AUTOMATED GENERATION OF PHASE DIAGRAMS FOR SUPERCRITICAL FLUIDS FROM EQUATIONS OF STATE

Phase behavior is of major importance in the analysis and development of applications of supercritical fluids. Different classes of phase diagrams of fluid mixtures are useful to understand mixing/demixing processes, to explore conditions at which such processes occur and to study the influence of temperature and pressure on solubility values. Equations of state are an important type of thermodynamic models. They can be used to model properties of liquid, vapor or supercritical phases, with continuous transitions among such states. Unfortunately, phase equilibrium calculations are not simple. They require iterative procedures, which have no guarantee for convergence, rely on often crucial initial estimates and provide solutions that need to be tested for stability. Special attention has been given in the literature to the development of calculation procedures for two-phase and multiphase flashes, saturation points, phase envelopes, critical points, etc [1]. However, the development of calculation algorithms for phase equilibria has not reached yet a plateau. For instance, a general algorithm for automated construction of phase diagrams for binary mixtures covering all possible situations of fluid-fluid and solid-fluid equilibria for systems of varying asymmetry is, to our knowledge, not yet available