Phase Equilibria by effective UNIFAC group-contribution method

Abstract

A group-contribution method similar to the UNIFAC model is presented for the estimation of liquid phase activity coefficients. The method is based on an extension of the effective UNIQUAC equation, which represents well vapor—liquid equilibria of alcohol-saturated hydrocarbon mixtures with two parameters. Group-interaction parameters for 35 groups are obtained from experimental vapor—liquid equilibrium and solubility data. Activity coefficients in many binary and multicomponent mixtures may be estimated with good accuracy. Calculations are carried out for vapor—liquid, liquid—liquid, and solid—liquid equilibria. Both UNIFAC and effective UNIFAC seem to provide comparable results in most cases. The method, like the SIGMA of Vera, may be used for the prediction of both vapor—liquid equilibrium and excess enthalpy data for binary and ternary systems containing CH 2, CCOH, and CCl groups.