Considering the dispersive interactions in the COSMO-SAC model for more accurate predictions of fluid phase behavior

Chieh Ming Hsieh, Shiang Tai Lin, Jadran Vrabec

Research output: Contribution to journalArticlepeer-review

39 Scopus citations

Abstract

A term to consider the contribution of the dispersive interactions to the non-ideality of mixtures is introduced into the COSMO-SAC model on the basis of molecular simulation data from classical model force fields. This dispersion term is a one-constant Margules equation, where the constant is determined from the molecular dispersion parameter of the components. Furthermore, an atomic contribution method is proposed to calculate the dispersion parameter for a given molecule. For binary systems containing molecules consisting of C, H, N, O, F and Cl atoms, a total of 13 global parameters is introduced with the COSMO-SAC-dsp model. These parameters are obtained from regression to a large training set of binary vapor-liquid equilibrium (VLE) data from experiment. The overall deviations for VLE calculations on this training set are reduced by 25% in terms of the vapor pressure and 12% in terms of the vapor phase mole fraction. This dispersion term can provide a significant improvement for infinite dilution activity coefficient predictions, where the accuracy was increased by around 33%.

Original languageEnglish
Pages (from-to)109-116
Number of pages8
JournalFluid Phase Equilibria
Volume367
DOIs
StatePublished - 15 Apr 2014

Keywords

  • COSMO-SAC
  • Dispersive interaction
  • Infinite dilution activity coefficient
  • Phase equilibria
  • Prediction

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