PHYSICAL CHEMISTRY ON THE MIN-MAX FORMULATION OF MULTIPHASE CHEMICAL EQUILIBRIUM PROBLEM AND STABILITY ANALYSIS

formulated as a min-max nonlinear primal geometric program with constraints, using the duality theorem. A reformulation of the nonlinear min-max program is suggested, that restates the problem in terms of mole fractions in a reference phase. The potential function, called tangent plan intersection (TPI), is the set of intersections, at the global mixture composition, of tangent plan to the Gibbs free energy of mixing. Based on this tangent plan intersection function, a new approach for the stability analysis is advanced, allowing to obtain the number and the identity of phases, as well as good approximates of the phase compositions. Numerical algorithms are advanced for solving the min-max program, with constraints corresponding to a system that include all the phases considered coexisting at equilibrium