A new extension for local composition model – From theory to Equation of State

Abstract

The Two-Layers Local Composition (TLLC) concept was introduced as an extension to classical local composition theory. The TLLC theory considers the two-layers neighborhood of a central molecule instead of one layer as in classic LC theory. Employing the TLLC, a new potential function as the Two-Square-Wells model was proposed. This model leads to a closer concept to the Lennard-Jones potential model compared to the well-known Square-Well potential. According to the TSW, a new coordination number model and consequently two new EoSs as CASW, and ASW were developed. Despite the simplicity in form and implementation, the new models present excellent results in both correlation and prediction approaches. Vapor pressure and liquid density data of 38 pure components were correlated, and overall AADs% equal to 2.429/2.609 and 1.552/0.849 were obtained by CASW/ASW EoSs, respectively. Moreover, vapor volumes of these components were predicted with overall AADs% of 4.533 and 3.410, respectively.