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02228 Experimental evaluation of prototype thermoelectric domestic-refrigerators[
10 Space heating and cooling/heat pumps obtained. The effect of building materials on the temperature and heat flux for the building envelope has been evaluated by calculating the temperature and heat flux for three buildings built with different building materials. The results show that the highest relative error in heat flux among the three envelopes built with various non-insulation material is 27.8%, which indicates the thermal conductivity of the building materials is an important factor of the heat transfer of the envelope.
06102225 Energy sustainable development through energy efficient heating devices and buildings Boji6, M. International Journal of Nuclear Governance, Economy and Ecology, 2006, 1, (1), 35 51. Energy devices and buildings are sustainable if, when they operate, they use sustainable (renewable and refuse) energy and generate negaenergy. This paper covers research examples of this type of sustainability: (1) use of air-to-earth heat exchangers, (2) computer control of heating and cooling of the building (via heat pumps and heat-recovery devices), and (3) design control of energy consumption in a house.
06•02226 wall
Entrainment of refrigerated air curtains down a
Field, B. S. and Loth, E. Experimental Thermal and Fluid Science, 2006, 30, (3), 175 184. Refrigerated air curtains are used in open supermarket display cases as a barrier between the warm ambient air and the cold refrigerated air. Entrainment of ambient air into the curtain by shear layer mixing contributes to both the sensible and the latent heat load on the display case. To better understand the fluid dynamics which govern entrainment, velocity and temperature measurements of the curtains were made in a refrigerated display case, which was modified to allow a more fundamental flow. In particular, a vertical solid wall was installed to approximately represent a fully-stocked configuration. As such, negatively-buoyant wall jets (with high inflow turbulence) in the Reynolds number range of 4200-8000 and in the Richardson number range of 0.13-0.58 were examined. To define the air curtain vortex structures, flow visualization of the curtain interface was employed. The results of which showed that the entrainment of the ambient air was found to be governed by a variety of eddy engulfing structures. Particle image velocimetry was used to examine the velocity profiles of the air curtains in a non-intrusive manner, the measurements of which indicated negatively-buoyant acceleration following the jet exhaust, followed by a more linear curtain growth characteristic of isothermal wall jets. In addition, thermocouples were used to obtain the net increase in temperature of the curtain due to entrainment, where it was found that the dimensionless thermal energy loss decreased with decreasing Reynolds number.
06/02227 Experimental analysis of R22 and R407c flow through electronic expansion valve Zhang, C. et al. Energy Conversion and Management, 2006, 47, (5), 529544. The objective of this study is to present test results and to develop a dimensionless correlation on the basis of experimental data to predict the mass flow rate of R22 and its alternative refrigerant R407c through an electronic expansion valve (EEV). The mass flow rate was measured at a series of condensing temperatures, evaporating temperatures and degrees of subcooling at the EEV inlet with five opening setting degrees of the EEV. The experimental results were analysed, and it was found that the operation condition, flow area and the thermophysical properties of the refrigerant would affect the mass flow rate through the EEV. A new correlation based on the Buckingham ~ theorem was developed to predict the mass flow rate of refrigerants through the EEV. The relative deviations of the predicted value by using this correlation are from -10.74% to 9.26% for R22 and from 14.20% to 22.10% for R407c. The average deviations and standard deviations are -0.79% and 5.02% for R22 and 0.67% and 8.08% for R407c, respectively. The relative deviation was analysed in terms of the operation condition and flow area of the EEV. This correlation can be used to predict the mass flow rate through EEVs whose largest flow area is less than 2.544 mm 2.
