Performance Research Of Solar Assisted Ejector Vapor Injection Air Source Heat Pump System

In order to make effective use of air energy and solar energy and improve the performance of heat pump system,a solar assisted ejector vapor injection air source heat pump system(SEVIHP)is proposed.The energy analysis model and exergy analysis model of the system are established,and the system is simulated by FORTRAN and TRNSYS software.The main research contents and conclusions are as follows:(1)The models of constant-area mixing two-phase ejector and intermediate vapor-injected rotor compressor are established and verified.Compared with the experimental values in the literature,the maximum error of the calculated values of the ejector model is5.5%,and the maximum error of the compressor model is 6.7%.(2)The influence of compressor structural parameters on vapor-injected compression performance is studied.The results show that the start of injection rotation angle increases with the increase of cylinder radius and injection port radius.With the increase of the cylinder radius and eccentricity,the total power consumption and heating capacity of the vapor injection compressor in a working cycle increase,and the increase of injection port radius has little effect on the total power consumption and heating capacity.(3)The influence of operating parameters on the system performance is analyzed.When the intermediate temperature rises from 21℃to 30℃,the evaporation temperature is-10℃,the condensation temperature is 50℃,the solar irradiance is 300W/m~2 and the injection rate is10%,the coefficient of heating performance COP_h and exergy efficiency of the system increase,and the heating capacity,total power consumption,the coefficient of thermal heating performance COP_r and total exergy loss decrease.When the condensation temperature increases,the COP_h of the system decreases,the total power consumption increases,and the power consumption of the vapor injection compressor increases significantly.Therefore,in the case of high pressure ratio,in order to improve the performance of the system,it can be adjusted by reducing the injection mass flow rate of the vapor injection compressor and increasing the mass flow rate of the auxiliary compressor.Compared with TSVI system,it is found that under the same working conditions,the coefficient of heating performance of SEVIHP system is better than that of TSVI system,and the coefficient of cooling performance is slightly lower than that of TSVI system;When the evaporation temperature is-20℃,the condensation temperature is 50℃and the solar irradiance is 300W/m~2,the COP_himprovement rate of SEVIHP system can reach 83.2%.(4)In the exergy analysis of various operating parameters,the exergy destruction of evaporator,vapor injection compressor and condenser account for the largest proportion of the total exergy destruction.Therefore,the key to improve the exergy efficiency and performance of the system is to select the evaporator and condenser with high heat exchange efficiency and small internal loss,and optimize the model of the vapor injection compressor.(5)TRNSYS simulation analysis of SEVIHP system on a winter meteorological day shows that:the pressure lift ratio of SEVIHP system first increases and then decreases with time,and the entrainment ratio first decreases and then increases with time.Under different evaporation and condensation temperatures,the total power consumption and heating capacity of the system first decrease and then increase with time,COP_h first increases and then decreases,and COP_r first decreases and then increases.