Vapor–Liquid Equilibrium Property Measurements for R32/R1234yf Binary Mixtures in Low R32 Concentration

This study obtained the precise measurements of the vapor–liquid equilibrium properties for R32/R1234yf binary mixtures, which are the key components for the next-generation refrigerant mixtures. To obtain the data more rapidly and precisely, two recirculation-type vapor–liquid equilibrium property measurement apparatuses installed in different universities are used. One apparatus, which was used to measure data in high temperature region, is installed at Toyama Prefectural University, and the other apparatus, which was for low temperatures, is installed at Kyushu University. To achieve the low GWP values less than 150 (European F gas regulation value), the composition of R32 (difluoromethane; CH₂F₂, GWP = 677) should be less than 22 % in mass fraction (38 % in mole fraction). Therefore, we tried to obtain precisely the data of lower R32 composition less than 0.38 mol fraction. The present data comparatively agreed with the only one set of reliable data by Hu in lower R32 compositions, from which we conclude that recent equation of state for R32/R1234yf, which is widely used recently all over the world, has systematic deviations less than 3 % in the bubble point pressures. Moreover, based on the present data and reliable literature data, the binary interaction parameter, k_ij, of the modified Peng-Robinson equation of state was regressed. As the result, we succeeded to reproduce the present bubble point and dew point pressure data with deviations smaller than 3 % as mentioned above for mixtures with low R32 concentrations.