Analysis of Condensation Heat Transfer Model in Small Channels

Abstract

There are many researches about condensation heat transfer in macro-channels,but the studies of condensation heat transfer in small channels is limited available,and the interaction of gravity,shear stress and surface tension in small channels is different with macro-channels,result that the mechanism of condensation heat transfer in small channels is different with macro-channels,therefore condensation heat transfer prediction model of macro-channels can not predict heat transfer coefficients of small channels very well.While,the research of condensation heat transfer in small channels is significance for designing and optimizing compact heat exchanger.Nine condensation heat transfer prediction models of small channels are addressed,and a database is setup by collecting 1 183 condensation heat transfer data points of small channels which involves six types of refrigerants(R134a,R32,R22,R123,R410A,R1234yf)from 11 independent research groups.On basis of the comparison between the prediction results and the database,it is found that most of prediction models cannot capture the points of all fluids under various operating conditions in small channels,proper model should be chosen according to refrigerants and operating conditions.Garimella's prediction model is the best one for R134a,R32,R22and R1234yf.Koyama's model can almost fit for all data under most of the operating conditions within an acceptable deviation.