The Experts below are selected from a list of 1578 Experts worldwide ranked by ideXlab platform
Shengqiang Shen - One of the best experts on this subject based on the ideXlab platform.
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Energy and exergy analysis of novel solar bi-Ejector Refrigeration system with injector
International Journal of Energy Research, 2009Co-Authors: Fei Wang, Shengqiang ShenAbstract:Energy and exergy balances were done on a novel solar bi-Ejector Refrigeration system with R123, whose circulation pump is replaced by an injector. The analysis result of the novel system was compared with that of the original one. The effect of operation condition on system energy efficiency, exergy efficiency and exergy loss was analyzed, and the dynamic performance of a designed solar bi-Ejector Refrigeration system was also studied. The comparative results indicate that under the same operating condition, the novel system and the original system have equal energy efficiency, exergy efficiency and exergy loss, and the only difference between them is the exergy losses of the generators and the added injector. The other conclusions mainly include: the solar collector has the largest exergy loss rate of over 90% and for the bi-Ejector Refrigeration subcycle, the Ejector has the largest exergy loss rate of about 5%; the total exergy loss changes inversely proportional to the evaporation temperature and positively proportional to the condensation temperature; when the other parameters are fixed, there exists an optimum generation temperature, at which the overall energy and exergy efficiencies are both the maximum and the total exergy loss is the minimum. The study points out the direction for optimizing the novel solar bi-Ejector Refrigeration system. Copyright © 2009 John Wiley & Sons, Ltd.
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A novel solar bi-Ejector Refrigeration system and the performance of the added injector with different structures and operation parameters
Solar Energy, 2009Co-Authors: Fei Wang, Shengqiang ShenAbstract:A novel solar bi-Ejector Refrigeration system was investigated, whose difference compared to the traditional system is that the circulation pump is replaced by a thermal injector. The new system works more stably and needs less maintenance work than the old one, and the whole system can more fully utilize the solar energy. The mathematical models for calculating the performance of the injector and the whole solar Refrigeration system were established. The pressure rise performance of injector under different structure and operation parameters and the performance of solar bi-Ejector Refrigeration system were studied with R123. The results show that the discharged pressure of injector is affected by structure dimensions of injector and operation conditions. With increasing generation temperature, the entrainment ratio of Ejector becomes better while that of injector becomes worse and the overall thermal efficiency of the solar bi-Ejector Refrigeration system first increases and then decreases with an optimum value of 0.132 at generation temperature of 105 °C, condensation temperature of 35 °C and evaporation temperature of 10 °C.
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Mathematical Simulation of a Solar Bi-Ejector Refrigeration System
Solar Energy, 2006Co-Authors: Bo Zhang, Jianhua Dong, Shengqiang ShenAbstract:This paper presents a mathematical simulation of the dynamic thermal behavior of an innovative solar bi-Ejector Refrigeration system with a capacity to produce cooling water. In the bi-Ejector Refrigeration system, the mechanical circulation pump is replaced by a vapor-liquid Ejector, in order to further reduce the electricity consumption and reinforce the system feasibility. Freon R123 is the working fluid at condensing temperature of 30°C generating temperature of 85°C and evaporating temperature of 8°C The generator heat load is 10kW and an obtained evaporator cooling load is around 3kW. The whole year simulation results are presented.Copyright © 2006 by ASME
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Study of a gas-liquid Ejector and its application to a solar-powered bi-Ejector Refrigeration system
Applied Thermal Engineering, 2005Co-Authors: Shengqiang Shen, Xiaoping Qu, Saffa Riffat, Bo Zhang, Mark GillottAbstract:Abstract A new configuration of a bi-Ejector Refrigeration system is presented. The system incorporates two Ejectors. The purpose of one is to suck refrigerant vapour from the evaporator and discharge to the condenser; the other acts as a jet pump to pump liquid refrigerant from the condenser to the generator. An analysis model for the bi-Ejector Refrigeration system and a one-dimensional flow model for the gas–liquid Ejector were established. The performances of the gas–liquid Ejector and the Refrigeration cycle were studied using numerical modelling. The results show that the performances of Ejectors and system depend a great deal on the refrigerants as well as on operation conditions.
