Evaporative heat transfer performance of R-513A in a Brazed Plate Heat Exchanger, and an updated universal heat transfer correlation

This paper experimentally investigates the evaporative heat transfer coefficient (HTC) and pressure drop of the low GWP refrigerant R-513 in a Brazed Plate Heat Exchanger. It is considered to be a potential alternative to R134a. The effects of heat flux, mass flux, vapor quality, and saturation temperature on the HTC and pressure drop are studied. The results show a strong dependence of HTC and pressure drop on heat flux and mass flux conditions, and the effect of vapor quality is only minor. It was observed that R-513A outperforms R-134a by about 25% in HTC and pressure drop at low heat flux and mass flux conditions, while R-134a is slightly better at higher operating heat flux and mass flux. However, the pressure drop of R-513A is significantly higher by more than 57% at higher imposed heat flux. This work also examines the applicability of existing heat transfer correlations and proposes a new correlation accounting for several non-dimensional parameters for accurate prediction. Over 600 experimental HTC data are gathered across five refrigerants and seven Chevron angles. The proposed correlation is compared with others based on Mean Absolute Deviation (MAD) and R2 values. The MAD and R2 values of the current correlation are 12.6% and 0.93, respectively, which are the best among the tested correlations. The superior heat transfer performance of R-513A at low mass fluxes and saturation temperatures makes it a viable low-GWP alternative to R-134a.