Thermal Transpiration. Rotational Relaxation Numbers for Nitrogen and Carbon Dioxide

Thermal transpiration studies were conducted with the gases Ar, Xe, N2, and CO2 in an effort to test a recently proposed relation between the translational component of the thermal-conductivity coefficient and the maximum transpiration effect that is observed for a particular gas under a given set of temperature and apparatus conditions. The phenomenon was generated by maintaining temperatures of about 290° and 545°K on the opposite ends of 14 0.1-mm i.d. Pyrex glass capillaries arranged in parallel. The rotational collision numbers for N2 and CO2 which were obtained from the thermal transpiration data were found to be 4.4 and 2.4, respectively, in good agreement with values determined by the more common methods.