- Email: [email protected]
00896 Optimal configuration and performance for a generalized Carnot cycle assuming the heat-transfer law Q ∞ (ΔD T)m
16 Fuel science and technology (fundamental science, analysis, instrumentation) such as the change in exergy are not frame indifferent, it is shown that mechanical dissipation and exergy destruction are both frame indifferent. The results of this work reveal that in many cases the exergy destruction rate is a small fraction of the mechanical energy dissipation rate typically used to determine losses in gas dynamics. This is particularly true when the initial temperature of the fluid is high relative to the environment temperature. In contrast, the results show that for very low initial temperatures that are below the environment temperature, the thermo-mechanical dissipation rate can be much greater than mechanical dissipation rate.
05/00888 Modeling of recent volcanic episodes at Phlegrean Fields (Italy): geochemical variations and ground deformation Todesco, M. et al. Geothermics, 2004, 33, (4), 531-547. The Phlegrean Fields is an active caldera structure, located on the periphery of Naples (Italy). After the last eruptive event (the Monte Nuovo eruption in 1538), periodic episodes of unrest have characterized the evolution of this volcanic district, involving seismic activity and slow ground motion (bradyseism). During these episodes of unrest, some remarkable changes have also affected the composition of the hydrothermal fluids discharged at La Solfatara fumarolic field. These unrest phenomena result from the complex interaction between magma chamber, hydrothermal fluid circulation, and country rocks undergoing thermal and mechanical stresses. In order to make an effective hazard assessment in such a densely populated area as the Phlegrean Fields, a better understanding is needed of the mechanism driving bradyseismic activity and determine the relation between ground deformation and hydrothermal fluid circulation. In this work, the results are presented of numerical modelling of both the hydrothermal fluid circulation at La Solfatara, and of its effects on rock deformation. The modelling results show that periods of intensified magmatic degassing can explain many features of the recent crises of unrest at Phlegrean Fields.
05/00889 Modeling the liquid-phase oxidation of hydrocarbons over a range of temperatures and dissolved oxygen concentrations with pseudo-detailed chemical kinetics Kuprowicz, N. J. et al. Fuel, 2004, 83, (13), 1795-1801. The ability of pseudo-detailed chemical kinetic modelling to simulate the oxidation behaviour of Exxsol D-80, a paraffin blend whose oxidative characteristics are representative of severely hydrotreated jet fuels, is assessed. The effects of temperature and initial dissolved 02 concentration on oxidation are considered. A 17-step pseudo-detailed mechanism is shown to provide reasonable simulations of Exxsol D-80 oxidation over a range of temperatures, but not over a range of initial dissolved Oz concentrations. The addition of alkyl-peroxy radical isomerization to the pseudo-detailed mechanism did not reconcile the initial dissolved Oz limitation. With the addition of a peroxy radical decomposition reaction to the original 17-step pseudo-detailed mechanism, reasonable simulations of Exxsol D-80 oxidation over a range of temperatures and initial dissolved O2 concentrations were obtained. Analysis of the rate parameters associated with peroxy radical decomposition suggests that aromatic hydrocarbons play a significant role in the oxidation of fuels, even at low (<1% by weight) aromatic levels.
05/00890 Modelling floor heating systems using a validated two-dimensional ground-coupled numerical model Weitzmann, P. et al. Building and Environment, 2005, 40, (2), 153-I63. This paper presents a two-dimensional simulation model of the heat losses and temperatures in a slab on grade floor with floor heating which is able to dynamically model the floor heating system. The aim of this work is to be able to model, in detail, the influence from the floor construction and foundation on the performance of the floor heating system. The ground-coupled floor-heating model is validated against measurements from a single-family house. The simulation model is coupled to a whole-building energy simulation model with inclusion of heat losses and heat supply to the room above the floor. This model can be used to design energy efficient houses with floor heating focusing on the heat loss through the floor construction and foundation. It is found that it is important to model the dynamics of the floor heating system to find the correct heat loss to the ground, and further, that the foundation has a large impact on the energy consumption of buildings heated by floor heating. Consequently, this detail should be in focus when designing houses with floor heating.