06•02228 Experimental evaluation of prototype thermoelectric domestic-refrigerators Min, G. et al. Applied Energy, 2006, 83, (2), 133 152. A number of prototype thermoelectric refrigerators are investigated and their cooling performances evaluated in terms of the coefficient-ofperformance, heat-pumping capacity and cooling-down rate. The coefficient-of-performance of a thermoelectric refrigerator is found to be around 0.3-0.5 for a typical operating temperature at 5°C with ambient at 25°C. The potential improvement in the cooling performance of a thermoelectric refrigerator is also investigated employing a realistic model, with experimental data obtained from this work. The
results show that an increase in its COP is possible through improvements in module contact resistances, thermal interfaces and the effectiveness of heat exchangers.
06/02229 Experimental investigation of a C02 automotive air conditioner Liu, H. et al. International Journal of ReJ?igeration, 2005, 28, (8), 12931301. In this study, a carbon dioxide automotive air conditioner prototype was designed and constructed. The compressor was of swash plate design; the gas cooler and evaporator were made of fin-tubes; a manual expansion valve and an internal heat exchanger accumulator were used. The lubricant, the carbon dioxide charge, the evaporator outlet pressure, the compressor speed, the air inlet temperature and flow rate of the gas cooler and the air flow rate of the evaporator were varied and the performance of the prototype was experimentally investigated in detail. The cooling capacity, compressor power consumption, carbon dioxide mass flow rate, and COP value were analysed. The experimental results showed that the carbon dioxide system performance was greatly affected by different lubricants; the carbon dioxide system performance was sensitive to the mass charge: the high side pressure affected the system performance greatly and a high side pressure controller was needed.
06•02230 Experimental study on automotive cooling and heating air conditioning system using C02 as a refrigerant Tamura, T. et al. International Journal of Refrigeration, 2005, 28, (8), 1302 1307. Recently, as one of the countermeasures against the global warming and energy conservation problems, natural refrigerants such as carbon dioxide are now paid attention as substitutes for HFCs in automotive air conditioning systems. Also, in recent years because the heat release from the eco-car's engine decreases, there is a problem that the present automotive heating air conditioning system cannot provide sufficient heating capacity. As an alternative approach, the authors focused on a solution utilizing a carbon dioxide-based heat pump, whereby the waste heat from the heat pump cycle during dehumidification of the incoming air (referred to as the dehumidifying condition) is recovered and used as an auxiliary heat source instead of an electric heater. Based on this concept, the aim was to develop an effective automotive cooling and heating air conditioning system using carbon dioxide as a refrigerant. As the result, a prototype carbon dioxide automotive cooling and heating air conditioning system for medium-sized cars was successfully developed. With this system, performance superior to that of the present HFC134a system can be achieved.
06•02231 Experimental study on the dynamic characteristics of adsorption heat pumps driven by intermittent heat source at heating mode Wang, D. et al. Applied Thermal Engineering, 2005, 25, (5 6). 927 940. The influence of intermittent heat source on adsorption heat pumps is an unavoidable problem when the system is put into practice. This work studies an adsorption heat pump system driven by intermittent waste heat supplied at 110°C and dynamic characteristics are obtained under eight working conditions with water temperature at about 41°C. The cycle time is 40 min including 120 s heat recovery time. This paper also gives the parameter variation regulations of the system driven by intermittent heat source. The experimental results show a decrease of specific heating power and coefficient of performance is up to 26% and 8.7%, respectively.
06/02232 Experimental unsteady characterization of heat transfer in a multi-layer wall including air layers application to vertically perforated bricks Lacarri6re, B. et al. Energy and Buildings, 2006, 38, (3), 232 237. Vertically perforated bricks were developed with a view to building environmentally friendly houses since they make insulating materials unnecessary. By an experimental approach, this study proposes to analyse the propagation of a temperature signal in this kind of brick, in order to characterize the thermal inertia of the brick. The steady-state knowledge is completed by the determination of properties like influence functions or characteristic depth concerned by a surface temperature variation. This allows to validate a simple unsteady surface model to be validated for this heterogeneous material which is classified as an insulating structural material. Furthermore, this study supplements the steady-state knowledge in local heat transfer through the air layers of the brick. Indeed, it is verified that convection heat transfer can be ignored in an unsteady heat transfer in this kind of brick, even in extreme conditions such as a sudden temperature fall.
