Viscosity of multicomponent mixtures of four complex gases

In a series of earlier papers it has been established that the viscosities of the pure gases CH₄, COcf2 ₂, CF₄, and SF₆ as well as those of their binary mixtures conform to the extended law of corresponding states formulated by Kestin, Ro, and Wakeham. In this paper, the kinetic-theory expressions for multicomponent gas mixtures are used in conjunction with the law of corresponding states and the appropriate binary scaling parameters σ_ij and ε_ij to generate the viscosities of several ternary and quatemary mixtures of these gases. The calculated viscosities are compared with direct measurements (accuracy ±0.2%) performed in an oscillating disk instrument in the temperature range 25-200°C. The comparison reveals that the generated data depart from the measured viscosities by a maximum of 0.5% and that the standard deviation is only 0.25% which is comparable with the experimental uncertainty. The validity of the calculation scheme presented for predictive purposes is thereby confirmed. It is emphasized that the calculation is based exclusively on previously published information and that it does not in any way utilize the data on multicomponent mixtures. Thus the calculation can be described as a true "prediction."