混合工质在复叠式热泵中的性能研究OA

To explore the influence of the selection of mixed working fluids on the performance of the cascade heat pump system,the working principle of the cascade heat pump is systematically elaborated,and the screening process of mixed working fluids is described.The model of the cascade heat pump is designed and simulated using Matlab,and the REFPROP software is called to analyze the effects of factors such as condensation and evaporation pressures,compressor power consumption,mass fraction,and intermediate condensation temperature of different mixed working fluids on the energy efficiency ratio(COP).The results show that the application of 3 types of mixed working fluids increases the condensation pressure by 8.60%to 25.40%and the evaporation pressure by 8.70%to 26.23%.When the mass fraction of R134a is 10%,the compressor power consumption of the R134a+R152a combination is lower,at 24.26 kW.Compared with the other 3 groups of working fluids,the COP of the R152a+R1234ze combination is higher,reaching 3.27.For the cascade heat pump system,different mixed working fluids have specific optimal intermediate condensation temperatures,and the R152a+R1234ze combination has the lowest power consumption of 48.28 kW.As a low-temperature-level mixed working fluid,R152a+R1234ze always maintains the maximum COP when the low-temperature evaporation temperature and high-temperature condensation temperature change.