Ivestigation on Flow Boiling Heat Transfer Characteristics of R404A in Horizontal Microfin Tube

Abstract

Considering R404A as a pure and mixed refrigerant respectively, the boiling heat transfer coefficients were calculated inside horizontal 9.52 mm o.d. microfin tube. The difference of less than 10% between the two calculations shows that R404A can be taken as pure fluid in practical calculation. Cavallini, Koyama and Thome correlations for boiling heat transfer inside microfin tube all indicate that the convective heat transfer plays a predominant role in total boiling heat transfer. The predicted values by the above correlations were compared with the experimental data. The result shows that Cavallini and Thome correlations can well predict the boiling heat transfer of azeotropic mixture R404A with the error of less than 21%.