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discrete simulation of controlled atmosphere (CA) cool storage systems: validation using industrial CA cool storage
10 Space heating and cooling/heat pumps This paper reports on the results obtained in the study of the cocombustion of PVC with hard coal from South Africa in a 0,5 MWth Bubbling Fluidized Bed Boiler. The research has included the study of the effect of combustion temperature, fluidization velocity and PVC content. The addition of urea to the raw fuel, as a dioxin-preventing compound has also been evaluated. Results have been analysed in terms of combustion efficiency, major pollutants emission (NOx, CO), and PCDD/Fs formation in the flue gas and in the fly ash. Under the experimental conditions tested, co-combustion of coal and PVC has proved to be feasible from the combustion efficiency and emission of PCDD/Fs points of view, whose levels remained below limits set by existing legislation on persistent organic pollutants. The addition of solid urea to the fuel blend reduces the amount of chlorinated compounds emitted. However, it has a negative impact on nitrogen pollutants formation.
06•01272 Simulation and experiment of segregating/mixing of rice husk-sand mixture in a bubbling fluidized bed Sun, Q. et al. Fuel, 2005, 84, (14 15), 1739 1748. The fluidization behaviour of rice husk sand mixture in the gas bubbling fluidized bed is experimentally and theoretically studied. The relevancy of the pressure drop profile of rice h u s ~ s a n d mixture to the definition of its minimum fluidization velocity is discussed, and the minimum fluidization velocity of rice husk sand binary mixture is determined. The distributions of mass fraction of rice husk particles along the bed height are measured, and the profiles of the mean particle diameter of mixture are determined. A multi-fluid gas solid flow model is presented where equations are derived from the kinetic theory of granular flow. Separate transport equations are constructed for each of the particle classes, allowing for the interaction between particle classes, as well as the momentum and energy are exchanged between the respective classes and the carrier gas. The distributions of the mass fraction of rice husk particles and the mean particle diameter of binary mixture are predicted. The numerical results are analysed, and compared with experimental data.
06•01273 The relationship between the tendency of lignites to agglomerate and their fusion characteristics in a fluidized bed combustor Atakfil, H. et al. Fuel Processing Technology, 2005, 86, (12 13), 1369 1383. Agglomeration temperatures of six lignite ashes were measured in a laboratory scale fluidized bed of quartz sand. The results were compared with the characteristic temperatures of the lignite ashes. The agglomeration temperatures of the burning lignites were determined by measuring the active bed temperature and pressure drop across the bed. The results show that, in such a fluidized bed, agglomeration can begin at temperatures well below the ash fusion temperature. For the six lignites tested, agglomeration started at 860 1060°C, which is about 125 200°C lower than their initial ash deformation temperatures and 300 400°C lower than their ash fusion temperatures. Considering the fact that burning particles in a fluidized bed are 150 200°C hotter than the bed, the results suggest that lignite ashes can agglomerate at temperature levels about the initial deformation temperature. Although the agglomeration tendency appears to decrease with increasing ash initial deformation or fusion temperatures, no meaningful correlation was found, at least for the lignite ashes tested, between the agglomeration and characteristic ash temperatures. In the fluidized bed combustor burning lignites, agglomeration temperature of ashes decreases with Na20 content and increases with A120 3 content. Fluidized bed combustor, on the other hand, becomes more vulnerable to agglomeration as the total basic oxide content of bed inventory increases.
06101274 Thermal aspects of a circulating fluidized bed with air staging Koksal, M. et al. International Journal of Energy Research, 2005, 29, (10), 923 935. In this study, effects of air staging on wall-to-bed heat transfer were investigated in a laboratory scale circulating fluidized bed (0.23 m ID, 7.6 m high). The bed was operated under ambient conditions with silica sand particles (dp= 89 ~tm, Pp=2650 kg m 3). Two different designs of secondary air (SA) injectors were used for air staging: radial and tangential. Bed-to-wall heat transfer measurements were carried out at three elevations above the SA injection port. The results indicate that similar to non-SA operation, the heat transfer with air staging depends strongly on the cross-sectional average suspension density. Tangential secondary injection was found to increase the bed-to-wall heat transfer above the SA injection port significantly due to increased suspension density compared with non-SA operation.
