The comparison of condensation heat transfer and frictional pressure drop of R1234ze(E), propane and R134a in a horizontal mini-channel

The steady-state condensation performance of R1234ze(E), propane and R134a in a horizontal circular mini-channel was numerically investigated. The effects of mass flux, vapor quality and physical properties on condensation performance were discussed. At the same condition, condensation heat performance of propane was the best and then the R134a and R1234ze(E). However, the pressure gradients of R1234ze(E) were larger than that of propane and R134a. The average film thickness of propane and R1234ze(E) were an average of 9.4% thicker and 15.7% thinner than that of R134a, respectively. The effective conductivity played an important role in the heat flow rate of three refrigerants. Unlike the R1234ze(E) and R134a for which the condensate tended to be stratified at x = 0.5, there was no obvious stratification for propane. The published correlations tended to underestimate the pressure gradients of R1234ze(E) significantly. (C) 2018 Elsevier Ltd and IIR. All rights reserved.