05/00891 Monte Carlo based operational and shutdown dose rate calculations of HT-7U tokamak Chert, Y. et al. Fusion Engineering and Design, 2004, 70, (2), 155-162. The superconducting tokamak HT-7U will perform D - D plasma experiments and the production rate of 2.45 MeV neutrons will achieve the level of 1015n/s. The dose rates during operation and after shutdown of HT-7U have been calculated based on a detailed threedimensional model with the Monte Carlo code MCNP-4C, the
inventory code FISPACT and the FENDL-2 nuclear data library. The so-called R2S method was used to perform the shutdown dose rate analyses. The results confirm that personnel access into the tokamak hall must be prohibited during operation. In addition the results show that the dose rate level near the outer wall of the tokamak hall slightly exceeds the dose limit. Additional shielding may be required. The shutdown dose rates of various experimental campaigns have been calculated and the waiting times for personnel access into the hall have been assessed. The results indicate that the in-vessel components of HT-7U will be considerably activated by neutrons and the shutdown dose rate level around the machine after long D - D plasma discharges is serious within a certain range of cooling time regarding the maintenance work.
05/00892 Monte Carlo importance sampling optimization for system reliability applications Campioni, L. and Vestrucci, P. Annals of Nuclear Energy, 2004, 31, (9), 1005-1025. This paper focuses on the reliability analysis of multi-component systems by the importance sampling technique, and, in particular, it tackles the optimization aspect. A methodology based on the minimization of the variance at the component level is proposed for the class of systems consisting of independent components. The claim is that, by means of such a methodology, the optimal biasing could be achieved without resorting to the typical approach by trials.
05/00893 Neutron kinetics of fluid-fuel systems by the quasi-static method Dulla, S. et al. Annals of Nuclear Energy, 2004, 31, (15), 1709 1733. The quasi-static method for the neutron kinetics of nuclear reactors is generalized for application to neutron multiplying systems fuelled by a fluid multiplying material, typically a mixture of fissile molten salts. The method is derived by the application of faetorization formulae for both the neutron density and the delayed precursor concentrations and the projection of the balance equations upon a weighting function. A physically meaningful weight can be assumed as the solution of the adjoint model, which is constructed for the situation considered, including delayed neutrons. The quasi-static scheme is then applied to calculations of some transients for a typical configuration of a moltensalt reactor, in a multigroup diffusion model with a one-dimensional slug-flow velocity field. The physical features associated to the motion of the fissile material are highlighted.
05100894 New brittle fracture model for the European pressure vessel standard Sandstr6m, R. et al. International Journal of Pressure Vessels and Piping, 2004, 81, (10 11), 837-845. A model for design against brittle failure based on recent fracture mechanics findings is proposed. The procedure is an update of that in the recent European pressure vessel standard EN 13445. The thickness dependence of the maximum permissible crack has been analysed with the help of research on non-destructive testing. Cracks with a quarter thickness depth are assumed to be readily detectable for larger gauges. For thinner gauges the cracks have to cover a larger fraction of the thickness to be safely observed. The model is verified by comparison to fracture mechanics test data for high strength steels. Results from individual wide plate tests are successfully reproduced by the model. Furthermore, T100 values (the temperature where Kjc = 100 MPa m 1/2) for test series are conservatively predicted by the model. The model adequately describes the influence of thickness and heat treatment on the T~00 values.
05•00895
On-line signal trend identification
Tambouratzis, T. and Antonopoulos-Domis, M. Annals of Nuclear Energy, 2004, 31, (14), 1541-1553. An artificial neural network, based on the self-organizing map, is proposed for on-line signal trend identification. Trends are categorized at each incoming signal as steady-state, increasing and decreasing, while they are further classified according to characteristics such signal shape and rate of change. Tests with model-generated signals illustrate the ability of the self-organizing map to accurately and reliably perform on-line trend identification in terms of both detection and classification. The proposed methodology has been found robust to the presence of white noise.
