The Experts below are selected from a list of 246 Experts worldwide ranked by ideXlab platform
Fengkun Wang - One of the best experts on this subject based on the ideXlab platform.
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determination of the optimum Heat Rejection pressure in transcritical cycles working with r744 r290 mixture
Applied Thermal Engineering, 2013Co-Authors: Xinzhe Zhang, Fengkun WangAbstract:Abstract The simulation and experimental investigations have been carried out to research the relationships between optimum Heat Rejection pressure and related operating parameters for a transcritical system using R744/R290 mixture as a refrigerant. The system is characterised by two expansion valves in series in order to conveniently control the Heat Rejection pressure. A cycle simulation code has been developed, and the simulation results reveal that for a transcritical cycle working with R744/R290 mixture in which the R744 mass fraction is greater than 0.78, there is an optimal Heat Rejection pressure, under which a maximum system coefficient of performance (COP) can be reached. Furthermore, the researches in this work show that the optimal Heat Rejection pressure mainly depends on the mass fraction, the outlet refrigerant temperature of the gas cooler, the evaporation temperature whereas the superHeat degree and the performance of the given compressor have weak effects on the optimum Heat Rejection pressure. Based on the orthogonal experimental simulation data, a correlation of the optimal Heat Rejection pressure with respect to mainly involved parameters is obtained under the specific conditions. The experimental data of optimal Heat Rejection pressure are in a relatively good agreement with the simulation results.
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Determination of the optimum Heat Rejection pressure in transcritical cycles working with R744/R290 mixture
Applied Thermal Engineering, 2013Co-Authors: Xinzhe Zhang, Fengkun WangAbstract:Abstract The simulation and experimental investigations have been carried out to research the relationships between optimum Heat Rejection pressure and related operating parameters for a transcritical system using R744/R290 mixture as a refrigerant. The system is characterised by two expansion valves in series in order to conveniently control the Heat Rejection pressure. A cycle simulation code has been developed, and the simulation results reveal that for a transcritical cycle working with R744/R290 mixture in which the R744 mass fraction is greater than 0.78, there is an optimal Heat Rejection pressure, under which a maximum system coefficient of performance (COP) can be reached. Furthermore, the researches in this work show that the optimal Heat Rejection pressure mainly depends on the mass fraction, the outlet refrigerant temperature of the gas cooler, the evaporation temperature whereas the superHeat degree and the performance of the given compressor have weak effects on the optimum Heat Rejection pressure. Based on the orthogonal experimental simulation data, a correlation of the optimal Heat Rejection pressure with respect to mainly involved parameters is obtained under the specific conditions. The experimental data of optimal Heat Rejection pressure are in a relatively good agreement with the simulation results.
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theoretical and experimental studies on optimum Heat Rejection pressure for a co2 Heat pump system
Applied Thermal Engineering, 2010Co-Authors: Xingxing Zhang, Fengkun Wang, H G ShenAbstract:Abstract The experimental and simulation researches have been conducted to investigate the relationships between optimum Heat Rejection pressure and other related operating parameters for a transcritical CO 2 Heat pump system with two throttle valves. It proved that it is relatively reliable to control the Heat Rejection pressure of the CO 2 system with two expansion valves in series. The experimental results also show similar trends with those from simulation, under widely different operating conditions. Thus both the simulation and experimental results meet here: for a transcritical CO 2 cycle, there exists an optimal Heat Rejection pressure, under which the system can reach the maximum Heating coefficient of performance (COP). Furthermore, the research also reveals that the optimal Heat Rejection pressure mainly depends on the refrigerant outlet temperature of gas cooler whereas the evaporating temperature and the performance of the given compressor have smaller effect on the optimum Heat Rejection pressure. Based on the experimental data, a correlation of the optimal Heat Rejection pressure with respect to mainly involved parameters is obtained for specific conditions.
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Experimental study of optimum Heat Rejection pressure for a CO2 Heat pump water Heater
2010 5th IEEE Conference on Industrial Electronics and Applications, 2010Co-Authors: Xianping Zhang, Fengkun Wang, Ma QiangAbstract:As an environmentally friendly refrigerant, CO2 is seen as one of the best fluids for a Heat pump water Heater application system. To investigate the relationships between optimum Heat Rejection pressure and other related operating parameters, an experimental research has been conducted for a transcritical CO2 Heat pump water Heater with two throttling valves. It proved that it is relatively reliable to control the Heat Rejection pressure of the CO2 system with two throttling valves; there exists an optimal Heat Rejection pressure, under which the system can reach the maximum Heating coefficient of performance. Meanwhile, the research also reveals that the optimal Heat Rejection pressure chiefly depends on the outlet refrigerant temperature of the gas cooler, and in the next place, the evaporating temperature; on the other hand, the superHeat degree of CO2 at the inlet of the compressor was found to have little to do with the optimum Heat Rejection pressure.
