Vapor-liquid equilibrium for R-32 and R-410A mixed with a polyol ester: Non-ideality and local composition modeling

Vapor-liquid equilibrium (VLE) data were obtained over a wide range of mixture compositions and saturation conditions for difluoromethane (R-32) mixed with a polyol ester oil (POE). These data were correlated using the following local-composition models from the literature: Wilson, Heil, Wang and Chao, Tsuboka and Katayama, NRTL and UNIQUAC. The results were used to evaluate the suitability of these models in predicting the saturation behavior of the R-32/POE mixture. The Heil model had the best performance, with a 2-σ error of 4.81% in the predicted saturation pressure. UNIQUAC was the worst, with a 2-σ error of more than 12%. Using VLE results from the literature for pentaflouroethane (R-125) mixed with the same oil and model parameters for that mixture, an effort was made to make a priori predictions of the p-T-x behavior of a blend containing 50% R-32+50% R-125 (R-410A) and the POE. Data were obtained for this blend, and the results indicate that the Heil model can make such predictions with a 2-σ error of about 11% in pressure.