06101275 Wind tunnel simulation on re-circulation of aircooled condensers of a power plant Gu, Z. et al. Journal of Wind Engineering and Industrial Aerodynamics, 2005, 93, (6), 509 520.
The criteria as well as the methods and measurements of wind tunnel simulation on wind effects on air-cooled condensers in a power plant were discussed. The parameter of re-circulation was suggested to describe the wind effects on the efficiency of the condenser. The result of practical project models shows that great wind effects of both wind speed and the angle of the incident flow on the efficiency of the condenser. It is recommended that in the initial stage of a new or an extension power plant, which is equipped with an air-cooled system, the wind tunnel simulation is necessary and helpful. Combined with the local wind climate data, a more reasonable, economic and safety schematic design of a power plant could be achieved.
06•01276 Effect of used edible oils in coal fluidised bed gasification Pinto, F. et al. Fuel, 2005, 84, (17), 2236 2247. Edible oil wastes (EOW) are generally used in the production of soap and/or disposed in waste water treatment stations. In Europe, their use for energy is almost exclusively for the production of biodiesel. However, the nature and quality of EOW may turn their use for biodiesel not always suitable. Therefore, for environmental reasons, it is important to investigate other options like co-gasification with coal. Gasification is generally considered more environmentally friendly and its impact is considerably less polluting than other thermochemical processes. Co-gasification requires that synergy exists between coal and EOW to take profit of their complementary advantages. Co-gasification runs were undertaken on a bench-scale atmospheric fluidized bed gasifier, using both steam and air-steam mixtures as gasification medium. Operating conditions like gasification temperature, steam/ air ratio and oil content in feedstock blends were varied to check their effect with the aim of optimizing the gasification process. Some difficulties in feeding the blend of coal with EO W were observed when the oil content increased, which also raised hydrocarbons content in the gas produced. Both the rise of temperature and of air flow rate allowed lower tars and gaseous hydrocarbons concentrations. Higher gas yields were obtained at higher gasification temperatures, the gas being richer in hydrogen content at the expense of hydrocarbons. Solid residues (ashes and char) produced by gasification of blends of coal and EOW were also analysed to understand their nature and to evaluate their impact on the environment.
l0
SPACE HEATING A N D COOLING/HEAT PUMPS
06101277 A continuous/discrete simulation of controlled atmosphere (CA) cool storage systems: evaluation of plant performance/design and product quality evolution Nahor, H. B. et al. International Journal qfRefrigeration, 2005, 28, (4), 471 480. As an application of the CA cool storage simulation model developed and validated earlier, the implications of different product loading strategies (batch-wise and step-wise) on the product quality, mechanical plants performance and design aspects were investigated by considering a hypothetical CA cool storage facility. The batch-wise product loading was found to be advantageous with regards to firmness loss of the produce but was marginally energy intensive over the stepwise product loading strategy. Moreover, the step-wise loading scheme required low capacity individual evaporators and higher plant capacity of the gas-handling unit (N2 generator and CO2 scrubber), as compared to the batch-wise product loading. It was demonstrated that using the model, appraisal of the implication of practical industrial operational procedures such as product loading strategy, on product quality and plant performance/design was possible, owing to the discrete continuous modelling approach.
