in the estimation of the fault distance. The response time, the variation of the line parameters, the fault inception angle, the presence of erroneous samples and the mutual coupling are considered in the study. These results are compared with those obtained using the Fourier algorithm. In both algorithms, the errors are significant when mutual coupling is present, reaching 12.59% for fault at the end of the line. In this paper, a new distance relaying called DEA with mutual coupling (DEAMC) has been presented. The new algorithm is an improvement to the DEA algorithm that takes into account the coupling effect in the analytical equations. The DEAMC response has been compared with the conventional algorithms results. The results show that the new algorithm improves the accuracy when mutual coupling is present. The DEAMC algorithm reduces the error to 1.93% for fault at the end of the line.

07/02459 Mathematical modeling for the prediction of biogas generation characteristics of an anaerobic digester based on food/vegetable residues Biswas, J. et al. Biomass and Bioenergy, 2007, 31, (1), 80–86. An anaerobic digester of 10 L capacity has been operated in batch mode at an optimum temperature of 40  C and at a pH of 6.8 using vegetable/food residues as the feed material. The effect of slurry concentration and that of the concentration of carbohydrate, protein and fat in the slurry on the biogas production rate and methane concentration in the biogas have been studied. The slurry concentration has been varied in the range of 72.0–700 kg m3. At a slurry concentration of 67.7 kg m3 the effect of carbohydrate concentration has been studied by varying the ratios of carbohydrate, protein and fat in the range of 6.9:4.3:1–12.1:4.3:1 by using a sole carbohydrate source, namely sucrose. The effect of protein concentration has been studied by varying the ratios of carbohydrate, protein and fat in the range of 5.6:7.0:1–5.6:13.0:1 by using a sole protein source, namely papain and that of fat concentration has been studied by varying the ratios of carbohydrate, protein and fat in the range of 7.2:10:1.6–7.2:10:5 by using a fat source, namely vanaspati. A deterministic mathematical model using differential system equations have been developed and it is capable of predicting the behaviour of the digester satisfactorily.

07/02460 Modeling of two-phase temperatures in a twolayer porous cathode of polymer electrolyte fuel cells Hwang, J. J. et al. International Journal of Hydrogen Energy, 2007, 32, (3), 405–414. The solid-phase and fluid-phase temperatures inside a two-layer porous cathode of a polymer electrolyte fuel cell are calculated simultaneously. The porous cathode consists of a catalyst layer and a gas diffusion layer. In the gas diffusion layer, a two-equation model is

14 Fuel science and technology (fundamental science, analysis, instrumentation) employed to deal with the local thermal non-equilibrium (LTNE) between the solid matrices and the fluids. In the catalyst layer, the energy equation is coupled with species transports via a macroscopic electrochemical model. As for the species transports, the Bruggemann model is employed to describe the effective diffusivities of the oxygen and water vapour in the porous cathode. Results show that fluid-phase temperature and the solid-phase temperature are different due to the LTNE effect. In addition, both the fluid-phase temperature and the solid-phase temperature increase with increasing the electrochemical reaction rate. Finally, the species fluxes and current density inside the catalyst layer and gas diffusion layer are also provided.

07/02461 Multi-scale correlation analyses of two lateral profiles of full-scale downburst wind speeds Chen, L. and Letchford, C. W. Journal of Wind Engineering and Industrial Aerodynamics, 2006, 94, (9), 675–696. Lateral correlation analyses are carried out in different scales for two sets of full-scale thunderstorm downburst full wind speed time series. These two sets of data were recorded at the TTU field site, Texas, USA, on June 4 and 15, 2002, respectively. The same data sets were also used in the authors’ previous paper, which presents a methodology to model downburst vertical profiles. The statistical procedures utilized, such as the POD technique, the wavelet shrinkage for timevarying mean inference, the two-stage weighted moving-average method for time-varying variance inference and the Priestley’s EPSD estimator, are also employed in this paper and their details are thus omitted. The authors employed the proper orthogonal decomposition (POD) to reduce the dimensions, POD in this article is employed to measure the degree of the correlation between two deterministic time series. Conventionally, wind speeds are decomposed to a time-varying mean speed and a nonstationary fluctuating speed by virtue of wavelet shrinkage. Time-varying mean speeds are in the largest scale, which are essentially due to translations of storms and radial velocities of spreading flow. It was observed that the time-varying standard deviations of fluctuating speeds are basically driven by time-varying mean speeds other than small-scale turbulence. Therefore, timevarying standard deviations are considered in the medium scale. Finally, the modulated fluctuating speeds are viewed in the smallest scale and due to small-scale turbulence. It is found that (1) the two lateral profiles are fully correlated and almost evenly spatially distributed in the largest and medium scales with more than 96% of the total energy; (2) they are uncorrelated in the smallest scale since the measurement locations are at least 263 m apart.

07/02462 Neural-network based analysis and prediction of a compressor’s characteristic performance map Yu, Y. et al. Applied Energy, 2007, 84, (1), 48–55. The difficulties, due to a lack of information about stage-by-stage axialcompressor performance, are analysed. To overcome these issues, a three-layer back-propagation neural-network applied Levenberg– Marquardt algorithm is presented and discussed. The experimental data provided by manufacturers are used for the neural-network training. Through twice training, the compressor’s performance map can be predicted. The results can be used for the development of an off-design model or overall dynamic simulation of the behaviour of a gas-turbine power-plant.

07/02463 Numerical and experimental investigations on the performance of coiled adiabatic capillary tubes

tubes with louvred fins have been conducted. Simulations are performed for different geometries with varying louvre pitch, louvre angle, fin pitch and tube pitch and for different Reynolds number. Conjugate heat transfer and conduction through the fins are considered. The air-side performance of heat exchanger is evaluated by calculating Stanton number and friction factor. The results are compared with experiment and a good agreement is observed. The local Nusselt number variation along the top surface of the louvre is calculated and effects of geometrical parameters on the average heat transfer coefficient is computed. Design curves are obtained which can used to predict the heat transfer and the pressure drop for a given louvre geometry.

07/02465 Numerical modeling of the flow conditions in a closed-circuit low-speed wind tunnel Moonen, P. et al. Journal of Wind Engineering and Industrial Aerodynamics, 2006, 94, (10), 699–723. A methodology for numerically simulating the flow conditions in closed-circuit wind tunnels is developed as a contribution to the general philosophy of incorporating computational fluid dynamics (CFD) in wind tunnel design and testing and to CFD validation studies. The methodology is applied to the full-scale Jules Verne climatic wind tunnel in which experimental data have been obtained. Due to the specific features of this closed-circuit wind tunnel, the conventional CFD modelling approach, in which only the flow in the wind tunnel test section is modelled, is inadequate. To obtain accurate results the entire wind tunnel has to be modelled. In the numerical closed-circuit wind tunnel, the conventional flow inlet and outlet are replaced by a single ‘fan boundary condition’. Special attention is given to the theoretical background and the practical implementation of this type of boundary condition in the CFD model. The numerical model is validated for the case of an empty wind tunnel and for the case in which a block-type building is placed in the test section. It will be shown that this methodology can generally reproduce the wind tunnel measurements of mean velocities with an error equal to or less than 10% despite the occurrence of multiple flow separations upstream of the test section. This provides perspectives for the future use of this methodology as a tool for wind tunnel design and testing and for CFD validation purposes.

07/02466 Observability analysis for state estimation using Hachtel’s augmented matrix method Bei, G. et al. Electric Power Systems Research, 2007, 77, (7), 865–875. This paper presents algorithms of observability analysis for state estimation when Hachtel’s augmented matrix method is used in the formulation of state estimation. It is shown that the authors’ previously presented algorithms for determining observable islands and deciding multiple measurement placement for gain matrix are ready to be extended to Hachtel’s augmented matrix method, which is commonly used in power networks due to its robustness. Triangular factors updating with multiple rank is also presented, and the updated factors of Hachtel’s augmented matrix can be directly used by state estimator if the real data are used by observability analysis. The proposed algorithms have been tested on IEEE 14 bus and IEEE 118 systems. Numerical examples are provided to illustrate the details of the proposed algorithms. The simplicity and efficiency of proposed algorithms make possible their on-line application for current power networks.

Zhou, G. and Zhang, Y. Applied Thermal Engineering, 2006, 26, (11– 12), 1106–1114. The objective of this study is to investigate the performance of coiled adiabatic capillary tubes both numerically and experimentally by comparison with the straight capillaries. With the developed model including metastable both liquid and two-phase regions, three methods (M&N equation, M&N + Giri method and developed C–M&N method) are discussed to calculate friction factors for coiled capillary tubes. A one-pass-through experiment apparatus is set up for model verification. Mass flow rate through the capillary is measured with different tube geometries and under various operating conditions. Compared with the present experimental data and that in literature, the developed C–M&N method gives the best prediction with the average deviation of 5%. The test results show that mass flow rate in a capillary tube increases with increase of coiled diameter (D), but changes little beyond D = 300 mm. And the mass flow rate with coiled diameter of 40 mm is approximately 10% less than that of straight capillary tube.

07/02467 Ocean wave forecasting using recurrent neural networks

07/02464 Numerical investigation of fluid flow and heat transfer over louvred fins in compact heat exchanger

Jang, T. S. et al. Ocean Engineering, 2006, 33, (11–12), 1552–1564. The authors present an iterative scheme to calculate the nonlinear wave profiles. The nonlinear operator was constructed from the dynamic boundary condition of the free surface. The initial input of the iterative process was linear potential. The linear dispersion relation was utilized. The authors of the present paper suggest an improved scheme in terms of accuracy and speed of convergence by utilizing the

Malapure, V. P. et al. International Journal of Thermal Sciences, 2007, 46, (2), 199–211. Numerical investigation of fluid flow and heat transfer characteristics over louvred fins and flat tube in compact heat exchangers is presented in this study. Three-dimensional simulations of single and double row

Mandal, S. and Prabaharan, N. Ocean Engineering, 2006, 33, (10), 1401–1410. The tremendous increase in offshore operational activities demands improved wave-forecasting techniques. With the knowledge of accurate wave conditions, it is possible to carry out the marine activities such as offshore drilling, naval operations, merchant vessel routing, nearshore construction, etc. more efficiently and safely. This paper describes an artificial neural network, namely recurrent neural network with rprop update algorithm and is applied for wave forecasting. Measured ocean waves off Marmugao, west coast of India are used for this study. Here, the recurrent neural network of 3, 6 and 12 hourly wave forecasting yields the correlation coefficients of 0.95, 0.90 and 0.87, respectively. This shows that the wave forecasting using recurrent neural network yields better results than the previous neural network application.

07/02468 On an improvement of a nonlinear iterative scheme for nonlinear wave profile prediction

Fuel and Energy Abstracts September 2007 369

14 Fuel science and technology (fundamental science, analysis, instrumentation) nonlinear dispersion relation. The existence and uniqueness of the improved scheme are illustrated in this paper. The calculation results together with Fast Fourier transform revealed that the improved scheme made it possible to predict higher-order nonlinear characteristics of the Stokes’ wave.

07/02469 Optimal operation of dispersed generation under uncertainty using mathematical programming Handschin, E. et al. International Journal of Electrical Power & Energy Systems, 2006, 28, (9), 618–626. The foreseen decentralization of the electrical energy supply has a significant impact on the overall system operation and control. To increase the economic efficiency of dispersed generation (DG) a powerful optimization technique is required. This paper presents a mathematical model including different kinds of DG units with respect to their technical characteristics as well as the optimization technique which is used to solve the problems under the existing uncertainties.

07/02470 Optimization of Mediterranean building design using genetic algorithms Znouda, E. et al. Energy and Buildings, 2007, 39, (2), 148–153. While it is possible to check the energy performance of a given building by means of several available methods, the inverse problem of determining the optimum configuration given a desired performance is more difficult to solve. In the Mediterranean region this problem is more complex due to the following two reasons: the air-conditioning load is as important as the heating load, and the energy needs depend on a high number of architectural parameters which have different, even contradictory, effects on summer and winter loads. Presented in this paper is an optimization algorithm that couples pseudo-random optimization techniques, the genetic algorithms (GA), with a simplified tool for building thermal evaluation for the purpose of minimizing the energy consumption of Mediterranean buildings. Since increasing the energy performance usually requires the use of special devices resulting in a high construction cost, it is also proposed that GA is used for the purpose of economical optimization.

(PAS) and small angle neutron scattering neutron (SANS) measurements were used to characterize the fine-scale microstructure in splitmelt A533B steels with varying Ni and Cu contents, irradiated at selected conditions from 270 to 310  C between 0.04 and 1.6  1023 n m2. The objective was to assess the character, composition and magnetic properties of Cu-rich precipitates, as well as to gain insight on the matrix features. The results suggest that the irradiated very low-Cu and intermediate Ni steel contains small vacancy-Mn–Ni– Si cluster complexes, but not large, well-formed and highly enriched Mn–Ni–Si phases. The hardening features in steels containing 0.2% and 0.4% Cu, and 0.8% and 1.6% Ni are consistent with well-formed, non-magnetic Cu–Ni–Mn precipitates. The precipitate number densities and volume fractions increase, while their sizes decrease, with increasing Ni and decreasing irradiation temperature. The precipitates evolve with fluence in stages of nucleation, growth and limited coarsening.

07/02474 Power quality analysis based on fuzzy estimation algorithm: voltage flicker measurements Al-Kandari, A. M. et al. International Journal of Electrical Power & Energy Systems, 2006, 28, (10), 723–728. This paper presents a method based on fuzzy linear estimation for voltage flicker measurements. The proposed algorithm uses the digitized samples of the voltage signal at the location where the power quality standards are implemented. The voltage signal is modelled as a fuzzy linear parameter estimation problem, where the coefficients are assumed to be fuzzy having certain middle and spread. A triangular membership is assumed. The linear programming based simplex method is used to solve the resulting linear optimization problem. Results for simulated examples are given in the text.

07/02475 Radiation exchange factors between specular inner surfaces of a rectangular enclosure such as transplant production unit

Arslanturk, C. Applied Thermal Engineering, 2006, 26, (11–12), 1149– 1157. Radiating extended surfaces are widely used to enhance heat transfer between primary surface and the environment. The performance of such a surface is significantly affected by variable thermal conductivity, particularly in the case of large temperature differences. In this paper, the Adomian decomposition method is used to evaluate the efficiency of a radiating rectangular fin with variable thermal conductivity. Because the resulting complicated fin efficiency expression is not convenient for further optimization calculations, the data from the present solutions is correlated for a suitable range of problem parameters. The correlation equations are used to find the optimum dimensions of space radiators that maximize the heat transfer rate per unit radiator mass. The optimization results are conveniently represented as two identical correlation equations for calculating the optimum dimensions.

Abdel-Ghany, A. M. and Kozai, T. Energy Conversion and Management, 2006, 47, (13–14), 1988–1998. General mathematical relations are presented for the specular exchange factors, FS, of diffuse radiation exchange between the inner surfaces of a rectangular enclosure. Three of these surfaces are specular reflectors, diffuse emitters and the fourth surface is a diffuse reflector, diffuse emitter. This enclosure can be used as a transplant production unit with artificial lighting for electric energy saving purposes. An image system and the crossed string method are used to derive these relations. The resulting expressions are conceptually simple and similar to the commonly known expressions of the exchange factors between diffuse surfaces, F. The accuracy of the presented FS relations was examined for different numbers of multiple reflections, N, on the specular surfaces and for different aspect ratios (ratio of the width, w to the height, h). The results proved that the relations are accurate and strongly satisfy the well-known relation of the radiation exchange between enclosure surfaces and satisfy the reciprocity relation. For any aspect ratio, considering N of 150 between highly reflective surfaces ( = 0.99) is sufficient to estimate the FS factors without any possible error. Using specular reflecting surfaces in such cases significantly reduces the electric energy consumption used for lighting.

