PHASE-EQUILIBRIUM OF COMPLEX-MIXTURES WITH EQUATIONS OF STATE - AN UPDATE

Here we review a new class of mixing rules that have extended range of mixtures and conditions that can now be described by equation of stat e models. One characteristic of these mixing rules is that they simult aneously satisfy the boundary conditions of producing a second virial coefficient that is quadratic in mole fraction, and a free energy of m ixing like that of an activity Coefficient model at high density, thou gh the mixing rule is itself independent of density. We show that usin g this mixing rule, various asymmetric, highly nonideal mixtures can b e accurately described. One serendipitous result is that the parameter s in this mixing rule model are almost independent of temperature, whi ch allows accurate extrapolations of phase behavior to be made over la rge ranges of temperature and pressure.