06101278 A continuous/discrete simulation of controlled atmosphere (CA) cool storage systems: validation using industrial CA cool storage Nahor, H. B. et al. International Journal of Refrigeration, 2005, 28, (4), 461 470. In this paper, a controlled atmosphere storage model, developed earlier, is validated using an industrial CA cool storage facility with stepwise product loading strategy. The proposed combined continuous and discrete CA cool storage simulation model was able to represent the step response transients and continuous events, with accuracy less than the observed variability or at best with accuracy level as set by the measurement instrument. Moreover, the handling of discrete/continuous events enabled the implementation of practical operational procedures and to investigate their implication on plant performance/ design and directly on the product quality. The model is a valid working
Fuel and Energy Abstracts
May 2006
191
10 Space heating and cooling~heat pumps model for design and optimization of CA cool storage facilities both with respect to plant performance and final quality of the stored product.
06•01279 A study on a porous residential building model in hot and humid regions: Part 1 - the natural ventilation performance and the cooling load reduction effect of the building model Hirano, T. et al. Building and Environment, 2006, 41, (1), 21 32. This study targets environmental load reduction in hot and humid regions. It reveals the effects that porous residential buildings have on the natural ventilation performance and, consequently, the cooling load reduction. Two residential building models, namely a model with a void ratio of 0% and a model with a void ratio of 50%, are evaluated using computational fluid dynamics (CFD) analysis and thermal and airflow network analysis. The analysis on components of the heat load indicates that improvements in the natural ventilation performance would significantly reduce the cooling load.
06•01280
An open oscillatory heat pipe water pump
Dobson, R. T. Applied Thermal Engineering, 2005, 25, (4), 603 621. The use of an open oscillatory heat pipe (or open pulsating heat pipe) for pumping water is considered, as the need to pump water in rural areas remains a primary requirement in developing rural areas. A possible design for the pump is given and has been constructed and tested and the pumping results are reported. A mathematical model whereby the pump may be theoretically simulated and its performance calculated is also given. The theoretical model is shown to reflect the complex non-linear behaviour of such a pump and a sensitivity analysis is conducted. Experimental flow rates of typically 0.2 mg/s at a pumping height of 100 mm were obtained. The simulation model calculated mechanical and theoretical efficiencies of 3% and 0.03% respectively. An experimentally determined thermal efficiency in the order of 0.00003% was obtained. It is concluded that unless the low pumping flow rates and pumping height limitations can be overcome that it is unlikely that an open oscillatory heat pipe water pump will be suitable for pumping the relatively large quantities of water required for agricultural purposes.
06•01281 Analysis on energy consumption of water-loop heat pump system in China Lian, Z. et al. Applied Thermal Engineering, 2005, 25, (1), 73 85. Annual energy consumption of water-loop heat pump system (WLHPS) and conventional air conditioning system (CACS) is compared and analysed when they are applied in different representative cities in China, respectively. The results show that, if coal-burning boiler is used as the heat source, the WLHPS does not have any effect of energy saving, but it has distinct effect under appropriate condition if electric boiler is used. Considering the other affecting factors, the system can be applied in most areas in China, especially along the Coast of Yangtze River and its northern parts.
06•01282 Application of the control methods for radiant floor cooling system in residential buildings Lim, J.-H. et al. Building and Environment, 2006, 41, (1), 60 73. In applying radiant floor cooling, its control system must prevent the floor surface condensation in hot and humid weather conditions. With no additional dehumidification system, only the radiant floor cooling system prevents floor condensation. In this case, the effects of the control of the cooling system on the indoor conditions can be changed because of the thermal inertia of the systems. Also different types of control system can be composed according to the control methods, which can affect the construction cost in the design stage. Therefore, the control methods for the radiant cooling system with respect to floor surface condensation must be studied. Furthermore, because Korean people's lifestyle involves sitting on the floor, it is necessary to evaluate if a floor cooling system will influence the thermal comfort of the occupants. This study intends to clarify the control methods of the radiant floor cooling system and to analyse the control performance and applicability of each control method with regard to the floor surface condensation and comfort by computer simulations and experiments on the control methods of the radiant floor cooling system. The results of computer simulations and experiments show that water temperature control is better than water flow control with respect to temperature fluctuations in controlling room air temperature. To prevent floor surface condensation, the supply water temperature could be manipulated according to the dew point temperature in the most humid room, and in individual rooms, the water flow rate (on/off control) can be controlled. Also, the results of radiant cooling experiments show that the floor surface temperature remained above 21°C, the temperature difference among surfaces remained below 6°C, and the vertical air temperature difference remained below 1.9°C, conforming well to comfort standards.
