Viscosity and Diffusion Coefficient of Six Binary Mixtures

The paper contains the results of measurements of the viscosity of six binary mixtures: CO2–Kr; H2–N2; He–O2; CH4–CO2; CH4–C4H10; H2–He. Measurements were made in an oscillating-disk viscometer at 20° and 30°C and at pressures from 1–25 atm, approximately; they were evaluated by the relative method. An analysis of the data shows that the interaction quantity μ12 which appears in the Chapman–Enskog theory for low densities is sensibly independent of composition. Although no direct check on the accepted mixing rules can be made owing to the narrowness of the temperature range covered, it is concluded that a knowledge of the viscosities μ1 and μ2 of the pure components together with that of μ12 at each temperature is sufficient to determine the dependence of the viscosity of the mixture on composition with the aid of the Chapman–Enskog theory. This dependence is reproduced well by the theory at virtually zero density and at a constant temperature. The experimental values of μ12 are used to calculate the binary diffusion coefficient D12 for all mixtures. The results agree well with the correlations provided by Mason and Marrero. The system H2–He does not exhibit the anomaly detected for thermal conductivity by Mukhopadhyay and Barua.