05100896 Optimal configuration and performance for a generalized Carnot cycle assuming the heat-transfer law Q oc (~DT) m Chen, L. et al. Applied Energy, 2004, 78, (3), 305-313. The finite-time thermodynamic performance of a generalized Carnot cycle, in which the heat transfer between the working fluid and the heat reservoirs obeys a generalized law Q oc (AD T)m, is studied. The optimal configuration and the fundamental optimal relation between power
Fuel and Energy Abstracts March 2005 129
16 Fuel science and technology (fundamental science, analysis, instrumentation) output and efficiency of the cycle are derived. Some special examples are discussed. The results can provide some theoretical guidance for the design of practical engines.
05•00897 Optimisation of ISI interval using genetic algorithms for risk informed in-service inspection Vinod, G. et al. Reliability Engineering & System Safety, 2004, 86, (3), 307-316. Risk informed in-service inspection (RI-ISI) aims at prioritizing the components for inspection within the permissible risk_ level thereby avoiding unnecessary inspections. Various constraints such as risk level, radiation exposure to the workers and cost of inspections are encountered, while planning the inspection programme. This problem has been attempted to solve using genetic algorithms, which has already established its suitability in optimizing surveillance and maintenance activities in nuclear power plants. The paper describes the application of genetic algorithm in optimizing the ISI of feeders, which are large in number and also fall in the same inspection category.
05•00898 Performance comparison of Fick's, dusty-gas and Stefan-Maxwell models to predict the concentration overpotential of a SOFC anode Suwanwarangkul, R. et al. Journal of Power Sources, 2003, 122, (1), 9 18. Models for mass transport inside a porous SOFC anode were developed based on Fick's model (FM), the dusty-gas model (DGM) and the Stefan-Maxwell model (SMM) to predict the concentration overpotential. All models were validated with experimental data for H2-HeO-Ar and CO-CO2 systems. The effect of pore size on all model predictions was discussed. It was concluded that the dusty-gas model is the most appropriate model to simulate gas transport phenomena inside a SOFC anode. However, this model requires numerical solution, whereas Fick's and Stefan-Maxwell's do not. It was found that the SMM, rather than the FM, is a good approximation of the dusty-gas model for H2-H20 system, except in the case of high current density, low H2 concentration and low porosity, where only the D G M is recommended. For the CO-CO2 system, there is no simple rule for selecting an alternate model to DGM. Depending on the CO concentration, porosity and current density, the FM or the SMM could be used. The only restriction is for small porosities where only the D G M should be used. This paper also demonstrated that only the D G M is recommended for a multicomponent system ( H 2 - H 2 0 - C O -
C02). 05/00899 Phase behavior applications of SAFT based equations of state - from associating fluids to polydisperse, polar copolymers Chapman, W. G. et al. Fluid Phase Equilibria, 2004, 217, (2), 137-143. The statistical associating fluid theory (SAFT) equation of state has been shown to accurately predict the effects of molecular weight, intermolecular association, and compressibility on the phase behaviour of mixtures containing solvents, monomers, and polymers. This paper briefly reviews the physical basis for the SAFT approach and present recent extensions of the equation of state. An advantage of theoretically based equations of state is that the theory can be systematically improved to address weaknesses or to extend the theory to more complex fluid systems. Recent developments beyond SAFT allow the prediction of the effects of multiple polar groups on the phase behaviour of polar copolymers, model the effects of intramolecular association, and efficiently calculate phase equilibrium for polydisperse polymer solutions. These points are illustrated through comparisons with phase equilibria data for monomers, solvents, and copolymer systems.
05•00900 Phase-equilibrium calculations for n-alkane + alkanol systems using continuous thermodynamics Browarzik, D. Fluid Phase Equilibria, 2004, 217, (2), 125-135. A new association model based on continuous thermodynamics is introduced and applied to six systems of the type n-alkane (n-hexane, nheptane, n-octane) + alkanol (methanol, ethanol). The alkanol is considered to be a mixture of chain associates with the composition described by a continuous distribution function. This distribution function is derived as an analytical expression from the mass action law applied to the association equilibrium. To consider the entropie contribution originating from the size differences of the molecules (associates) activity coefficients based on Flory-Huggins model are included in the mass action law. Unlike the molecular-mass distribution of a polymer the chain-length distribution of the associates depends on the temperature and on the mole fraction of the alkanol. The treatment of vapour-liquid equilibrium and liquid-liquid equilibrium is similar to that of an oil system or of a polymer solution using continuous thermodynamics. Different to other chemical models of association there is no additive split into a physical and a chemical contribution. The equilibrium constants of association were fitted to vapour-pressure data of methanol and ethanol. The model needs only one interaction
130
Fuel and Energy Abstracts March 2005
parameter being independent of temperature and taking the same value for all systems studied. Considering the simplicity of the model, both the liquid-liquid equilibrium of the three methanol systems and the vapour-liquid equilibrium of all six systems are predicted with reasonable accuracy.
