Phase equilibria in mixtures of glycerides and carbon dioxide and application of continuous thermodynamics to mixtures of rapeseed oil and carbon dioxide

Abstract

A lattice model equation of state recently developed by Kumar et al. is used to model phase equilibria in binary and quaternary mixtures of trilaurin, trimyristin, tripalmitin and carbon dioxide. In order to obtain an accurate description of the thermodynamic properties of the supercritical fluid, we introduce the Bender equation of state into the lattice model. As expected, the Kumar-Bender equation of state leads to an improved representation of the triglyceride solubilities. Considering rapeseed oil to be a mixture of triglycerides, the Kumar-Bender model is applied to the rapeseed oil-carbon dioxide system. The efficiency of continuous thermodynamics is compared with a conventional pseudocomponent technique. These investigations indicate that for mixtures of vegetable oils and carbon dioxide, the capability of an equation of state to model phase equilibria of asymmetric mixtures accurately is more important than the exact knowledge of the composition of the complex mixture.