Topological and thermodynamic classification of ternary vapor-liquid equilibria

Abstract

Vapor-liquid equilibrium relationships in ternary systems can be classified according to the number and types of azeotropes in them. All combinations of azeotropes however cannot exist because of thermodynamic and topological constraints. Two necessary conditions for the existence of the combinations are presented in this paper. One is the thermodynamic condition expressed as the relation among boiling temperatures of the pure materials and azeotropes in the system. The other is the topological one given in terms of indices of singular points in the vector field composed of residue curves which represents topological properties of the vapor-liquid equilibrium relationship. By use of these conditions ternary systems are classified into 113 groups. © 1977, The Society of Chemical Engineers, Japan. All rights reserved.