05/00901 Prediction of liquid-liquid interfacial tension in multi-component systems Bahramian, A. and Danesh, A. Fluid Phase Equilibria, 2004, 221, (1-2), 197-205. An equation for prediction of liquid-liquid interracial tension (IFT) in multi-component systems has been developed using the lattice theory and the regular solution assumptions. The equation does not include any empirical parameter and there is no limitation on the number of components comprising the system. The reliability of the equation has been evaluated by comparing its prediction with experimental data and other methods.
05100902 Preparation and characterization of supported H3PW12040 on silica gel: a potential catalyst for green chemistry processes Dias, J. et al. Catalysis Today, 2004, 85, (1), 39-48. The solid acidity of 12-tungstophosphoric acid (H3PW) supported on silica gel has been measured by calorimetry and adsorption in liquidphase using pyridine as probe. The results indicate a strong interaction of H3PW with silica, forming a weaker catalyst (AH1 = -27.9 kcal toolcompared to AH1 = -32.7 kcat tool -1 for pure H3PW). However, there is an increased amount of total titrated protons (sites) for the supported acid, which shows good dispersion of H3PW over silica. The original low surface area of H3PW, which implies a small amount of protons available on the surface, is improved by supporting on silica, and their protons become considerably exposed over SiO2 surface. The dispersion of H3PW on silica was estimated from X R D pattern, and it decreases with acid content. FTIR spectra of supported H3PW-SiO2 reacted with pyridine have shown the characteristic bands of Br6nsted acid-type for the strongest site, and a weaker hydrogen-bonded acidtype. FTIR spectra of mechanical mixtures of H3PW are similar to the supported samples, thus this method cannot distinguish these materials. X R D characteristics can promptly differentiate between supported H3PW on silica and mechanical mixtures.
05/00903
Principles of failure probability assessment (PoF)
Giribone, R. and Valette, B. International Journal of Pressure Vessels and Piping, 2004, 81, (10-11), 797-806. This abstract presents a method for computing probability of failure (PoF) that is the method integrating the so-called 'Bayesian approach'. PoF along with the assessment of the consequences of failure are required when it comes to assessing 'risks'. More and more frequently in modern industries the trend is to rely on the use of risk-based approaches for the scheduling of the inspection of static pressure vessels. Equipment PoF is the main driver for scheduling periodical inspections. Within the Bayesian approach, it is expected that the performance of inspection, provided effective techniques are used, increases the knowledge on equipment condition and provides confidence in the planning of future inspections. This paper describes the theoretical principles yielding to the calculation of the PoF prior to conduct an inspection and after its performance. PoF calculation within risk-based inspection (RBI) planning is one of the aspects covered by the E U project called 'RIMAP' (Risk-Based Inspection and Maintenance Procedure). PoF calculation using Bayes theorem is the cornerstone of the RBI methodology described in American Petroleum Institute reference 'API 581'.
05•00904 Procedure for determination of combustion relevant data of combustible materials planned for energy generation Marzi, T. and Moehle, E. Ger. Often. DE 10,202,119 (C1. G01N33/22), 14 Aug 2003, Appl. 10,202,119. (In German) This invention concerns a procedure for determining data for combustible materials. In the initial step, the combustible material (e.g. biomass) is thermally decomposed under a lack of oxygen. Subsequently resulting gaseous products are subjected to a complete oxidation by heating, the oxidation products are conventionally detected, and the type and amount of liberated combustion- and pyrolysis products and/or the heat value of the produced fuel gases and/or gasification products are concluded from the detection results and/or >1 of the liberated C-, N-, S-, and H-containing decomposition products are quantity detected and/or the residue is subjected to the thermal decomposition under oxidative conditions, and where the formed CO2 is quantity detected. The detection is done by using IR measuring cells and/or mass spectrometers.
