Statistical Associating Fluid Theory. 2. Estimation of Parameters To Predict Lube-Ranged Isoparaffin Properties

Abstract

Building on part 1, we present a method by which statistical associating fluid theory (SAFT) parameters can be generated for any isoparaffin structure. The SAFT parameters that characterize a pure component are linked to functional relationships based on a number of easily computed topological indices. Simple relationships for the effective number of segments, m, and segment volume, v 00 , are formalized based on observed trends in regressed parameters in the previous work. We also employ a simulated annealing procedure to develop an accurate equation for u 0 /k, the segment interaction energy. The robustness of the parameter estimation method is demonstrated by comparing the quality of the equation of state predictions to the performance of the original SAFT parameter set determined in part 1. Perhaps most importantly, this approach opens the door for quantitative structure-property relationship studies, with particular emphasis on how branching affects specific properties. This is demonstrated by examining the influence of branching on the normal boiling point for a variety of lube-ranged isoparaffins.