HIGH-PRESSURE VAPOR-LIQUID-EQUILIBRIUM WITH A UNIFAC-BASED EQUATION OF STATE

Recent procedures developed by Heidemann (1990) and by Michelsen (1990a,b) enable us to formally incorporate excess Gibbs energy model parameters into a fully consistent equation of state, cith accurate reproduction of the behavior of the excess Gibbs energy model at atmospheric pressure. This paper investigates the ability of the mixing rules proposed by Michelsen to predict high-pressure phase equilibrium, when used in combination with the parameter table of modified UNIFAC. Considering that a group contribution method is used for the excess Gibbs energy and that model parameters are extrapolated over a 200 K temperature interval, quite satisfactory results are obtained for the mixtures investigated.