PARTIAL DERIVATIVE QUANTITIES FROM PHASE-EQUILIBRIA RELATIONSHIPS FORMIXTURES

A systematic formulation of multicomponent/multiphase phase equilibria as a linear algebra problem in the fugacities, mole fractions, partia l molar volumes, and partial molar enthalpies is given. The algorithm takes advantage of the Gibbs-Duhem relationships for each phase and a modified Gaussian elimination technique to reduce the system of equati ons. These algorithmic steps allow current symbolic manipulation packa ges to generate useful partial derivative relationships in terms of me asurable thermodynamic quantities. Features of the algorithm are demon strated by applying a computer implementation of the method to a simpl e two-phase/two-component system and to the more complicated examples of a two-phase/three-component supercritical fluid chromatography expe riment and a mass-conserving closed system.