07/02472 Passive harmonic filters design using Fortran feasible sequential quadratic programming

07/02476 Re-establishment of the continuity of knowledge in the safeguards of interim storages using NDA techniques

Abdel Aziz, M. M. et al. Electric Power Systems Research, 2007, 77, (5– 6), 540–547. This paper presents an application of Fortran feasible sequential quadratic programming optimization method for finding the optimum fixed shunt inductive–capacitive compensator for power factor correction of non-linear loads, where source voltage and load current harmonics are considered. Optimization minimizes the transmission line losses, and maximizes the load power factor. The performance of the proposed solution is discussed by means of numerical examples.

Peerani, P. and Galletta, M. Nuclear Engineering and Design, 2007, 237, (1), 94–99. This paper aims to provide an answer to the question: is it possible to detect the diversion of a fuel assembly from a Castor container by means of passive neutron measurements? Monte Carlo simulations performed on suitably validated models suggest a correct way to tackle the problem with success perspectives. Under the assumption of ideal boundary conditions, that is neglecting the effects related to the presence of other canisters and of the environment surrounding the cask, it has been demonstrated that it is possible to establish a sort of ‘fingerprint’ of a sealed Castor cask. This fingerprint could be used for future verification of the integrity of the cask in order to re-establish the continuity of knowledge in case of failure of the C/S measures. In particular, it is shown that it is possible to detect the removal of a PWR bundle from a Castor V21/A cask by means of passive neutron measurements, only if the removed bundle was originally located in peripheral positions of the fuel basket grid.

07/02471 Optimum design of space radiators with temperature-dependent thermal conductivity

07/02473 Positron annihilation spectroscopy and small angle neutron scattering characterization of nanostructural features in high-nickel model reactor pressure vessel steels Glade, S. C. et al. Journal of Nuclear Materials, 2006, 351, (1–3), 197– 208. Irradiation embrittlement in nuclear reactor pressure vessel steels results from the hardening by a high number density of nanometer scale features. In steels with more than 0.10% Cu, the dominant features are often Cu-rich precipitates typically alloyed with Mn, Ni and Si. At low-Cu and low-to-intermediate Ni levels, so-called matrix hardening features are believed to be vacancy-solute cluster complexes, or their remnants. However, Mn–Ni–Si rich precipitates, with Mn plus Ni contents greater than Cu, can form at high alloy Ni contents and are promoted at irradiation temperatures lower than the nominal 290  C. Even at very low-Cu levels, late blooming Mn–Ni–Si rich precipitates are a significant concern due to their potential to form large volume fractions of hardening features. Positron annihilation spectroscopy

370 Fuel and Energy Abstracts September 2007

07/02477 Single-wall carbon nanotubes prepared with different kinds of Ni–Co catalysts: Raman and optical spectrum analysis Lin, X. et al. Carbon, 2007, 45, (1), 196–202. The addition of acetates and nitrates for the synthesis of single-wall carbon nanotubes via laser ablation was explored. Targets containing nominal amounts of acetates or nitrates in addition to Ni and Co catalysts were compared to a standard target containing only Ni and Co at temperatures ranging from 1000 to 1200  C. The as produced web-

14 Fuel science and technology (fundamental science, analysis, instrumentation) like soot was characterized by transmission electron microscopy, Raman spectroscopy and optical absorption spectroscopy. All samples showed a linear increase in SWCNT mean diameter with temperature; however, the rate of mean diameter change with temperature differed for the various targets, more so at lower temperatures. The addition of nitrates improved the SWCNT relative yield over all the temperatures used, whereas the inclusion of acetates improved the relative yield only at lower temperatures. The above results were discussed and analysed according to the porous structure of the targets resulting from the decomposition of the acetates and nitrates and consequential thermal diffusion changes.

07/02478 Solute interaction with point defects in a Fe during thermal ageing: a combined ab initio and atomic kinetic Monte Carlo approach Vincent, E. et al. Journal of Nuclear Materials, 2006, 351, (1–3), 88–99. Solute Cu plays a major role in the embrittlement of reactor pressure vessel (RPV) steels under radiation. In RPV steels and dilute FeCu alloys, characterization techniques such as the tomographic atom probe (TAP), or the small angle neutron scattering (SANS) have revealed the formation of solute rich clusters (with Cu, Ni, Mn and Si) under neutron flux. It is thus very important to characterize the interactions of these solutes with radiation-induced point defects in order to understand the elementary mechanisms behind the formation of these clusters. Ab initio calculations based on the density functional theory have been made in order to build a database used to parameterize an atomic kinetic Monte Carlo model. The interactions of point defects and solute atoms in dilute FeX alloys (X = Cu, Mn, Ni or Si) have been evaluated for different configurations of small solute clusters and solute–vacancy complexes. First results obtained with the kinetic Monte Carlo model will be presented and compared to some experimental observations.

07/02479 Sorption isotherms: a review on physical bases, modeling and measurement Limousin, G. et al. Applied Geochemistry, 2007, 22, (2), 249–275. The retention (or release) of a liquid compound on a solid controls the mobility of many substances in the environment and has been quantified in terms of the ‘sorption isotherm’. This paper does not review the different sorption mechanisms. It presents the physical bases underlying the definition of a sorption isotherm, different empirical or mechanistic models, and details several experimental methods to acquire a sorption isotherm. For appropriate measurements and interpretations of isotherm data, this review emphasizes four main points: (i) the adsorption (or desorption) isotherm does not provide automatically any information about the reactions involved in the sorption phenomenon. So, mechanistic interpretations must be carefully verified. (ii) Among studies, the range of reaction times is extremely wide and this can lead to misinterpretations regarding the irreversibility of the reaction: a pseudo-hysteresis of the release compared with the retention is often observed. The comparison between the mean characteristic time of the reaction and the mean residence time of the mobile phase in the natural system allows knowing if the studied retention/release phenomenon should be considered as an instantaneous reversible, almost irreversible phenomenon, or if reaction kinetics must be taken into account. (iii) When the concentration of the retained substance is low enough, the composition of the bulk solution remains constant and a singlespecies isotherm is often sufficient, although it remains strongly dependent on the background medium. At higher concentrations, sorption may be driven by the competition between several species that affect the composition of the bulk solution. (iv) The measurement method has a great influence. Particularly, the background ionic medium, the solid/solution ratio and the use of flow-through or closed reactor are of major importance. The chosen method should balance easy-to-use features and representativity of the studied natural conditions.

07/02480 waves

Specific kinetic energy concept for regular

Pinto, F. T. and Silva, R. Ocean Engineering, 2006, 33, (10), 1283–1298. The global kinetic energy of regular waves is usually characterized through the characteristic parameters wave height and wave length without reference to its vertical distribution. In this paper a new methodology to evaluate the vertical energy distribution from the velocity components is presented. The methodology could also be an alternative for irregular wave fields, with several wave lengths, to which the traditional method in the evaluation of the energy per unit area or wavelength is not applicable. The squared velocity components functions for each water level can be theoretical or determined from long enough measurements time series. The average of those functions at one specific depth level over the length of interest gives the mean horizontal and vertical specific kinetic energy at that level. The global kinetic energy corresponds to the total specific kinetic energy integration in depth.

07/02481 Spectroscopic and microscopic study of the corrosion of iron–silicon steel by lead–bismuth eutectic (LBE) at elevated temperatures Johnson, A. L. et al. Journal of Nuclear Materials, 2006, 350, (3), 221– 231. The performance of iron–silica alloys with different silicon composition was evaluated after exposure to an isothermal bath of lead–bismuth eutectic (LBE). Four alloys were evaluated: pure iron, Fe–1.24%Si, Fe–2.55%Si and Fe–3.82%Si. The samples were exposed to LBE in a dynamic corrosion cell for periods from 700 to 1000 h at a temperature of 550  C. After exposure, the thickness and composition of the oxide layer were examined using optical microscopy, scanning electron microscopy (SEM) and X-ray photoelectron spectrometry (XPS), including sputter depth profiling. Particular attention was paid to the role, spatial distribution, and chemical speciation of silicon. Lowbinding-energy silicon (probably silicates or SiO 44) was found in the oxide; while elemental silicon (Si) was found in the metal as expected, and silica (SiO2) was found at the bottom of the oxide layer, consistent with the formation of a layer between the oxide and the metal. Alloys with low concentrations of Si contained only silicate in the oxide. Alloys with higher concentrations of Si contained a layer of silica at the boundary between the oxide and the bulk metal. All of the alloys examined showed signs of oxide failure. This study has implications for the role of silicon in the stability of the oxide layer in the corrosion of steel by LBE.

07/02482 Testing functional forms in energy modeling: an application of the Bayesian approach to U.S. electricity demand Xiao, N. et al. Energy Economics, 2007, 29, (2), 158–166. In the estimation of demand functions for energy resources, linear, log–linear, translog, or AIDS functional forms are commonly assumed. It is frequently debated which is the ‘best’ functional forms to employ in order to accurately represent the underlying relationships between the consumption of various energy resources and explanatory variables such as energy prices, weather variables, income, and other factors. In an example analysis of residential energy demand employing crosssectional household-level data, it is found that the AIDS model is slightly better than the translog model, which is superior to the log– linear model, and which in turn is better than the linear model. This is in sharp contrast to previous findings in this context.

07/02483 The effects of disjunct sampling and averaging time on maximum mean wind speeds Guo, X. et al. Journal of Wind Engineering and Industrial Aerodynamics, 2006, 94, (8), 581–602. Conventionally, long-term wind speed information is calculated on the basis of the annual maxima of consecutive 10-min averages. Very often, however, the averages are saved with a temporal spacing of several hours. This is disjunct sampling. It may also happen that the wind speeds are averaged over a longer time period before being saved. In either case, the extreme wind will be underestimated. This paper investigates the effects of the disjunct sampling interval and the averaging time on the attenuation of the extreme wind estimation by means of a simple theoretical approach as well as measurements. The measurements include climates dominated by extratropical lows, as well as more complicated, wind climate types. For both, the investigations are done for omni-directional and sector-wise situations. The theory assumes the time series is a Gaussian Markov chain and it performs adequately for sites in the extratropical regions. The sectorwise situation is more complicated. The attenuation of the extreme mean winds for a sector shows a dependency on the frequency of occurrence from that sector.

07/02484 Thermal modeling and analysis of a quasi-poloidal stellarator modular coil Chaudhri, A. et al. Applied Thermal Engineering, 2006, 26, (10), 974– 982. A computer model of the racetrack coil of a quasi-poloidal stellarator is used to investigate thermal transient behaviour when pulsed with high-ampere currents to generate magnetic field. The analysis was carried out to determine hotspots and collect temperature data in the process. The rate of cooling under natural convective boundary conditions is determined. Also fluid cooling using liquid nitrogen is investigated. The optimal design location of the cooling lines in the racetrack is confirmed. Experiments have also been carried out to determine the property data for the copper-glass-epoxy composite conductor coil, which is used in the computational analysis.

07/02485 Three dimensional visualization and animation of travelling waves in power systems Evrenosoglu, C. Y. et al. Electric Power Systems Research, 2007, 77, (7), 876–883.

Fuel and Energy Abstracts September 2007 371

14 Fuel science and technology (fuel cell technology) This paper is concerned about the animation of power system transients for educational purposes. The electromagnetic transients programs simulate voltage signals at the line terminals only. These may not be sufficient to observe and understand the travelling wave phenomenon, which is of primary interest in most relaying and fault location studies. One way to capture the travelling waves is by animating the voltage profile along the studied line. This is accomplished by a new animation software, which is described in detail in this paper. Various visualization and animation methods are employed in order to bring out different features of voltage transients. Examples involving single-phase and three-phase power systems are given to illustrate the use of the developed tool.

This article gives a critical review of the current data on the specific conductivity of aqueous potassium hydroxide (KOH) solutions. Empirical correlations relating concentration to density were developed to compare specific conductivity data given in weight percentage KOH and molarity of KOH. Available data on specific conductivity are related with respect to one another and compared to experimental data. Based on these comparisons, specific sets of reported data were used to develop an equation relating specific conductivity of aqueous KOH to temperature and concentration. This empirical correlation was developed over a molarity range of 0–12 at temperatures of 0–100 C. The correlation has been compared with that proposed by others and shows greater accuracy over the concentration range modelled.

07/02486 Uncertainty and the Tyndall decarbonisation scenarios

07/02490 Catalytic ammonia decomposition over CMK-3 supported Ru catalysts: effects of surface treatments of supports

Mander, S. et al. Global Environmental Change, 2007, 17, (1), 25–36. The transition to a low carbon energy system must occur in the context of numerous uncertainties that occur at all scales, from the extent of the carbon reduction required through to the technologies and policies which will bring the reductions about. Against this background, the Tyndall Decarbonisation Scenarios project has sought to develop a new approach for the generation of energy scenarios, which focuses explicitly upon the transition to a low carbon energy system. Using a backcasting approach, the scenarios explore areas of uncertainty in relation to a low carbon energy system and how the low carbon transition may be brought about.

07/02487 Validation study of the Monte Carlo code MVP for analysis of two-region TCA critical experiments with PWRtype MOX fuels Rahman, M. et al. Progress in Nuclear Energy, 2006, 48, (7), 703–726. A series of critical experiments containing pressurized water reactor (PWR)-type mixed oxide (MOX) fuels conducted at the TCA facility of Japan Atomic Energy Research Institute have been analysed. The cores were composed of a central 4.91 wt% plutonium enriched mixedoxide (PuO2–UO2) 10  10 test lattice with water-to-fuel volume ratio of 2.40 or 2.96, surrounded by 2.6 wt% enriched UO2 driver lattice with water-to-fuel volume ratio of 1.50 with a water gap in-between. The fissile plutonium content was 91.4 wt%. The critical water level, the power distribution in the test region, and the neutron activation distribution of Au-wire were measured for six different cores of which two contain soluble boron of 309.4 and 554.0 ppm, one contains four equidistant water holes in the central test lattice and one contains cross water gap at the core centre. Calculation of corresponding effective multiplication factor, the fission reaction-rate distribution in the test region, and the capture reaction-rate distribution of Au have been performed using a continuous-energy Monte Carlo code MVP with two nuclear data sets based on JENDL-3.2 and JENDL-3.3. The calculated results agreed to the measurements within a maximum difference of 0.27% for the effective multiplication factors, 3.0% for the power distributions, 5.9% for the thermal activation distributions throughout the whole region, and 4.3% for the epithermal activation distributions in the core region.

07/02488 Verification of the Lagrangian particle model using the ETEX experiment Suh, K. S. et al. Annals of Nuclear Energy, 2006, 33, (14–15), 1159– 1163. A Lagrangian particle model named long-range accident dose assessment system has been developed to understand the characteristics of the long-range transport and diffusion of a radioactive material released into the atmosphere. The developed numerical model was compared with the results of European tracer experiment (ETEX), a long-range field tracer experiment. Several simulations were performed to investigate the effects according to the variation of the mixing height. As a comparative study, the calculated concentration distributions agreed well in the case of the usage of the mixing height calculated by the Richardson number than the usage of the constant mixing height in the computational domain. The calculated particle cloud represented well the phenomenon that was transported northwesterly from a release point such as the ETEX results.

Fuel cell technology 07/02489 A review of specific conductivities of potassium hydroxide solutions for various concentrations and temperatures Gilliam, R. J. et al. International Journal of Hydrogen Energy, 2007, 32, (3), 359–364.

