.ThermalSeparation.Media.Correlations.ActivityCoefficient.UNIFAC

Information

UNIFAC

The UNIFAC model uses interactions between the functional groups of molecules for activity estimation for non-ideal mixtures.

This model splits up the activity coefficient for each species in the system into two components; a combinatorial γc and a residual component γr.

The combinatorial part is the same as in the UNIQUAC model. The residual part is due to the interactions of the functional groups.

There are some parameters which appear in both parts, like the group surface area and volume contributions R and Q(given in "References") and other interaction parameters which only occur in the residual part like A. A is due to the interaction energy between groups and are listed in the following references. Note that it is not the case that Anm=Amn.

All theses Parameters for each group interaction have to be put in the media model. Just as the number of different groups SG_v, the number of different groups within one molecule SG_nS and the number of occurrences of the functional group on each molecule v[nS,SG_v].

References

UNIFAC Structural Groups and Parameters

http://www.aim.env.uea.ac.uk/aim/info/UNIFACgroups.html

H. K. Hansen, P. Rasmussen, A. Fredenslund, M. Schiller, and J Gmehling (1991) Ind. Eng. Chem. Res. 30, 2352-2355.

R. Wittig, J. Lohmann, and J. Gmehling (2003) Ind. Eng. Chem. Res. 42, 183-188

K. Balslev and J. Abildskov (2002) Ind. Eng. Chem. Res. 41, 2047-205.