PREDICTION OF VAPOR-LIQUID-EQUILIBRIA AT LOW AND HIGH-PRESSURES FROM UNIFAC ACTIVITY-COEFFICIENTS AT INFINITE DILUTION

A modified procedure of using the Huron-Vidal mixing rule based on UNI FAC activity coefficients at infinite dilution (HVID) at low pressures is shown to be useful for making vapor-liquid equilibrium (VLE) predi ctions for polar and nonpolar systems at low and high pressures. Four cases were considered: (a) symmetric polar systems; (b) systems contai ning alkanols and hydrocarbons; (c) systems containing acetone and hyd rocarbons; (d) hydrocarbon mixtures. Prediction of both low- and high- pressure VLE for binary systems is good. The HVID model, using UNIFAC '93 activity coefficients at infinite dilution, performs satisfactoril y in the VLE predictions of ternary systems also.