The Experts below are selected from a list of 78111 Experts worldwide ranked by ideXlab platform
Yi Jiang - One of the best experts on this subject based on the ideXlab platform.
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simplified calculation for cooling Heating Capacity surface temperature distribution of radiant floor
Energy and Buildings, 2012Co-Authors: Lun Zhang, Yi JiangAbstract:Abstract Radiant floor is a low temperature Heating and high temperature cooling system. Three parameters, cooling/Heating Capacity of radiant floor, uniformity of surface temperature distribution, and the lowest temperature in surface, are concerned most by designers and users of radiant floor. A simplified calculation of these parameters is presented in this paper. The error between experiment results in literature and calculation of cooling Capacity and mean surface temperature is within 8% and 0.5 °C respectively. A simulation model is established to verify simplified calculation on surface temperature distribution. The absolute error between simulation value and calculation is within 0.2 °C. From the perspective of heat resistance, the most important limitation of cooling/Heating Capacity of radiant floor is heat transfer between floor surface and indoor environment. The thickness and heat conductivity of each layer has important influence on performance of radiant floor. The influence of water pipes should not be ignored.
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Simplified calculation for cooling/Heating Capacity, surface temperature distribution of radiant floor
Energy and Buildings, 2012Co-Authors: Lun Zhang, Yi JiangAbstract:Abstract Radiant floor is a low temperature Heating and high temperature cooling system. Three parameters, cooling/Heating Capacity of radiant floor, uniformity of surface temperature distribution, and the lowest temperature in surface, are concerned most by designers and users of radiant floor. A simplified calculation of these parameters is presented in this paper. The error between experiment results in literature and calculation of cooling Capacity and mean surface temperature is within 8% and 0.5 °C respectively. A simulation model is established to verify simplified calculation on surface temperature distribution. The absolute error between simulation value and calculation is within 0.2 °C. From the perspective of heat resistance, the most important limitation of cooling/Heating Capacity of radiant floor is heat transfer between floor surface and indoor environment. The thickness and heat conductivity of each layer has important influence on performance of radiant floor. The influence of water pipes should not be ignored.
Lun Zhang - One of the best experts on this subject based on the ideXlab platform.
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simplified calculation for cooling Heating Capacity surface temperature distribution of radiant floor
Energy and Buildings, 2012Co-Authors: Lun Zhang, Yi JiangAbstract:Abstract Radiant floor is a low temperature Heating and high temperature cooling system. Three parameters, cooling/Heating Capacity of radiant floor, uniformity of surface temperature distribution, and the lowest temperature in surface, are concerned most by designers and users of radiant floor. A simplified calculation of these parameters is presented in this paper. The error between experiment results in literature and calculation of cooling Capacity and mean surface temperature is within 8% and 0.5 °C respectively. A simulation model is established to verify simplified calculation on surface temperature distribution. The absolute error between simulation value and calculation is within 0.2 °C. From the perspective of heat resistance, the most important limitation of cooling/Heating Capacity of radiant floor is heat transfer between floor surface and indoor environment. The thickness and heat conductivity of each layer has important influence on performance of radiant floor. The influence of water pipes should not be ignored.
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Simplified calculation for cooling/Heating Capacity, surface temperature distribution of radiant floor
Energy and Buildings, 2012Co-Authors: Lun Zhang, Yi JiangAbstract:Abstract Radiant floor is a low temperature Heating and high temperature cooling system. Three parameters, cooling/Heating Capacity of radiant floor, uniformity of surface temperature distribution, and the lowest temperature in surface, are concerned most by designers and users of radiant floor. A simplified calculation of these parameters is presented in this paper. The error between experiment results in literature and calculation of cooling Capacity and mean surface temperature is within 8% and 0.5 °C respectively. A simulation model is established to verify simplified calculation on surface temperature distribution. The absolute error between simulation value and calculation is within 0.2 °C. From the perspective of heat resistance, the most important limitation of cooling/Heating Capacity of radiant floor is heat transfer between floor surface and indoor environment. The thickness and heat conductivity of each layer has important influence on performance of radiant floor. The influence of water pipes should not be ignored.
Wenxing Shi - One of the best experts on this subject based on the ideXlab platform.
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Performance analysis on compression-assisted absorption heat transformer: A new low-temperature Heating system with higher Heating Capacity under lower ambient temperature
Applied Thermal Engineering, 2018Co-Authors: Jian Wang, Baolong Wang, Wenxing ShiAbstract:Abstract With the acceleration of urbanization, the energy consumption of space Heating and domestic hot water has increased rapidly. Air source heat pump (ASHP), water source heat pump (WSHP) and absorption heat pump (AHP) have been widely used. However, when the ambient temperature decreases, the building Heating load increases gradually, while the Heating capacities of ASHP and air source AHP degrade quickly, and that of WSHP remains unchanged; this is detrimental for the selection and cost of Heating systems. Therefore, a new low-temperature Heating system with higher Heating Capacity under lower ambient air temperature is proposed here, meeting the ever-rising building Heating load. It is based on compression-assisted absorption heat transformer (CAHT), and its performance is analyzed under various parameters, including the ambient air temperature, the driving temperature and the Heating temperature. In addition, the cumulative electricity consumption of a Heating system, consisting of CAHT and WSHP, is calculated during the Heating periods in five Chinese cities. Consequently, both the Heating efficiency and Capacity of CAHT increase with the decrease of ambient temperature. And compared with WSHP and ASHP Heating systems in five cities, the energy-saving rates of CAHT Heating system are 2.02–24.88% and 36.65–57.28%, respectively.
