1988 Volume 21 Issue 5 Pages 509-515
An expression for the excess Gibbs energy of expandable liquid mixtures, such as liquefied gas mixtures, is obtained by considering the effect of molar volume change on the structure of a solution. A new equation is derived through the introduction of two limiting states: the close-packed and hypothetical expanded states. From this model, the deviation of the excess Gibbs energy from the close-packed state is determined by hole fraction and solution structure parameter. The model, which requires only binary parameters, was tested on vapor-liquid and liquid-liquid equilibria of various mixtures including liquefied gas mixtures, and gave better data representation than the UNIQUAC model.