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Experimental study of optimum Heat Rejection pressure for a CO 2 Heat pump water Heater
2010 5th IEEE Conference on Industrial Electronics and Applications, 2010Co-Authors: Xianping Zhang, Fengkun Wang, Ma QiangAbstract:As an environmentally friendly refrigerant, CO 2 is seen as one of the best fluids for a Heat pump water Heater application system. To investigate the relationships between optimum Heat Rejection pressure and other related operating parameters, an experimental research has been conducted for a transcritical CO 2 Heat pump water Heater with two throttling valves. It proved that it is relatively reliable to control the Heat Rejection pressure of the CO 2 system with two throttling valves; there exists an optimal Heat Rejection pressure, under which the system can reach the maximum Heating coefficient of performance. Meanwhile, the research also reveals that the optimal Heat Rejection pressure chiefly depends on the outlet refrigerant temperature of the gas cooler, and in the next place, the evaporating temperature; on the other hand, the superHeat degree of CO 2 at the inlet of the compressor was found to have little to do with the optimum Heat Rejection pressure.
Ruben Pesch - One of the best experts on this subject based on the ideXlab platform.
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Heat Rejection and primary energy efficiency of solar driven absorption cooling systems
International Journal of Refrigeration-revue Internationale Du Froid, 2012Co-Authors: Ursula Eicker, Dirk Pietruschka, Ruben PeschAbstract:Abstract Efficient Heat Rejection is crucial for the overall primary energy balance of sorption systems, as it dominates the auxiliary energy consumption. Low ratios of cooling power to auxiliary electricity of 3.0 or less are still common in sorption system, so that the primary energy efficiency is not always higher than for conventional compression chillers. Whereas dry Heat Rejection systems require electricity for fan operation, hybrid or wet cooling systems in addition need pumping energy for the cooling water and the water itself. The energy efficiency can be improved for Heat Rejection to the ground, where only pumping energy is needed for the geothermal Heat exchange. Dynamic simulation models were used for a single effect absorption chiller powered by solar thermal collectors via a hot storage tank. The chiller models were coupled to a three dimensional numerical ground Heat exchanger model or to cooling tower models. The models were validated with operating data of a 15 kW solar cooling system installed in an office building. Primary energy efficiency ratios were determined for different Heat Rejection systems and improved control strategies were developed. The installed system primary energy ratios varied between 1.1 and 2.2 for auxiliary Heating and between 1.2 and 2.5 for auxiliary cooling depending on the Heat Rejection and control strategy chosen. The low electrical energy consumption of the geothermal Heat Rejection saves 30% of auxiliary electricity and results in an electrical coefficient of performance of 13. The maximum primary energy ratios for solar fractions up to 88% are 2.7 for auxiliary Heating and 3.2 for auxiliary cooling, i.e. nearly three times higher than for the reference electrical compression system of 1.2.
Xiangzhao Meng - One of the best experts on this subject based on the ideXlab platform.
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experimental investigation of the optimal Heat Rejection pressure for a transcritical co2 Heat pump water Heater
Applied Thermal Engineering, 2013Co-Authors: Pengcheng Qi, Yaling He, Xiaolin Wang, Xiangzhao MengAbstract:Abstract The system performance of a transcritical CO 2 Heat pump is significantly influenced by the Heat Rejection pressure due to the nature of the transcritical refrigeration cycle. It has received wide attention in the scientific community. In this article, an experimental investigation of the optimal Heat Rejection pressure for a transcritical CO 2 Heat pump water Heater is presented. It is found that the optimal Heat Rejection pressure varies with gas-cooler outlet refrigeration temperature at different ambient temperatures. The further experimental results show that the Coefficient of Performance (COP) at the optimal Heat Rejection pressure decreases substantially with increasing gas-cooler outlet refrigeration temperature in a range from 25 to 45 °C. Based on the experimental data, a simple correlation of the optimal Heat Rejection pressure in terms of gas-cooler outlet refrigeration temperature is obtained. The analysis shows that the deviation of the correlation is within ±5%, and the predicted COP at the optimal Heat Rejection pressure is within 6%.
Xinzhe Zhang - One of the best experts on this subject based on the ideXlab platform.