05/00905 Quality based energy contents and carbon coefficients for building materials: a systems approach Dias, W. P. S. and Pooliyadda, S. P. Energy, 2004, 29, (4), 561-580.
05/00888 Modeling of recent volcanic episodes at Phlegrean Fields (Italy): geochemical variations and ground deformation Todesco, M. et al. Geothermics, 2004, 33, (4), 531-547. The Phlegrean Fields is an active caldera structure, located on the periphery of Naples (Italy). After the last eruptive event (the Monte Nuovo eruption in 1538), periodic episodes of unrest have characterized the evolution of this volcanic district, involving seismic activity and slow ground motion (bradyseism). During these episodes of unrest, some remarkable changes have also affected the composition of the hydrothermal fluids discharged at La Solfatara fumarolic field. These unrest phenomena result from the complex interaction between magma chamber, hydrothermal fluid circulation, and country rocks undergoing thermal and mechanical stresses. In order to make an effective hazard assessment in such a densely populated area as the Phlegrean Fields, a better understanding is needed of the mechanism driving bradyseismic activity and determine the relation between ground deformation and hydrothermal fluid circulation. In this work, the results are presented of numerical modelling of both the hydrothermal fluid circulation at La Solfatara, and of its effects on rock deformation. The modelling results show that periods of intensified magmatic degassing can explain many features of the recent crises of unrest at Phlegrean Fields.
05/00889 Modeling the liquid-phase oxidation of hydrocarbons over a range of temperatures and dissolved oxygen concentrations with pseudo-detailed chemical kinetics Kuprowicz, N. J. et al. Fuel, 2004, 83, (13), 1795-1801. The ability of pseudo-detailed chemical kinetic modelling to simulate the oxidation behaviour of Exxsol D-80, a paraffin blend whose oxidative characteristics are representative of severely hydrotreated jet fuels, is assessed. The effects of temperature and initial dissolved 02 concentration on oxidation are considered. A 17-step pseudo-detailed mechanism is shown to provide reasonable simulations of Exxsol D-80 oxidation over a range of temperatures, but not over a range of initial dissolved Oz concentrations. The addition of alkyl-peroxy radical isomerization to the pseudo-detailed mechanism did not reconcile the initial dissolved Oz limitation. With the addition of a peroxy radical decomposition reaction to the original 17-step pseudo-detailed mechanism, reasonable simulations of Exxsol D-80 oxidation over a range of temperatures and initial dissolved O2 concentrations were obtained. Analysis of the rate parameters associated with peroxy radical decomposition suggests that aromatic hydrocarbons play a significant role in the oxidation of fuels, even at low (<1% by weight) aromatic levels.
05/00890 Modelling floor heating systems using a validated two-dimensional ground-coupled numerical model Weitzmann, P. et al. Building and Environment, 2005, 40, (2), 153-I63. This paper presents a two-dimensional simulation model of the heat losses and temperatures in a slab on grade floor with floor heating which is able to dynamically model the floor heating system. The aim of this work is to be able to model, in detail, the influence from the floor construction and foundation on the performance of the floor heating system. The ground-coupled floor-heating model is validated against measurements from a single-family house. The simulation model is coupled to a whole-building energy simulation model with inclusion of heat losses and heat supply to the room above the floor. This model can be used to design energy efficient houses with floor heating focusing on the heat loss through the floor construction and foundation. It is found that it is important to model the dynamics of the floor heating system to find the correct heat loss to the ground, and further, that the foundation has a large impact on the energy consumption of buildings heated by floor heating. Consequently, this detail should be in focus when designing houses with floor heating.
