Comparison between a Homo- and a Heterosegmented Group Contribution Approach Based on the Perturbed-Chain Polar Statistical Associating Fluid Theory Equation of State

Abstract

Depending on the molecular model, group contribution (GC) approaches based on the statistical associating fluid theory (SAFT) can be classified in homosegmented and heterosegmented GC approaches. In homosegmented GC approaches, molecules are modeled as chains composed of identical segments. Heterosegmented GC approaches, on the other hand, consider molecular chains composed of different segment types and thus maintain a more detailed picture of real molecules. Therefore, heterosegmented GC approaches are arguably more physically realistic and ought to give more accurate descriptions of thermodynamic properties. In this work, we evaluate the performance of a homosegmented and a heterosegmented GC approach based on the perturbed-chain polar SAFT (PCP-SAFT) equation of state (EoS). To ensure a meaningful comparison between both GC approaches, a dipole term for the heterosegmented GC approach is formulated. Group parameters of 22 functional groups were adjusted to pure component property data. The comparison between both GC approaches shows that the heterosegmented GC approach leads to significantly better agreement with experimental data for various chemical families.