Thermodynamic analysis of a modified solar assisted ejector-compression heat pump cycle with zeotropic mixture R290/R600a

This paper proposes a modified solar assisted ejector-compression heat pump cycle with zeotropic mixture R290/R600a (MHP) for water heater applications, which could efficiently utilize both the air source energy and solar energy. Depending on the solar radiation intensity, MHP contains two operation modes, i.e., Mode-A/-B for high/low solar radiation intensity conditions, respectively. In MHP, the use of zeotropic mixture ensures a better matching characteristic between the temperature variations of the refrigerant and water in the condenser due to its temperature glide feature. The simulation results show that compared with the conventional heat pump cycle (CHP), as the condenser inlet saturated temperature ranges 45-80 degrees C, MHP-A yields 28-33% higher COP and 22-47% higher volumetric heating capacity at a fixed evaporator outlet temperature of 10 degrees C. And increasing the solar radiation intensity is beneficial to the performance improvement of MHP-A. Additionally, in order to display the cycle characteristic, the effects of other critical parameters are studied in detail, including the evaporator outlet temperature, mixture composition, heat source capacity ratio, etc.