05/00891 Monte Carlo based operational and shutdown dose rate calculations of HT-7U tokamak Chert, Y. et al. Fusion Engineering and Design, 2004, 70, (2), 155-162. The superconducting tokamak HT-7U will perform D - D plasma experiments and the production rate of 2.45 MeV neutrons will achieve the level of 1015n/s. The dose rates during operation and after shutdown of HT-7U have been calculated based on a detailed threedimensional model with the Monte Carlo code MCNP-4C, the
inventory code FISPACT and the FENDL-2 nuclear data library. The so-called R2S method was used to perform the shutdown dose rate analyses. The results confirm that personnel access into the tokamak hall must be prohibited during operation. In addition the results show that the dose rate level near the outer wall of the tokamak hall slightly exceeds the dose limit. Additional shielding may be required. The shutdown dose rates of various experimental campaigns have been calculated and the waiting times for personnel access into the hall have been assessed. The results indicate that the in-vessel components of HT-7U will be considerably activated by neutrons and the shutdown dose rate level around the machine after long D - D plasma discharges is serious within a certain range of cooling time regarding the maintenance work.
05/00892 Monte Carlo importance sampling optimization for system reliability applications Campioni, L. and Vestrucci, P. Annals of Nuclear Energy, 2004, 31, (9), 1005-1025. This paper focuses on the reliability analysis of multi-component systems by the importance sampling technique, and, in particular, it tackles the optimization aspect. A methodology based on the minimization of the variance at the component level is proposed for the class of systems consisting of independent components. The claim is that, by means of such a methodology, the optimal biasing could be achieved without resorting to the typical approach by trials.
05/00893 Neutron kinetics of fluid-fuel systems by the quasi-static method Dulla, S. et al. Annals of Nuclear Energy, 2004, 31, (15), 1709 1733. The quasi-static method for the neutron kinetics of nuclear reactors is generalized for application to neutron multiplying systems fuelled by a fluid multiplying material, typically a mixture of fissile molten salts. The method is derived by the application of faetorization formulae for both the neutron density and the delayed precursor concentrations and the projection of the balance equations upon a weighting function. A physically meaningful weight can be assumed as the solution of the adjoint model, which is constructed for the situation considered, including delayed neutrons. The quasi-static scheme is then applied to calculations of some transients for a typical configuration of a moltensalt reactor, in a multigroup diffusion model with a one-dimensional slug-flow velocity field. The physical features associated to the motion of the fissile material are highlighted.
05100894 New brittle fracture model for the European pressure vessel standard Sandstr6m, R. et al. International Journal of Pressure Vessels and Piping, 2004, 81, (10 11), 837-845. A model for design against brittle failure based on recent fracture mechanics findings is proposed. The procedure is an update of that in the recent European pressure vessel standard EN 13445. The thickness dependence of the maximum permissible crack has been analysed with the help of research on non-destructive testing. Cracks with a quarter thickness depth are assumed to be readily detectable for larger gauges. For thinner gauges the cracks have to cover a larger fraction of the thickness to be safely observed. The model is verified by comparison to fracture mechanics test data for high strength steels. Results from individual wide plate tests are successfully reproduced by the model. Furthermore, T100 values (the temperature where Kjc = 100 MPa m 1/2) for test series are conservatively predicted by the model. The model adequately describes the influence of thickness and heat treatment on the T~00 values.
05•00895
On-line signal trend identification
Tambouratzis, T. and Antonopoulos-Domis, M. Annals of Nuclear Energy, 2004, 31, (14), 1541-1553. An artificial neural network, based on the self-organizing map, is proposed for on-line signal trend identification. Trends are categorized at each incoming signal as steady-state, increasing and decreasing, while they are further classified according to characteristics such signal shape and rate of change. Tests with model-generated signals illustrate the ability of the self-organizing map to accurately and reliably perform on-line trend identification in terms of both detection and classification. The proposed methodology has been found robust to the presence of white noise.
05100896 Optimal configuration and performance for a generalized Carnot cycle assuming the heat-transfer law Q oc (~DT) m Chen, L. et al. Applied Energy, 2004, 78, (3), 305-313. The finite-time thermodynamic performance of a generalized Carnot cycle, in which the heat transfer between the working fluid and the heat reservoirs obeys a generalized law Q oc (AD T)m, is studied. The optimal configuration and the fundamental optimal relation between power
Fuel and Energy Abstracts March 2005 129
16 Fuel science and technology (fundamental science, analysis, instrumentation) output and efficiency of the cycle are derived. Some special examples are discussed. The results can provide some theoretical guidance for the design of practical engines.
