Experimental research of frictional performance of R4 1 0A-oil mixture flow condensation inside a 5 mm internally spiral grooved enhanced tube

An experimental study of frictional pressure drop characteristics of R410A-oil mixture flow condensation inside aa 5 mm internally spiral grooved enhanced tube was performed to investigate the influence of oil concentration,vapor quality and mass flux on the frictional pressure drop.The experimental conditions include the condensation temperature of 40~C,the mass flux from 200 to 400 kg·m~(-2)·s~(-1),the heat flux from 4.21 to 8.42 kW·m~(-2),the inlet vapor quality from 0.3 to 0.9,nominal oil concentration from 0 to 5%.The test results show that the frictional pressure drop of R410A and R410Aoil mixture increases with mass flux and vapor quality;for R410A-ester oil RB68EP mixture,the influences of oil on frictional pressure drop are relevant with vapor quality.At the range of low and intermediate vapor qualities,the presence of oil will reduce the frictional pressure drop,which descends 29%maximally as the oil concentration increases from 0 to 5%;while at high vapor quality,on the contrary,the presence of oil will increase the frictional pressure drop,which enhances 8%maximally as the oil concentration increases from 0 to 5%.