Performance assessment of a modified two-evaporator ejector expansion heat pump cycle using mixture R290/R600a

In this study, a modified two-evaporator ejector expansion heat pump cycle is proposed. The use of the ejector recovers the expansion work and enhances the compressor performance. The application of dual evaporator and dual internal heat exchanger increases the evaporating pressure. In addition, the zeotropic refrigerant mixtures R290/R600a are employed due to their friendly environmental performance and favorable thermodynamic properties. The thermodynamic performance and economic performance for the basic heat pump cycle, condenser outlet split heat pump cycle and modified cycle are compared by using the developed mathematical model. The results indicated that the volumetric heating capacity of modified cycle is 35.9 % and 17.5 % higher than that of basic cycle and condenser outlet split cycle, the modified cycle achieved a heating coefficient of performance improvement of 19.8 % and 10.2 % over the reference cycles. The modified cycle exhibits a significant reduction in exergy destruction of expansion components by 40.8 % and 32.1 %. Therefore, the exergy efficiency of modified cycle demonstrated a significant enhancement, outperforming the reference cycles by 19.8 % and 10.2 %. The cost per unit of exergy production of modified cycle is 12.2 % and 4.8 % lower than the reference cycles. The modified cycle exhibits significantly high thermodynamic performance and cost-effectiveness features under a wide range of operating conditions. Considering the irreversibility of heat exchanger, the zeotropic refrigerant R290/R600a can be applied in heat pump water heater applications for higher temperature glide in condensation.