192
Fuel and Energy Abstracts
May 2006
06•01283 Artificial neural networks applications in building energy predictions and a case study for tropical climates Yalcintas, M. and Akkurt, S. International Journal qf Energy Research, 2005, 29, (10), 891 901. This study presents artificial neural network (ANN) methods in building energy use predictions. Applications of the ANN methods in energy audits and energy savings predictions due to building retrofits are emphasized. A generalized ANN model that can be applied to any building type with minor modifications would be a very useful tool for building engineers. ANN methods offer faster learning time, simplicity in analysis and adaptability to seasonal climate variations and changes in the building's energy use when compared to other statistical and simulation models. The model herein is presented for predicting chiller plant energy use in tropical climates with small seasonal and daily variations. It was successfully created based on both climatic and chiller data. The average absolute training error for the model was 9.7% while the testing error was 10.0%. This indicates that the model can successfully predict the particular chiller energy consumption in a tropical climate.
06•01284 Building and experimentation of a solar powered adsorption refrigerator Lemmini, F. and Errougani, A. Renewable Energy, 2005, 30, (13), 1989 2003. A solar powered adsorption refrigerator using the pair activated carbon AC35-methanol is presented in this paper. It has been built and tested in the solar laboratory of the faculty of sciences of Rabat. Rabat is a site of Morocco with a Mediterranean climate. Description of the different elements of the unit is given. Experimental results show that such refrigerator, simply fabricated, gives promising results and could be used in developing countries where there is a growing interest in refrigeration.
06•01285 CEPHEUS results: measurements and occupants' satisfaction provide evidence for Passive Houses being an option for sustainable building Schnieders, J. and Hermelink, A. Energy Policy, 2006, 34, (2), 151 171. Passive houses offer extended living comfort with only 15 20% of the space heating demand of conventional new buildings while the extra costs of this standard are only about 10% of the total building costs. In the first part of this paper, detailed measurements for 11 'Passive House' projects with more than 100 dwelling units from the EU-funded demonstration project CEPHEUS (Cost Efficient Passive Houses as EUropean Standards) are presented. All projects exhibit extraordinarily low space heat consumptions. Compared with ordinary, newly erected buildings, 80% of the space heat consumption could be saved. The total primary energy consumption (including household electricity) was less than 50% of that of conventional new buildings. The measurements show that the buildings also offer comfortable indoor conditions in both summer and winter. Several social research studies revealed that the users are well pleased with their homes. The second part of the paper focuses on low-income tenant's satisfaction in the world's first multi-story Passive Houses in Kassel, Germany. This building contrasts sharply with the 'standard' Passive House, occupied by its owners. A 2.5 year study was conducted from spring of 2000 to autumn of 2002. The development of opinions, attitudes, behaviour, and satisfaction over time could be recorded. The building is a clear success, the tenant's satisfaction is high. It is concluded that this building type fulfils the conditions of sustainability in social, ecological and economic respects and should therefore be disseminated on a larger scale. To this end, the last part of the paper describes the development of the Passive House standard in Germany, Austria and Switzerland, from the first demonstration project in 1991 to about 3500 dwelling units today. The prerequisites for this development are analysed. Finally, the authors give their view about the political possibilities for pushing Passive Houses into the market as well as for stimulating a market pull for this comfortable and energy efficient building type.
