Coordination number models and equations of state for square-well pure andmixture fluids, Part II: Equations of state

Equations of state (EOSs) for square-well (SW) pure and mixture fluids were derived based on the coordination number models (CNM) proposed in the prec eding paper (Cao & Wang, 1999, Chemical Engineering Science). The EOS propo sed for the SW pure fluid is compared with previous CNM EOS and three theor etical perturbation theory EOS with respect to the capability of estimating the compressibility and critical point, covering wide density range and va riable well width. The results indicate that the new EOS gives better accur acy than the other CNM EOSs, and is comparable with the first-order, but le ss accurate than the second-order perturbation theory EOSs. More importantl y, the new EOS for the SW mixture fluids is a remarkable improvement over t he other two feasible CNM EOSs at high densities, in particular. Consequent ly, the EOSs proposed in this work lead to a reasonable framework for the d evelopment of practical EOSs, in which the SW fluid is a reference system. (C) 2000 Elsevier Science Ltd. All rights reserved.