The exergy analysis and finite time thermodynamic methods had been employed to analyze the compound condensation process (CCP). It was based on the air-cooling heat pump unit. The cooling capacity of the chiller unit ...The exergy analysis and finite time thermodynamic methods had been employed to analyze the compound condensation process (CCP). It was based on the air-cooling heat pump unit. The cooling capacity of the chiller unit is about 1 kW, and the work refrigerant is R22/R407C/R410A/CO2. The MATLAB/SIMULINK software was employed to build the simulation model. The thermodynamic simulation model is significant for the optimization of parameters of the unit, such as condensation and evaporation temperature and mass flow of the sanitary hot water and size of hot water storage tank. The COP of the CCP of R410A system is about 3% - 5% higher than the CCP of the R22 system, while CCP of the R407C system is a little lower than the CCP of R22 system. And the CCP of CO2 trans-critical system has advantage in the hot supply mode. The simulation method provided a theoretical reference for developing the production of CCP with substitute refrigerant R407C/R410A/CO2.展开更多
The application of air conditioning heat pump(ACHP) in electric vehicles could lead to significant electrical power saving effect. As for an air conditioning heat pump system for electric vehicles, the influence of re...The application of air conditioning heat pump(ACHP) in electric vehicles could lead to significant electrical power saving effect. As for an air conditioning heat pump system for electric vehicles, the influence of refrigerant charge amount should be investigated during the design phase. In this study, experimental method was employed to investigate the influence of the refrigerant charge amount on the performance of the ACHP system. The results showed that the refrigerant charge amount had different influence on the refrigerant properties at various locations within the system. The coefficient of performance and pressure-enthalpy diagram were calculated, and showed a close relationship with refrigerant charge amount under different compressor speeds. The degree of subcooling and the degree of superheating were recorded and the critical charge amount was determined by a typical practical test method. In addition, the critical refrigerant charge amount determined by the experimental method was also compared with two typical void fraction correlation models, and the model with consideration of two phase stream reaction of the refrigerant showed a good estimation accuracy on the critical charge amount.展开更多
针对空气源热泵在夏季高温天气下制冷性能衰减的问题,提出在冷凝器翅片外部增设喷雾装置的方法,达到提升系统性能的目的。设计了不喷雾、向外喷雾、向内喷雾、向内喷淋四种实验工况。基于实验数据,分析了不同温湿度条件下四种工况的系...针对空气源热泵在夏季高温天气下制冷性能衰减的问题,提出在冷凝器翅片外部增设喷雾装置的方法,达到提升系统性能的目的。设计了不喷雾、向外喷雾、向内喷雾、向内喷淋四种实验工况。基于实验数据,分析了不同温湿度条件下四种工况的系统性能。实验结果表明,与未喷雾时机组的能效比(Coefficient Of Performance,简称COP)相比,向外喷雾时机组的COP最大增幅为4.67%,向内喷雾时机组的COP最大增幅为6.07%,向内喷淋时机组的COP最大增幅为6.70%;理论喷雾量与实际喷雾量对比结果表明,以室外干球温度25~30℃、相对湿度55%为例,向外喷雾的实际喷雾量约是理论喷雾量的90%,向内喷雾的实际喷雾量约是理论喷雾量的81%;提出喷雾节能比的概念,结果表明,向内喷雾的喷雾节能比最大,为最优喷雾方式。展开更多
Liquid air energy storage(LAES)has been regarded as a large-scale electrical storage technology.In this paper,we first investigate the performance of the current LAES(termed as a baseline LAES)over a far wider range o...Liquid air energy storage(LAES)has been regarded as a large-scale electrical storage technology.In this paper,we first investigate the performance of the current LAES(termed as a baseline LAES)over a far wider range of charging pressure(1 to 21 MPa).Our analyses show that the baseline LAES could achieve an electrical round trip efficiency(e RTE)above 60%at a high charging pressure of 19 MPa.The baseline LAES,however,produces a large amount of excess heat particularly at low charging pressures with the maximum occurred at~1 MPa.Hence,the performance of the baseline LAES,especially at low charging pressures,is underestimated by only considering electrical energy in all the previous research.The performance of the baseline LAES with excess heat is then evaluated which gives a high e RTE even at lower charging pressures;the local maximum of 62%is achieved at~4 MPa.As a result of the above,a hybrid LAES system is proposed to provide cooling,heating,hot water and power.To evaluate the performance of the hybrid LAES system,three performance indicators are considered:nominal-electrical round trip efficiency(ne RTE),primary energy savings and avoided carbon dioxide emissions.Our results show that the hybrid LAES can achieve a high ne RTE between 52%and 76%,with the maximum at~5 MPa.For a given size of hybrid LAES(1 MW×8 h),the primary energy savings and avoided carbon dioxide emissions are up to 12.1 MWh and 2.3 ton,respectively.These new findings suggest,for the first time,that small-scale LAES systems could be best operated at lower charging pressures and the technologies have a great potential for applications in local decentralized micro energy networks.展开更多
文摘The exergy analysis and finite time thermodynamic methods had been employed to analyze the compound condensation process (CCP). It was based on the air-cooling heat pump unit. The cooling capacity of the chiller unit is about 1 kW, and the work refrigerant is R22/R407C/R410A/CO2. The MATLAB/SIMULINK software was employed to build the simulation model. The thermodynamic simulation model is significant for the optimization of parameters of the unit, such as condensation and evaporation temperature and mass flow of the sanitary hot water and size of hot water storage tank. The COP of the CCP of R410A system is about 3% - 5% higher than the CCP of the R22 system, while CCP of the R407C system is a little lower than the CCP of R22 system. And the CCP of CO2 trans-critical system has advantage in the hot supply mode. The simulation method provided a theoretical reference for developing the production of CCP with substitute refrigerant R407C/R410A/CO2.
