Density-and-temperature-dependent volume translation for the SRK EOS: 2. Mixtures

A density-and-temperature-dependent volume translation function, originally developed for pure component, cubic volumetric equations of states (EOSs) has been extended to mixtures and applied to the Soave–Redlich–Kwong cubic EOS. This density modified translation (DMT) function has been used to estimate mixture properties for a set of 18 representative fluids: water, carbon dioxide, ammonia, hydrogen sulfide, tetrafluoromethane, acetone, hydrogen, nitrogen, oxygen, argon, and the normal alkanes through octane. Accuracy in mixture molar volumes is substantially improved with respect to the accuracy achievable though consistent translation functions independent of density, but bubble and dew point pressures remain largely unaffected by the DMT function. Incorporating density dependence into the DMT function does affect estimated mixture equilibrium properties, but not in a manner that provides systematic improvement. Application of the DMT function specifically for estimating mixture densities provides the greatest benefit.