Nonrandom two-liquid activity coefficient model with association theory

Yifan Hao, Chau Chyun Chen

Research output: Contribution to journalArticlepeer-review

12 Scopus citations


Considered one of the most versatile and widely used classical thermodynamic models to correlate phase equilibria behavior of nonideal systems, the nonrandom two-liquid (NRTL) theory does not explicitly account for specific chemical associations such as hydrogen bonding. This deficiency has been recognized as the cause for unsatisfactory representation of association systems like methanol–alkanes binaries. This work presents a practical approach to integrate Wertheim's perturbation theory for association contribution with the classical NRTL model. Specifically, the association contribution is calculated from pre-determined molecule-specific association strengths while the physical interaction contribution is captured with NRTL binary interaction parameters. The resulting association NRTL model correlates fluid phase equilibria of association systems with few adjustable parameters and offers improved predictive capability for higher order systems.

Original languageEnglish
Article numbere17061
JournalAIChE Journal
Issue number1
StatePublished - Jan 2021


  • phase equilibrium
  • thermodynamics/classical


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