CALCULATION OF CRITICAL LINES IN BINARY-MIXTURES WITH THE SIMPLIFIED PERTURBED HARD CHAIN THEORY

In this paper it is shown that the simplified perturbed hard chain (SPHCT) equation of state is able to describe critical lines in binary hydrocarbon mixtures with good accuracy, as long as the size ratio of the unlike molecules is less than two. To perform the calculations of critical points in binary mixtures a modified Hicks-Young algorithm is used. The Hicks-Young algorithm and its modifications are extensively discussed in this paper. For many hydrocarbon mixtures binary interaction coefficient values (k12) were evaluated from critical data. This systematic investigation of critical curves in binary hydrocarbon mixtures is a continuation of our previous investigations (van Pelt, A., Peters, C.J., and de Swaan Arons, J., 1992. Fluid Phase Equilibria, 74: 67-83) in which the SPHCT equation of state was used to describe the saturated vapour pressures in the critical region of pure components.