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determination of the optimum Heat Rejection pressure in transcritical cycles working with r744 r290 mixture
Applied Thermal Engineering, 2013Co-Authors: Xinzhe Zhang, Fengkun WangAbstract:Abstract The simulation and experimental investigations have been carried out to research the relationships between optimum Heat Rejection pressure and related operating parameters for a transcritical system using R744/R290 mixture as a refrigerant. The system is characterised by two expansion valves in series in order to conveniently control the Heat Rejection pressure. A cycle simulation code has been developed, and the simulation results reveal that for a transcritical cycle working with R744/R290 mixture in which the R744 mass fraction is greater than 0.78, there is an optimal Heat Rejection pressure, under which a maximum system coefficient of performance (COP) can be reached. Furthermore, the researches in this work show that the optimal Heat Rejection pressure mainly depends on the mass fraction, the outlet refrigerant temperature of the gas cooler, the evaporation temperature whereas the superHeat degree and the performance of the given compressor have weak effects on the optimum Heat Rejection pressure. Based on the orthogonal experimental simulation data, a correlation of the optimal Heat Rejection pressure with respect to mainly involved parameters is obtained under the specific conditions. The experimental data of optimal Heat Rejection pressure are in a relatively good agreement with the simulation results.
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Determination of the optimum Heat Rejection pressure in transcritical cycles working with R744/R290 mixture
Applied Thermal Engineering, 2013Co-Authors: Xinzhe Zhang, Fengkun WangAbstract:Abstract The simulation and experimental investigations have been carried out to research the relationships between optimum Heat Rejection pressure and related operating parameters for a transcritical system using R744/R290 mixture as a refrigerant. The system is characterised by two expansion valves in series in order to conveniently control the Heat Rejection pressure. A cycle simulation code has been developed, and the simulation results reveal that for a transcritical cycle working with R744/R290 mixture in which the R744 mass fraction is greater than 0.78, there is an optimal Heat Rejection pressure, under which a maximum system coefficient of performance (COP) can be reached. Furthermore, the researches in this work show that the optimal Heat Rejection pressure mainly depends on the mass fraction, the outlet refrigerant temperature of the gas cooler, the evaporation temperature whereas the superHeat degree and the performance of the given compressor have weak effects on the optimum Heat Rejection pressure. Based on the orthogonal experimental simulation data, a correlation of the optimal Heat Rejection pressure with respect to mainly involved parameters is obtained under the specific conditions. The experimental data of optimal Heat Rejection pressure are in a relatively good agreement with the simulation results.
Ma Qiang - One of the best experts on this subject based on the ideXlab platform.
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Experimental study of optimum Heat Rejection pressure for a CO2 Heat pump water Heater
2010 5th IEEE Conference on Industrial Electronics and Applications, 2010Co-Authors: Xianping Zhang, Fengkun Wang, Ma QiangAbstract:As an environmentally friendly refrigerant, CO2 is seen as one of the best fluids for a Heat pump water Heater application system. To investigate the relationships between optimum Heat Rejection pressure and other related operating parameters, an experimental research has been conducted for a transcritical CO2 Heat pump water Heater with two throttling valves. It proved that it is relatively reliable to control the Heat Rejection pressure of the CO2 system with two throttling valves; there exists an optimal Heat Rejection pressure, under which the system can reach the maximum Heating coefficient of performance. Meanwhile, the research also reveals that the optimal Heat Rejection pressure chiefly depends on the outlet refrigerant temperature of the gas cooler, and in the next place, the evaporating temperature; on the other hand, the superHeat degree of CO2 at the inlet of the compressor was found to have little to do with the optimum Heat Rejection pressure.
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Experimental study of optimum Heat Rejection pressure for a CO 2 Heat pump water Heater
2010 5th IEEE Conference on Industrial Electronics and Applications, 2010Co-Authors: Xianping Zhang, Fengkun Wang, Ma QiangAbstract:As an environmentally friendly refrigerant, CO 2 is seen as one of the best fluids for a Heat pump water Heater application system. To investigate the relationships between optimum Heat Rejection pressure and other related operating parameters, an experimental research has been conducted for a transcritical CO 2 Heat pump water Heater with two throttling valves. It proved that it is relatively reliable to control the Heat Rejection pressure of the CO 2 system with two throttling valves; there exists an optimal Heat Rejection pressure, under which the system can reach the maximum Heating coefficient of performance. Meanwhile, the research also reveals that the optimal Heat Rejection pressure chiefly depends on the outlet refrigerant temperature of the gas cooler, and in the next place, the evaporating temperature; on the other hand, the superHeat degree of CO 2 at the inlet of the compressor was found to have little to do with the optimum Heat Rejection pressure.
