Excess Gibbs free energy model for calculating the viscosity of binary liquid mixtures

In this article we present a model for correlating dynamic and kinematic viscosities of liquid. mixtures, which is based on Eyring's absolute rate theory for liquid viscosity and the UNIQUAC equation. The proposed model involves the concept of ideal viscosity and uses the UNIQUAC equation to represent the deviation from ideal. behavior. The expression adopted to describe the ideal term viscosity has been chosen after a thorough investigation of the performance of different equations previously proposed in the literature. The correlation results have shown a strong dependence on the expression used to account for the ideal viscosity contribution. Besides size and shape parameters, for each pure component, the model requires only two adjustable parameters per binary system. The binary interaction parameters have been determined by fitting literature viscosity data. More than 350 binary systems, 4619 viscosity data points at 0.1 MPa, have been correlated using this model. The binary systems investigated are representative of different types of intermolecular interactions (e.g., nonpolar/nonpolar, nonpolar/polar, and polarlpolar). The calculated values are in good agreement with the experimental ones. The overall average mean relative standard deviation of the correlations is 1.20%, which is comparable with those of other correlation models available in the literature.