LAUSR

Abstract The 2nd degree polynomial volume function ( v 2 + u b v + w b 2 ), involved in the attractive term of cubic equations of state, has a strong influence on the calculated volumetric properties and, to a lesser extent, influences the calculated vapor-liquid equilibrium properties such as vapor pressure and enthalpy of vaporization. This function contains two parameters ( u and w ) that were either selected constant or constituent-dependent in the literature. In this work, it is analyzed through a systematic methodology how parameters u and w influence the accuracy of predicted volumetric and vapor-liquid equilibrium properties, both for untranslated and translated cubic equations of state. It was thus possible to determine the optimum values of such parameters and to discuss if the values selected in well-known cubic equations of state are the most relevant.