Determination of Thermal Transport Properties from Thermal Transpiration Measurements

Abstract

The magnitude of the thermomolecular pressure difference across capillary tubes has been measured for the gases argon, nitrogen, oxygen, carbon monoxide, and methane at mean temperatures of 162.3, 233.5, 292.0, and 340.5°K. From these data, the translational part of the thermal conductivity (Eucken factor) has been determined for each of the polyatomic gases. Estimates have been made for the rotational relaxation number and the total thermal conductivity (Eucken factor) for these gases using the thermal conductivity formulas of Mason and Monchick (in the full and linearized forms) and of Saxena and co-workers. It is observed that: (a) These three sets of formulas are equivalent, except for a scaling of the rotational relaxation number; (b) the rotational relaxation number for these gases is an increasing function of temperature; and (c) the values of the Eucken factor and rotational relaxation number obtained here are in very good agreement with the data for these parameters gotten by other methods.