Effect of combining rules for cubic equations of state on the prediction of double retrograde vaporization

Marcelo F. Alfradique, Marcelo Castier

Research output: Contribution to journalArticle

5 Citations (Scopus)


In this work, the phenomenon of double retrograde vaporization (DRV) is simulated using the Peng-Robinson equation of state with the classical mixing rules and several combining rules for the cross-energy and cross-co-volume parameters. The binary interaction parameters are set equal to zero in all cases, i.e., the calculations are entirely predictive. An interesting conclusion is that the predictions using the classical combining rules (geometric mean rule for aij and arithmetic mean rule for bij) provide the best agreement with the experimental data for all the systems tested: methane + n-butane, methane + n-pentane, ethane + limonene, and ethane + linalool. Another interesting observation is that several combining rules for b ij, other than the arithmetic mean rule, predict the existence of three phases in equilibrium in a very narrow temperature range close to the critical temperature of methane in the methane + n-pentane system, even though, literature data indicates that n-hexane is the first n-alkane to present partial liquid phase immiscibility with methane.

Original languageEnglish
Pages (from-to)1-8
Number of pages8
JournalFluid Phase Equilibria
Issue number1-2
Publication statusPublished - Mar 2005
Externally publishedYes



  • Combining rule
  • Dew point
  • Equation of state
  • Retrograde vaporization
  • Vapor-liquid equilibrium

ASJC Scopus subject areas

  • Fluid Flow and Transfer Processes
  • Physical and Theoretical Chemistry

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