372 Fuel and Energy Abstracts September 2007

Li, L. et al. Carbon, 2007, 45, (1), 11–20. CMK-3 carbon was used as a catalyst support for Ru catalyst for ammonia decomposition. The supports were treated with acid, and the effects of treatment on the properties of CMK-3 supports were studied by N2 adsorption, XRD, XPS and mass titration. The chemical treatment of carbon support cause significant changes in carbon surface chemistry and in turn had significant effects on both catalyst dispersion and catalytic activity. It is found that the as-synthesized CMK-3 carbon is not a good catalyst support for this reaction. However, surface functional groups produced by acid treatments led to larger Ru catalyst particles, while alkali treatments made the Ru catalyst dispersion even worse due to the residue alkali or earth alkali metals. Interestingly, relatively larger Ru catalyst particles but still well dispersed in the channel of the mesoporous structures of the carbon improves NH3 conversion into H2. This is determined by the chemical reaction rate-limiting step of ammonia decomposition. The catalytic activity follows the order: Ru–K/CMK-3 > Ru–Na/CMK-3 > Ru–Ca/ CMK-3 > Ru–Cl/CMK-3 > Ru–SO4/CMK-3 > Ru–PO4/CMK-3 > Ru/ CMK-3 > Ru–Li/CMK-3. CMK-3 is not a good carbon catalyst support due to its amorphous structure resulting in the poor electron conductivity.

07/02491 Characterising fuel cell technology: challenges of the commercialisation process Hellman, H. L. and van den Hoed, R. International Journal of Hydrogen Energy, 2007, 32, (3), 305–315. The commercialization of a new technology is a challenging and uncertain process. Likewise, the emerging fuel cell (FC) industry experiences numerous technical and market uncertainties to shift from primarily research and development activities to activities in production, marketing and sales. This paper aims to gain a better understanding of the management challenges FC firms face in the current pre-commercialization phase. First, a brief literature review on technology commercialization is given. Second, a characterization is made of (i) the technology, (ii) the market for FC products, (iii) the environment and (iv) the FC industry to highlight the key uncertainties and challenges of managing the commercialization of FC technology. In the final discussion this paper suggests that FC firms face dilemmas in decision-making, regarding resource acquisition, competence development, product development and niche market selection. This research may provide insight into the challenges of managing the commercialization of FC technology.

07/02492 Comparison of CNF and XC-72 carbon supported palladium electrocatalysts for magnesium air fuel cell Yang, W. et al. Carbon, 2007, 45, (2), 397–401. Palladium catalysts supported on carbon nanofibres (CNFs) and XC-72 carbon were developed by chemically reducing palladium chloride with ethylene glycol. The morphologies and crystal structure of the Pd/CNF catalyst and Pd/XC-72 catalyst were investigated by TEM and XRD, respectively. The electrocatalytical activity of the catalysts was examined via cyclic voltammetry testing techniques. The performance of the air electrodes was examined by linear polarization methods. Magnesium air fuel cells with Pd/CNF catalyst and Pd/XC-72 catalyst were fabricated and characterized. The results showed that the Pd/CNF catalyst had higher catalytic activity for the oxygen reduction reaction and achieved better performance of the magnesium air fuel cell compared with the Pd/XC-72 catalyst.

07/02493 Conversion of propane to propylene in a protonconducting solid oxide fuel cell Feng, Y. et al. Fuel, 2007, 86, (1–2), 123–128. The feasibility of conversion of propane to propylene in a fuel cell using yttrium-doped barium cerate as the proton-conducting electrolyte and platinum as anode and cathode catalysts was investigated. The distribution of gas products from anode outlet was analysed by gas chromatography and, discussed under open circuit conditions and when discharging the fuel cell. Under open circuit conditions, because there were only chemically catalytic reactions and thermal reactions in

15 Environment (pollution, health protection, applications) the anode chamber, the gas slate was little selective to propylene. However, the propylene selectivity was obviously enhanced when discharging the fuel cell, through activating the electro-catalytic dehydrogenation of propane. The propylene yield obtained from the electro-catalytic reaction reached 70–80%. In addition, relatively good fuel cell performances were achieved. The influences of the operating temperature and propane flow rate on the fuel cell performances were also discussed.

07/02494 Dynamic characteristics of a PEM fuel cell system for individual houses Obara, S. International Journal of Energy Research, 2006, 30, (15), 1278–1294. The method of determination of the control variables for a system controller, which controls the electric power output of a solid-polymermembrane (PEM) fuel cells system during electric power load fluctuations, was considered. The operation was clarified for the response characteristics of electric power generation for setting the control variables of proportional action and integral action considered to be the optimal for the system controller. The power load pattern of an individual house consists of loads usually moved up and down rapidly for a short time. Until now, there have been no examples showing the characteristics of the power generation efficiency of a system that follows a load pattern that moves up and down rapidly. Therefore, this paper investigates the relation of the control variables and power generation efficiency when adding change that stimulates the load of a house to PEM fuel cell cogeneration. As a result, it was shown that an operation, minimally influenced by load fluctuations, can be performed by changing the control variables using the value of the electric power load of a system.

07/02495 Influence of the support in selective CO oxidation on Pt catalysts for fuel cell applications Souza, M. W. V. M. et al. International Journal of Hydrogen Energy, 2007, 32, (3), 425–429. One crucial requirement for the proton exchange membrane fuel cells (PEMFC) is to feed clean hydrogen to the anode, which is rapidly poisoned by traces of CO present from the upstream hydrocarbon reforming and water–gas shift processes. The removal of CO can be achieved by using catalysts able to selectively oxidize CO in the presence of excess hydrogen. Herein we report the effect of the support on Pt catalysts for total and selective oxidation (SELOX) of CO. The catalysts supported on ceria and zirconia presented higher activity than alumina and silica supported catalysts in SELOX reaction at low temperatures, but with lower CO conversions.

07/02496 Modeling and control of distributed generation systems including PEM fuel cell and gas turbine Jagaduri, R. T. and Radman, G. Electric Power Systems Research, 2007, 77, (1), 83–92. This paper concentrates on the modelling and control of distributed generation systems including fuel cell and gas turbine. The fuel cell is connected to the power system through a dc/ac converter, which is equipped with both voltage- and power-control loops. The gas turbine is also assumed to be equipped with both voltage-control and generation (or frequency)-control loops. Moreover the gas turbine is modelled using the d–q frame of reference. The interfacing of the gas turbine with the power system is achieved by transforming its equations from the d–q frame of reference to power system frame of reference. A multivariable supplementary fuzzy logic controller is proposed for improving the dynamics of the combined fuel cell and gas turbine system. This fuzzy logic controller is designed using the Matlab fuzzy logic toolbox; A distribution test system including a load, a fuel cell and a gas turbine, connected to a power grid is simulated using Matlab/ Simulink software package. The dynamics of the combined distributed generation plant are analysed for the cases of with and without controller. The accuracy of the presented model and the effectiveness of the proposed multivariable supplementary fuzzy controller are deduced from the simulation results.

07/02497 Parameter estimation of internal thermal mass of building dynamic models using genetic algorithm Wang, S. and Xu, X. Energy Conversion and Management, 2006, 47, (13–14), 1927–1941. Building thermal transfer models are essential to predict transient cooling or heating requirements for performance monitoring, diagnosis and control strategy analysis. Detailed physical models are time consuming and often not cost effective. Black box models require a significant amount of training data and may not always reflect the physical behaviours. In this study, a building is described using a simplified thermal network model. For the building envelope, the model parameters can be determined using easily available physical details. For building internal mass having thermal capacitance, including components such as furniture, partitions, etc., it is very difficult to obtain detailed physical properties. To overcome this

problem, this paper proposes to present the building internal mass with a thermal network structure of lumped thermal mass and estimate the lumped parameters using operation data. A genetic algorithm estimator is developed to estimate the lumped internal thermal parameters of the building thermal network model using the operation data collected from site monitoring. The simplified dynamic model of building internal mass is validated in different weather conditions.

07/02498 Study of operational parameters on the performance of micro PEMFCs with different flow fields Hsieh, S.-S. et al. Energy Conversion and Management, 2006, 47, (13– 14), 1868–1878. The effects of different operating parameters on micro proton exchange membrane fuel cell (PEMFC) performances were experimentally studied for three different flow field configurations (interdigitated, mesh, and serpentine). Experiments with different cell operating temperatures and different backpressures on the H2 flow channels, as well as various combinations of these parameters, have been conducted for three different flow geometries. The micro PEMFCs were designed and fabricated inhouse through a deep UV lithography technique and the SU-8 photoresist was used as microstructure material for the fuel cell flow field plates. Results are presented in the form of polarization VI curves and PI curves under different operating conditions. The possible transport mechanisms associated with the parametric effects were discussed. In addition, it was found that among the three flow patterns considered, significant improvements can be reached with a specified flow geometry.

07/02499 The effect of plasma pre-treatment of carbon used as a Pt catalyst support for methanol electrooxidation Tang, Z. et al. Carbon, 2007, 45, (1), 41–46. Vulcan XC-72 carbon black for use as a catalyst support was treated in three different plasma atmospheres, H2, Ar and O2. The results showed that the microstructure and surface functional groups were significantly changed after plasma treatment. Pt/C catalysts were prepared by chemical reduction of H2PtCl6 with HCHO and those with untreated and plasma treated carbon black supports were characterized and tested for methanol electrooxidation. TEM showed that the platinum nanoparticles on H2 and Ar plasma treated carbon were uniform and well distributed. Those on untreated carbon were uniform in most regions but coalesced in others. On O2 plasma treated carbon agglomeration of the platinum nanoparticles was significant. XRD showed that the catalysts were composed of face-centred cubic Pt nanoparticles and XPS showed that they were metallic with no oxides present. Cyclic voltammetry and chronoamperometry were used to study methanol electrooxidation on the Pt/C catalysts in a solution of 0.5 M H2SO4 + 0.5 M CH3OH, and showed that the catalytic activity those using H2 and Ar plasma treated carbon was higher than for the untreated one. Catalysts supported by O2 plasma treated carbon showed no catalytic activity. The treatment atmosphere of carbon therefore had a large effect on the catalyst performance, with the H2 plasma being the best.

15 ENVIRONMENT Pollution, health protection, applications 07/02500 A wind-tunnel study on exhaust gas dispersion from road vehicles – Part I: velocity and concentration fields behind single vehicles Kanda, I. et al. Journal of Wind Engineering and Industrial Aerodynamics, 2006, 94, (9), 639–658. By a reduced-scale model in a wind tunnel, the authors investigate the dispersion behaviour of exhaust gas from automobiles. Two types of vehicles are considered, a passenger car and a small-size truck. Tracer gas experiments show that the exhaust gas dispersion is enhanced significantly by the vehicle wake compared to the case when the vehicle body is absent. The passenger car and the truck promote dispersion in the horizontal and the vertical direction, respectively. The wake field is analysed by particle image velocimetry, and the distribution of the mean and the fluctuation fields is found to conform to the concentration field of the exhaust gas. The buoyancy of the exhaust gas has minor effect except on the vertical spread behind the truck whose wake flow amplifies the vertical displacement generated near the pipe exit.

Fuel and Energy Abstracts September 2007 373

15 Environment (pollution, health protection, applications) 07/02501 A wind-tunnel study on exhaust-gas dispersion from road vehicles – Part II: Effect of vehicle queues Kanda, I. et al. Journal of Wind Engineering and Industrial Aerodynamics, 2006, 94, (9), 659–673. By a reduced-scale wind-tunnel experiment, the authors investigate the dispersion behaviour of exhaust gas from automobiles. Based on the results of single-vehicle cases in Part I of this work, the authors consider vehicle queues consisting of passenger cars (P) and small-size trucks (T). The roles of the vehicles before and after the gas-emitting vehicle are as follows. By their turbulent wake, the preceding vehicles make the concentration field approximately symmetric in the spanwise direction despite the significant lateral offset of the exhaust pipe. The vehicles behind the gas-emitter expand the exhaust plume considerably in the spanwise direction; T expands the plume also in the vertical direction in its roll-up wake, while P scoops up the oncoming plume only around the centreline. For vehicle queues of mixing ratio P:T=2:1, the concentration fields when one of the component vehicles emit the gas are measured. It turns out that the plume shape is determined mostly by the type of the gas-emitting vehicle whereas the type of the following vehicles has minor effect. The authors also present an analytical procedure to approximate the overall contribution from all the queue-forming vehicles by a Gaussian line-source plume formula.

07/02502 Biomonitoring of atmospheric trace element deposition around an industrial town in Ghana Nyarko, B. J. B. et al. Radiation Physics and Chemistry, 2006, 75, (9), 954–958. Parmelia sulcata lichen species have been used to study the atmospheric deposition of heavy metals and other toxic elements around an industrial area in Ghana. Natural soil samples were collected at all the sampling points and analysed in order to investigate surface accumulation of the heavy metals. The sampling points used for the study were: Afienya, Doryemu Cemetery and Doryemu River. The surface accumulation of the heavy metals would be used to examine the correlation of the elements in the lichen and soil samples in order to separate contributions from atmospheric deposition and from that of soil minerals. Thermal neutron activation analysis techniques employing a 30 kW tank-in-pool research reactor operating at a thermal neutron flux of 51011 s 1 cm2 was used to determine Al, Cr, Mn, Fe, Ti, Th and V in both the lichen and soil samples. The level of contamination was quantified using the enrichment factor approach. This approach was adopted in order to ascertain whether these elements are enriched in the soil or in the atmosphere. The sampling points were enriched in the atmosphere with Cr, Mn, Fe, Ti, Th and V in the decreasing order of Afienya, Doryemu Cemetery and Doryemu River.

07/02503

CDM: taking stock and looking forward

Ellis, J. et al. Energy Policy, 2007, 35, (1), 15–28. The Kyoto Protocol’s clean development mechanism (CDM) was established in 1997 with the dual purposes of assisting non-Annex I Parties in achieving sustainable development and assisting Annex I Parties in achieving compliance with their quantified greenhouse gas emission commitments. This paper looks at the development of the CDM portfolio as well as achievements of the CDM to date in the context of wider private and public flows of investment into developing countries. These achievements include the development of 325 (by May 2005) proposed CDM projects which are together expected to generate more than 79 Mt CO2-eq credits/year during 2008–2012, increasing awareness of climate change mitigation options among possible investors and others that may facilitate transactions (i.e. governments), and the strengthening of climate-relevant institutions within countries. The paper also draws lessons from this experience to date, and outlines what changes may be needed to transform the CDM concept to a broader scale after the end of the first commitment period in 2012.

07/02504 Effect of toluene as gaseous cosubstrate in bioremediation of hydrocarbon-polluted soil Ortiz, I. et al. Journal of Hazardous Materials, 2006, 131, (1–3), 112– 117. The stimulation of the microbial population by a more bioavailable supplementary carbon source and by a surfactant pretreatment was studied in petroleum hydrocarbon-polluted soils bioremediation. Two types of soils were used, Soil A which had been recently polluted and the aged Soil B. They contained 52.4 and 50.4 g of total petroleum hydrocarbons per kg of dry soil, respectively. The effect of passing a continuous small stream of air containing a low concentration of gaseous toluene through packed 0.5 l ( = 5.5 cm) columns was studied. For Soil A, after 62 days the THPs degradation was 28% higher in the toluene treated columns than in controls. In aged Soil B the effect of toluene was not significant, probably due to bioavailability limitations. With Soil B, the combined effect of toluene as cosubstrate and a surfactant pretreatment was studied and the hydrocarbons degradation was 29% higher in the toluene-amended columns than in the controls.