06•01286 Characteristics of a series-connected twoevaporator refrigerating system Li, C.-J. and Su, C.-C. Applied Thermal Engineering, 2005, 25, (4), 519 532. Based on the Buckingham Pi theorem, this study derives the dimensionless correlations to characterize a series-connected twoevaporator refrigerating system with propane (R-290) as the refrigerant. Experimental data are substituted into the correlations to demonstrate the most relevant factors. Simplified correlations are then obtained. The analytical results show that the mass flow rate of refrigerant (mr) is primarily affected by the condensing pressure, length of the high-temperature capillary tube, and the subcooling of refrigerant, while the heat transfer coefficients of refrigerant in the evaporators (hcH and hCL) are affected by the condensing pressure and the logarithmic-mean temperature difference of the specific evaporator. However, hcH and hCL are also affected by the lengths of the low-
06•01272 Simulation and experiment of segregating/mixing of rice husk-sand mixture in a bubbling fluidized bed Sun, Q. et al. Fuel, 2005, 84, (14 15), 1739 1748. The fluidization behaviour of rice husk sand mixture in the gas bubbling fluidized bed is experimentally and theoretically studied. The relevancy of the pressure drop profile of rice h u s ~ s a n d mixture to the definition of its minimum fluidization velocity is discussed, and the minimum fluidization velocity of rice husk sand binary mixture is determined. The distributions of mass fraction of rice husk particles along the bed height are measured, and the profiles of the mean particle diameter of mixture are determined. A multi-fluid gas solid flow model is presented where equations are derived from the kinetic theory of granular flow. Separate transport equations are constructed for each of the particle classes, allowing for the interaction between particle classes, as well as the momentum and energy are exchanged between the respective classes and the carrier gas. The distributions of the mass fraction of rice husk particles and the mean particle diameter of binary mixture are predicted. The numerical results are analysed, and compared with experimental data.
06•01273 The relationship between the tendency of lignites to agglomerate and their fusion characteristics in a fluidized bed combustor Atakfil, H. et al. Fuel Processing Technology, 2005, 86, (12 13), 1369 1383. Agglomeration temperatures of six lignite ashes were measured in a laboratory scale fluidized bed of quartz sand. The results were compared with the characteristic temperatures of the lignite ashes. The agglomeration temperatures of the burning lignites were determined by measuring the active bed temperature and pressure drop across the bed. The results show that, in such a fluidized bed, agglomeration can begin at temperatures well below the ash fusion temperature. For the six lignites tested, agglomeration started at 860 1060°C, which is about 125 200°C lower than their initial ash deformation temperatures and 300 400°C lower than their ash fusion temperatures. Considering the fact that burning particles in a fluidized bed are 150 200°C hotter than the bed, the results suggest that lignite ashes can agglomerate at temperature levels about the initial deformation temperature. Although the agglomeration tendency appears to decrease with increasing ash initial deformation or fusion temperatures, no meaningful correlation was found, at least for the lignite ashes tested, between the agglomeration and characteristic ash temperatures. In the fluidized bed combustor burning lignites, agglomeration temperature of ashes decreases with Na20 content and increases with A120 3 content. Fluidized bed combustor, on the other hand, becomes more vulnerable to agglomeration as the total basic oxide content of bed inventory increases.
06101274 Thermal aspects of a circulating fluidized bed with air staging Koksal, M. et al. International Journal of Energy Research, 2005, 29, (10), 923 935. In this study, effects of air staging on wall-to-bed heat transfer were investigated in a laboratory scale circulating fluidized bed (0.23 m ID, 7.6 m high). The bed was operated under ambient conditions with silica sand particles (dp= 89 ~tm, Pp=2650 kg m 3). Two different designs of secondary air (SA) injectors were used for air staging: radial and tangential. Bed-to-wall heat transfer measurements were carried out at three elevations above the SA injection port. The results indicate that similar to non-SA operation, the heat transfer with air staging depends strongly on the cross-sectional average suspension density. Tangential secondary injection was found to increase the bed-to-wall heat transfer above the SA injection port significantly due to increased suspension density compared with non-SA operation.
06101275 Wind tunnel simulation on re-circulation of aircooled condensers of a power plant Gu, Z. et al. Journal of Wind Engineering and Industrial Aerodynamics, 2005, 93, (6), 509 520.
