Accommodation Coefficients for Heat Conduction Between Gas and Bright Platinum, for Nine Gases Between 80°K (or Their Boiling Points) and 380°K

Accommodation coefficients toward bright platinum for air, oxygen, nitric oxide, carbon monoxide, carbon dioxide, nitrous oxide, methane, hydrogen, and helium are computed from the (1/Ka) versus (1/P) slopes of the thermal conductivity measurements of Taylor and Johnston and of Johnston and Grilly. The results—which cover the temperature range 80°K to 380°K—are tabulated for the several gases, and are collected in a graph where comparison with results obtained by other investigators are also included. Our results with hydrogen rise toward a coefficient of unity with lowering temperature, in confirmation of measurements by others, but those for other gases drop steeply at temperatures between room temperature and that of liquid air. Our data are in generally good agreement with the recent accurate work of Amdur, Jones, and Pearlman, at room temperature. The accommodation coefficients which are derived from the reciprocal K versus reciprocal P plots differ slightly from Knudsen accommodation coefficients, and are referred to as ``Maxwell-Knudsen'' coefficients. Equations are derived which give the relationship between the reciprocal slopes, the temperature jump constants g′, and the M-K accommodation coefficients.