Vapor-liquid equilibria for R-22, R-134a, R-125, and R-32/125 with a polyol ester lubricant: measurements and departure from ideality

The effect of a polyol ester lubricant on equilibrium pressure, liquid density, and viscosity is presented for R-22, R-125, and R-134a at varying temperatures and concentrations. Preliminary vapor-liquid equilibrium (VLE) data and miscibility observations are also presented for an R-32/R-125 blend (50%/50%) with the ISO 68 polyol ester (POE). Real-gas behavior is modeled using the vapor-phase fugacity, and vapor pressure effects on liquid fugacities are taken into account with the Poynting effect. Positive, negative, and mixed deviations from the Lewis-Randall rule are observed in the activity coefficient behavior. Departures from ideality are related to molecular size differences, intermolecular forces in the mixture, and other factors. The data are discussed in the context of previous results for other refrigerants and thermodynamic modeling of refrigerant and oil mixtures.