The criteria as well as the methods and measurements of wind tunnel simulation on wind effects on air-cooled condensers in a power plant were discussed. The parameter of re-circulation was suggested to describe the wind effects on the efficiency of the condenser. The result of practical project models shows that great wind effects of both wind speed and the angle of the incident flow on the efficiency of the condenser. It is recommended that in the initial stage of a new or an extension power plant, which is equipped with an air-cooled system, the wind tunnel simulation is necessary and helpful. Combined with the local wind climate data, a more reasonable, economic and safety schematic design of a power plant could be achieved.
06•01276 Effect of used edible oils in coal fluidised bed gasification Pinto, F. et al. Fuel, 2005, 84, (17), 2236 2247. Edible oil wastes (EOW) are generally used in the production of soap and/or disposed in waste water treatment stations. In Europe, their use for energy is almost exclusively for the production of biodiesel. However, the nature and quality of EOW may turn their use for biodiesel not always suitable. Therefore, for environmental reasons, it is important to investigate other options like co-gasification with coal. Gasification is generally considered more environmentally friendly and its impact is considerably less polluting than other thermochemical processes. Co-gasification requires that synergy exists between coal and EOW to take profit of their complementary advantages. Co-gasification runs were undertaken on a bench-scale atmospheric fluidized bed gasifier, using both steam and air-steam mixtures as gasification medium. Operating conditions like gasification temperature, steam/ air ratio and oil content in feedstock blends were varied to check their effect with the aim of optimizing the gasification process. Some difficulties in feeding the blend of coal with EO W were observed when the oil content increased, which also raised hydrocarbons content in the gas produced. Both the rise of temperature and of air flow rate allowed lower tars and gaseous hydrocarbons concentrations. Higher gas yields were obtained at higher gasification temperatures, the gas being richer in hydrogen content at the expense of hydrocarbons. Solid residues (ashes and char) produced by gasification of blends of coal and EOW were also analysed to understand their nature and to evaluate their impact on the environment.
l0
SPACE HEATING A N D COOLING/HEAT PUMPS
06101277 A continuous/discrete simulation of controlled atmosphere (CA) cool storage systems: evaluation of plant performance/design and product quality evolution Nahor, H. B. et al. International Journal qfRefrigeration, 2005, 28, (4), 471 480. As an application of the CA cool storage simulation model developed and validated earlier, the implications of different product loading strategies (batch-wise and step-wise) on the product quality, mechanical plants performance and design aspects were investigated by considering a hypothetical CA cool storage facility. The batch-wise product loading was found to be advantageous with regards to firmness loss of the produce but was marginally energy intensive over the stepwise product loading strategy. Moreover, the step-wise loading scheme required low capacity individual evaporators and higher plant capacity of the gas-handling unit (N2 generator and CO2 scrubber), as compared to the batch-wise product loading. It was demonstrated that using the model, appraisal of the implication of practical industrial operational procedures such as product loading strategy, on product quality and plant performance/design was possible, owing to the discrete continuous modelling approach.
06101278 A continuous/discrete simulation of controlled atmosphere (CA) cool storage systems: validation using industrial CA cool storage Nahor, H. B. et al. International Journal of Refrigeration, 2005, 28, (4), 461 470. In this paper, a controlled atmosphere storage model, developed earlier, is validated using an industrial CA cool storage facility with stepwise product loading strategy. The proposed combined continuous and discrete CA cool storage simulation model was able to represent the step response transients and continuous events, with accuracy less than the observed variability or at best with accuracy level as set by the measurement instrument. Moreover, the handling of discrete/continuous events enabled the implementation of practical operational procedures and to investigate their implication on plant performance/ design and directly on the product quality. The model is a valid working
Fuel and Energy Abstracts
May 2006
191
10 Space heating and cooling~heat pumps model for design and optimization of CA cool storage facilities both with respect to plant performance and final quality of the stored product.