基金supported by The Open Project Program of State Key Laboratory of Fire Science (No. HZ2018-KF03)Shanghai Sailing Program (No. 18YF1417900)Huaqiao University Scientific Research Foundation (No. 16BS801)
文摘The application of air conditioning heat pump(ACHP) in electric vehicles could lead to significant electrical power saving effect. As for an air conditioning heat pump system for electric vehicles, the influence of refrigerant charge amount should be investigated during the design phase. In this study, experimental method was employed to investigate the influence of the refrigerant charge amount on the performance of the ACHP system. The results showed that the refrigerant charge amount had different influence on the refrigerant properties at various locations within the system. The coefficient of performance and pressure-enthalpy diagram were calculated, and showed a close relationship with refrigerant charge amount under different compressor speeds. The degree of subcooling and the degree of superheating were recorded and the critical charge amount was determined by a typical practical test method. In addition, the critical refrigerant charge amount determined by the experimental method was also compared with two typical void fraction correlation models, and the model with consideration of two phase stream reaction of the refrigerant showed a good estimation accuracy on the critical charge amount.
文摘针对空气源热泵在夏季高温天气下制冷性能衰减的问题,提出在冷凝器翅片外部增设喷雾装置的方法,达到提升系统性能的目的。设计了不喷雾、向外喷雾、向内喷雾、向内喷淋四种实验工况。基于实验数据,分析了不同温湿度条件下四种工况的系统性能。实验结果表明,与未喷雾时机组的能效比(Coefficient Of Performance,简称COP)相比,向外喷雾时机组的COP最大增幅为4.67%,向内喷雾时机组的COP最大增幅为6.07%,向内喷淋时机组的COP最大增幅为6.70%;理论喷雾量与实际喷雾量对比结果表明,以室外干球温度25~30℃、相对湿度55%为例,向外喷雾的实际喷雾量约是理论喷雾量的90%,向内喷雾的实际喷雾量约是理论喷雾量的81%;提出喷雾节能比的概念,结果表明,向内喷雾的喷雾节能比最大,为最优喷雾方式。
基金the partial support from UK EPSRC Manifest Project under EP/N032888/1,EP/P003605/1a UK FCO Science&Innovation Network grant(Global Partnerships Fund)an IGI/IAS Global Challenges Funding(IGI/IAS ID 3041)。
文摘Liquid air energy storage(LAES)has been regarded as a large-scale electrical storage technology.In this paper,we first investigate the performance of the current LAES(termed as a baseline LAES)over a far wider range of charging pressure(1 to 21 MPa).Our analyses show that the baseline LAES could achieve an electrical round trip efficiency(e RTE)above 60%at a high charging pressure of 19 MPa.The baseline LAES,however,produces a large amount of excess heat particularly at low charging pressures with the maximum occurred at~1 MPa.Hence,the performance of the baseline LAES,especially at low charging pressures,is underestimated by only considering electrical energy in all the previous research.The performance of the baseline LAES with excess heat is then evaluated which gives a high e RTE even at lower charging pressures;the local maximum of 62%is achieved at~4 MPa.As a result of the above,a hybrid LAES system is proposed to provide cooling,heating,hot water and power.To evaluate the performance of the hybrid LAES system,three performance indicators are considered:nominal-electrical round trip efficiency(ne RTE),primary energy savings and avoided carbon dioxide emissions.Our results show that the hybrid LAES can achieve a high ne RTE between 52%and 76%,with the maximum at~5 MPa.For a given size of hybrid LAES(1 MW×8 h),the primary energy savings and avoided carbon dioxide emissions are up to 12.1 MWh and 2.3 ton,respectively.These new findings suggest,for the first time,that small-scale LAES systems could be best operated at lower charging pressures and the technologies have a great potential for applications in local decentralized micro energy networks.
