A SIMPLE PERTURBATION TERM FOR THE CARNAHAN-STARLING EQUATION OF STATE

A simple perturbation term is presented for the Carnahan-Starling (CS) hard-sphere reference equation of state (EOS). This perturbed CS EOS is compared with seven other two-parameter EOSs; it represents the critical isotherms of eight fluids with the lowest deviations in density and pressure. After a generalized temperature dependence is introduced for parameters a and b, the perturbed CS EOS is compared with the well-known Peng-Robinson equation. For 11 non-polar pure fluids, the perturbed CS EOS represents liquid densities significantly better, but it is not superior for vapor pressures. For mixtures, the CS reference term is given by the Boublik-Mansoori hard-sphere mixture EOS. Some calculations for binary mixtures are given, using conventional mixing rules for parameters a and b in the simple perturbation term. © 1990.