Basirat - Department of Chemical Engineering –Shiraz University –Shiraz- Iran
Fathikalajahi - Department of Chemical Engineering –Shiraz University –Shiraz- Iran

The present study investigates the use of different GE mixing rules models in cubic equation of state for prediction of phase behavior for multicomponent hydrocarbon systems .To predict VLE data in multicomponent symmetric and asymmetric mixtures such as systems that contain light gases (nitrogen, carbon dioxide,...) and heavy hydrocarbons, we have combined SRK equation of state with excess Gibbs energy models. In this study, we re-examined PSRK method, which developed by Holderbuom and Gmehling for VLE data prediction. To visualize the effect of different mixing rules in predicting VLE data, Wong and Sander mixing rule were applied. New group and molecular interaction parameters in UNIFAC and W-S models were introduced. These parameters were obtained by regression the available VLE data. The results of comparisons between applied models and experimental data are presented. These indicate that although all suggested models could provide reasonably good VLE information for the systems containing components of similar size at a wide range of temperature and pressures, but only PSRK method show minimum absolute and relative errors for both vapor and liquid compositions in asymmetric systems

VLE, State equation, GE Models, PSRK