The effect of accommodation on heat conduction through gases

Abstract

An experimental determination of the thermal conductivity of a gas necessarily involves a number of corrections which must either be determined or eliminated before an absolute value can be obtained. With the " hot-wire " method the inherent errors are: (1) the beat lost by radiation ; (2) the beat losses due to convection; (3) the temperature discontinuity between the gas and solid surfaces ; and (4) the fact that the interchange of energy between the gas molecules and the solid surfaces is not perfect. The true temperature attained by a molecule striking a bot surface always being less than the temperature of that surface. previous investigators using this method have applied a correction for the beat lost by radiation, determined by measuring the beat loss in the best obtainable vacuum ; while the convective beat loss has been eliminated, either by simply reducing the pressure or by using a double system of tubes. Both methods are debatable, for the first is very inaccurate, while the second necessarily complicates the experimental arrangement.