Simplified crossover SAFT equation of state for pure fluids and fluid mixtures

Abstract

A simplified modification of the crossover statistical associating fluid theory (SAFT) EOS is used to describe thermodynamic properties of pure fluids and binary mixtures over a wide range of parameters of state including the nearest vicinity of the critical point. For pure fluids, the simplified crossover (SCR) SAFT model contains only three adjustable parameters but allows an accurate prediction of the critical parameters of pure fluids and yields a better representation of the thermodynamic properties of pure fluids than the original SAFT equation of state. For binary mixtures, simple mixing rules with only one adjustable parameter are used. A comparison is made with experimental data for pure refrigerants R12, R22, R32, R125, R134a, R143a, and mixtures R22+R12, R32+R134a and R125+R32 in the one- and two-phase regions. The SCR SAFT EOS reproduces the saturated pressure data with an average absolute deviation (AAD) of about 1.1% and the saturated liquid densities with an AAD of about 0.9%. In the one-phase region, the SCR SAFT equation represents the experimental values of pressure with an AAD of about 2.2% in the range of temperatures and density bounded by T≥Tc and ρ≤2ρc.