SAFT-VR-Mie with an incorporated polar term for accurate holistic prediction of the thermodynamic properties of polar components

Abstract

The SAFT-VR Mie equation of state is extended to polar components and their mixtures by incorporating an explicit polar term into the residual Helmholtz energy expansion. The transferability of the Jog & Chapman (JC) and Gross & Vrabec (GV) polar terms to this framework is demonstrated, yielding the SAFT-VR Mie-JC and SAFT-VR Mie-GV models. Numerical challenges common to the parameterization of both SAFT-VR Mie and polar SAFT are found to characterize the regression of parameter sets in these new models, most notably for the JC term. These challenges hampered the performance of SAFT-VR Mie-JC, which was consistently outperformed by its GV counterpart as a result. Excellent predictions of mixture behaviour for ketones, esters and ethers are in evidence if the mixture data (MD) and fixed polar parameter (FPP) regression approaches are employed to yield unique parameter sets. The performance of the latter is particularly significant, as accurate predictions for both phase equilibrium and speed of sound are in evidence from parameter sets regressed using pure component properties alone, without the need for experimental mixture data. Based on the functional groups and systems under investigation, the SAFT-VR Mie-GV model with FPP parameter sets represents a holistic, predictive approach for the thermodynamic description of polar components and their mixtures.