Fuel and Energy Abstracts
September 2006 341
06102225 Energy sustainable development through energy efficient heating devices and buildings Boji6, M. International Journal of Nuclear Governance, Economy and Ecology, 2006, 1, (1), 35 51. Energy devices and buildings are sustainable if, when they operate, they use sustainable (renewable and refuse) energy and generate negaenergy. This paper covers research examples of this type of sustainability: (1) use of air-to-earth heat exchangers, (2) computer control of heating and cooling of the building (via heat pumps and heat-recovery devices), and (3) design control of energy consumption in a house.
06•02226 wall
Entrainment of refrigerated air curtains down a
Field, B. S. and Loth, E. Experimental Thermal and Fluid Science, 2006, 30, (3), 175 184. Refrigerated air curtains are used in open supermarket display cases as a barrier between the warm ambient air and the cold refrigerated air. Entrainment of ambient air into the curtain by shear layer mixing contributes to both the sensible and the latent heat load on the display case. To better understand the fluid dynamics which govern entrainment, velocity and temperature measurements of the curtains were made in a refrigerated display case, which was modified to allow a more fundamental flow. In particular, a vertical solid wall was installed to approximately represent a fully-stocked configuration. As such, negatively-buoyant wall jets (with high inflow turbulence) in the Reynolds number range of 4200-8000 and in the Richardson number range of 0.13-0.58 were examined. To define the air curtain vortex structures, flow visualization of the curtain interface was employed. The results of which showed that the entrainment of the ambient air was found to be governed by a variety of eddy engulfing structures. Particle image velocimetry was used to examine the velocity profiles of the air curtains in a non-intrusive manner, the measurements of which indicated negatively-buoyant acceleration following the jet exhaust, followed by a more linear curtain growth characteristic of isothermal wall jets. In addition, thermocouples were used to obtain the net increase in temperature of the curtain due to entrainment, where it was found that the dimensionless thermal energy loss decreased with decreasing Reynolds number.
06/02227 Experimental analysis of R22 and R407c flow through electronic expansion valve Zhang, C. et al. Energy Conversion and Management, 2006, 47, (5), 529544. The objective of this study is to present test results and to develop a dimensionless correlation on the basis of experimental data to predict the mass flow rate of R22 and its alternative refrigerant R407c through an electronic expansion valve (EEV). The mass flow rate was measured at a series of condensing temperatures, evaporating temperatures and degrees of subcooling at the EEV inlet with five opening setting degrees of the EEV. The experimental results were analysed, and it was found that the operation condition, flow area and the thermophysical properties of the refrigerant would affect the mass flow rate through the EEV. A new correlation based on the Buckingham ~ theorem was developed to predict the mass flow rate of refrigerants through the EEV. The relative deviations of the predicted value by using this correlation are from -10.74% to 9.26% for R22 and from 14.20% to 22.10% for R407c. The average deviations and standard deviations are -0.79% and 5.02% for R22 and 0.67% and 8.08% for R407c, respectively. The relative deviation was analysed in terms of the operation condition and flow area of the EEV. This correlation can be used to predict the mass flow rate through EEVs whose largest flow area is less than 2.544 mm 2.
06•02228 Experimental evaluation of prototype thermoelectric domestic-refrigerators Min, G. et al. Applied Energy, 2006, 83, (2), 133 152. A number of prototype thermoelectric refrigerators are investigated and their cooling performances evaluated in terms of the coefficient-ofperformance, heat-pumping capacity and cooling-down rate. The coefficient-of-performance of a thermoelectric refrigerator is found to be around 0.3-0.5 for a typical operating temperature at 5°C with ambient at 25°C. The potential improvement in the cooling performance of a thermoelectric refrigerator is also investigated employing a realistic model, with experimental data obtained from this work. The
results show that an increase in its COP is possible through improvements in module contact resistances, thermal interfaces and the effectiveness of heat exchangers.
