PREDICTION OF VAPOR-LIQUID-EQUILIBRIA AT HIGH-PRESSURES USING MIXING RULES BASED ON EXCESS GIBBS ENERGY MODELS

A modified procedure of using the Huron-Vidal (1979) mixing rule based on activity coefficients at infinite dilution at low pressures, is sh own to be useful for making vapor-liquid equilibrium predictions for n on ideal mixtures at high temperatures and pressures. We compare the p erformances of this mixing rule (called HVID model), coupled with the SRK equation of state and a reduced UNIQUAC model with those of two ot her equations of state mixing rules, one by Dahl and Michelsen (MHV2) and another by Wong and Sandler (WS). Six. binary systems are used in this study, and we find that the errors in the predicted pressure with the new mixing rule are, on the average, less than those obtained whe n using-the MHV2 model. As compared with the three parameters WS mixin g rule, the HVID model performs similarly, but using two temperature d ependent parameters.