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Toluene removal was higher than 99% in all cases. Surfactant addition increased hydrocarbon degradation when toluene was also added suggesting that the biological reaction was the limiting process. The study shows the possibilities of using gaseous substrates, such as toluene, for the in situ or ex situ treatment of petroleum hydrocarbonpolluted soil in processes limited by the biological reaction. The main advantage of the treatment is that the compound can be easily and directly delivered to the polluted soil through the venting system.

07/02505 Effective diffusion and microbiologic activity as constraints describing pyrite oxidation in abandoned lignite mines Kohfahl, C. et al. Applied Geochemistry, 2007, 22, (1), 1–16. This paper reports detailed oxygen measurements of pyrite bearing sediments in a column study and their interpretation based on a hydrogeochemical modelling approach. The research focuses on the quantitative effects of effective diffusion and microbiologic activity on pyrite weathering and acidification. A column experiment was set up and oxygen saturation and moisture contents were monitored over 100 days. The anoxic material used for the column experiment was taken from a sediment core of a mining waste dump in the southern periphery of the Lohsa storage system in the Lusatia region of Germany. The measured oxygen breakthrough curves were modelled using the simulator SAPY, a one-dimensional reactive transport code which considers the kinetics of chemical reactions and the delivery of oxygen into the sediment. The simulation yielded a strong dependence of pyrite oxidation on the moisture content, which was quantified by an empirical equation. It was shown that the oxidation rate was catalysed by microbial activity exceeding the rate of diffusive oxygen delivery. In order to develop a management tool for predictive issues the results have already been applied to natural environments in another study using the adapted model.

07/02506 Health and climatic hazards: framing social research on vulnerability, response and adaptation Few, R. Global Environmental Change, 2007, 17, (2), 281–295. Floods, windstorms, drought and wildfires have major implications for human health. To date, conceptual advances in analysis of vulnerability and adaptation to climatic hazards from the environmental and social sciences have not been widely applied in terms of health, though key progress is being made particularly in relation to climate change. This paper seeks to take this conceptual grounding further, examining how key themes relate to health concerns, exploring connections with existing health literatures, and developing an organising framework to aid analysis of how vulnerability to health impacts varies within society and how actors make decisions and take action in relation to climatic hazards and health. Social science research on this theme is challenging in part because of the complex mechanisms that link hazard events to health outcomes, and the many-layered factors that shape differential vulnerability and response within changing societal and environmental contexts (including the dual effect of hazards on human health and health systems, and the combination of ‘external’, ‘personal’ and ‘internal’ elements of vulnerability). Tracing a ‘health impact pathway’ from hazard event through health risk effects to health outcomes can provide a research tool with which to map out where the different factors that contribute to vulnerability/coping capacity come into effect.

07/02507 How powerful is ARAMIS methodology in solving land-use issues associated with industry based environmental and health risks? Kontic´, D. et al. Journal of Hazardous Materials, 2006, 130, (3), 271– 275. The first experience on how a part of the ARAMIS methodology has contributed to demonstration of safety in the licensing process in Slovenia for a new Seveso II plant is described. There are two foci of this description: first, trustworthy of the methodology for evaluating safety, and second, the role of a land-use plan in issuing a construction permit for the new plant. The authors consider why the safety report was first rejected by the regulator, and later-on accepted after applying components of the ARAMIS methodology in its revised version. They also discuss a relationship between the land-use plan and the licensing process for the new plant. The outcomes of this Seveso II plant licensing case are that the ARAMIS approach, in spite it was still under development when applied, is more transparent and credible comparing to the others, which have also been applied. This is related to the demonstration of how safety management system and general safety behaviour is integrated into the overall management policy. The conclusions take into account regulator’s response in the licensing process.

07/02508 stations

Investigation of pollutants dispersion from power

Yousif, S. A. et al. International Journal of Energy Research, 2006, 30, (15), 1352–1362.

15 Environment (CO2, NOx, SO2 and particulate emissions) Theoretical investigations were conducted of pollutants dispersion, NOx, SO2 and particulate matter (PM), from stacks of arbitrary four power plants in Libya, e.g. North Benghazi, South Tripoli, Zweitina, Khoms. The first four stations are gas power plants, while the last one is gas and steam station. Gaussian plume model has been used to identify ground-level NOx concentrations profile downwind and crosswind of the chimneys through urban regions and also the location of maximum pollutant concentrations. The study is based on the worstcase emission conditions of Pasquill stability categories (class D). Results indicate that maximum ground-level NOx, impacts for all plants locate at a distance of approximately 1.0–2.5 km from stacks. The site most critical to ambient air NOx impact is Zweitina, where the plant site is in direct vicinity to residential areas. Khoms electric station exhibits the maximum emitted NOx, SO2, and PM intensity, about 305, 48, and 0.7 mg/m3, respectively, that is lower than allowable concentrations recommended by World Health Organization.

07/02509 Isolation and characterization of biosurfactant/ bioemulsifier-producing bacteria from petroleum contaminated sites Batista, S. B. et al. Bioresource Technology, 2006, 97, (6), 868–875. Biosurfactant-producing bacteria were isolated from terrestrial and marine samples collected in areas contaminated with crude oil or its byproducts. Isolates were screened for biosurfactant/bioemulsifier production in different carbon sources (glucose, fructose, sucrose and kerosene) using the qualitative drop-collapse test. Glucose produced the highest number of positive results (17 of 185 isolates). All 17 isolates produced emulsions with kerosene and 12 exhibited high emulsion-stabilizing capacity, maintaining 50% of the original emulsion volume for 48 h. Eight of the 17 isolates reduced the growth medium surface tension below 40 mN m1 with five exhibiting this capacity in cell-free filtrates. Onset of biosurfactant production differed among the isolates, with some initiating synthesis during the exponential growth phase and others after the stationary phase was reached. Increasing temperature from 25 to 35  C accelerated onset of biosurfactant production in only two isolates while pH (6.5–7.6) had no effect in any isolate tested. Isolation from petroleum contaminated sites using the screening protocol presented proved to be a rapid and effective manner to identify bacterial isolates with potential industrial applications.

07/02510 Polycyclic aromatic hydrocarbons and polychlorinated biphenyls in urban soils from Kathmandu, Nepal Aichner, B. et al. Organic Geochemistry, 2007, 38, (4), 700–715. Kathmandu, the capital of Nepal, faces increasing environmental problems such as heavy air pollution and lack of proper waste management. The aim of this study was to examine if the soils are also affected by pollution, with the focus on polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs). The sum of 20 PAHs in surface soils ranged between 184 and 10279 mg kg1. The most abundant PAHs were perylene (14.6%), benzo(b+j+k)fluoranthene (10.7%), naphthalene (10.7%) and phenanthrene (9.8%), with perylene concentrations varying strongly. The significantly more positive 13C values of perylene in samples with elevated concentrations indicate biological production, possibly by anaerobic degradation of perylene quinones. PAH ratios also indicate the influence of petrogenic PAH sources, especially at petrol stations and some street samples. The sum of 12 PCBs ranged from 356 to 44,710 ng kg1. The most abundant were congeners 52 (19.4%), 101 (14.3%), 118 (13.4%) and 138 (11.7%). The low PCB concentrations and pattern were interpreted as a diffuse background contamination being the main PCB source in the urban soils. Indications for recent contamination were found in river sediments from the inner city, as well as in industrial and street samples. Classified by land use, the samples taken from the gutter contained the highest PAH and PCB concentrations as a result of accumulation. The lowest values were found in surface soils from Swayambunath (a park) and a garden area. A gradual decrease in concentration with depth was present for both compound classes in the profiles sampled at Swayambunath. No trend was visible in the garden profiles as a result of soil disturbance of the soil by agricultural treatment. Enhanced microbial degradation and volatilization in the warm/humid monsoon climate is probably the main cause for low pollutant concentrations. Increased photodegradation and the short accumulation period might be other important factors. Concerning its state of soil pollution, Kathmandu fits rather well into a global distribution pattern of persistent organic pollutants, with high concentrations in temperate (higher latitude) regions and very low ones in the tropics (lower latitude regions) due to global distillation.

07/02511 Small-scale forest carbon projects: adapting CDM to low-income communities Boyd, E. et al. Global Environmental Change, 2007, 17, (2), 250–259.

Given the decision to include small-scale sinks projects implemented by low-income communities in the clean development mechanism of the Kyoto Protocol, the paper explores some of the basic governance conditions that such carbon forestry projects will have to meet if they are to be successfully put in practice. To date there are no validated small-scale sinks projects and investors have shown little interest in financing such projects, possibly to due to the risks and uncertainties associated with sinks projects. Some suggest however, that carbon has the potential to become a serious commodity on the world market, thus governance over ownership, rights and responsibilities merit discussion. Drawing on the interdisciplinary development, as well as from the literature on livelihoods and democratic decentralization in forestry, the paper explores how to adapt forest carbon projects to the realities encountered in the local context. It also highlights the importance of capitalizing on synergies with other rural development strategies, ensuring stakeholder participation by working with accountable, representative local organizations, and creating flexible and adaptive project designs.

07/02512 The simulator experimental study on the operator reliability of Qinshan nuclear power plant Zhang, L. et al. Reliability Engineering & System Safety, 2007, 92, (2), 252–259. The scarcity of human failure data is a major problem that embarrasses human reliability analysts for a long time. In the human reliability analysis of Qinshan nuclear power plant, a full-size simulator was used to conduct an experiment on the operator’s reliability. The experiment involves 23 abnormal events and 55 human interactions covering three cognitive types: skill-based, rule-based and knowledge-based. The response time and conditions of 38 operators were recorded and the data were analysed and processed to develop human cognitive reliability model parameters, which match with the features of Qinshan nuclear power plant system and its staff. This paper introduces the background, theory, methods, process, conclusion of the experiment and their comparison with data obtained abroad.

CO2, NOx, SO2 and particulate emissions 07/02513 A model to estimate fossil CO2 emissions during the harvesting of forest residues for energy – with an application on the case of chipping Van Belle, J.-F. Biomass and Bioenergy, 2006, 30, (12), 1067–1075. In order to fulfil the targets set by the Kyoto protocol, Belgium established a series of regulations for renewable electricity and put in place a virtual market of green certificates. Their attribution is correlated to the reduction of fossil CO2 emissions. For biomass, emissions occurring during harvest have a significant impact. This paper proposes a model to estimate CO2 emissions during this step and applies it to the chipping of poplar forest residues in Southern Belgium. The factors entering into the CO2 ratio per MWh of biofuel are modelled according to the most influential characteristic of forest residues, i.e. mean initial diameter. The results show that if the diameter of the chipped material increased from 4 to 16 cm (factor 4), the CO2 emissions per MWh decreased by a factor 7. This stresses the value of modelling the emissions in order to identify the most critical supply routes for attribution and valuation of the green certificates.

07/02514 Computation of maximum rate of water–sulphuric acid nucleation in diesel exhaust Lemmetty, M. et al. Journal of Aerosol Science, 2006, 37, (11), 1596– 1604. The origin of nucleation mode observed in the diesel engine exhaust is unclear. In this work, the mechanism of simple classical homogeneous water–sulfuric acid nucleation was studied using the parameterization of Vehkama¨ki, Kulmala, Lehtinen, and Noppel. In the simple model used, condensation and coagulation were taken into account as sink terms in respective equations. The focus of the study was on the total amount of stable clusters formed, which provides an upper limit for nucleation mode number concentration. It was seen that the nucleation can be achieved even with relatively low sulfuric acid concentrations (of the order of 5  1017 m3). However, the efficiency depends strongly on the cooling and dilution experienced by the exhaust. According to the results obtained, the assumption of homogeneous sulfuric acid–water nucleation depicted by Vehkama¨ki parameterization gives physically meaningful results with low-sulfur content fuels if the sulfur-to-sulfuric acid conversion factor is close to 100%. Nonetheless, there are published results of nucleation mode in diesel exhaust which cannot be explained by the sulfuric acid–water mechanism.

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15 Environment (CO2, NOx, SO2 and particulate emissions) 07/02515 CO2 benefit from the increasing percentage of diesel passenger cars in Sweden Zervas, E. and Lazarou, C. International Journal of Energy Research, 2007, 31, (2), 192–203. Control of carbon dioxide emissions is a major environmental issue in most countries. The Swedish car market shows remarkably low new diesel passenger car registrations compared to the average European Union car market. Therefore, a simple way to decrease carbon dioxide emissions from the transport sector in Sweden would be the replacement of gasoline by diesel passenger cars, which emit less carbon dioxide. The combined effects of probable changes in diesel and gasoline future fuel consumption, new passenger car sales and market segmentation have been evaluated for different diesel passenger cars penetrations. The results show a benefit in carbon dioxide emissions of about 2.8% with 30% diesel penetration; if diesel penetration reaches 50%, the benefit attains 7.5%. Future rises of carbon dioxide emissions caused by higher new passenger car registrations or unfavourable market segmentation could be at least partially counterbalanced by the introduction of more diesel passenger cars.

07/02516 Design of sensor networks for long term monitoring of geological sequestration Saripalli, P. et al. Energy Conversion and Management, 2006, 47, (13– 14), 1968–1974. Analysis of geologic sequestration on a wide scale with the aid of integrated assessment models showed earlier that overall leakage rates from the storage sites must be less than 0.1% of stored volume per year if the strategy is to be effective for long term control of atmospheric CO2 concentrations. Early detection and characterization of a nascent leak significantly increases the probability that a timely solution can be found. Because potential leakage pathways are not necessarily known a priori, monitoring must be done across a region as large as 100 km2 in the vicinity of a CO2 injection well, which represents the area of review of the supercritical CO2 bubble under typical injection scenarios. The relatively high background levels of CO2 present in the atmosphere and soil, coupled with their seasonal and diurnal modulation, make immediate detection of a small CO2 leak difficult. Co-injection of tracers during sequestration eliminates the ambiguity and delay in positive identification of a leak. The authors report here on the design of sensor networks, as a part of the development of a prototypical, field deployable sensor/tracer technology for monitoring the rate of leakage of geologically sequestered CO2. The primary focus is on conservative tracer technology for immediate leak detection. In so doing, the authors are laying a foundation from which reactive tracer technology for pathway characterization can be developed. A semi-analytical model developed earlier for modelling the injection, fate and transport of sequestered CO2 was adapted for sensor network design. The design simulations are developed to answer several key questions about the sensor network layout. Simulation results indicate that the key parameters governing the monitoring network design are the sensor node spacing (S), sampling density D (no. of sensors/km2), minimum detection limit of sensor (L), injected tracer concentration (Co) and dispersed tracer concentration (Ct) in the environment. Environmental dispersal modelling shows that Ct is a strong function of environmental conditions such as wind velocity. Analysis of the trade-offs indicates that a low detection limit allows effective monitoring with a minimal sensor sampling density and low tracer Co.

07/02517 Estimating GHG emission mitigation supply curves of large-scale biomass use on a country level Dornburg, V. et al. Biomass and Bioenergy, 2007, 31, (1), 46–65. This study evaluates the possible influences of a large-scale introduction of biomass material and energy systems and their market volumes on land, material and energy market prices and their feedback to greenhouse gas (GHG) emission mitigation costs. GHG emission mitigation supply curves for large-scale biomass use were compiled using a methodology that combines a bottom-up analysis of biomass applications, biomass cost supply curves and market prices of land, biomaterials and bioenergy carriers. These market prices depend on the scale of biomass use and the market volume of materials and energy carriers and were estimated using own-price elasticities of demand. The methodology was demonstrated for a case study of Poland in the year 2015 applying different scenarios on economic development and trade in Europe. For the key technologies considered, i.e. medium density fibreboard, poly lactic acid, electricity and methanol production, GHG emission mitigation costs increase strongly with the scale of biomass production. Large-scale introduction of biomass use decreases the GHG emission reduction potential at costs below 50 e/Mg CO2eq with about 13–70% depending on the scenario. Biomaterial production accounts for only a small part of this GHG emission reduction potential due to relatively small material markets and the subsequent strong decrease of biomaterial market prices at large scale of production. GHG emission mitigation costs depend strongly on biomass supply curves, own-price elasticity of land and

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market volumes of bioenergy carriers. The analysis shows that these influences should be taken into account for developing biomass implementations strategies.

