Thermodynamic calculations of linear chain molecules using a SAFT model

The recently proposed model of statistical associated-fluid theory (SAFT) by Tang, Y. and Lu, B. C.-Y. (2000, Fluid Phase Equilibria, 171, 27) is applied to phase diagram calculations of non-associating and associating linear chain molecules in which n-alkanes and n-alkenes (representing the non-associating type) and water, 1-alkanols, acids and amines (representing the associating type) are investigated. For polar molecules, the dipole-dipole interaction is taken into consideration. Overall, the proposed model yields similar accuracy to the original SAFT model, It is found that the volume and energy parameters of non-associating chain segments in the same family follow certain linear relations with the carbon number. Remarkably, these linear relations are found to hold equally well in associating chain molecules. These observations suggest that SAFT may be implemented in a more predictive manner. Furthermore, the inclusion of the contribution from dipole-dipole interaction improves the calculated values for strong polar molecules like water.