Experimental Study on Evaporation Heat Transfer Characteristicsof R32 in A Plate Heat Exchanger

Abstract

This study experimentally investigates the evaporation heat transfer and frictional pressure drop characteristics of R32 in a plate heat exchanger with a chevron angle of 60°. The evaporation heat transfer coefficient and friction factor are measured at mass fluxes of 50, 70, and 90 kg/ms, a heat flux of 6.45 kW/m, and saturation temperatures of 5 and 15 °C. The heat transfer coefficient increases with the mass flux, saturation temperature, and vapor quality because the forced convective boiling is dominant in this study. The frictional pressure drop also increases gradually with the vapor quality owing to the high velocity difference between the two phases. R32 exhibits a higher heat transfer coefficient and frictional pressure drop than R410A due to the high thermal conductivity and low vapor density. Furthermore, the friction factor of R32 decreases up to a certain quality (0.4) and then increases slightly afterwards. The frictional pressure drop of R32 is greater than R410A owing to the influence of density despite the lower viscosity. The friction factor of R32 is also higher than R410A due to the lower liquid and vapor density.