A mixing rule for the size parameter from Carnahan-Starling equation and Boublik-Mansoori equation

A density-dependent one-fluid mixing rule for the size parameter is proposed from Carnahan-Starling equation and Boublik-Mansoori equation using a numerical method. This mixing rule coincides with the mixing rules usually used at zero pressure and at infinite pressure. It also tends to Carnahan-Starling equations for pure fluids at limiting conditions, such as infinite dilute solution, diameter ratio and equal diameters. Its application to equations of state is also carried out for Lennard-Jones mixtures including binary and ternary mixtures. Compared with the van der Waals one-fluid mixing rule, distinct improvement is obtained, especially for predictions of PVT, chemical potential and vapor-liquid equilibrium data.