Comparison of predictions of the PC-SAFT equation of state and molecular simulations for the metastable region of binary mixtures

TL;DR

This study compares the PC-SAFT equation of state with molecular simulations to evaluate their accuracy in predicting the metastable regions and spinodals of various binary mixtures, finding good agreement in gases but broader metastable regions with PC-SAFT in liquids.

Contribution

It demonstrates that PC-SAFT EOS can reliably predict metastable states and spinodals, extending its applicability to metastable regions of binary mixtures.

Findings

Good agreement between PC-SAFT and molecular simulations for gas phases.

PC-SAFT predicts broader metastable regions in liquids than simulations.

No unphysical results were observed with PC-SAFT in metastable states.

Abstract

The metastable region of binary mixtures is examined with the PC-SAFT equa-tion of state (EOS) and compared to molecular simulations. The studied mixtures are Methane + Ethane, Methanol + Ethanol, Carbon Dioxide + Toluene, Carbon Dioxide + Hydrogen Chloride and Hydrogen Chloride + Toluene. In order to cal-culate the spinodal, the second partial derivatives with respect to the components molarities are analytically determined for the PC-SAFT EOS. Thermal properties as well as the spinodal points determined using PC-SAFT and molecular simula-tion are compared. For the studied metastable gas phases the results obtained with PC-SAFT and the molecular simulations agree well. For liquid phases the meta-stable region calculated with the PC-SAFT EOS is typically broader than that ob-tained from the molecular simulations. No unphysical results were obtained with PC-SAFT for metastable states. Hence, PC-SAFT EOS is found to be principally suitable for predicting metastable states and spinodals of mixtures.