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Vapor−liquid equilibria (VLE) for new refrigerant mixtures containing hydrofluorocarbons, alkanes, alkenes, dimethyl ether, CO2, and perfluoroalkanes are of great interest. Those mixtures generally exhibit azeotropes, high nonideality, association effects, and contain supercritical compounds. The modified Soave−Redlich−Kwong equation of state is used with zero reference pressure GE−EoS mixing rules and the UNIFAC group contribution model in this study to form a group contribution model for predicting vapor−liquid equilibria. A new functional group assignment strategy is used, and the values of interaction parameters between groups are provided. These parameters are optimized from selected binary vapor−liquid equilibria data to give good representations of the experimental VLE data. A ternary system was also accurately predicted using the group contribution model. The method is totally predictive because only the structures and the critical constants of the pure components are needed to calculate the thermodynamic properties of new refrigerant mixtures.

Alternative working fluid mixtures containing hydrofluoroethers, hydrofluorocarbons, alkanes, alcohols, ketones, and esters widely used as process fluids generally exhibit azeotropes, high nonideality, and association effects. In this work, the vapor-liquid equilibria for these mixtures are predicted using a combination of the Soave-Redlich-Kwong equation of state, zero reference pressure G E -EoS mixing rules, and the UNIFAC group contribution model. A new functional group assignment strategy was developed, and the model interaction parameters between groups were obtained from selected binary vapor-liquid equilibria data to give fairly good agreement between the calculated results and the experimental data. The method is also extended to ternary systems for VLE representations in a totally predictive manner with only the molecular structures, the critical parameters, and the acentric factors of the pure components needed.