Prediction of phase equilibria in the systems carbon dioxide (1)-fatty acids (2) by two cubic EOS models and classical mixing rules without binary adjustable parameters

This study evaluates the accuracy of estimating data in the series of systems carbon dioxide (1)-fatty acids (2) by two cubic equations of state, namely the EOS of Peng and Robinson in its original form and the recently proposed cubic EOS. The classical mixing rules are implemented in entirely predictive manner, i.e. without binary adjustable parameters. It is demonstrated that both models may yield reliable predictions of the data. However the EOS of Peng and Robinson fails in predicting the topology of phase behavior of the heavy homologues. The second cubic EOS predicts the Global Phase Behavior in the homologous series under consideration satisfactorily accurate, which in particular means qualitatively correct estimation of the liquid-liquid equilibria. The recently proposed EOS has no significant advantage over the EOS of Peng and Robinson in predicting the vapour-liquid equilibria data under consideration.