Critical curves and phase equilibria of water- n-alkane binary systems to high pressures and temperatures

Abstract

The critical curves of the six binary systems water-methane to water-hexane and water-dodecane have been calculated up to 200 MPa and, in part, to 670 K. An equation of state of the perturbation type with a repulsion and an attraction term with square-well potential for intermolecular interaction is used. With pairwise combination rules for these potentials, three adjustable parameters are needed. The values of these parameters for the series of alkanes obtained from comparison with experiments are given and discussed. For water with methane, butane, and hexane the extent of the three-dimensional two-phase regions is calculated. It is suggested to use this procedure as a basis for predictions for analogous binary polar-nonpolar systems to high pressures and temperatures.