A. Introduction

The viscosity of fluid mixtures is an important property and is required in the design of pumping systems, heat and mass transfer applications and the optimal selection of process equipment. Various schemes are available for the estimation of the viscosity of low and high pressure gas mixtures and saturated liquids. However, no reliable methods are yet available for the estimation of liquid mixtures under high pressure conditions.

B. Low-pressure gas mixture viscosity

Kinetic theory provides a framework for the development of predictive schemes for the calculation of the viscosity of low pressure gas mixtures. However, the final expressions are quite complex to implement and are therefore not widely used in practice. Furthermore, these methods require the viscosities of the pure components of the mixture of interest. In essence, these methods are interpolative. Although less theoretically rigorous, simplified schemes are available and are widely used for the estimation of the viscosity of low pressure gas mixtures. The techniques based on the principle of corresponding states, although less accurate are attractive since they do not require the viscosity of the pure components. Among the simplified schemes, the method of Reichenberg (1975, 1971), although still quite complex to use, yields accurate results. The corresponding states methods are easy to implement but are comparatively less accurate.

(a) Method of Reichenberg