Research on solar-assisted ejector-enhanced air source heat pump cycle with dual-pressure condensation

Abstract

ABSTRACT A novel solar-assisted ejector-enhanced air source heat pump cycle with dual-temperature condensation (SEASHP-DC) is proposed in this study. Two types of hot water with different temperatures can be supplied for heating. By using solar energy and ejector, the COP of the system can be improved in cold regions. The cycle can change operation mode according to the solar radiation intensity, which can turn into a conventional heat pump cycle with dual-pressure condensation (CHP-DC) when the solar radiation intensity is low or at night. The performance of the proposed cycle is simulated with different refrigerants (R134a, R1234yf, and R1234ze(E)). Results show that the R1234ze(E) is an ideal substitute for the R134a. The performance of the SEASHP-DC is investigated and compared with that of the CHP-DC under the given condition. Compared with the CHP-DC, a considerable improvement of 55.9% in COP at a heating capacity ratio equal to 1.5 is reached by the SEASHP-DC. The largest exergy destruction occurs at the solar collector due to the huge temperature difference between the solar collector and the environment. The feasibility of applying this system during the heating season is confirmed, with daily working hours ranging from 6 to 8 h.