07/02518 Greenhouse gases embodied in the international trade and final consumption of Finland: an input–output analysis Ma¨enpa¨a¨, I. and Siikavirta, H. Energy Policy, 2007, 35, (1), 128–143. The estimation of greenhouse gas (GHG) emissions associated with international trade and final consumption gives a more complete and balanced picture of the responsibilities of various countries for the emissions that cause the climate change. The aim of this study was to look at the impact of the coverage of the GHGs and their sources and assumptions regarding the emissions of imports on the results of GHG emissions associated with international trade and final consumption of Finland. In addition to a single year study, a trend covering years 1990– 2003 was produced for Finland to study the development of the GHG emissions associated with domestic consumption and the reasons behind the development. According to the results, Finland was in 1999 a net exporter of CO2 from fossil fuel combustion, CO2 from all sources and GHGs of 4(4.2), 5 or 7 Gkg, respectively. The impact of different assumptions concerning the emissions embodied in imports in the case of Finland was tested by using the domestic emission intensities and the ratios of embodied emissions in imports in relation to domestic products by utilizing the data from recent studies. In the case of Finland, the differences of results calculated with these two methods remained rather small. The total emissions embodied in the imports changed from 33.8 to 34.4 Gkg and consequently the net export of CO2 from fossil fuel combustion changed from 4.2 to 3.6 Gkg. The results for 1990–2003 show that the GHG emissions embodied in the exports have exceeded the GHG emissions embodied in the imports from early 1990s. The reason for the increasingly positive GHG trade balance in the case of Finland has been the change in the magnitude of trade rather than the changes in its structure. The results show also that the impact of international transport on the emission intensity of imports is significant and merits further research.

07/02519

LiCoO2 catalyst for diesel particulate abatement

Fino, D. et al. Catalysis Today, 2007, 119, (1–4), 257–261. This paper concerns the development of a LiCoO2 catalyst which shows appreciable activity towards the catalytic combustion of soot already at 300  C. An in situ combustion synthesis method was then tailored to the preparation of a LiCoO2-catalysed trap based on a silicon carbide wallflow monolith. Engine bench tests on this catalytic trap (trap loading with soot and then its regeneration induced by a temperature rise entailed by catalytic combustion of post-injected fuel) showed that the presence of the catalyst in the wall-flow trap enables both a more complete regeneration (78% opposed to just 52% of the non-catalytic trap) and a reduction of the regeneration time, with consequent saving of post-injected fuel.

07/02520 Multi-gas emission envelopes to meet greenhouse gas concentration targets: costs versus certainty of limiting temperature increase den Elzen, M. et al. Global Environmental Change, 2007, 17, (2), 260– 280. This paper presents a set of technically feasible multi-gas emission pathways (envelopes) for stabilising greenhouse gas concentration at 450, 550 and 650 ppm CO2-equivalent and their trade-offs between direct abatement costs and probabilities to meet temperature targets. There are different pathways within the envelope. Delayed response pathways initially follow the upper boundary of the emission envelope and reduce more by the end of the century. In contrast, early action pathways first follow the lower boundary and then the upper boundary. The latter require an early peak in the global emissions but keeps the option open for shifting to lower concentration targets in the future. Costs evaluations depend on the discount rate. Early action profiles have high costs early on, but learning-by-doing and smoother reduction rates over time lead to in most cases to lower costs across the century [net present value (NPV)]. To achieve the 450 ppm CO 2-equivalent, the global emissions need to peak before 2020. The NPV of costs increase from 0.2% of cumulative gross domestic product to 1.0% as the shift is made from 650 to 450 ppm (discount rate 5%). However, the chances of limiting global mean warming to 2  C above pre-industrial levels are very small for peaking and stabilization at 650 ppm (1–23%) and 550 ppm (1–48%), but increase for a peaking at 510 ppm with subsequent stabilization 450 ppm to 14–67%.

07/02521 Noble-free potassium-bimetallic catalysts supported on beta-zeolite for the simultaneous removal of NOx and soot from simulated diesel exhaust Nejar, N. et al. Catalysis Today, 2007, 119, (1–4), 262–266. This paper deals with the activity of the KCu and KCo catalysts supported on beta-zeolite for the simultaneous NOx/soot removal from a simulated diesel exhaust, containing C3H6 as model hydrocarbon. In

15 Environment (hydrocarbon emissions) order to reveal the effect of potassium, the corresponding monometallic catalysts (Co/beta and Cu/beta) were analysed and different potassium loadings were used. In addition, for comparative purpose, the performance of a platinum based catalyst (Pt/beta) was studied. All noble-free catalysts show, at 450  C, a high activity for the simultaneous NOx/soot removal. Among them, K1Cu/beta presents the best global performance at 350 and 450  C achieving a high soot consumption rate (comparable to platinum catalysts) and the highest NO x reduction. In contrast to platinum catalysts, K1Cu/beta has the advantage that the main reaction products are N2 and CO2.

07/02522 NOx reduction from compression ignition engines with DC corona discharge – an experimental study Vinogradov, J. et al. Energy, 2007, 32, (2), 174–186. An experimental study of DC corona discharge technology for NOx reduction from diesel engine exhaust is presented. The DC corona reactor consists of a flat electrode against a multi-needle electrode. The results are presented in terms of the cleanness (mass of NOx removed relative to its initial mass), and the efficiency (the energy required to theoretically dissociate 1 g of NOx, relative to the energy actually needed). For both cleanness and efficiency, negative polarity (negative needles) is preferable. Cleanness was found to be independent of the engine load. The results show that the performance of a DC corona reactor depends on the reactor length L, electrode separation distance D, and needle density a. The cleanness and efficiency of the NOx decomposition were mapped, and optimal geometrical parameters for the best reactor performance have been obtained. It is concluded that for best performance, the residence time of the exhaust gas inside the reactor should be longer than 1 second ( >1 s); the electrode separation distance D must be less than 30 mm (for the electric field intensity to remain sufficiently high for dissociation reactions); and the needle separation distance a must not exceed 20 mm (to provide sufficiently dense distribution of plasma regions from each needle). The cleanness and efficiency values for the optimal geometry lay between 55% (cleanness) with 10% (efficiency), and 50% (cleanness) with 18% (efficiency), for needle separation distances a of 10 and 20 mm, respectively.

07/02523 On-road evaluation of two Diesel exhaust aftertreatment devices Kittelson, D. B. et al. Journal of Aerosol Science, 2006, 37, (9), 1140– 1151. Two diesel particulate matter emission control devices; the continuously regenerating trap (CRTTM) and the catalysed continuously regenerating trap (CCRTTM) were evaluated using a mobile emissions laboratory. The source of emissions was the lab’s engine that was fueled with 15 ppm sulfur fuel, and specially formulated, low sulfur (1300 ppm) lubrication oil. The objective was to characterize performance using real-time aerosol instrumentation, real-world dilution, and on-road driving conditions. The devices when combined with low S fuel and lube oil effectively removed diesel particulate matter. The CRT produced large quantities of nuclei mode particles, the quantity of which increased as a function of exhaust temperature. The CCRT reduced the exhaust particle number concentration to levels not detectable above background storage sites, thus eliminating precursors that form nuclei mode particles. Use of low S fuel and lubrication oil prolongs the storage process. Over time it is expected that this material would be released.

07/02524 Preparation of carbon dioxide adsorbents from the chemical activation of urea–formaldehyde and melamine–formaldehyde resins Drage, T. C. et al. Fuel, 2007, 86, (1–2), 22–31. Adsorption is considered to be one of the more promising technologies for the capture of CO2 from flue gases. In general, nitrogen enrichment is reported to be effective in enhancing the specific adsorbent– adsorbate interaction for CO2. Nitrogen enriched carbons were produced from urea–formaldehyde and melamine–formaldehyde resins polymerized in the presence of K2CO3 as a chemical activation agent, with activation undertaken over a range of temperatures. CO2 adsorption capacity was determined to be dependent upon both textural properties and more importantly nitrogen functionality. Adsorbents capable of capturing above 8 wt.% CO2 at 25  C were produced from the chemical activation of urea–formaldehyde resin at 500  C. Chemical activation seems to produce more effective adsorbents than CO2 activation.

07/02525 Study of water–oil emulsion combustion in large pilot power plants for fine particle matter emission reduction Allouis, C. et al. Experimental Thermal and Fluid Science, 2007, 31, (5), 421–426. The combustion of heavy fuel oil for power generation is a great source of carbonaceous and inorganic particle emissions, even though the combustion technologies and their efficiency are improving. The information about the size distribution function of the particles

originated by trace metals present into the fuels is not adequate. In this paper, attention was focused on the influence of emulsion oil-water on the larger distribution mode of both the carbonaceous and metallic particles. Isokinetic sampling was performed at the exhausts of flames of a low-sulfur content heavy oil and its emulsion with water produced in two large pilot plants. The samples were size-segregated by mean of an eight-stage Andersen impactor. Further investigation performed on the samples using electronic microscopy coupled with X-ray analysis (EDX) evidenced the presence of solid spherical particles, plerosphere, with typical dimensions ranging between 200 nm and 2–3 mm, whose atomic composition contains a large amount of the trace metals present in the parent oils (Fe, V, Ni, etc.). EDX analyses revealed that the metal concentration increases as the plerosphere dimension decreases. It was also observed that the use of emulsion slightly reduce the emission of fine particles (D50 < 8 mm) in the large scale plant.

07/02526 stove

The emissions from a space-heating biomass

Koyuncu, T. and Pinar, Y. Biomass and Bioenergy, 2007, 31, (1), 73–79. In this paper, the flue gas emissions of carbon monoxide, nitrogen oxides, sulfur dioxide and soot from an improved space-heating biomass stove and thermal efficiency of the stove have been investigated. Various biomass fuels such as firewood, wood shavings, hazelnut shell, walnut shell, peanut shell, seed shell of apricot (sweet and hot seed type), kernel removed corncob, wheat stalk litter (for cattle and sheep pen), cornhusk and maize stalk litter (for cattle pen) and charcoal were burned in the same space-heating biomass stove. Flue gas emissions were recorded during the combustion period at intervals of 5 min. It was seen from the results that the flue gas emissions have different values depending on the characteristics of biomass fuels. Charcoal is the most appropriate biomass fuel for use in the space-heating biomass stoves because its combustion emits less smoke and the thermal efficiency of the stove is approximately 46%.

07/02527 Titania-supported iron oxide as oxygen carrier for chemical-looping combustion of methane Corbella, B. M. and Palacios, J. M. Fuel, 2007, 86, (1–2), 113–122. Chemical-looping combustion is a two-stage process proposed as an alternative for the combustion of carbonaceous materials, such as natural gas or coal gas, for almost complete CO2 capture. In the reduction stage, the structural oxygen contained in the lattice of a reducible inorganic oxide, is used for combustion of the carbonaceous material. In the regeneration stage the oxygen carrier, found in a reduced state after the reduction stage, is regenerated with pure air to recover the physical and chemical properties of the carrier, ready to reinitiate a new cycle reduction-regeneration. In a typical multicycle reactor test, the carriers are subjected to accumulative chemical and thermal stresses and the performance will, probably, decay progressively with the number of cycles. The occurrence of some side reactions may limit the efficiency of the overall process in CO2 capture. In this paper, titania-supported iron oxides with different iron loadings have been tested in multicycle tests in a fixed-bed reactor at 900  C and atmospheric pressure, as oxygen carriers for the chemical-looping combustion of methane. The study shows that the available oxygen for methane combustion in the reduction stage is lower than expected since the active phase interacts with the support forming FeTiO3 ilmenite. The reactivity of these iron based carriers in the reduction stage is independent on the iron oxide content but lower than that exhibited by other tested carriers, such as CuO or NiO. However, iron carriers are cheaper no showing any tendency to carbon deposition.

Hydrocarbon emissions 07/02528 Emission of volatile organic compounds from composting of different solid wastes: abatement by biofiltration Pagans, E. et al. Journal of Hazardous Materials, 2006, 131, (1–3), 179– 186. Emission of volatile organic compounds (VOCs) produced during composting of different organic wastes [source-selected organic fraction of municipal solid wastes (OFMSW), raw sludge (RS) and anaerobically digested wastewater sludge (ADS) and animal byproducts (AP)] and its subsequent biofiltration have been studied. Composting was performed in a laboratory scale composting plant (30 l) and the exhaust gases generated were treated by means of a compost biofilter. VOCs concentration in the composting exhaust gases for each composting process ranged from 50 to 695 mg C m3 for OFMSW (5:1), from 13 to 190 mg C m3 for OFMSW (1:1), from 200 to 965 mg C m3 for RS, from 43 to 2900 mg C m3 for ADS and from 50 to 465 mg C m3 for AP. VOCs emissions were higher during the beginning of the composting process and were not generally related to

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15 Environment (life cycle analysis) the biological activity of the process. These emissions corresponded to an average loading rate applied to the biofilter from 2.56 to 29.7 g C m3 biofilter h1. VOCs concentration in the exhaust gas from the biofilter ranged from 55 to 295 mg C m3 for OFMSW (5:1), from 12 to 145 mg C m3 for OFMSW (1:1), from 55 to 270 mg C m3 for RS, from 42 to 855 mg C m3 for ADS and from 55 to 315 mg C m 3 for AP. Removal efficiencies up to 97% were achieved although they were highly dependent of the composted waste. An important observation was that the compost biofilter emitted VOCs with an estimated concentration of 50 mg C m3.

07/02529 Flue gas cleaning in power stations by using electron beam technology. Influence on PAH emissions Calle´n, M. S. et al. Fuel Processing Technology, 2007, 88, (3), 251–258. The electron beam technology (EBT), proven treatment for SO2 and NOx removal, is applied to different power stations as hot gas cleaning system. In this paper, an assessment of this technique installed in a Bulgarian power station on organic emissions is analysed. The polycyclic aromatic hydrocarbons (PAH) content, not only emitted in the gas phase but also trapped in the solid phase, has been carried out before and after the irradiation. The main aim has been to know whether the EBT affects organic emissions, like PAH, as it happens with inorganic pollutants, like SO2 and NOx, studying EBT effects from an organic environmental point of view. The PAH quantification was performed by using a very sensitive analytical technique, gas chromatography with mass spectrometry mass spectrometry detection (GC–MS–MS). Results showed that PAH are influenced by the EBT showing a reduction of the most volatile PAH in the gas phase. PAH concentrations in the fertilizers obtained after irradiation were found to be similar to those in the fly ashes produced when no irradiation is applied. These fertilizers were considered like unpolluted soils being adequate for agriculture applications with PAH concentrations below the target value set up by the Dutch government.

