Fluid Phase Equilibria, Vol.174, No.1-2, 143-164, 2000
Prediction of halocarbon mixture thermodynamics using an innovative g(E)-EoS mixing rule in a three-parameter CS framework
Historical models with g(E)-EoS mixing rules, which combine a cubic equation of state (EoS) requiring only the three parameters T-c, P-c and omega as individual inputs with a g(E) model for the liquid phase, are only applied to the saturation surfaces. A limitation of this rule is basically the number of parameters of the one-fluid EoS considered, which cannot exceed 2 or 3. By integrating an improved Teja corresponding states EoS (T), which requires the same individual parameters as a cubic equation, in a g(E)-EoS mixing rule framework, a new technique is obtained with two modes, one correlative and one predictive. In the correlative mode, the liquid phase gamma is generated from input VLE data using the improved T model and the historical Wong-Sandler-Teja mixing rules for the pseudocritical functions, except for T-cmix. In the predictive mode, the same general procedure is followed, but with the Liquid phase gamma coming from a UNIFAC g(L)(E) model, which makes the mixing rule predictive. The T-cmix values are locally generated from these new rules and are correlated as an individual function, which in both cases presents a very smooth trend for the systems studied. The two proposed rules are applied to systems of halogenated alkanes, which are known to be polar and deviating, and are compared with the dedicated EoS available for these mixtures. The results for both modes show an interesting level of accuracy in representing the whole thermodynamic behaviour of a mixture.