06•01279 A study on a porous residential building model in hot and humid regions: Part 1 - the natural ventilation performance and the cooling load reduction effect of the building model Hirano, T. et al. Building and Environment, 2006, 41, (1), 21 32. This study targets environmental load reduction in hot and humid regions. It reveals the effects that porous residential buildings have on the natural ventilation performance and, consequently, the cooling load reduction. Two residential building models, namely a model with a void ratio of 0% and a model with a void ratio of 50%, are evaluated using computational fluid dynamics (CFD) analysis and thermal and airflow network analysis. The analysis on components of the heat load indicates that improvements in the natural ventilation performance would significantly reduce the cooling load.
06•01280
An open oscillatory heat pipe water pump
Dobson, R. T. Applied Thermal Engineering, 2005, 25, (4), 603 621. The use of an open oscillatory heat pipe (or open pulsating heat pipe) for pumping water is considered, as the need to pump water in rural areas remains a primary requirement in developing rural areas. A possible design for the pump is given and has been constructed and tested and the pumping results are reported. A mathematical model whereby the pump may be theoretically simulated and its performance calculated is also given. The theoretical model is shown to reflect the complex non-linear behaviour of such a pump and a sensitivity analysis is conducted. Experimental flow rates of typically 0.2 mg/s at a pumping height of 100 mm were obtained. The simulation model calculated mechanical and theoretical efficiencies of 3% and 0.03% respectively. An experimentally determined thermal efficiency in the order of 0.00003% was obtained. It is concluded that unless the low pumping flow rates and pumping height limitations can be overcome that it is unlikely that an open oscillatory heat pipe water pump will be suitable for pumping the relatively large quantities of water required for agricultural purposes.
06•01281 Analysis on energy consumption of water-loop heat pump system in China Lian, Z. et al. Applied Thermal Engineering, 2005, 25, (1), 73 85. Annual energy consumption of water-loop heat pump system (WLHPS) and conventional air conditioning system (CACS) is compared and analysed when they are applied in different representative cities in China, respectively. The results show that, if coal-burning boiler is used as the heat source, the WLHPS does not have any effect of energy saving, but it has distinct effect under appropriate condition if electric boiler is used. Considering the other affecting factors, the system can be applied in most areas in China, especially along the Coast of Yangtze River and its northern parts.
06•01282 Application of the control methods for radiant floor cooling system in residential buildings Lim, J.-H. et al. Building and Environment, 2006, 41, (1), 60 73. In applying radiant floor cooling, its control system must prevent the floor surface condensation in hot and humid weather conditions. With no additional dehumidification system, only the radiant floor cooling system prevents floor condensation. In this case, the effects of the control of the cooling system on the indoor conditions can be changed because of the thermal inertia of the systems. Also different types of control system can be composed according to the control methods, which can affect the construction cost in the design stage. Therefore, the control methods for the radiant cooling system with respect to floor surface condensation must be studied. Furthermore, because Korean people's lifestyle involves sitting on the floor, it is necessary to evaluate if a floor cooling system will influence the thermal comfort of the occupants. This study intends to clarify the control methods of the radiant floor cooling system and to analyse the control performance and applicability of each control method with regard to the floor surface condensation and comfort by computer simulations and experiments on the control methods of the radiant floor cooling system. The results of computer simulations and experiments show that water temperature control is better than water flow control with respect to temperature fluctuations in controlling room air temperature. To prevent floor surface condensation, the supply water temperature could be manipulated according to the dew point temperature in the most humid room, and in individual rooms, the water flow rate (on/off control) can be controlled. Also, the results of radiant cooling experiments show that the floor surface temperature remained above 21°C, the temperature difference among surfaces remained below 6°C, and the vertical air temperature difference remained below 1.9°C, conforming well to comfort standards.
