Effect of inner diameter ratio of different diameter parallel micro channels in airfoil-shaped tube on refrigerant distribution and evaporation characteristics

Abstract

This study experimentally investigated the refrigerant distribution and evaporation characteristics of different diameter parallel micro channels in airfoil-shaped tube for smaller diameter tubes compared with previous study. Test section consisted of two stainless tubes that have different inner diameter using R134a as the refrigerant. The effects of tube diameter difference, total heat transfer rate and heat transfer rate ratio on refrigerant distribution, pressure drop and evaporation heat transfer were investigated. The results revealed that mass flow rate ratio of the windward tube increased with decreasing diameter of the leeward tube. Moreover, desirable tube diameter of the leeward tube is less than that of the windward tube when the heat transfer rate of the leeward tube is smaller than that of the windward tube.