화학공학소재연구정보센터
Fluid Phase Equilibria, Vol.427, 414-420, 2016
Incorporation of a volume translation in an equation of state for fluid mixtures: which combining rule? which effect on properties of mixing?
In a previous work, we showed that the incorporation of a temperature-dependent volume-translation parameter in an equation of state for pure components alters necessarily the prediction of 1-phase and 2-phase properties. On the contrary, if a temperature-independent volume translation parameter is used, most of the 1-phase and 2-phase properties are preserved. In the present study, the influence of the incorporation of a volume translation in an equation of state, on mixture properties (essentially phase equilibria and properties of mixing) is addressed. It is first assumed that the volume-translation parameter of a mixture (c) is related to mole fractions through a quadratic mixing rule involving mutual volume translation parameters (c(ij)). It is found that only a simple arithmetic-mean combining rule for c(ij) makes it possible to preserve phase equilibria. Using such a combining rule entails that the quadratic mixing rule for the c parameter degenerates to a linear mixing rule. Secondly, it is proved that properties of mixing (g(M), h(M), s(M), c(P)(M) ...) are preserved if a linear mixing rule is used for the c parameter and altered otherwise. (C) 2016 Elsevier B.V. All rights reserved.