Experimental research on vapor-injected water source heat pump using R1234ze(E)

As a low GWP alternative refrigerant to R134a, the direct use of R1234ze(E) in water source heat pumps leads to significant performance degradation. Vapor injection combined with R1234ze(E) is a possible solution to this problem. In this study, a vapor-injected water source heat pump using R1234ze(E) as the working fluid was experimentally investigated. The results indicate that vapor injection using a flash tank or internal heat exchanger can significantly increase the coefficient of performance and heating capacity of the proposed heat pump. The improvements in the heating capacity and coefficient of performance corresponded to 22.3% and 8.1% for the flash tank system, and 19.5% and 7.3% for the internal heat exchanger system compared with the no-injection system.