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A theoretical study on a novel bi-Ejector Refrigeration cycle
Applied Thermal Engineering, 2005Co-Authors: Bo Zhang, Shengqiang ShenAbstract:Abstract In this paper, a new bi-Ejector Refrigeration cycle is presented, in which the mechanical pump of a single Ejector Refrigeration cycle is replaced by a vapor–liquid Ejector. Thus in the bi-Ejector Refrigeration cycle, no electricity is required. The relation between the vapor–liquid Ejector performance and operation parameters is studied. Simulation on the system COP, the generating temperature and the condensing temperature is provided. The vapor–liquid Ejector entrainment ratio is relatively high, so the system performance remains competitive although a part of motive vapor is used to drive the vapor–liquid Ejector, without counting the saving of electricity.
Fei Wang - One of the best experts on this subject based on the ideXlab platform.
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Theoretical research on the performance of the transcritical Ejector Refrigeration cycle with various refrigerants
Applied Thermal Engineering, 2015Co-Authors: Fei Wang, Y. ZhouAbstract:The transcritical Ejector Refrigeration cycle (TERC), which has shown an attractive alternative to the Ejector Refrigeration systems, can better match large variable-temperature heat sources and yields higher COP. In this paper, in order to find a proper working fluid for the TERC, the performance of the TERC with CO2 and various working fluids with low critical temperatures including R1270, R32, R143a, R125 and R115 are studied and compared. A thermodynamic model for Ejector is set up to simulate the Ejector by introducing the real properties of refrigerants. The results indicate that R1270 has the highest COP at the same heat source condition and medium working pressures, and is one of environment-friendly working fluids, hence R1270 is the most proper one. The COP of the transcritical cycle is higher than that of the subcritical cycle, and The effective performance coefficient COPm of the transcritical cycle is also better. When the heater outlet temperature is increased, its system COPm improves, but its system COP almost does not change.
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Energy and exergy analysis of novel solar bi-Ejector Refrigeration system with injector
International Journal of Energy Research, 2009Co-Authors: Fei Wang, Shengqiang ShenAbstract:Energy and exergy balances were done on a novel solar bi-Ejector Refrigeration system with R123, whose circulation pump is replaced by an injector. The analysis result of the novel system was compared with that of the original one. The effect of operation condition on system energy efficiency, exergy efficiency and exergy loss was analyzed, and the dynamic performance of a designed solar bi-Ejector Refrigeration system was also studied. The comparative results indicate that under the same operating condition, the novel system and the original system have equal energy efficiency, exergy efficiency and exergy loss, and the only difference between them is the exergy losses of the generators and the added injector. The other conclusions mainly include: the solar collector has the largest exergy loss rate of over 90% and for the bi-Ejector Refrigeration subcycle, the Ejector has the largest exergy loss rate of about 5%; the total exergy loss changes inversely proportional to the evaporation temperature and positively proportional to the condensation temperature; when the other parameters are fixed, there exists an optimum generation temperature, at which the overall energy and exergy efficiencies are both the maximum and the total exergy loss is the minimum. The study points out the direction for optimizing the novel solar bi-Ejector Refrigeration system. Copyright © 2009 John Wiley & Sons, Ltd.
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A novel solar bi-Ejector Refrigeration system and the performance of the added injector with different structures and operation parameters
Solar Energy, 2009Co-Authors: Fei Wang, Shengqiang ShenAbstract:A novel solar bi-Ejector Refrigeration system was investigated, whose difference compared to the traditional system is that the circulation pump is replaced by a thermal injector. The new system works more stably and needs less maintenance work than the old one, and the whole system can more fully utilize the solar energy. The mathematical models for calculating the performance of the injector and the whole solar Refrigeration system were established. The pressure rise performance of injector under different structure and operation parameters and the performance of solar bi-Ejector Refrigeration system were studied with R123. The results show that the discharged pressure of injector is affected by structure dimensions of injector and operation conditions. With increasing generation temperature, the entrainment ratio of Ejector becomes better while that of injector becomes worse and the overall thermal efficiency of the solar bi-Ejector Refrigeration system first increases and then decreases with an optimum value of 0.132 at generation temperature of 105 °C, condensation temperature of 35 °C and evaporation temperature of 10 °C.
