Elemental composition method for computation and analysis of simultaneous chemical and phase equilibrium

An elemental composition method for computation and analysis of simultaneou s chemical and phase equilibrium (CPE) of non-ideal mixtures is proposed. T he concept of element is defined, the relationship between component compos ition and elemental composition is derived, and the concept of elemental po tential and its physical meaning are further cleared from the view point of thermodynamics. The relationship between chemical potential and elemental potential is derived in the thermodynamic principles, and the computation e quations for CPE problem are obtained based on elemental potential. A simpl e form of necessary and sufficient condition in terms of elemental composit ion for reactive azeotropes is derived, which takes the same functional for m as the condition for azeotropes in non-reactive systems. The element in t his note may be atoms, molecules or group radicals. The presented method is applicable to CPE problem of non-ideal mixtures, and the computation can b e simplified by the dimension reducing method. The presented method was sup plied to compute and analyze CPE problem of several examples and it is foun d that it is a robust and efficient method.