Prediction of fluid phase equilibrium of ternary mixtures in the critical region and the modified Leung–Griffiths theory

The modified Leung–Griffiths theory of vapor–liquid equilibrium (VLE) is generalized to the case of three components. The principle of ‘‘corresponding states’’ is reconsidered along with certain functions of ‘‘field variables’’ within the model. The mathematical form of the coexistence boundary in terms of the field variables remains practically unchanged and conforms to modern scaling theory. The new model essentially predicts ternary fluid mixture phase boundaries in the critical region from previous vapor–liquid equilibrium data correlations of the three binary fluid mixture limits. Predicted saturation isotherms of the ethane+n‐butane+n‐pentane and ethane+n‐butane+n‐heptane mixtures are compared with experimental ternary VLE data in the literature.