SIMPLE NEW EOS MIXING RULES WHICH INCORPORATE LATTICE FLUID EXCESS FUNCTIONS

New mixing rules which incorporate lattice fluid excess functions (for example Wilson and NRTL) and the correct quadratic concentration depe ndence of the second virial coefficient are presented. It is shown tha t the excess Gibbs funct:ions derived for activity coefficient models correspond to the attractive part of the excess Helmholtz energy deriv ed from EOS. This allows the formulation of a class of mixing rules wh ich are independent of the repulsive term in the EOS, and are applicab le to both cubic and noncubic EOS. The mixing rules are applied to dif ferent low-pressure phase equilibria and to two near-critical and supe rcritical systems. (C) 1998 Elsevier Science Ltd. All rights reserved.