#chemistry #thermodynamics #vle


Crate to calculate non-ideal vapor-liquid equilibria using UNIFAC model

6 releases

0.1.5 Jun 7, 2021
0.1.4 May 19, 2021
0.1.2 Feb 23, 2021
0.1.1 Jan 6, 2021

#384 in Science

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UNIFAC   action license version docs

Implementation of the UNIFAC model to calculate activity coefficients in VLE using Rust

Table of contents

UNIFAC model

The Universal Quasichemical Functional Group Activity Coefficients (UNIFAC) allows to calculate the activity coefficients of substances within non-ideal mixtures. Despite other models like UNIQUAC, NRTL or van Laar, UNIFAC requires no substance-specific data. As a group contribution method, UNIFAC works with substances as a combination of functional groups. These functional groups are defined alongside the model and hold the data required to apply the model.

For more information about the model, see the original paper Group‐contribution estimation of activity coefficients in nonideal liquid mixtures from Aage Fredenslund, Russell L. Jones and John M. Prausnitz (Nov 1975) in AIChE Journal.


The model assumes that the input mixture (substances, fractions, temperature) results in a vapor-liquid-equilibrium and does not check this itself. The model calculates activity coefficients either way. Make sure you are working on a VLE yourself!

Please see the crate's documentation for more info.


All UNIFAC parameters are obtained from UNIFAC Consortium as published here. These parameters are published originally within the following articles:

Skjold-Joergensen S., Kolbe B., Gmehling J., Rasmussen P., "Vapor-Liquid Equilibria by UNIFAC Group Contribution. Revision and Extension", Ind.Eng.Chem. Process Des.Dev., 18(4), 714-722, 1979
Gmehling J., Rasmussen P., Fredenslund Aa., "Vapor-Liquid Equilibria by UNIFAC Group Contribution. Revision and Extension. 2", Ind.Eng.Chem. Process Des.Dev., 21(1), 118-127, 1982
Macedo E.A., Weidlich U., Gmehling J., Rasmussen P., "Vapor-Liquid Equilibria by UNIFAC Group-Contribution. Revision and Extension. 3", Ind.Eng.Chem. Process Des.Dev., 22(4), 676-678, 1983
Tiegs D., Gmehling J., Rasmussen P., Fredenslund A., "Vapor-Liquid Equilibria by UNIFAC Group Contribution. 4. Revision and Extension", Ind.Eng.Chem.Res., 26(1), 159-161, 1987
Hansen H.K., Rasmussen P., Fredenslund A., Schiller M., Gmehling J., "Vapor-Liquid Equilibria by UNIFAC Group-Contribution. 5. Revision and Extension", Ind.Eng.Chem.Res., 30(10), 2352-2355, 1991
Wittig R., Lohmann J., Gmehling J., "Vapor-Liquid Equilibria by UNIFAC Group Contribution. 6. Revision and Extension", Ind.Eng.Chem.Res., 42(1), 183-188, 2003

As cited from DDBST. Used parameters have been fetched on Oct 6, 2020.

Please not that all data is created by the listed articles' authors and maintained by DDBST / UNIFAC Consortium. When using this crate, you are required to reference to not only the crate but also the data sources.

See also

Project origin

This crate originates from a University project at Baden-Wuerttemberg Cooperative State University (DHBW) by sarcaustech and heringerp.


~57K SLoC