Flow boiling heat transfer characteristics over horizontal smooth and microfin tubes: An empirical investigation utilizing R407c

Abstract

The flow boiling heat transfer performance of horizontal smooth and microfin tubes was investigated using the refrigerant R407c. The evaporator test tube contains an outside, inner diameter and length of 9.52, 8.52, and 1000 mm, respectively. The investigations were performed out at 283.15 and 303.15 K saturation temperatures with hot water circulation heat flux of 75 kW.m-2, refrigerant heat flux varying from 5 to 85 kW.m-2, and mass flux varied from 15 to 250 kg.m-2.s-1, keeping the area ratio of microfin tube 1.68%. The experimental results are compared to several previously recognised correlations. Experimental outcomes demonstrated that the heat transfer rate of the microfin tube is superior to the smooth tube. The percentage of heat transfer enhancement was considered to exceed in microfin tube by 28–280%. The pressure drop in regard to R407c was found to be augmented than smooth tube according to the experimental results and enhancement was achieved in microfin tube by 68–110%. Finally, a sensitivity analysis is carried out in flow boiling heat transfer phenomenon via the smooth tube.