Critical points with the Wong-Sandler mixing rule-I. Calculations with the Van der Waals equation of state

Marcelo Castier, Stanley I. Sandler

Research output: Contribution to journalArticle

23 Citations (Scopus)


This is the first of two papers in which critical point calculations in binary systems were performed utilizing cubic equations of state (EOS) combined with excess energy models using the Wong-Sandler mixing rule. In this paper, the van der Waals equation of state is combined with the NRTL model in order to investigate the influence of the model parameters on the shapes of the calculated critical phase diagrams. Due to the large number of parameters in the model, it is not possible to obtain a two-dimensional global phase diagram, however the results indicate that many different types of critical phase diagrams can be obtained from the model. Due to comparatively simple functional form of the van der Waals EOS, no attempt was made to compare the calculated critical phase diagrams with experimental data. Such a comparison is made on the second paper of this series, in which the Peng Robinson EOS is combined with the NRTL model and the resulting model is used in the computation of the critical loci of several real systems.

Original languageEnglish
Pages (from-to)3393-3399
Number of pages7
JournalChemical Engineering Science
Issue number19
Publication statusPublished - 1 Oct 1997



  • Critical phenomena
  • Equations of state
  • Excess free energy
  • Local composition
  • Mixing rules
  • Phase diagrams

ASJC Scopus subject areas

  • Chemistry(all)
  • Chemical Engineering(all)
  • Industrial and Manufacturing Engineering

Cite this