ALGORITHMS FOR THE ESTIMATION OF PHASE-STABILITY IN HETEROGENEOUS THERMODYNAMIC SYSTEMS

Two critical aspects of the computation of equilibrium phase relations in highly nonideal thermodynamic systems are discussed: (1) identification of the saturation conditions and likely compositions of a suite of phases relative to a pervasive fluid phase, and (2) detection of phase separation within a homogeneous phase and estimation of compositions in the resulting equilibrium multiphase assemblage. New algorithms are described which address both of these problems in multicomponent thermodynamic systems and numerical results are presented for two and three component cases. An appendix illustrates a method of deriving analytical expressions for derivatives of the Gibbs free energies of phases characterized by internal ''ordering'' parameters.