Two-phase heat transfer performance of ternary mixtures of HFOs and HFCs inside channels

Some blends of low-GWP refrigerants have been developed to satisfy the demand for a wide range of working conditions and substitute R410A in air-conditioning applications and R404A in refrigeration applications. The present paper investigates the two-phase heat transfer performance of R455A (mixture of R1234yf, R32, CO2 at 75.5/21.5/3.0% by mass composition) and R452B (mixture of R32, R1234yf, R125 at 67.0/26.0/7.0% by mass composition). New experimental heat transfer coefficients obtained during convective condensation in 1 mm and 8 mm inner diameter channels have been compared with those of the pure components R1234yf and R32. This allows to analyze the heat transfer penalization due to the zeotrope of the mixture and to assess available predicting models for condensation. In order to fully characterize the performance of the two blends, the pressure drop during adiabatic two-phase flow are measured and compared to predicting models.