EXPERIMENTAL STUDY OF BOILING HEAT TRANSFER AND PRESSURE DROP OF R410A IN MICRO-FIN TUBES

An experimental investigation of boiling characteristics in two types of micro-fin tubes with 7 mm outside diameter and 1 m length was conducted. The refrigerant tested was R410A with vapor quality from 0.1 to 0.9, mass flux between 100 and 500 kg.m(-2).s(-1) at three different heat fluxes: 10, 15 and 20 kW.m(-2). The saturation temperature was 10 degrees C. The results show that the heat transfer coefficient increases with mass flux over the whole range of vapor qualities tested. It decreases with the increase of vapor quality in small mass flux condition while increases in large mass flux condition. The deterioration of heat transfer occurs in the condition of large vapor quality and mass flux. The smaller the mass flux and the higher the heat flux, the earlier the heat transfer deterioration occurs.