Cycle Performance Of Working Fluids For High Temperature Heat Pump And Preliminary Study On The Molecular Model

High temperature heat pump technology has a broad application prospect due to its ability to lift temperature,which can provide high temperature heat demand for industrial process.If the upper limit value of output temperature of the heat pump can be increased,the heat pump system can be applicable to provide heat in more processes and application areas,which can not only reduce energy consumption,but also can improve the energy utilization rate.One of an important ways to achieve this purpose is to look for some working fluids with good performance.In this paper,we have developed an interactive program for the calculation of the theoretical cycle of working fluids,which can be used for preliminary screening of the working fluids.By entering the name and ratio of the mix refrigerant,the temperature of evaporation and condensation,some basic physical parameters such as molar mass,critical temperature and pressure of the mixture as well as some performance parameters including the input power,exhaust temperature,and COP can be obtained directly.HFC365mfc,HFC245 ca,HFO1233zd(E)and HFC245 fa were selected from 15 kinds of working fluids in condition of evaporation temperature and condensation temperature of 80? and 140? respectively.This paper discussed the thermodynamic properties of mix refrigerant in different proportions in the proposed high-temperature working conditions.The results showed that HFO1233zd(E)/HFC365 mfc and HFO1233zd(E)/HFC245 ca can be applied to higher temperature condition.For HFC245fa/ HFC245 ca and HFC245fa/ HFC365 mfc,the mass fraction of HFC245 fa should be 0.6~0.8.For HFC245fa/ HFO1233zd(E),the mass fraction of HFC245 fa should be 0.5~0.7.Finally,a new working fluids BY-5 is presented.The high temperature heat pump experiment platform was designed and set up,and debugged under the normal condition of air conditioning with HCFC22 as refrigerants.The paper explored the effect of different water flow of low and high temperature side,the water input temperature of low temperature side,the water output temperature of high temperature side as well as the opening of the expansion valve on the heating capacity,input power and COP.The highest value of water output temperature can reach 130? with the self-developed binary mixture BY-5,which achieved the new high temperature experiment level.Through remolding the experiment platform,the paper studied the influence of four-way directional control valve on the COP of the system.In this paper,a molecular model of high temperature working fluids was established by COSMO-RS.Some thermodynamic properties of working fluids such as saturation vapor pressure,boiling point and vapor-liquid equilibrium were predicted by COSMO-RS,and then were compared with the values provided in previous literatures and the values calculated by REFPROP software.Results showed that the predicted values of saturated vapor pressure had a good consistency with the experiment values;the predicted values of boiling point of HFC245 fa and HFC365 mfc was relatively accurate in low pressure area,HFO1233zd(E)was more accurate at higher pressure,while the HFC245 ca was more accurate in 1.7~2.3MPa.The prediction values of vapor-liquid equilibrium of binary mixture HFC134a+HC290 and HFC245fa+HC600 have the same variation tendency with the experimental values,and it reached a good consistency with experimental values at the low temperature.