05•00897 Optimisation of ISI interval using genetic algorithms for risk informed in-service inspection Vinod, G. et al. Reliability Engineering & System Safety, 2004, 86, (3), 307-316. Risk informed in-service inspection (RI-ISI) aims at prioritizing the components for inspection within the permissible risk_ level thereby avoiding unnecessary inspections. Various constraints such as risk level, radiation exposure to the workers and cost of inspections are encountered, while planning the inspection programme. This problem has been attempted to solve using genetic algorithms, which has already established its suitability in optimizing surveillance and maintenance activities in nuclear power plants. The paper describes the application of genetic algorithm in optimizing the ISI of feeders, which are large in number and also fall in the same inspection category.
05•00898 Performance comparison of Fick's, dusty-gas and Stefan-Maxwell models to predict the concentration overpotential of a SOFC anode Suwanwarangkul, R. et al. Journal of Power Sources, 2003, 122, (1), 9 18. Models for mass transport inside a porous SOFC anode were developed based on Fick's model (FM), the dusty-gas model (DGM) and the Stefan-Maxwell model (SMM) to predict the concentration overpotential. All models were validated with experimental data for H2-HeO-Ar and CO-CO2 systems. The effect of pore size on all model predictions was discussed. It was concluded that the dusty-gas model is the most appropriate model to simulate gas transport phenomena inside a SOFC anode. However, this model requires numerical solution, whereas Fick's and Stefan-Maxwell's do not. It was found that the SMM, rather than the FM, is a good approximation of the dusty-gas model for H2-H20 system, except in the case of high current density, low H2 concentration and low porosity, where only the D G M is recommended. For the CO-CO2 system, there is no simple rule for selecting an alternate model to DGM. Depending on the CO concentration, porosity and current density, the FM or the SMM could be used. The only restriction is for small porosities where only the D G M should be used. This paper also demonstrated that only the D G M is recommended for a multicomponent system ( H 2 - H 2 0 - C O -
C02). 05/00899 Phase behavior applications of SAFT based equations of state - from associating fluids to polydisperse, polar copolymers Chapman, W. G. et al. Fluid Phase Equilibria, 2004, 217, (2), 137-143. The statistical associating fluid theory (SAFT) equation of state has been shown to accurately predict the effects of molecular weight, intermolecular association, and compressibility on the phase behaviour of mixtures containing solvents, monomers, and polymers. This paper briefly reviews the physical basis for the SAFT approach and present recent extensions of the equation of state. An advantage of theoretically based equations of state is that the theory can be systematically improved to address weaknesses or to extend the theory to more complex fluid systems. Recent developments beyond SAFT allow the prediction of the effects of multiple polar groups on the phase behaviour of polar copolymers, model the effects of intramolecular association, and efficiently calculate phase equilibrium for polydisperse polymer solutions. These points are illustrated through comparisons with phase equilibria data for monomers, solvents, and copolymer systems.
05•00900 Phase-equilibrium calculations for n-alkane + alkanol systems using continuous thermodynamics Browarzik, D. Fluid Phase Equilibria, 2004, 217, (2), 125-135. A new association model based on continuous thermodynamics is introduced and applied to six systems of the type n-alkane (n-hexane, nheptane, n-octane) + alkanol (methanol, ethanol). The alkanol is considered to be a mixture of chain associates with the composition described by a continuous distribution function. This distribution function is derived as an analytical expression from the mass action law applied to the association equilibrium. To consider the entropie contribution originating from the size differences of the molecules (associates) activity coefficients based on Flory-Huggins model are included in the mass action law. Unlike the molecular-mass distribution of a polymer the chain-length distribution of the associates depends on the temperature and on the mole fraction of the alkanol. The treatment of vapour-liquid equilibrium and liquid-liquid equilibrium is similar to that of an oil system or of a polymer solution using continuous thermodynamics. Different to other chemical models of association there is no additive split into a physical and a chemical contribution. The equilibrium constants of association were fitted to vapour-pressure data of methanol and ethanol. The model needs only one interaction
130
Fuel and Energy Abstracts March 2005
parameter being independent of temperature and taking the same value for all systems studied. Considering the simplicity of the model, both the liquid-liquid equilibrium of the three methanol systems and the vapour-liquid equilibrium of all six systems are predicted with reasonable accuracy.
