Modeling fluorocarbon vapor–liquid equilibria using the Wong–Sandler model

Vapor–liquid equilibrium (VLE) data for seven binary fluorocarbon mixtures were modeled using the Wong–Sandler (WS) model. A variety of fluorocarbon azeotropes were chosen for testing the accuracy of the model. The azeotropes tested were CF2H2 and CF3CH3, CF2H2 and CF3CF3, CF2H2 and CHF2CF3, CF2H2 and CH3CH2CH3, CF3H and CF3CF3, CF3CF3 and CO2, CHF2CF3 and NH3. Using the WS mixing rule and the nonrandom two-liquid (NRTL) activity coefficient model, a three-parameter fit was calculated for each binary mixture. These parameters were then used to predict the VLE behavior at other temperatures which were compared with experimental data. The results showed that the WS mixing rules with the NRTL activity coefficient model could be accurately fitted to binary fluorocarbon VLE data and used for predictions at other temperatures.