Viscosity of Helium and Nitrogen and their Mixtures at Low Temperatures and Elevated Pressures

Experimental viscosity data have been determined for the helium—nitrogen system for five approximately equally spaced compositions at 50°C over the pressure range from 10 to 500 atm, nine compositions at 0°C from 10 to 500 atm, seven compositions at −50°C from 10 to 400 atm, and five compositions at −90°C from 10 to 200 atm. The maximum probable error of the calculated viscosity data is 0.137%. Most of the data taken cover hitherto uncharted regions of pressure, temperature, and compositions. Both maximum and minimum viscosity of gas mixtures at some isothermal—isobaric conditions have been observed. To the authors' knowledge the phenomenon of minimum isobaric—isothermal viscosity is reported for the first time in nonpolar mixtures. Within the experimental accuracy of this study, it has been found that the temperature-independent residual-viscosity concept holds for a fixed composition only on an approximate basis. The residual viscosities of helium, nitrogen, and their mixtures show about 0.5% spread with temperature from 50.00° to −90.00°C at constant density.