(321v) Triangular Well Equation of State for Fluid Mixtures

The use of the triangular well (TW) potential as an effective potential [1] provides a non-conformal behavior for pure compounds. In the chemical Industry it is also necessary that a model can be used to represent properties of fluid mixtures.

Van Konynburg and Scott showed that even the van der Waals EoS can qualitative describe different types of phase behavior [2]. However this EoS describes a corresponding state principle for pure fluids and mixtures. The use of an EoS based on a non-conformal potential has not been widely explored.

In this work the TW EoS is used to represent the vapor-liquid equilibria of binary mixtures composed by carbon dioxide and hydrocarbons up to C10. The quadrupolar moment is not explicit taking into account for the carbon dioxide molecule, but the third parameter of the TW potential allows that this type of interaction can be expressed by effective parameters of the potential [3]

Results show a good agreement with available experimental data, however the influence of the third parameter of the potential to describe the phase behavior is not clear.

[1] A. Gil-Villegas, F. del Río, A.L. Benavides, Fluid Phase Equilb. 119 (1996) 97.

[2] P. H. Van Konynburg, R. L. Scott, Philos. Trans. R. Soc. London, 298 (1980) 495.

[3] E. Avalos, F, del Río, S. Lago, J. Phys. Chem. B 109 (2005) 508.