SAFT-VR is a widely used molecular-based equation of state that has been successfully applied to study a wide range of fluid systems. It provides a framework in which the effects of molecular shape and interactions on the thermodynamics and phase behavior of fluids can be separated and quantified. In the original SAFT-VR approach, molecules were modeled as chains composed of identical segments [1]. Hence the heterogeneity of molecules was described implicitly through effective parameters. In order to explicitly take into account heterogeneity, the hetero-SAFT-VR approach was developed and has been validated against simulation data in earlier work [2, 3]. In this work, we apply the hetero-SAFT-VR approach to studying the effect of molecular topology on the thermodynamic properties of real fluid systems. The parameters for each type of segment are determined through fitting to experimental vapor pressure and liquid density data for a selected group of compounds containing key chemical groups. Transferability of the parameters is tested by comparing the theoretical predictions with experimental data for pure fluids and binary mixtures not included in the fitting process.

1. Gil-Villegas, A., et al., Statistical associating fluid theory for chain molecules with attractive potentials of variable range. Journal Of Chemical Physics, 106(10) 4168-4186 (1997). 2. McCabe, C., et al., The thermodynamics of heteronuclear molecules formed from bonded square-well (BSW) segments using the SAFT-VR approach. Molecular Physics, 97(4) 551-558 (1999). 3. Peng, Y., H.G. Zhao, and C. McCabe, On the thermodynamics of diblock chain fluids from simulation and heteronuclear statistical associating fluid theory for potentials of variable range. Molecular Physics, 104(4) 571-586 (2006).