Experimental investigation on flow boiling heat transfer performance of a new near azeotropic refrigerant mixture R290/R32 in horizontal tubes

Abstract

A new refrigerant mixture composed of R290 and R32 is proposed by the present paper. With a mass ratio of m32/m290=68/32, the new refrigerant mixture is near azeotropic, zero ODP and low GWP, which will be a competitive R22 replacement in household air conditioners. An experimental apparatus has been designed and built to analyze the flow boiling performance of this new refrigerant mixture. Flow boiling heat transfer performances of the new refrigerant mixture inside different horizontal heat transfer tubes including 5mm smooth and micro-fin tubes, 7mm smooth and micro-fin tubes and 9.52 micro-fin tube, have been experimentally investigated. Variations of flow boiling heat transfer coefficient with mass flux under the condition of different evaporation temperature and different tube inner diameters were obtained. Comparison of flow boiling heat transfer coefficient of the new R32/R290 mixture with that of R410A has been carried out. Flow boiling heat transfer coefficient of the new R32/R290 mixture is 14.3–68.4% higher than that of R410A. The researching results of the present study will be of great help in evaporator design and optimization for R32/R290 refrigeration units.