Circulation composition, Zeotropic refrigerant mixture, R1234ze, R32
This study presents an experimental investigation of the circulation composition in a heat pump cycle for considering the effect of its difference from the charged composition on the cycle performance prediction. The experiment was conducted with a vapor compression heat pump cycle using a compressor developed for R410A. The tested refrigerants are R1234ze(E)/R32 (20/80 mass%)，R1234ze(E)/R32 (50/50 mass%), and R1234ze(E)/R32 (80/20 mass%). Compared with the charged composition, the measured mass fraction of the more volatile component R1234ze(E)increases at inlet of the expansion valve. When the difference between vapor and liquid composition is large in the two-phase flow, the difference between circulation and changed composition is large enough to affect the COP evaluation. The circulation composition depends on the velocity ratio of vapor and liquid, the operating pressure of heat pump cycle, and the degree of subcool at condenser outlet.