where the vapor-liquid surface tension correlations, σi,vl, must be specified for all species i, and are evaluated at the temperature of the liquid phase.

Following Winterfeld (Ref. 77), the vapor-liquid surface tension is predicted by mixing the pure species correlations according to

It is independent of pressure, vapor temperature and composition. The vapor-liquid surface tension correlations and liquid density correlations must be specified for all species i, and are evaluated at the temperature of the liquid phase.