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 vi scosities of liquid. mixtures, which is based on Eyring's absolute rate the ory for liquid viscosity and the UNIQUAC equation. The proposed model invol ves the concept of ideal viscosity and uses the UNIQUAC equation to represe nt the deviation from ideal. behavior. The expression adopted to describe t he ideal term viscosity has been chosen after a thorough investigation of t he 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 shap e parameters, for each pure component, the model requires only two adjustab le parameters per binary system. The binary interaction parameters have bee n determined by fitting literature viscosity data. More than 350 binary sys tems, 4619 viscosity data points at 0.1 MPa, have been correlated using thi s model. The binary systems investigated are representative of different ty pes of intermolecular interactions (e.g., nonpolar/nonpolar, nonpolar/polar , and polarlpolar). The calculated values are in good agreement with the ex perimental ones. The overall average mean relative standard deviation of th e correlations is 1.20%, which is comparable with those of other correlatio n models available in the literature.