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 mixt ure compositions and saturation conditions for difluoromethane (R-32) mixed with a polyol ester oil (POE). These data were correlated using the follow ing local-composition models from the literature: Wilson, Hell, Wang and Ch ao, Tsuboka and Katayama, NRTL and UNIQUAC. The results mere used to evalua te the suitability of these models in predicting the saturation behavior of the R-32/POE mixture. The Hell model had the best performance, with a 2-si gma error of 4.81% in the predicted saturation pressure. UNIQUAC was the wo rst, with a 2-sigma error of more than 12%. Using VLE results from the lite rature for pentaflouroethane (R-125) mixed with the same oil and model para meters 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 Hell model can make such predictions with a 2-sigma error of about 11% in pressure. (C) 1999 Elsevier Science Ltd and IIR. All rights reserved.