Condensation Heat Transfer of HFC and HFO Refrigerants in a Horizontal Single Rectangular Mini-channel

Abstract

In this study, to clarify the fundamental characteristics of condensation heat transfer of refrigerant in a horizontal rectangular mini-channel at low mass fluxes down to 40 kg/(m²ꞏs), experiments were performed using a single rectangular small tube with a hydraulic diameter of 1.02 mm. HFC134a, HFC32 and HFO1234ze(E) are used as test refrigerants. The range of refrigerant mass flux condition was 40-400 kg/(m²ꞏs), and that of heat flux was 2-8 kW/m². From the present data, it was clarified that the condensation heat transfer coefficient at a low mass flux 100 kg/(m²ꞏs) or less was noticeably high value compared with that at relatively high mass flux conditions. Besides, this tendency was different from that was seen in experimental studies using multiport tubes and tendency predicted by existing correlations applied by extension to the low mass flux condition.