Comparison of two crossover procedures for describing thermodynamic behavior of normal alkanes from singular critical to regular classical regions

Abstract

In this work, two crossover procedures were applied to the Soave-Redlich-Kwong (SRK) equation of state (EoS) in order to describe the thermodynamic behavior of hydrocarbons from far away up to close to the critical point. The first one is based on a renormalization group theory method, which uses a recursive procedure originally proposed by White and coworkers (Salvino and White, J. Chem. Phys. 96 (1992) 4559–4568). The second one incorporates the scaling laws close to the critical point into the cubic EoS, and was developed by Kiselev (Kiselev, Fluid Phase Equilibria, 147 (1998) 7–23). The classical and crossover SRK EoS are applied to describe the phase behavior of pure n-alkanes (from methane to n-decane), and the comparison with experimental data indicates that the non-mean-field models are superior to the classical one for the representations of vapor-liquid coexistence data, isothermal pressure-density data and critical properties. Additionally, a thorough comparison of the two crossover approaches is done indicating the advantages and disadvantages of each approach.