Performance evaluation of a solar-assisted ejector-enhanced vapor injection heat pump cycle

Abstract

In this study, a solar-assisted ejector-enhanced flash tank vapor injection heat pump cycle (SEE-FVIC) is proposed. Compare to the flash tank vapor injection heat pump cycle (FVIC), the modified cycle introduces solar energy and ejector. On the one hand, the heat from the solar energy is used. On the other hand, the booster function of the ejector effectively reduces the refrigerant mass flowing into the low-pressure stage of the compressor, leading to reducing power consumption of the compressor and improving cycle performance. The cycle performance is studied under typical operating conditions. In particular, a comprehensive analysis of the optimum intermediate pressure Pio of the compressor is also carried out. The results show that the optimum Pio of the SEE-FVIC is higher than that of FVIC for the same operating conditions, which is 1100 kPa and 1300 kPa, respectively. Compared to the FVIC, the heating coefficient of performance (COPh) and volumetric heat capacity (Qcv) of the SEE-FVIC are increased by 38.4 % and 89.2 %, respectively, at the corresponding optimum Pio. Besides, the change of Pio has a significant effect on the volume ratio (β) and vapor injection ratio (δ) of the compressor. It is indicated that the δ varies from 0.48 to 0.67 and the corresponding β from 0.90 to 1.16 when the COPh of the SEE-FVIC reaches its maximum value for a given operating conditions.