Heat transfer correlations of forced convective boiling for pure refrigerants in micro-fin tubes

The evaporation heat transfer coefficient of pure refrigerants R-22 and R-124 in micro-fin tubes were measured at the reduced pressure of 0.15, the mass flux from 100 to 400 kg/m2 s, the flow quality from 0.1 to 0.9, and the heat flux from 5 to 20 kW/m2. The evaporation heat transfer coefficient of pure refrigerant in micro-fin tube is 1.5-3.0 times higher than that of smooth tube. In this article, the single phase forced convection heat transfer coefficient of micro-fin tube is introduced to predict the evaporation heat transfer coefficient of pure refrigerant in micro-fin tubes. The present correlations provide reasonable agreement with the experimental data. The prediction values mostly fall within ±30%.