Thermal transpiration measurements on a porous ceramic

Abstract

Thermal transpiration measurements were made at the steady and unsteady states for several gases on a membrane of porous ceramic. At the steady state the heat of transport was examined as a function of the average gas pressure. At the unsteady state, comparisons were presented between gas permeabilities determined from the transpiration data and conventional isothermal permeabilities obtained from an independent investigation using the same sample of ceramic. Unsteady state measurements also showed that if the gas was adsorbed on the ceramic the gas tended to flow transiently to the cold side of the membrane; a reversal of behaviour predicted by classical theory for non-sorbed gases.