APPLICATION OF THE PENG-ROBINSON EQUATION OF STATE TO CALCULATE INTERFACIAL-TENSIONS AND PROFILES AT VAPOR-LIQUID INTERFACES

In this work gradient theory of inhomogeneous fluids is used to descri be planar interfaces. With the Helmholtz energy of the homogeneous flu id and the influence parameter of the inhomogeneous fluid, the interfa cial profiles and tensions of interfaces can be predicted by gradient theory. The interfacial tension calculations, based on the Peng-Robins on equation of state and related models for the influence parameter, a re presented. Laboratory as well as field studies have established tha t carbon dioxide is an efficient oil-displacing agent in enhanced oil recovery. Therefore special attention was given to the interfacial ten sion behaviour of some binary and ternary model systems, containing ca rbon dioxide, butane and decane. In general the predictions from the m ethod presented in this contribution are superior in comparison with t he parachor estimations.