192
Fuel and Energy Abstracts
May 2006
06•01283 Artificial neural networks applications in building energy predictions and a case study for tropical climates Yalcintas, M. and Akkurt, S. International Journal qf Energy Research, 2005, 29, (10), 891 901. This study presents artificial neural network (ANN) methods in building energy use predictions. Applications of the ANN methods in energy audits and energy savings predictions due to building retrofits are emphasized. A generalized ANN model that can be applied to any building type with minor modifications would be a very useful tool for building engineers. ANN methods offer faster learning time, simplicity in analysis and adaptability to seasonal climate variations and changes in the building's energy use when compared to other statistical and simulation models. The model herein is presented for predicting chiller plant energy use in tropical climates with small seasonal and daily variations. It was successfully created based on both climatic and chiller data. The average absolute training error for the model was 9.7% while the testing error was 10.0%. This indicates that the model can successfully predict the particular chiller energy consumption in a tropical climate.
06•01284 Building and experimentation of a solar powered adsorption refrigerator Lemmini, F. and Errougani, A. Renewable Energy, 2005, 30, (13), 1989 2003. A solar powered adsorption refrigerator using the pair activated carbon AC35-methanol is presented in this paper. It has been built and tested in the solar laboratory of the faculty of sciences of Rabat. Rabat is a site of Morocco with a Mediterranean climate. Description of the different elements of the unit is given. Experimental results show that such refrigerator, simply fabricated, gives promising results and could be used in developing countries where there is a growing interest in refrigeration.
06•01285 CEPHEUS results: measurements and occupants' satisfaction provide evidence for Passive Houses being an option for sustainable building Schnieders, J. and Hermelink, A. Energy Policy, 2006, 34, (2), 151 171. Passive houses offer extended living comfort with only 15 20% of the space heating demand of conventional new buildings while the extra costs of this standard are only about 10% of the total building costs. In the first part of this paper, detailed measurements for 11 'Passive House' projects with more than 100 dwelling units from the EU-funded demonstration project CEPHEUS (Cost Efficient Passive Houses as EUropean Standards) are presented. All projects exhibit extraordinarily low space heat consumptions. Compared with ordinary, newly erected buildings, 80% of the space heat consumption could be saved. The total primary energy consumption (including household electricity) was less than 50% of that of conventional new buildings. The measurements show that the buildings also offer comfortable indoor conditions in both summer and winter. Several social research studies revealed that the users are well pleased with their homes. The second part of the paper focuses on low-income tenant's satisfaction in the world's first multi-story Passive Houses in Kassel, Germany. This building contrasts sharply with the 'standard' Passive House, occupied by its owners. A 2.5 year study was conducted from spring of 2000 to autumn of 2002. The development of opinions, attitudes, behaviour, and satisfaction over time could be recorded. The building is a clear success, the tenant's satisfaction is high. It is concluded that this building type fulfils the conditions of sustainability in social, ecological and economic respects and should therefore be disseminated on a larger scale. To this end, the last part of the paper describes the development of the Passive House standard in Germany, Austria and Switzerland, from the first demonstration project in 1991 to about 3500 dwelling units today. The prerequisites for this development are analysed. Finally, the authors give their view about the political possibilities for pushing Passive Houses into the market as well as for stimulating a market pull for this comfortable and energy efficient building type.
06•01286 Characteristics of a series-connected twoevaporator refrigerating system Li, C.-J. and Su, C.-C. Applied Thermal Engineering, 2005, 25, (4), 519 532. Based on the Buckingham Pi theorem, this study derives the dimensionless correlations to characterize a series-connected twoevaporator refrigerating system with propane (R-290) as the refrigerant. Experimental data are substituted into the correlations to demonstrate the most relevant factors. Simplified correlations are then obtained. The analytical results show that the mass flow rate of refrigerant (mr) is primarily affected by the condensing pressure, length of the high-temperature capillary tube, and the subcooling of refrigerant, while the heat transfer coefficients of refrigerant in the evaporators (hcH and hCL) are affected by the condensing pressure and the logarithmic-mean temperature difference of the specific evaporator. However, hcH and hCL are also affected by the lengths of the low-