05/00901 Prediction of liquid-liquid interfacial tension in multi-component systems Bahramian, A. and Danesh, A. Fluid Phase Equilibria, 2004, 221, (1-2), 197-205. An equation for prediction of liquid-liquid interracial tension (IFT) in multi-component systems has been developed using the lattice theory and the regular solution assumptions. The equation does not include any empirical parameter and there is no limitation on the number of components comprising the system. The reliability of the equation has been evaluated by comparing its prediction with experimental data and other methods.
05100902 Preparation and characterization of supported H3PW12040 on silica gel: a potential catalyst for green chemistry processes Dias, J. et al. Catalysis Today, 2004, 85, (1), 39-48. The solid acidity of 12-tungstophosphoric acid (H3PW) supported on silica gel has been measured by calorimetry and adsorption in liquidphase using pyridine as probe. The results indicate a strong interaction of H3PW with silica, forming a weaker catalyst (AH1 = -27.9 kcal toolcompared to AH1 = -32.7 kcat tool -1 for pure H3PW). However, there is an increased amount of total titrated protons (sites) for the supported acid, which shows good dispersion of H3PW over silica. The original low surface area of H3PW, which implies a small amount of protons available on the surface, is improved by supporting on silica, and their protons become considerably exposed over SiO2 surface. The dispersion of H3PW on silica was estimated from X R D pattern, and it decreases with acid content. FTIR spectra of supported H3PW-SiO2 reacted with pyridine have shown the characteristic bands of Br6nsted acid-type for the strongest site, and a weaker hydrogen-bonded acidtype. FTIR spectra of mechanical mixtures of H3PW are similar to the supported samples, thus this method cannot distinguish these materials. X R D characteristics can promptly differentiate between supported H3PW on silica and mechanical mixtures.
05/00903
Principles of failure probability assessment (PoF)
Giribone, R. and Valette, B. International Journal of Pressure Vessels and Piping, 2004, 81, (10-11), 797-806. This abstract presents a method for computing probability of failure (PoF) that is the method integrating the so-called 'Bayesian approach'. PoF along with the assessment of the consequences of failure are required when it comes to assessing 'risks'. More and more frequently in modern industries the trend is to rely on the use of risk-based approaches for the scheduling of the inspection of static pressure vessels. Equipment PoF is the main driver for scheduling periodical inspections. Within the Bayesian approach, it is expected that the performance of inspection, provided effective techniques are used, increases the knowledge on equipment condition and provides confidence in the planning of future inspections. This paper describes the theoretical principles yielding to the calculation of the PoF prior to conduct an inspection and after its performance. PoF calculation within risk-based inspection (RBI) planning is one of the aspects covered by the E U project called 'RIMAP' (Risk-Based Inspection and Maintenance Procedure). PoF calculation using Bayes theorem is the cornerstone of the RBI methodology described in American Petroleum Institute reference 'API 581'.
05•00904 Procedure for determination of combustion relevant data of combustible materials planned for energy generation Marzi, T. and Moehle, E. Ger. Often. DE 10,202,119 (C1. G01N33/22), 14 Aug 2003, Appl. 10,202,119. (In German) This invention concerns a procedure for determining data for combustible materials. In the initial step, the combustible material (e.g. biomass) is thermally decomposed under a lack of oxygen. Subsequently resulting gaseous products are subjected to a complete oxidation by heating, the oxidation products are conventionally detected, and the type and amount of liberated combustion- and pyrolysis products and/or the heat value of the produced fuel gases and/or gasification products are concluded from the detection results and/or >1 of the liberated C-, N-, S-, and H-containing decomposition products are quantity detected and/or the residue is subjected to the thermal decomposition under oxidative conditions, and where the formed CO2 is quantity detected. The detection is done by using IR measuring cells and/or mass spectrometers.
05/00905 Quality based energy contents and carbon coefficients for building materials: a systems approach Dias, W. P. S. and Pooliyadda, S. P. Energy, 2004, 29, (4), 561-580.