Application of GC-SAFT EOS to polar systems using a segment approach

The GC-SAFT equation of state proposed by Tamouza et al. (Fluid Phase Equilib. 222–223 (2004) 67) is here extended to model phase equilibria of polar fluid (dipolar and quadrupolar) mixtures using an extension of the theory from Gubbins and Twu (Chem. Eng. Sci. 33 (1978) 863) to chain molecules inspired by the segment approach proposed by Jog and Chapman (Mol. Phys. 97 (1999) 307). Systematic tests with three different SAFT EOSs versions are carried out on vapor–liquid equilibria (VLE) of pure 1-alkanol, alkyl-benzenes, xylenes and their binary mixtures. Binary mixtures with n-alkanes and cyclohexane are also investigated. The tests on these systems were as comprehensive as possible.Vapor pressure of heavy polar compounds is predicted satisfactorily within 5–8% for GC-SAFT-0 and GC-PC-SAFT, 3–4% for GC-VR-SAFT. The average deviation on bubble pressure is about 4% and 1–3% on dipolar and quadrupolar mixtures, respectively, for the three versions of GC-SAFT. Computations of mixtures VLE were made assuming zero binary parameters (kij = lij = 0). The current approach compares well to an earlier treatment by Tamouza et al. (Fluid Phase Equilib. 222–223 (2004) 67; Fluid Phase Equilib. 228–229 (2005) 409) restricted to some of the polar systems modeled here.