07/02530 Hot gas cleaning in power stations by using electron beam technology. Influence on PAH emissions Calle´n, M. S. et al. Fuel Processing Technology, 2007, 88, (3), 273–280. The electron beam technology (EBT), proven treatment for SO2 and NOx removal, is applied to different power stations as a hot gas cleaning system. In this paper, an assessment of this technique installed in a Bulgarian power station on organic emissions is analysed. The polycyclic aromatic hydrocarbons (PAH) content, not only emitted in the gas phase but also trapped in the solid phase, has been carried out before and after the irradiation. The main aim has been to know whether the EBT affects organic emissions, like PAH, as it happens with inorganic pollutants, like SO2 and NOx, studying EBT effects from an organic environmental point of view. The PAH quantification was performed by using a very sensitive analytical technique, gas chromatography with mass spectrometry mass spectrometry detection. Results showed that PAH are influenced by the EBT showing a reduction of the most volatile PAH in the gas phase. With regard to the solid by-products obtained after the irradiation, fertilizers, similar PAH concentration to the fly ashes produced when no irradiation is applied were found. These fertilizers were considered like unpolluted soils being adequate for agriculture applications with PAH concentrations below the target value set up by the Dutch government.

07/02531 Influence of fuel oxygen content on diesel engine exhaust emissions Sendzikiene, E. et al. Renewable Energy, 2006, 31, (15), 2505–2512. The aim of this work was to investigate: the intersolubility of mixtures of rapeseed oil methyl esters, diesel fuel and ethanol; to determine the dependence of solubility upon temperature; and finally to evaluate emissions of exhaust gases of these stable fuel mixtures. Bearing in mind that the cloud point is an important parameter of diesel fuel, the variation of solubility of a tri-component rapeseed oil methyl ester– diesel fuel–ethanol (RME–D–E) system at temperature (20; 0; 10  C) was also investigated. It was found that temperature decrease causes the RME–D–E system solubility limits to become narrow. Solubility investigations allowed the determination of the optimal solubility limits and select mixtures containing 6.9–25.7% of oxygen for engine tests. The highest oxygen content in biodiesel fuel that allowed the engine to work normally at 2000 and 1200 min1 was 19.5%. The lowest concentration of polycyclic aromatic hydrocarbons (PAH) and smoke index of exhaust gases were determined when fuel mixtures contained 19.5% of oxygen. The carbon monoxide concentration depended on the rotational speed and varied from 10.7% to 16.8%. Apparently, optimal diesel fuel on this basis will contain from 15% to 19% of oxygen.

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Life cycle analysis 07/02532 Environmental advantages of superconducting devices in distributed electricity-generation Hartikainen, T. et al. Applied Energy, 2007, 84, (1), 29–38. Distributed generation (DG) is emerging as an alternative to a centralized electricity-generation system. The goals of DG include the minimization of the environmental impacts of energy production and introduction of new renewable energy-sources to the distribution network. Superconducting devices are also proposed for DG because of their high efficiencies as well as smaller size and more stable operation during peak loads. This study concentrates on the environmental benefits of superconducting machinery by comparing suitable devices with their competitors in DG-networks. Exploitable superconducting devices in DG include superconducting magnetic energy-storage (SMES), flywheels and cable systems. Life-cycle assessment (LCA) is used as a tool in comparisons of energy-storage devices suitable for DG: SMES, flywheels and batteries. In LCA, all material inputs, energy consumptions, wastes, and emissions are assessed over the life-cycle of the product. Finally, a commercialization schedule for HTS-cables is presented and an unconventional concept for a DG-network is suggested for further examination.

07/02533 Greece

Environmental assessment of brick production in

Koroneos, C. and Dompros, A. Building and Environment, 2007, 42, (5), 2114–2123. Brick constitutes one of the major materials used for the construction of buildings. The present study analyses the different stages followed during brick production and the materials and energy used in each stage. The purpose is to identify ‘hot-spots’, i.e. parts of the life cycle that are important to the total environmental impact. The analysis is performed using life cycle assessment (LCA) methodology, which is a method used to identify and quantify the environmental performance of a process or a product from ‘cradle to grave’. LCA methodology provides a quantitative basis for assessing potential improvements in environmental performance of a system throughout the life cycle. The system investigated includes raw material acquisition, industrial production, packaging and transportation. Energy use and emissions are quantified and the potential environmental effects are assessed. The main energy inputs to the production system are electricity, diesel and solid fuel (Pet-Coke). The environmental burdens that arise from the operation of a brick industry are mainly due to air emissions derived from fossil fuel utilization.

07/02534 Life cycle assessment: a case study of a dwelling home in Scotland Asif, M. et al. Building and Environment, 2007, 42, (3), 1391–1394. The article provides a life cycle assessment (LCA) of a three-bedroom semi-detached house in Scotland. Detailed LCA of five main construction materials, i.e. wood, aluminium, glass, concrete and ceramic tiles have been provided to determine their respective embodied energy and associated environmental impacts. Embodied energy of various construction materials involved has been estimated to be equal to 227.4 GJ. It is found that concrete, timber and ceramic tiles are the three major energy expensive materials involved. It as been calculated that concrete alone consumes 65% of the total embodied energy of the home while its share of environmental impacts is even more crucial.

07/02535 Life cycle cost analysis of a car, a city bus and an intercity bus powertrain for year 2005 and 2020 Hellgren, J. et al. Energy Policy, 2007, 35, (1), 39–49. The international economy, in the beginning of the 20th century, is characterized by uncertainty about the supply and the price of oil. Together with the fast decrease of electrical propulsion component prices, it becomes more and more cost effective to develop vehicles with alternative powertrains. This paper focuses on two questions: (a) are alternative powertrains especially cost effective for specific applications? And (b) how does an increased fossil fuel price influences the choose of powertrain? To assess these questions, a computer tool named THEPS is used. Three applications and three scenarios are analysed. The applications, a car, a city bus and an intercity bus, are vehicles all assumed to operate in Sweden. One scenario represents year 2005, the other two year 2020. The two future scenarios are characterized by different fossil fuel prices. The study, presented in the paper, indicates that alternative powertrains can be competitive from a cost perspective, in some applications, already in year 2005. It is for example cost effective to equip a city bus, running in countries with a high fuel price, with a hybrid powertrain. The study also indicates that pure electric, hybrid and/or fuel cell cars will probably be a more cost effective choice than conventional cars in year 2020. Another

16 Energy (supplies, policy, economics, forecasts) indication is that it will not be clear which powertrain concept to choose. The reason is that many cost effective powertrain concepts will be offered. The best choice will depend on the application.

07/02536 Life cycle energy and environmental analysis of a microgrid power pavilion Spitzley, D. V. et al. International Journal of Energy Research, 2007, 31, (1), 1–13. Microgrids – generating systems incorporating multiple distributed generator sets linked together to provide local electricity and heat – are one possible alterative to the existing centralized energy system. Potential advantages of microgrids include flexibility in fuel supply options, the ability to limit emissions of greenhouse gases, and energy efficiency improvements through combined heat and power applications. As a case study in microgrid performance, this analysis uses a life cycle assessment approach to evaluate the energy and emissions performance of the Next Energy microgrid Power Pavilion in Detroit, Michigan and a reference conventional system. The microgrid includes generator sets fueled by solar energy, hydrogen, and natural gas. Hydrogen fuel is sourced from both a natural gas steam reforming operation and as a by-product of a chlorine production operation. The chlorine plant receives electricity exclusively from a hydropower generating station. Results indicate that the use of this microgrid offers a total energy reduction potential of up to 38%, while reductions in non-renewable energy use could reach 51%. Similarly, emissions of CO2, a key global warming gas, can be reduced by as much as 60% relative to conventional heat and power systems. Hydrogen fuels are shown to provide a net energy and emissions benefit relative to natural gas only when sourced primarily from the chlorine plant.

16 ENERGY Supplies, policy, economics, forecasts 07/02537 A conceptual framework for exploring transitions to decarbonised energy systems in the United Kingdom Shackley, S. and Green, K. Energy, 2007, 32, (3), 221–236. Drawing upon ‘transitions theory’ and a typology which produces five types of transitions, the changes that have taken place in the United Kingdom’s energy system over the past several decades are described and analysed in terms of three of these transition pathways, namely reproduction (e.g. incremental improvements in energy efficiency), transformation (e.g. more directed efforts towards energy efficiency gains, e.g. through voluntary and compulsory standards-setting processes) and substitution (e.g. the shift from coal to natural gas). Looking into the future, and drawing upon a programme of UK-based research which covered a wide range of potential new supply technologies and changes on the demand side, the key drivers of change are identified, including economic and commercial, technological, policy and regulatory imperatives. This analysis opens up the prospect for two further transition pathways to become manifest. These are: de-alignment/re-alignment (e.g. shift from conventional coal to coal technologies with carbon dioxide capture and storage) and reconfiguration (e.g. integrating renewables within buildings and the possible emergence of the ‘hydrogen economy’). The authors conclude with a discussion of the opportunities for policy learning and experimentation consistent with transitions theory to facilitate the deployment of more sustainable energy systems.

07/02538 A new analytic method for finding policy-relevant scenarios Groves, D. G. and Lempert, R. J. Global Environmental Change, 2007, 17, (1), 73–85. Scenarios play a prominent role in policy debates over climate change, but questions continue about how best to use them. We describe a new analytic method, based on robust decision making, for suggesting narrative scenarios that emerge naturally from a decision analytic framework. We identify key scenarios as those most important to the choices facing decision makers and find such cases with statistical analysis of datasets created by multiple runs of computer simulation models. The resulting scenarios can communicate quantitative judgments about uncertainty as well as support a well-defined decision process without many drawbacks of current approaches. We describe an application to long-term water planning in California.

07/02539 A reform strategy of the energy sector of the 12 countries of North Africa and the Eastern Mediterranean Patlitzianas, K. D. et al. Energy Conversion and Management, 2006, 47, (13–14), 1913–1926. The development of an energy reform strategy based on the market economy so as to introduce competition in the market segments is of crucial importance for provision of a stable and favourable environment for energy investments. Reform strategies have begun developing in most of the 12 Mediterranean countries of North Africa and the Eastern Mediterranean, especially in the context of the EuroMediterranean Free Trade Area. Even though energy sector reforms have been initiated, they are still at an early stage in most of these countries. The majority of energy utilities remain state owned, vertically integrated monopolies. Few of these countries have established energy regulators, and where they have, these institutions have many difficulties in effective development. In addition, competition is virtually absent from the sector, and private participation has been confined to independent power plants, which tend to be introduced into unreformed sectors. The aim of this paper is to propose energy reform strategies for the reform of the sector by 2010 in terms of the development of the regional oil, gas and electricity sectors in these countries.

07/02540 Allocation of emission permits with leakage through capital markets Mæstad, O. Resource and Energy Economics, 2007, 29, (1), 40–57. This paper analyses how tradable emission permits should be allocated to firms when capital is internationally mobile. When international environmental problems are attempted solved through uncoordinated policies between countries, it might be desirable for the home country to issue free emission permits in proportion to the use of capital in order to prevent leakage through international capital movements. The desirability of free emission permits will however be reduced if capital also can be employed in a domestic non-polluting sector. In this case, it may even be optimal to tax the use of capital in the polluting sector. It is also shown that it is always optimal to subsidize the use of capital in the polluting sector if the use of labour is taxed at an optimal rate. Finally, leakage does not affect the optimal domestic emission limit as long as appropriate capital subsidies and labour taxes are implemented.

07/02541 Decomposition for emission baseline setting in China’s electricity sector Steenhof, P. A. Energy Policy, 2007, 35, (1), 280–294. Decomposition analysis is used to generate carbon dioxide emission baselines in China’s electricity sector to the year 2020. This is undertaken from the vantage point of the final consumer of electricity, and therefore considers factors influencing electricity demand, efficiency of generation, sources of energy used for generation purposes, and the effectiveness of transmission and distribution. It is found that since 1980, gains in efficiency of generation have been the most important factor affecting change in the emission intensity of electricity generated. Based upon known energy and economic policy, efficiency gains will continue to contribute to reductions in the emission intensity of electricity generated, however, fuel shifts to natural gas and increases in nuclear generation will further these trends into the future. The analysis confirms other sources in the literature that decomposition is an appropriate technique available for baseline construction, thereby suitable for the emerging carbon market and its related mechanisms.

07/02542 Downscaling drivers of global environmental change: enabling use of global SRES scenarios at the national and grid levels van Vuuren, D. P. et al. Global Environmental Change, 2007, 17, (1), 114–130. Global environmental change scenarios typically distinguish between about 10–20 global regions. However, various studies need scenario information at a higher level of spatial detail. This paper presents a set of algorithms that aim to fill this gap by providing downscaled scenario data for population, gross domestic product (GDP) and emissions at the national and grid levels. The proposed methodology is based on external-input-based downscaling for population, convergence-based downscaling for GDP and emissions, and linear algorithms to go to grid levels. The algorithms are applied to the IPCC-SRES scenarios, where the results seem to provide a credible basis for global environmental change assessments.

07/02543 Energy policies of Turkey during the period 1923–2003 Yilmaz, A. O. and Uslu, T. Energy Policy, 2007, 35, (1), 258–264. Turkey has been developing since the foundation of the Republic of Turkey in 1923. Turkish government played a leading role in energy production and in energy use, as well as in other fields, and implemented several policies to increase electricity production. By 1950s, thermal power plants were used commonly in electricity

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16 Energy (supplies, policy, economics, forecasts) production. In the following years, hydroelectric power plants were put into operation in order to use the considerable amount of water resources of the country. Coal-fired power plants using national resources accounted for 70–80% of the thermal electricity production. After 1960s, oil, an imported resource, was replaced with national resources due to two petroleum crises. Therefore, the proportion of use of lignite in the energy field increased. By 1980s, energy production lead by the government went on. Afterwards, applications of liberal economy policies resulted in implementation of different energy production methods, and the country had a increasing tendency to meet energy demand by imports as a result of improvement in international economic relations. Natural gas became prevalent in the country as well as all over the world and accounted for 45% of the electricity production in 2003. In this paper, implemented policies in the energy field during different periods since the foundation of the Republic of Turkey in 1923 was investigated.

07/02548

07/02549 07/02544 Energy taxes as a signaling device: an empirical analysis of consumer preferences Ghalwash, T. Energy Policy, 2007, 35, (1), 29–38. This paper presents an econometric study dealing with household demand in Sweden. The main objective is to empirically examine the differences in consumer reaction to the introduction of, or the change, in environmental taxes. Main focus is on environmental taxes as a signaling device. The hypothesis is that the introduction of an environmental tax provides new information about the properties of the directly taxed goods. This in turn may affect consumer preferences for these goods, hence altering the consumption choice. The result from the econometric analysis shows that all goods have negative ownprice elasticities, and positive income elasticities. Concerning the signalling effect of environmental taxes the results are somewhat ambiguous. The tax elasticity for energy goods used for heating seems to be significantly higher than the traditional price elasticity, whereas the opposite seems to be the case for energy goods used for transportation.

07/02545 Household energy consumption versus income and relative standard of living: a panel approach Joyeux, R. and Ripple, R. D. Energy Policy, 2007, 35, (1), 50–60. The fundamental premise is that energy consumption at the household level is a key indicator of standard of living. State-of-the-art panel cointegration techniques are employed to evaluate the nature of the relationship between income measures and energy consumption measures for seven East Indian Ocean countries. The general finding is that income and household electricity consumption are not cointegrated. Given this finding, it is concluded that standard of living measures that rely on income measures and do not include householdlevel energy consumption information will necessarily miss important indications of both levels and changes of standard of living.