Jingming Dong - One of the best experts on this subject based on the ideXlab platform.
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experimental investigation on low temperature thermal energy driven steam Ejector Refrigeration system for cooling application
Applied Thermal Engineering, 2017Co-Authors: Weining Wang, Jingming Dong, Mengqi Yu, He Song, Celue LiAbstract:Abstract In recent years, Ejector Refrigeration has been a hot topic for research because it can utilize low-grade energy such as solar energy or industrial waste heat. Even more importantly, it uses the most environmentally friendly substance, water, as the working fluid. According to the literatures, the utilization of the thermal energy from a low-temperature heat source below 80 °C is a considerable challenge for the steam Ejector Refrigeration system. In this paper, an experimental prototype of the steam Ejector Refrigeration system was designed and built up. Three Ejectors with a same nozzle for the primary nozzle and three different constant-area sections were designed and fabricated. The effects of the operating temperatures, the nozzle exit position (NXP) and the area ratio of the Ejector ( AR ) on the working performance of the steam Ejector were investigated. The generating temperature is ranged from 40 °C to 70 °C. The experimental results show that a steam Ejector can operate successfully for a certain configuration size of the steam Ejector with a generating temperature ranging from 40 °C to 70 °C and an evaporating temperature of 15 °C. The results of this investigation provided a better understanding for the cooling application of the steam Ejector Refrigeration system powered by low-temperature heat source. It demonstrates that the steam Ejector Refrigeration system is a very promising alternative to the absorption Refrigeration system, when the heat source temperature is lower than 80 °C.
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An experimental investigation of steam Ejector Refrigeration system powered by extra low temperature heat source
International Communications in Heat and Mass Transfer, 2017Co-Authors: Jingming Dong, Chunlu Kang, Weining Wang, Xuli Chen, Hongbin MaAbstract:A steam Ejector Refrigeration system is a low capital cost solution for utilizing industrial waste heat or solar energy. When the heat source temperature is lower than 80 °C, the utilization of the thermal energy from such a low-temperature heat source can be a considerable challenge. In this investigation, an experimental prototype for the steam Ejector Refrigeration system was designed and manufactured, which can operate using extra low-temperature heat source below 80 °C. The effects of the operation temperature, the nozzle exit position (NXP) and the diameter of the constant area section on the working performance of the steam Ejector were investigated at generating temperatures ranging from 40 °C to 70 °C. Three Ejectors with a same de Laval nozzle for the primary nozzle and three different constant-area sections were designed and fabricated. The experimental results show that a steam Ejector can function for a certain configuration size of the steam Ejector with a generating temperature ranging from 40 °C to 70 °C and an evaporating temperature of 10 °C. For a given NXP, the system COP and cooling capacity of the steam Ejector decreased until inoperative as the diameter of the constant area section reduced. The results of this investigation provided a good solution for the Refrigeration application of the steam Ejector Refrigeration system powered by an extra low-temperature heat source.
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Study of optimum nozzle exit position (NXP) in a steam Ejector Refrigeration system
2013Co-Authors: Jingming Dong, H. B.Abstract:A steam Ejector Refrigeration system with a movable primary nozzle was developed to study the optimum nozzle exit position (NXP) in the Ejector system. Three nozzles and two diffusers were fabricated to investigate the nozzle and diffuser effect on the optimum NXP. Experimental results show that an optimum NXP exists for an Ejector system. In addition, the effects of boiler temperature and evaporator temperature on the system coefficient of performance (COP) were studied. The results indicate that the optimum NXP is not related to the operating temperature and the nozzle dimension and diffuser size. The investigation provides a better understanding of optimum NXP in a steam Ejector Refrigeration system.
