A New Modified van Laar Model for Associating Mixtures

Abstract

In this study, a modification is presented for van Laar model (van der Waals mixture theory) for association mixtures. The molecular association effects are considered in van der Waals mixture theory by adding two new steps to van Laar cycle. The excess Gibbs free energy function and corresponding activity coefficient equations are derived for presented model. In addition to general case when both components are associating fluids, model simplified for two interesting cases: (i) only one fluid is associating, (ii) two fluids are associating but only self-associated species exist in the mixture. This model also is used for VLE calculations for 16 different binary mixtures in which one or both components are associating fluids. Results of the presented model show satisfactory improvement over the nonassociating case for vapor liquid equilibrium (VLE) prediction.

Keywords:

• Association
• chemical theory
• van Laar model
• VLE

The authors acknowledge the support of University of Isfahan for this work.

Notes

n.a: data not available.