07/02546 Increased energy efficiency and the rebound effect: effects on consumption and emissions Bra¨nnlund, R. et al. Energy Economics, 2007, 29, (1), 1–17. The main objective of this paper is to examine how exogenous technological progress, in terms of an increase in energy efficiency, affects consumption choice by Swedish households and thereby emissions of carbon dioxide (CO2), sulfur dioxide (SO2) and nitrogen oxide. The aim of the paper is closely related to the discussion of what is termed the ‘rebound effect’. To neutralize the rebound effect, it is estimated that the necessary change in CO2 tax, i.e. the CO2 tax that keeps CO2 emissions at their initial level. In addition, the authors estimate how this will affect emissions of sulfur dioxide and nitrogen oxides. The results indicate that an increase in energy efficiency of 20% will increase emissions of CO2 by approximately 5%. To reduce the CO2 emissions to their initial level, the CO2 tax must be raised by 130%. This tax increase will reduce the emissions of sulfur dioxide to below their initial level, but will leave the emissions of nitrogen oxides at a higher level than initially. Thus, if marginal damages from sulfur dioxide and nitrogen dioxide are non-constant, additional policy instruments are needed.

07/02547 Influencing user behaviour with energy information display systems for intelligent homes Wood, G. and Newborough, M. International Journal of Energy Research, 2007, 31, (1), 56–78. This paper considers the design of energy consumption displays from a theoretical standpoint in relation to user-appliance interactions in the home. It presents the main options for display position and discusses what detailed information to display in order to promote energy saving. To guide the designer in making decisions regarding the merits of displaying appliance-specific information and grouped appliance information around the home, classifications are presented of appliance-associated micro-behaviours and appliance control to enduse relationships. A hybrid display approach is suggested as a most effective solution.

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Opportunities to boost bioenergy in Lithuania

Silveira, S. et al. Biomass and Bioenergy, 2006, 30, (12), 1076–1081. Significant efforts have been made in Lithuania to enhance the utilization of bioenergy since the early 1990s. While opportunities are large and signs of development visible, bioenergy still needs technical, institutional and policy-related support for further development side by side with other industries. This paper discusses the existing bioenergy potential in Lithuanian forests, biofuels market formation in the region and possible roads to boost development. The retrofitting of heat plants, forest management and policies are reviewed as a way to identify opportunities to promote bioenergy in the country. It is shown that the interplay between national and regional forces can promote technological and managerial improvements in the forest industry while also enhancing the biomass supply and sustainability of bioenergy systems.

Perspectives for natural working fluids in China

Wang, R. Z. and Li, Y. International Journal of Refrigeration, 2007, 30, (4), 568–581. China has become one of the largest refrigerants market in the world with the rapid economy development. This paper details the status of natural working fluid research and application developments in China as an essential element for the sustainable economic development and environmental protection. The natural working fluids examined include carbon dioxide, water, ammonia, air and hydrocarbon. Prestigious universities and enterprises in China have made significant achievements in recent years, especially on the application of carbon dioxide, water, and ammonia. Application of absorption and adsorption systems using water and ammonia as refrigerants are promising technically and economically, and various commercialized products have been developed for utilization in industry as well as commercial building. Evaporative/desiccant cooling markets are also expanding quickly in China. However, commercialized products with carbon dioxide as working fluid are still not available in China. Academic and industrial sectors should work together promote the application of carbon dioxide. With the strong support from government and society, it can be expected that more achievements could be obtained in near future.

07/02550 Price elasticities, policy measures and actual developments in household energy consumption – a bottom up analysis for the Netherlands Boonekamp, P. G. M. Energy Economics, 2007, 29, (2), 133–157. In the Netherlands it seems likely that the large number of new policy measures in the past decade has influenced the response of households to changing prices. To investigate this issue the energy trends in the period 1990–2000 have been simulated with a bottom-up model, applied earlier for scenario studies, and extensive data from surveys. For a number of alternative price cases the elasticity values found are explained using the bottom-up changes in energy trends. One finding is that the specific set of saving options defines for a great part the price response. The price effect has been analysed too in combination with the policy measures standards, subsidies and energy taxes. The simulation results indicate that the elasticity value could be 30–40% higher without these measures.

07/02551 Security of energy supply: comparing scenarios from a European perspective Costantini, V. et al. Energy Policy, 2007, 35, (1), 210–226. This paper compares different results from a set of energy scenarios produced by international energy experts, in order to analyse projections on increasing European external energy dependence and vulnerability. Comparison among different scenarios constitutes the basis of a critical review of existing energy security policies, suggesting alternative or complementary future actions. According to the analysis, the main risks and negative impacts in the long term could be the increasing risk of collusion among exporters due to growing dependence of industrialized countries and insufficient diversification; and a risk of demand/supply imbalance, with consequent instability for exporting regions due to insufficient demand, and lack of infrastructures due to insufficient supply. Cooperation with exporting countries enhancing investments in production capacity, and with developing countries in order to reinforce negotiation capacity of energyimporting countries seem to be the most effective policies at international level.

07/02552 Use of multicriteria decision analysis methods for energy planning problems Løken, E. Renewable and Sustainable Energy Reviews, 2007, 11, (7), 1584–1595. Most decision-making requires the consideration of several conflicting objectives. The term multiple criteria decision analysis (MCDA) describes various methods developed for aiding decision makers in reaching better decisions. Energy planning problems are complex problems with multiple decision makers and multiple criteria. Therefore, these problems are quite suited to the use of MCDA. A multitude

16 Energy (energy conservation) of MCDA methods exists. These methods can be divided in three main groups; value measurement models, goal, aspiration and reference level models, and outranking models. Methods from all of these groups have been applied to energy planning problems, particularly in the evaluation of alternative electricity supply strategies. Each of the methods has its advantages and drawbacks. However, it cannot be concluded that one method generally is better suited than the others for energy planning problems. A good alternative might be to apply more than one method, either in combination to make use of the strengths of both methods, or in parallel to get a broader decision basis for the decision maker. Until now, studies of MCDA in energy planning have most often considered energy networks with only one energy carrier. More advanced energy systems with multiple energy carriers have been neglected, even though this field ought to be suitable for use of MCDA due to its high complexity, many decision makers and many conflicting criteria.

Growing concern in Taiwan has arisen about energy consumption and its adverse environmental impact. The current situation of energy conservation in high energy-consuming industries in Taiwan, including the iron and steel, chemical, cement, pulp and paper, textiles and electric/electrical industries has been presented. Since the energy consumption of the top 100 energy users (T100) comprised over 50% of total industry energy consumption, focusing energy consumption reduction efforts on T100 energy users can achieve significant results. This study conducted on-site energy audits of 314 firms in Taiwan during 2000–2004, and identified potential electricity savings of 1,022,656 MWH, fuel oil savings of 174,643 kilolitres (KL), steam coal savings of 98,620 ton, and natural gas (NG) savings of 10,430 kilo cubic metres. The total potential energy saving thus was 489,505 KL of crude oil equivalent, representing a reduction of 1,447,841 ton in the carbon dioxide emissions, equivalent to the annual carbon dioxide absorption capacity of a 39,131-ha plantation forest.

07/02553 Variations in energy use by Indian households: an analysis of micro level data

07/02557 Dynamic earth-contact building: a sustainable low-energy technology

Rao, M. N. and Reddy, B. S. Energy, 2007, 32, (2), 143–153. In this paper an attempt has been made to determine the factors that influence individual’s decision to choose a particular energy carrier, namely, firewood, LPG, kerosene, and electricity. From the economic perspective, an individual’s propensity to choose a particular energy carrier is determined by his/her economic status, carrier availability and prices, household size and other regional and demographic variables. For this reason, the choice of selecting a carrier for a service (e.g. cooking) is expected to vary among individuals. To assess this, the study uses the 1999–2000 National Sample Survey data covering over 118,000 households and analyses the rural and urban areas separately. A multinomial logit selection model has been applied for estimating the energy carrier choice decision. The results show that individuals are influenced by per capita income, household size, educational status of the head of the household, occupation of the household members, in addition to other household location characteristics. It is found that the monthly household income and household size have nonlinear relationship on the probability of choosing a fuel.

Kumar, R. et al. Building and Environment, 2007, 42, (6), 2450–2460. Sustainable development includes low-energy buildings to reduce energy consumption, greenhouse gases emission, water usage, etc. The choice of subsurface wall at varying depths for construction of buildings has a direct impact on energy consumption and the environment. This paper includes in its scope all building structures in which a significant area is in direct contact with the earth, and excludes indirect earth contact. A two-dimensional simplified analytical Fourier boundary series was developed to study dynamic earth-contact heat transfer and humidity variation in building. It was used in conjunction with the whole-building energy simulation program developed in the TRNSYS environment. The predictions were compared with extensive experimental data measured from typical existing earth-contact buildings situated in the Indian Institute of Technology Delhi campus. Heat transfer through earth-contact building structures was predicted to decrease with increasing soil contact. The results obtained from the detailed model showed that earth-contact structures form excellent passive technology that can be exploited for energy conservation. This work is part of an effort to develop zero energy building models in India. The presented model can be easily incorporated into indirect earth-contact structures in order to describe the impact of cooling tubes, earth-air tunnels or heat pumps in indoor environment.

Energy conservation 07/02554 A discussion on potentials of saving energy use for commercial buildings in Hong Kong Yu, P. C. H. and Chow, W. K. Energy, 2007, 32, (2), 83–94. A typical commercial building was selected for a detailed study of energy use by mechanical ventilation and air-conditioning (MVAC) systems. Data from preliminary building energy auditing were analysed and compared with the energy use of other similar buildings. Correlation relationships between the building envelope heat gain and the electrical energy use for MVAC system with key parameters were derived with approaches similar to the Princeton scorekeeping method. Further, the energy simulation program TRACE 600 was used to justify the results. A total of 20 energy-saving measures were investigated for possible use in local commercial buildings. The results provided are useful for engineers in designing energy-efficient commercial buildings or generating new design concepts for better MVAC systems.

07/02555 An energy benchmarking model for ventilation systems of air-conditioned offices in subtropical climates Mui, K. W. et al. Applied Energy, 2007, 84, (1), 89–98. Since the energy crisis in 1973, engineers have endeavoured to implement energy conservation in buildings. Unfortunately, the effort resulted in energy savings without the fundamental delivery of indoor satisfaction in many cases. In this study, a benchmarking model for the energy consumption of ventilation systems in air-conditioned offices was proposed. This model was developed from the fundamental psychrometric analysis under probable office design conditions in Hong Kong. The results showed that the annual energy-consumption of a ventilation system per unit floor area would be correlated closely with the carbon dioxide concentration in the space, but its correlation with the air temperature set-point would be less significant. In some offices, significant energy-savings potential was demonstrated to provide satisfactory indoor air quality without any comfort penalty to the occupants. This model would be useful for the energy performance evaluation and benchmarking of ventilation systems in air-conditioned offices.

07/02556 Current situation of energy conservation in high energy-consuming industries in Taiwan Chan, D. Y. et al. Energy Policy, 2007, 35, (1), 202–209.

07/02558 Energy-efficient housing for low-income students in a highly variable environment of central Argentina Filippı´n, C. and Beascochea, A. Renewable Energy, 2007, 32, (1), 1–20. Socio-economic, educational and environmental reasons have driven the building of energy-efficient dwellings for low-income students in University of La Pampa. The buildings are located in the central region of Argentina (35 700 of South latitude), an area of warm temperate climate. Energy conservation devices, passive solar heating, natural ventilation and solar protection were the main strategies of design. The resulting design comprised three blocks of housing with a useful floor area of 900 m2. Two bedrooms, a dining room and essential services make up each house. Solar gains through transparent areas to the North are provided for all main spaces. Northern shading devices and metallic pergolas protect all windows in summer. In spite of high external temperature variability, the simulated performance during the design stage showed a remarkable internal thermal stability. The thermal and energy monitoring started in September 1999 and had two phases: (a) under real conditions of use and (b) during student’s summer holidays (when the buildings were not inhabited). The results from the monitoring process suggest that interpretations about the building behaviour cannot be restricted to constructive issues. Useful inferences cannot be done from design and building technology only. The thermal behaviour was the result of construction, non-construction factors like dwellers habits, and their interaction. Energy saving in heating during the winter season was around 50%.

07/02559 Experimental investigation of an adsorptive thermal energy storage Dawoud, B. et al. International Journal of Energy Research, 2007, 31, (2), 135–147. A zeolite-water adsorption module, which ahs been originally constructed for an adsorption heat pump, has been experimentally investigated as an adsorptive thermal energy storage unit. The adsorber/desorber heat exchanger contains 13.2 kg of zeolite 13X and is connected to an evaporator/condenser heat exchanger via a butterfly valve. The flow rate of the heat transfer fluid in the adsorber/desorber unit has been changed between 0.5 and 2.01 min1, the inlet temperature to the evaporator between 10 and 40 C. It turned out that the higher the flow rate inside the adsorber/desorber unit the faster and more effective is the discharge of heat. However, at lower flow rates higher discharge temperatures are obtained. Storage capacities of 2.7 and 3.1 kWh have been measured at the evaporator

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16 Energy (energy conservation) inlet temperatures of 10 and 40 C, respectively, corresponding to thermal energy storage densities of 80 and 92 kWh m3 based on the volume of the adsorber unit. The measured maximum power density increases from 144 to 165 kWh m2 as the flow rate in the adsorber increases from 0.5 to 21 min1. An internal insulation in form of a radiation shield around the adsorber heat exchanger is recommended to reduce the thermal losses of the adsorptive storage.

07/02560 HRTEM study of diesel soot collected from diesel particulate filters Vander Wal, R. L. et al. Carbon, 2007, 45, (1), 70–77. HRTEM study of several soot samples collected on diesel particulate filters (DPF) under conditions relevant to practical applications of DPF technology, revealed nano-structure, to the authors’ knowledge, not reported previously for diesel soot. In particular, some of the primary particles were found to have hollow interior, and the outer shell exhibiting evidence of graphitization, with a higher crystallinity compared to the non-hollowed particles. The percentage of such particles varied between different soot samples and tentatively appeared to be related to the oxidation history of the sample. Remarkably, similar effect was not reproduced for a carbon black sample, Printex-U, suggesting that propensity to such oxidationinduced graphitization is related to the original nano-structure of the particle. These initial observations were independently confirmed for the same set of soot samples by two different HRTEM facilities, at NASA-Glenn and PNNL.

07/02561 Parametric analysis of alternative energy conservation measures in an office building in hot and humid climate Iqbal, I. and Al-Homoud, M. S. Building and Environment, 2007, 42, (5), 2166–2177. The growth of demand for electrical energy in the rapidly expanding towns, cities and industries exceeds the growth of the power being made available. Therefore, energy conservation is becoming an increasingly important issue in Saudi buildings. The objective of this study was to investigate the impact of alternative energy conservation measures on energy requirements in office buildings in hot–humid climates. The study was conducted on a five-storey office building located in Dammam, Saudi Arabia, which has been in use since 1998. Different types of HVAC systems were selected and different feasible and practical operational energy conservation measures were evaluated using the energy simulation software of Visual DOE 4.0. Previous studies conducted in this area were reviewed. Data was collected through review of design drawings, building audit and the analysis of 4 years of utility bills. All the collected data was analysed and the utility bills data was used to calibrate the base case of the existing building using Visual DOE energy simulation software. Conclusions and recommendations were developed for conserving energy using various appropriate ECMs in office buildings in hot and humid climates.