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Experimental investigation and theoretical analysis of an Ejector Refrigeration system
International Journal of Thermal Sciences, 2013Co-Authors: Daniel A Pounds, Jingming Dong, Peng ChengAbstract:Abstract The Ejector Refrigeration system can be powered from low-grade thermal energy such as solar generated hot water or waste heat, especially when electricity supply is limited or does not exist. An experimental investigation of an Ejector Refrigeration system was conducted to determine the effects of nozzle size, axial nozzle location, high-temperature evaporator temperature, and Refrigeration temperature. The tested conditions include the effects of the high-temperature evaporator (HTE) temperatures ranging from 120 to 135 °C, low-temperature evaporator (LTE) temperatures ranging from 5 to 15 °C, and condenser temperatures of 7–30 °C. It was found that an optimum nozzle location which can produce a maximum coefficient of performance (COP) exists for a given set of operating conditions. At the same time, a mathematical model has been developed to predict the system COP, which agrees well with experimental data. The experimental results show that the Ejector Refrigeration system can achieve a COP of 1.7, which is much higher than the results typically reported in the literature, but at the expense of critical backpressure. Current investigation demonstrates that the Ejector Refrigeration system is a very promising alternative to the status quo vapor compression systems.
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An Experimental Investigation of Steam Ejector Refrigeration Systems
Journal of Thermal Science and Engineering Applications, 2012Co-Authors: Jingming Dong, Daniel A Pounds, Peng Cheng, Hongbin MaAbstract:A steam Ejector Refrigeration system with a movable primary nozzle was developed in order to determine the nozzle exit position (NXP) effect on the coefficient of performance (COP). Experimental results show that there exists an optimum NXP for the Ejector system investigated herein. The effects of the operating temperature, diffuser size, nozzle throat diameter, and mixing chamber configuration on the COP and critical back pressure were investigated experimentally. It is found that the critical back pressure and COP can be increased by increasing the low temperature evaporator (LTE) temperature and pressure. Although an increase of the high temperature evaporator (HTE) temperature can increase the critical condenser pressure, the system COP does not increase as the HTE temperature increases. The diffuser size significantly affects the critical back pressure but had almost no effect on the system COP. A finned mixing chamber was tested at NXP = 0 mm and NXP = 36 mm. Compared with the regular mixing chamber, the finned mixing chamber can increase the critical back pressure.
Per Lundqvist - One of the best experts on this subject based on the ideXlab platform.
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A new Ejector Refrigeration system with zeotropic mixtures
2011Co-Authors: Jianyong Chen, Bjorn Palm, Per LundqvistAbstract:A new Ejector Refrigeration system (NERS) using zeotropic mixture is theoretical studied in the paper.R32/R134a, R32/R152a, R134a/R142b, R152a/R142b, R290/R600a and R600a/R600 are selected as thewo ...
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a year round dynamic simulation of a solar driven Ejector Refrigeration system with iso butane as a refrigerant
International Journal of Refrigeration-revue Internationale Du Froid, 2007Co-Authors: Wimolsiri Pridasawas, Per LundqvistAbstract:In this paper, the performance of the solar-driven Ejector Refrigeration system with iso-butane (R600a) as the refrigerant is studied. The effects that both the operating conditions and the solar collector types have on the system's performance are also examined by dynamic simulation. The TRNSYS and EES simulation tools are used to model and analyze the performance of a solar-driven Ejector Refrigeration system. The whole system is modelled under the TRNSYS environment, but the model of the Ejector Refrigeration subsystem is developed in the Engineering Equations Solver (EES) program. A solar fraction of 75% is obtained when using the evacuated tube solar collector. In the very hot environment, the system requires relatively high generator temperature, thus a flat plate solar collector is not economically competitive because the high amount of auxiliary heat needed to boost up the generator temperature. The results from the simulation indicate that an efficient Ejector system can only work in a region with decent solar radiation and where a sufficiently low condenser temperature can be kept. The average yearly system thermal ratio (STR) is about 0.22, the COP of the cooling subsystem is about 0.48, and the solar collector efficiency is about 0.47 at Te 15 °C, Tc 5 °C above the ambient temperature, evacuated collector area 50 m2 and hot storage tank volume 2 m3.