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Experimental investigation on NH3–H2O compression-assisted absorption heat pump (CAHP) for low temperature Heating under lower driving sources
Applied Energy, 2016Co-Authors: Wenxing Shi, Jian Wang, Baolong WangAbstract:The absorption heat pump (AHP) Heating system is an efficient alternative to the conventional fuel-based Heating systems, with energy saving rate reaching 20–50%. However, the coefficient of performance (COP) and Heating Capacity of normal AHP decreased obviously as the available driving source temperature dropped. Compression-assisted AHP (CAHP) could operate efficiently under lower driving sources, and an experimental prototype was constructed for performance investigation. At an evaporator inlet of −10°C, as the generator inlet decreases from 130°C to 115°C, the COP changes from 1.442 to 1.271, while the Heating Capacity drops from 68.21kW to 31.28kW. At an increased evaporator inlet of −5°C, as the generator inlet decreases from 130°C to 110°C, the COP changes from 1.511 to 1.103, while the Heating Capacity drops from 78.72kW to 21.71kW. Comparisons between CAHP and normal AHP indicated that CAHP can extend the lower limit of generator inlet temperature from 125–130°C to 110–115°C. Besides, CAHP can enhance the Heating Capacity by 96.4% even when AHP can operate normally at a generator inlet of 130°C. Moreover, performance improvement contributed by CAHP is greater under lower-temperature driving sources.
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Experimental investigation on NH3–H2O compression-assisted absorption heat pump (CAHP) for low temperature Heating in colder conditions
International Journal of Refrigeration, 2016Co-Authors: Baolong Wang, Shang Sheng, Wenxing ShiAbstract:Abstract The coefficient of performance (COP) and Heating Capacity of the absorption heat pump (AHP) decreased obviously as the evaporator inlet temperature dropped. Compression-assisted AHP (CAHP) could operate efficiently in colder conditions, and a prototype was constructed for experimental investigation. At a generator inlet of 130 °C, as the evaporator inlet decreases from −5 °C to −25 °C, the COP drops from 1.513 to 1.372, while the Heating Capacity deteriorates from 77.26 kW to 47.11 kW. Comparisons between CAHP and normal AHP indicated that CAHP can extend the lower limit of evaporator inlet temperature from −10 °C to −25 °C. Besides, CAHP can enhance the Heating Capacity by approximately 55.5–85.0% even when AHP can operate normally. Moreover, the improvement contributed by CAHP is greater under much colder conditions. The Heating COP and Capacity of CAHP are improved in all the conditions, while the primary energy efficiency is advantageous under lower evaporator inlet temperatures.
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DEVELOPMENT AND EXPERIMENTAL INVESTIGATION ON TWO-STAGE COMPRESSION VARIABLE FREQUENCY AIR SOURCE HEAT PUMP
2006Co-Authors: Changqing Tian, Nan Liang, Wenxing ShiAbstract:A two-stage compression variable frequency air source heat pump is proposed combining variable frequency technology with two-stage compression cycle. The empirical formula of optimal intermediate pressure is calculated, and two-control-model with the priority target as coefficient of performance (COP) or Heating Capacity is advanced in this paper. A test bench is developed for the two-stage compression variable frequency air source heat pump in order to observe the practical operation and obtain the measured data. The COP and compressor discharge temperature in the single-stage compression system and two-stage compression system at different evaporating temperatures are measured, and the variation of Heating Capacity in the two-stage compression system along with the evaporating temperature and power frequency of low pressure stage compressor is investigated experimentally too. The experimental results show that the COP is over 2, the compressor discharge temperature under 120 o C, and the Heating Capacity can meet the Heating load needed when the condensing temperature is 50 o C and evaporating temperature -25 o C. Also the experiment shows this system runs safely and steadily, which can be used in the cold regions where outdoor temperature is not lower than -18 o C.
Minsoo Kim - One of the best experts on this subject based on the ideXlab platform.
