The Pressure Dependence of the Thermal Conductivity of Polyatomic Gases at 0°C

Abstract

A form of " hot wire " apparatus is described in which the hot wire is replaced by a thin-walled nickel tube � in. in diameter mounted in a similar nickel tube in, in diameter. The gas under investigation occupies the narrow annular space between the two tubes. It is shown that the apparatus is completely free from convection up to pressures somewhat greater than 1 atm, and that the temperature discontinuity effect is inappreciable down to pressures of a few cm. of mercury. The apparatus is used to test the pressure dependence of the thermal conductivity of several polyatomic gases. The thermal conductivity (at 0 �C.) of the gases carbon dioxide and methane is found to increase slowly with the pressure over the range 10-80 cm. of mercury. It is suggested that this effect may be taken as evidence of the incomplete participation of the energy of vibration of the molecules in the conduction process.

Optimally accurate thermal-wave cavity photopyroelectric measurements of pressure-dependent thermophysical properties of air: Theory and experiments

“…The existing studies contain the data for temperatures of 0 and 100°C only. [21][22][23][24] The experimental data of those authors show slight decrease of thermal conductivity at the pressure range of up to about 50 Torr, which may be explained by the dimensionality of the setup construction. However, the investigated pressure range in our experiments is still far from the ballistic heat transfer, mean-free-path-limited regime for the experimental conditions of our study.…”

“…The most recent of those were published more than half a century ago. [21][22][23][24] Even fewer papers have been published on the thermal diffusivity measurements at low pressures. 3 In this study, we applied the thermal-wave cavity method and the developed three-dimensional ͑3D͒ theoretical approach to obtain the thermal diffusivity ␣ and heat transfer coefficient H of air at low pressures in the range from 760 to 2.6 Torr at ambient temperature.…”

Thermal Conductivity of Light Hydrocarbons and Methane-Propane Mixtures at Low Pressures.

“…(w) (f) (12) where X¿ is the experimental value of the conductivity for pure component i, x¡ is the mole fraction, n is the number of components, and the first approximation to the diffusion ratio Du/D¡j may be related to the frozen thermal conductivity ratio X?/X" as (Du/D¡j)(A¡j/A2í) -(Kl/Klj). In most cases and over a wide temperature range (A*/Au) s* 1.…”

Thermal Conductivity of Fluids. Methane

“…d Reference (10). 6 Values of thermal conductivity at this pressure extrapolated from data at lower pressures. as from the temperature differences between the two surfaces, is an indication of the reproducibility and accuracy of the instrument now in use.…”