Local composition model for chainlike molecules: A new simplified version of the perturbed hard chain theory

Abstract

AbstractA simple analytical equation for chainlike molecules interacting with square‐well potential is derived by replacing the complicated attractive term in the perturbed hard chain theory (PHCT) of Beret, Donohue, and Prausnitz with a theoretical but simple expression derived by Lee, Lombardo, and Sandler. The resulting simplified perturbed hard chain theory (SPHCT) reproduces both experimental vapor pressure and liquid density data for a number of fluids over a wide temperature and pressure range with good accuracy.The three pure‐component parameters in the SPHCT have been obtained for several n‐alkanes and multipolar fluids. Average errors in predicted vapor pressures and liquid densities, over a wide temperature and pressure range, are about 3 and 4%, respectively. Preliminary mixture calculations indicate that the SPHCT predicts K factors and Henry's constants with reasonable accuracy without the use of any binary parameters.