CONDENSATION HEAT TRANSFER AND PRESSURE DROP OF AZEOTROPIC MIXTURE REFRIGERANT R32/R1270 INSIDE HORIZONTAL SMALL-DIAMETER TUBES

摘要

This paper describes an experimental study on condensation heat transfer and pressure drop using the smalldiameter tube and refrigerants R410A and R32, along with the azeotropic mixture R32/R1270 (70 mass% R32; 30 mass% R1270 (propylene)), which was used as a test refrigerant existing at the azeotropic point. The experimental apparatus was a vapor compression heat pump system. Smooth and internally helically grooved small-diameter tubes were used as test tubes. The test heat exchanger consisted of four double-tube test sections with countercurrent flow. In each test section, a test tube in an annulus was cooled by cooling water, and the refrigerant flowed within an inner tube. The condensation temperature was maintained at 35 °C, and the refrigerant mass flux ranged from 320 to 750 kg/(m~2s). The experimental values for condensation heat transfer and pressure drop were compared with values obtained for R32 and R410A refrigerants and with the results of previous studies.