07/02562 Solar filters based on iron oxides used as efficient windows for energy savings Chavez-Galan, J. and Almanza, R. Solar Energy, 2007, 81, (1), 13–19. The application of windows coated with solar filters is intended to improve the interior comfort of buildings by blocking the transmittance of heat while allowing visible light to pass through. In this report, the authors test the physical properties and thermal behaviour of solar filters based on iron oxides. These filters consisted of a thin film of FeO and Fe2O3. This film was deposited on soda-lime glass substrates of 600  300 mm2 by rf magnetron sputtering using a high-purity Fe target (99.99%) in an argon plasma. Since the sputtering conditions and the dimensions of the equipment used facilitated the oxidation of iron, the authors subjected small samples of 45  22 mm2 to a heating reduction treatment in a hydrogen and nitrogen atmosphere for 10 min at 400  C. This treatment allowed us to obtain the desired oxidation state of iron within these thin films. The solar filters had a transmittance of 30.2% for the visible light spectrum and 39.9% for the near-infrared spectrum. Furthermore, the reflectance of these filters was determined to be 17.5% and 19% for visible and near-infrared light, respectively. A simulation of thermal behaviour in houses at different locations in Me´xico was performed using Energy-10 software. These data were used to determine energy savings attributed to the use of when iron-based solar filters are used on windows. These solar filters resulted in a 9– 16% reduction in the amount of energy required for air conditioning (heating and cooling). In addition, a simulation was made at Mexicali BC using the commercial glass Reflectasol1AP Tintex of Vitro Co., which concluded that the FeO-based solar filters performed better than the other tested.

07/02563 The impact of lifestyle on energy use and CO2 emission: an empirical analysis of China’s residents Wei, Y.-M. et al. Energy Policy, 2007, 35, (1), 247–257.

382 Fuel and Energy Abstracts September 2007

Based on the application of a consumer lifestyle approach, this paper quantifies the direct and indirect impact of lifestyle of urban and rural residents on China’s energy use and the related CO2 emissions during the period 1999–2002. The results show that approximately 26 per cent of total energy consumption and 30 per cent of CO2 emission every year are a consequence of residents’ lifestyles, and the economic activities to support these demands. For urban residents the indirect impact on energy consumption is 2.44 times greater than the direct impact. Residence; home energy use; food; and education, cultural and recreation services are the most energy-intensive and carbon-emissionintensive activities. For rural residents, the direct impact on energy consumption is 1.86 times that of the indirect, and home energy use; food; education, and cultural recreation services; and personal travel are the most energy-intensive and carbon-emission-intensive activities. This paper provides quantitative evidence for energy conservation and environmental protection focused policies. China’s security for energy supply is singled out as a serious issue for government policy-makers, and the authors suggest that government should harmonize the relationships between stakeholders to determine rational strategies.

07/02564 The paradigm of sustainability in the Brazilian energy sector da Paz, L. R. L. et al. Renewable and Sustainable Energy Reviews, 2007, 11, (7), 1558–1570. The concept of sustainability can be a way to understand the dynamics of reality and to consider not only the economic growth but also the social, environmental and cultural aspects of development. This new paradigm questions the role of nature as an instrument only to satisfy the human needs and brings into consideration the rational use of natural resources through responsible environmental policies keeping in mind the needs of the future generations. The economic growth, considered as the notion of progress, brings intrinsically not only the extensive nature exploitation but also the intensification of the energy use. Energy sources become, then, a strategic variable for the economic development. The Brazilian energy policy is an appropriate case study for the paradigm of sustainability overview as it is characterized by isolated initiatives and programmes, all of which culminated into a huge crisis. This paper aims to discuss the concepts of sustainability and ethics through the analysis of the Brazilian energy policy and its social and environmental implications.

07/02565 Transition to a sustainable urban energy system from a long-term perspective: case study in a Japanese business district Yamaguchi, Y. et al. Energy and Buildings, 2007, 39, (1), 1–12. This paper investigates alternative prospects for an urban energy system from a long-term perspective in order to achieve a reduction in CO2 emission by more than 50% of the current emission in the Japanese commercial sector. This will assist in making strategic choices with regard to the implementation of available technologies in order to create a substantial change. A simulation model based on the bottomup approach – a fundamental part of the evaluation framework of technology implementation scenarios – provides insights into the changes required in all the components of urban energy systems from the equipment level to the entire building and systems level and finally to the neighbourhood and city levels. This model is applied to the Yodoyabashi district, a central business district in Osaka, Japan, in order to predict the end-use energy consumption and CO2 emission under various scenarios. This is based on different concepts of community energy management. The results of this case study suggest that a reduction of 60–90% of the current CO2 emission by the middle of the 21st century is achievable.

07/02566 Using intelligent clustering techniques to classify the energy performance of school buildings Santamouris, M. et al. Energy and Buildings, 2007, 39, (1), 45–51. The present paper deals with the energy performance, energy classification and rating and the global environmental quality of school buildings. A new energy classification technique based on intelligent clustering methodologies is proposed. Energy rating of school buildings provides specific information on their energy consumption and efficiency relative to the other buildings of similar nature and permits a better planning of interventions to improve its energy performance. The overall work reported in the present paper, is carried out in three phases. During the first phase energy consumption data have been collected through energy surveys performed in 320 schools in Greece. In the second phase an innovative energy rating scheme based on fuzzy clustering techniques has been developed, while in the third phase, 10 schools have been selected and detailed measurements of their energy efficiency and performance as well as of the global environmental quality have been performed using a specific experimental protocol. The proposed energy rating method has been applied while the main environmental and energy problems have been identified. The potential for energy and environmental improvements has been assessed.

17 Energy conversion and recycling

17 ENERGY CONVERSION AND RECYCLING 07/02567 Autothermal two-stage gasification of low-density waste-derived fuels Hamel, S. et al. Energy, 2007, 32, (2), 95–107. In order to increase the efficiency of waste utilization in thermal conversion processes, pre-treatment is advantageous. With the Herhof Stabilat1 process, residual domestic waste is upgraded to wastederived fuel by means of biological drying and mechanical separation of inerts and metals. The dried and homogenized waste-derived Stabilat fuel has a relatively high calorific value and contains high volatile matter which makes it suitable for gasification. As a result of 1 extensive mechanical treatment, the Stabilat produced is of a fluffy appearance with a low density. A two-stage gasifier, based on a parallel-arranged bubbling fluidized bed and a fixed bed reactor, has been developed to convert Stabilat into hydrogen-rich product gas. This paper focuses on the design and construction of the configured laboratory-scale gasifier and experience with its operation. The processing of low-density fluffy waste-derived fuel using small-scale equipment demands special technical solutions for the core components as well as for the peripheral equipment. These are discussed here. The operating results of Stabilat gasification are also presented.

07/02568 Flash-type barometric desalination plant powered by waste heat from electricity power stations in Cyprus Maidment, G. G. et al. Applied Energy, 2007, 84, (1), 66–77. This paper describes and evaluates the results of a study into the problems of freshwater production and shortages on the island of Cyprus. The use of a novel barometric flash-type desalinator, driven by otherwise waste-heat from the island’s power-stations, is proposed as a means of increasing freshwater supplies. Mathematical models are described and used to investigate the thermodynamic performance and economic viability of the proposed system. Although water and electricity-supply data for the island of Cyprus were used for the purposes of this investigation, the overall findings are thought to have a wider applicability.

07/02569 High-pressure catalytic and thermal cracking of polyethylene Mosio-Mosiewski, J. et al. Fuel Processing Technology, 2007, 88, (4), 359–364. The thermal cracking and catalytic cracking processes of low-density polyethylene were studied in a closed autoclave. The compositions of gaseous and liquid products were analysed by means of GC/FID and GS/MS chromatographic methods. The fractional composition of liquid products was found by distillation. Increased temperature of PE depolymerization process increases the production of gaseous products and low-boiling liquid compounds; more aromatic hydrocarbons are formed instead of alkenes. When a lower temperature and longer time are adopted for the process to reach the assumed conversion, more straight chained hydrocarbons are produced. The acidic aluminosilicate catalyst yields more low-boiling liquid fractions, more isoalkanes and more aromatics. The neutral alumina is favourable for the production of alkenes and vacuum gas oil fraction in comparison to a non-catalytic process. The Ni–Mo/Al2O3 catalyst is efficient in hydrogenation of depolymerization products. The reaction products contain only saturated compounds then and no aromatics are formed.

07/02570 Mathematical modelling of slow pyrolysis of segregated solid wastes in a packed-bed pyrolyser Yang, Y. B. et al. Fuel, 2007, 86, (1–2), 169–180. Waste segregation is being explored as one of the potential effective ways for waste management, where wastes are separated for either recycling or energy recovery. In this paper, three segregated wastes, contaminated waste wood, cardboard and waste textile are pyrolysed in a slow-heating packed-bed reactor for the purpose of solid, liquid and gas recovery. The effect of final temperature was investigated and product yields and compositions were measured. Mathematical modelling was employed to simulate the heat, mass transfer and kinetic processes inside the reactor. Both a parallel reaction model and a function group model were used to predict the product yields as well as their compositions. Char yield of 21–34%, tar 34–46% and gas 23– 43% were obtained. It is found that packed-bed pyrolysis produces 30– 100% more char compared to standard TGA tests and the local heating rate across the packed-bed reactor differs remarkably from the programmed wall-heating rate and varies greatly in both time and space. Mathematical modelling suggests that wood has higher tar cracking ability than cardboard and textile wastes during pyrolysis, and the effects of mineral contents in the fuel need to be explored. CO2, CO, tar and water are the main released species during the major stage

of the pyrolysis processes which occurs between 250 and 450  C, whereas noticeable quantity of hydrogen and light hydrocarbons is observed only at higher temperature levels and at the final stage.

07/02571 Microfinance for renewable energy: financing the ‘former poor’ Srinivasan, S. World Review of Entrepreneurship, Management and Sustainable Development , 2007, 3, (1), 79–89. Microbanking facilities have helped large numbers of developing country nationals by supporting the establishment and growth of microenterprises. And yet, the microfinance movement has grown on the back of passive replication and needs to be revitalized with new product offerings and innovative service delivery. Renewable energy systems namely, solar home systems, biogas digesters, etc., serve to improve indoor air quality, provide superior light and extend working and study hours. Such applications are not inherently income generating and returns on such investments accrue from cost avoidance, but, should qualify for microfunding, as such ‘quality of life’ investments, reflect borrower maturity and simultaneously contribute to MFI sustainability.

07/02572 Pilot plant evaluation of PFS from coal-fired power plant waste Lloyd, H. et al. Chemical Engineering and Processing, 2007, 46, (3), 257–261. Pilot plant studies were conducted to evaluate the performance of a polymeric ferric sulfate (PFS) coagulant synthesized from waste SO 2. Aluminium sulfate (alum), ferric sulfate and ferric chloride were compared with PFS. Preliminary jar tests were performed to determine coagulant dose range and expected turbidity removal. The studies were conducted at the City of Savannah Industrial and Domestic Water Treatment Plant in Port Wentworth, GA. The raw water source, a tributary of the Savannah River, was high in organic content. Due to its proximity to the coast, the tributary is tidally affected resulting in continuous water quality changes. Of the three iron-based coagulants tested, all provided nearly 10% greater reductions in total organic carbon when compared to alum. The pH ranges using the iron-based coagulants were much lower than those experienced with alum. Turbidity removal was approximately 100% for all coagulants. Ferric sulfate required the highest average dosage for proper coagulation/ flocculation with efficient turbidity removal at 110 ppm. The performance of the PFS was comparable to that of ferric sulfate.

07/02573 RDF to energy plant for a central Italian region SUW management system: energetic and economical analysis Di Maria, F. and Pavesi, G. Applied Thermal Engineering, 2006, 26, (11– 12), 1291–1300. It is well known that a rise in a country’s prosperity is parallel to an increase in the amount of waste produced by the population. The specific solid urban waste production off a European citizen is actually about 500 kg per inhabitant per year. In reference to the whole European population, the global solid urban waste production requires an adequate management system, able to satisfy economical, social and environmental needs. Before final disposal (i.e. sanitary landfill), wastes need some kind of recovery, reuse and ad hoc treatments operation, in compliance with European state laws. The aim of these rules is to achieve an environmentally sound waste management system that allows the reduction of the raw materials and fossil fuel consumption, dangerous waste production and the amount of disposed materials. Among the technologies available for the different treatments, incineration with energy recovery seems to have many advantages mainly because it reduces waste volume and fossil fuel consumption, and because its sterilization effects are achieved on the inlet substances. The main drawbacks of such plants are represented by the emission off gaseous pollutant, thus requiring important exhaust gasses treatment systems, by producing a non-negligible amount of dangerous substances, and by high capital and operating costs. In this paper the solid urban waste production of a central Italian region and the amount of available residual derived fuel for thermal treatment has been assessed. Then, the possibility of exploiting a fluid bed combustor based power plant, able to treat the residual derive fuel fraction produced through the years, has been analysed both from an energetic and an economical point of view.

07/02574 Recycling of chemicals from alkaline waste generated during preparation of UO3 microspheres by sol– gel process Kumar, A. et al. Journal of Nuclear Materials, 2006, 350, (3), 254–263. Internal gelation process, one of the sol–gel processes for nuclear fuel fabrication, offers many advantages over conventional powder pellet route. However, one of the limitation of the process is generation of large volume of alkaline liquid waste containing hexamethylenetetramine, urea, ammonium nitrate, ammonium hydroxide etc. Pre-

Fuel and Energy Abstracts September 2007 383

17 Energy conversion and recycling sence of ammonium nitrate with hexamethylenetetramine and urea presents a fire hazard which prevents direct disposal of the waste as well as its recycle by evaporation. The paper describes the studies carried out to suitably process the waste. Nitrate was removed from the waste by passing through Dowex 1  4 anion exchange resin in OH form. 1.0 M NaOH was used to regenerate the resin. The nitrate-free waste was further treated to recover and recycle hexamethylenetetramine, urea and ammonium hydroxide for preparation of UO3 microspheres. The quality of the microspheres obtained was satisfactory. An optimized flow sheet for processing of the waste solution has been suggested.

07/02575

Sintered glass-ceramics from mixtures of wastes

Bernardo, E. et al. Ceramics International, 2007, 33, (1), 27–33. Panel glass from dismantled cathode ray tubes, mining residues from feldspar excavation and lime from fume abatement systems of the glass industry have been employed as raw materials for several glass compositions. The prepared glasses were ground into fine powders and subjected to sintering treatments at low temperatures (880– 930  C), with concurrent crystallization, thus obtaining sintered glassceramics. The mechanical properties (for example, bending strength exceeding 100 MPa) and the aesthetic appearance of the materials, together with the simplicity of the manufacturing method, are promising for applications in the building industry.

384 Fuel and Energy Abstracts September 2007

07/02576 Vermicomposting of different types of waste using Eisenia foetida: a comparative study Garg, P. et al. Bioresource Technology, 2006, 97, (3), 391–395. A study (100 days duration) was conducted to evaluate the efficiency of an exotic earthworm species (epigeic – Eisenia foetida) for decomposition of different types of organic substrates (kitchen waste, agroresidues, institutional and industrial wastes including textile industry sludge and fibres) into valuable vermicompost. The percentage of, nitrogen, phosphorous and potassium in vermicompost was found to increase while pH and total organic carbon declined as a function of the vermicomposting period. Increases of 4.4–5.8-fold in TKN were observed in different feed mixtures at the end of vermicomposting period. The increase in TKN for different feed substrates was found in the order: textile sludge > textile fibre = institutional waste > agroresidues > kitchen waste. Available Phosphorus increased 1.4 to 6.5fold in different feed mixtures in comparison to control. Reduction in TOC was highest in agro-residues (3-fold) followed by kitchen waste (2.2-fold), institutional waste (1.7-fold) and textile industrial wastes (sludge, 1.5-fold and fibre, 1.68-fold) in earthworm-inoculated pots than control. The data reveals that vermicomposting (using E. foetida) is a suitable technology for the decomposition of different types of organic wastes (domestic as well as industrial) into value-added material.