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Butane, as a refrigerant for a solar-driven Ejector Refrigeration system.
2004Co-Authors: Wimolsiri Pridasawas, Per LundqvistAbstract:In this paper, the properties, thermodynamic characteristics and safety issues of n-butane and isobutane are discussed. The effect of the operating conditions on a solar-driven Ejector Refrigeration system with n-butane and isobutane is studied. The whole system was modelled by using the TRNSYS program but the model of the Ejector Refrigeration sub-system is developed in the engineering equations solver program. The solar collector subsystem and the load are modelled by using TRNSYS. The performance of the whole system is presented in the form of the system thermal ratio, which depends on both the COP of the Ejector Refrigeration subsystem and solar collector efficiency. The simulation results show that the system using normal butane has slightly better performance than the system using isobutane.
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an exergy analysis of a solar driven Ejector Refrigeration system
Solar Energy, 2004Co-Authors: Wimolsiri Pridasawas, Per LundqvistAbstract:Energy analysis is used as a tool to analyse the performance of an Ejector Refrigeration cycle driven by solar energy. The analysis is based on the following conditions: a solar radiation of 700 W/ ...
Bo Zhang - One of the best experts on this subject based on the ideXlab platform.
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Mathematical Simulation of a Solar Bi-Ejector Refrigeration System
Solar Energy, 2006Co-Authors: Bo Zhang, Jianhua Dong, Shengqiang ShenAbstract:This paper presents a mathematical simulation of the dynamic thermal behavior of an innovative solar bi-Ejector Refrigeration system with a capacity to produce cooling water. In the bi-Ejector Refrigeration system, the mechanical circulation pump is replaced by a vapor-liquid Ejector, in order to further reduce the electricity consumption and reinforce the system feasibility. Freon R123 is the working fluid at condensing temperature of 30°C generating temperature of 85°C and evaporating temperature of 8°C The generator heat load is 10kW and an obtained evaporator cooling load is around 3kW. The whole year simulation results are presented.Copyright © 2006 by ASME
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Study of a gas-liquid Ejector and its application to a solar-powered bi-Ejector Refrigeration system
Applied Thermal Engineering, 2005Co-Authors: Shengqiang Shen, Xiaoping Qu, Saffa Riffat, Bo Zhang, Mark GillottAbstract:Abstract A new configuration of a bi-Ejector Refrigeration system is presented. The system incorporates two Ejectors. The purpose of one is to suck refrigerant vapour from the evaporator and discharge to the condenser; the other acts as a jet pump to pump liquid refrigerant from the condenser to the generator. An analysis model for the bi-Ejector Refrigeration system and a one-dimensional flow model for the gas–liquid Ejector were established. The performances of the gas–liquid Ejector and the Refrigeration cycle were studied using numerical modelling. The results show that the performances of Ejectors and system depend a great deal on the refrigerants as well as on operation conditions.
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A theoretical study on a novel bi-Ejector Refrigeration cycle
Applied Thermal Engineering, 2005Co-Authors: Bo Zhang, Shengqiang ShenAbstract:Abstract In this paper, a new bi-Ejector Refrigeration cycle is presented, in which the mechanical pump of a single Ejector Refrigeration cycle is replaced by a vapor–liquid Ejector. Thus in the bi-Ejector Refrigeration cycle, no electricity is required. The relation between the vapor–liquid Ejector performance and operation parameters is studied. Simulation on the system COP, the generating temperature and the condensing temperature is provided. The vapor–liquid Ejector entrainment ratio is relatively high, so the system performance remains competitive although a part of motive vapor is used to drive the vapor–liquid Ejector, without counting the saving of electricity.