Condensation heat transfer performance and integrated correlations of low GWP refrigerants in plate heat exchangers

In this study, the effects of mass flux, heat flux, and condensation pressure according to mean vapor quality on the condensation heat transfer coefficient and frictional pressure drop of R124 were analyzed for plate heat exchangers with different chevron angles. The heat transfer coefficient increased with an increase in the mean vapor quality, mass flux, and heat flux. However, it decreased with an increase in the condensation pressure. The frictional pressure drop exhibited a similar trend to that of the heat transfer coefficient, but it was not significantly affected by a change in the heat flux. Furthermore, Nusselt number and friction factor correlations were developed based on the experimental data of R124. Two types of integrated correlations, namely those for the heat transfer coefficient and friction factor, were developed considering R1233zd(E) and R1234ze(E), based on previous studies. Subsequently, integrated correlations were developed for R124, R1233zd(E) and R1234ze(E). For the integrated correlations, the correction factors C₁ and C₂ are introduced and compared with those proposed in previous studies. For the validation of the correction factors, the final integrated correlations including R134a and R410A were developed, and the correlations predicted 88.1% and 73.2%, respectively within the error range of 25%.