Prediction of the Viscosity of Supercritical Fluid Mixtures

A method for predicting the viscosity of supercritical, multicomponent fluid mixtures, at any density, from the zero-density viscosity of pure components is preseInted. The method is based upon the results for a rigid-sphere model, suitably iInterpreted to apply to real fluids, and on the finding that the excess viscosity of pure supercritical fluids can be adequately described by a density function independent of temperature. The density range of the method extends to twice the critical density of the pure component with the smallest critical density. The only exception is for the methane-rich mixtures where the mixture density should not exceed 12000 mol • m - 3 . The uncertainty ascribed to the predictions made by this method is of the order of ±5%.