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Performance analysis of vapor injection heat pump system for electric vehicle in cold startup condition
International Journal of Refrigeration, 2017Co-Authors: Young Uk Choi, Mo Se Kim, Gwi Taek Kim, Minsung Kim, Minsoo KimAbstract:Abstract In this study, a vapor-injection (VI) cycle designed for indoor Heating of electric vehicle (EV) was investigated for low temperature Heating purposes. The Heating Capacity variation was observed both in mathematical and experimental ways to verify the influence of vapor injection at different injecting positions and under different intermediate pressure. From this study, the optimal injection position of the scroll compressor and intermediate pressure ratio were evaluated that maximizes Heating Capacity and coefficient of performance (COP) of the cycle. To validate the numerical results, the experiment was also conducted in the prototype of a vapor-injection (VI) Heating system for electric vehicle. The experiment was carried out under the steady-state condition and the same parameters as those of numerical analysis were employed. The comparison between the results of numerical analysis and that of experiments showed a good agreement. For the increase of Heating Capacity, the optimal injecting port position was observed in specific value which was close to 300°. As the opening of the main expansion valve was decreased, the performance of the VI system generally got better but the system had much restricted intermediate pressure ratio in which the performance was drastically decreased. As a result, the optimal intermediate pressure ratio occurred in specific value below 0.25 in startup condition.
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comparison of the Heating performance of an inverter driven heat pump system using r410a vapor injection into accumulator and compressor
International Journal of Refrigeration-revue Internationale Du Froid, 2012Co-Authors: Chul Woo Roh, Minsoo KimAbstract:In cold regions, a refrigerant injection technique has been used for enhancing Heating Capacity and avoiding the excessively high discharge temperature which is detrimental to reliability of a heat pump system. The heat pump system in this study having an additional refrigerant injection line into the accumulator was tested to compare with the Heating performances of classic vapor-injection cycle. The heat pump system was designed to inject vapor refrigerant into the compressor and accumulator, selectively. Although the refrigerant injection into the compressor (classic vapor-injection cycle) was more effective to enhance Heating Capacity, the refrigerant injection into the accumulator could decrease discharge temperature and increase both Heating Capacity and COP slightly at the condition of high compressor frequency. In terms of mass balance, the injection stream into the accumulator substituted the evaporator's suction stream flowing to the compressor, so the mass flow rate of condenser was not increased as much as the amount of injected refrigerant.
Changqing Tian - One of the best experts on this subject based on the ideXlab platform.
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Experimental Investigation on Heat Pump for Electric Vehicles with different Refrigerant Injection Compressors
Energy Procedia, 2015Co-Authors: Fei Qin, Qingfeng Xue, Guiying Zhang, Huiming Zou, Changqing TianAbstract:Abstract Poor Heating performance and operating safety in low ambient temperature of Air Source Heat Pump (ASHP) for Electric Vehicles (EVs) limits the development of EVs in cold region, because of no engines wash heat to use and low efficiency of electric Heating. ASHP with refrigerant injection is a potential method to reduce the battery power consumption by increasing the Heating Capacity and operating safety of ASHP system. In this paper, a test bench which can be switched between with refrigerant injection ASHP system and traditional ASHP system for EVs aiming at cold region is developed. In order to analyze the influence of refrigerant injection porthole shapes to system performance, two scroll compressors with different injection portholes are refitted from comment electric compressor. The experiment results show that the Heating Capacity of refrigerant injection system is raised up to 27% than that of the traditional system. The bigger area of injection portholes can and make help to increase the Heating Capacity when in-car inlet air temperature is higher. The research will also promote the industrialization and practicability of refrigerant injection system and EVs.
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DEVELOPMENT AND EXPERIMENTAL INVESTIGATION ON TWO-STAGE COMPRESSION VARIABLE FREQUENCY AIR SOURCE HEAT PUMP
2006Co-Authors: Changqing Tian, Nan Liang, Wenxing ShiAbstract:A two-stage compression variable frequency air source heat pump is proposed combining variable frequency technology with two-stage compression cycle. The empirical formula of optimal intermediate pressure is calculated, and two-control-model with the priority target as coefficient of performance (COP) or Heating Capacity is advanced in this paper. A test bench is developed for the two-stage compression variable frequency air source heat pump in order to observe the practical operation and obtain the measured data. The COP and compressor discharge temperature in the single-stage compression system and two-stage compression system at different evaporating temperatures are measured, and the variation of Heating Capacity in the two-stage compression system along with the evaporating temperature and power frequency of low pressure stage compressor is investigated experimentally too. The experimental results show that the COP is over 2, the compressor discharge temperature under 120 o C, and the Heating Capacity can meet the Heating load needed when the condensing temperature is 50 o C and evaporating temperature -25 o C. Also the experiment shows this system runs safely and steadily, which can be used in the cold regions where outdoor temperature is not lower than -18 o C.
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State of the Art of Air-source Heat Pump for Cold Regions
2006Co-Authors: Changqing Tian, Nan LiangAbstract:In this paper, research on air source heat pump systems for cold regions in recent years is first summarized and compared. These systems can be divided into three kinds: a single-stage compression heat pump, liquid/vapor injection heat pump, and a two-stage heat pump. Finally, our research with a two-stage compression variable frequency air source heat pump is presented. A two-control-model with the priority target as COP or Heating Capacity is advanced. The experimental results show that the COP of this heat pump system is over 2, the compressor discharge temperature under 120 �, and the Heating Capacity can meet the Heating load needed when the condensing temperature is 50 � and outdoor air temperature is over -18�.