06/02229 Experimental investigation of a C02 automotive air conditioner Liu, H. et al. International Journal of ReJ?igeration, 2005, 28, (8), 12931301. In this study, a carbon dioxide automotive air conditioner prototype was designed and constructed. The compressor was of swash plate design; the gas cooler and evaporator were made of fin-tubes; a manual expansion valve and an internal heat exchanger accumulator were used. The lubricant, the carbon dioxide charge, the evaporator outlet pressure, the compressor speed, the air inlet temperature and flow rate of the gas cooler and the air flow rate of the evaporator were varied and the performance of the prototype was experimentally investigated in detail. The cooling capacity, compressor power consumption, carbon dioxide mass flow rate, and COP value were analysed. The experimental results showed that the carbon dioxide system performance was greatly affected by different lubricants; the carbon dioxide system performance was sensitive to the mass charge: the high side pressure affected the system performance greatly and a high side pressure controller was needed.
06•02230 Experimental study on automotive cooling and heating air conditioning system using C02 as a refrigerant Tamura, T. et al. International Journal of Refrigeration, 2005, 28, (8), 1302 1307. Recently, as one of the countermeasures against the global warming and energy conservation problems, natural refrigerants such as carbon dioxide are now paid attention as substitutes for HFCs in automotive air conditioning systems. Also, in recent years because the heat release from the eco-car's engine decreases, there is a problem that the present automotive heating air conditioning system cannot provide sufficient heating capacity. As an alternative approach, the authors focused on a solution utilizing a carbon dioxide-based heat pump, whereby the waste heat from the heat pump cycle during dehumidification of the incoming air (referred to as the dehumidifying condition) is recovered and used as an auxiliary heat source instead of an electric heater. Based on this concept, the aim was to develop an effective automotive cooling and heating air conditioning system using carbon dioxide as a refrigerant. As the result, a prototype carbon dioxide automotive cooling and heating air conditioning system for medium-sized cars was successfully developed. With this system, performance superior to that of the present HFC134a system can be achieved.
06•02231 Experimental study on the dynamic characteristics of adsorption heat pumps driven by intermittent heat source at heating mode Wang, D. et al. Applied Thermal Engineering, 2005, 25, (5 6). 927 940. The influence of intermittent heat source on adsorption heat pumps is an unavoidable problem when the system is put into practice. This work studies an adsorption heat pump system driven by intermittent waste heat supplied at 110°C and dynamic characteristics are obtained under eight working conditions with water temperature at about 41°C. The cycle time is 40 min including 120 s heat recovery time. This paper also gives the parameter variation regulations of the system driven by intermittent heat source. The experimental results show a decrease of specific heating power and coefficient of performance is up to 26% and 8.7%, respectively.
06/02232 Experimental unsteady characterization of heat transfer in a multi-layer wall including air layers application to vertically perforated bricks Lacarri6re, B. et al. Energy and Buildings, 2006, 38, (3), 232 237. Vertically perforated bricks were developed with a view to building environmentally friendly houses since they make insulating materials unnecessary. By an experimental approach, this study proposes to analyse the propagation of a temperature signal in this kind of brick, in order to characterize the thermal inertia of the brick. The steady-state knowledge is completed by the determination of properties like influence functions or characteristic depth concerned by a surface temperature variation. This allows to validate a simple unsteady surface model to be validated for this heterogeneous material which is classified as an insulating structural material. Furthermore, this study supplements the steady-state knowledge in local heat transfer through the air layers of the brick. Indeed, it is verified that convection heat transfer can be ignored in an unsteady heat transfer in this kind of brick, even in extreme conditions such as a sudden temperature fall.
Fuel and Energy Abstracts
September 2006 341