An equation of state for non-polar substances based on the generalized van der Waals model

Abstract

Abstract Van Nhu, Nguyen, Iglesias-Silva, G.A. and Kohler, F., 1993. An equation of state for non-polar substances based on the generalized van der Waals model. Fluid Phase Equilibria, 91: 215-237. An equation of state is proposed on the basis of the generalized van der Waals model. The equation is a development of an earlier model (Svejda and Kohler, 1983, Ber. Bunsenges. Phys. Chem., 87: 672-680) to cover the whole range of densities and temperatures with a small number of parameters. The performance of the equation is shown for eleven non-polar substances, i.e. argon, nitrogen, oxygen, methane, ethene, ethane, propene, propane, butane, pentane, and benzene, and is very satisfactory for the subcritical region and satisfactory for the supercritical region. Features of the formulation are a positive medium density correction, which becomes increasingly positive for low temperatures, and a temperature dependence of the attractive coefficient such that the coefficient decreases from a plateau value at low temperatures to a plateau value at high temperatures.