Permeation dynamic of hydrogen through a palladium membrane in an environment of varying pressure was investigated and analyzed experimentally. By monitoring the instantaneous pressure and mass transfer rate of hydrogen in the conducted system, the present study provides a comprehensive and precise measurement on the permeance of the membrane. It was found that a threshold of pressure difference between the both sides of the membrane for hydrogen permeation was exhibited. That is, when the driving force of the mass transfer was below the minimum pressure difference, hydrogen permeation will not occur. Accordingly, a modified equation accounting for the hydrogen permeation flux through the membrane was suggested. As a whole, the hydrogen permeation flux versus the pressure difference was characterized by a linear relationship, regardless of what the pressure exponent is. Nevertheless, the optimal pressure exponent was located between 0.5 and 0.7. A dimensionless time, the permeation number, was derived to describe the permeation process. The characteristic time of hydrogen permeation depends on the pressure exponent. The experiments reveal that the permeation number was around 7–13 for the hydrogen permeation flux in the system reaching the quasi-steady state.

Hydrogen Permeation Dynamics Across a Palladium Membrane in a Varying Pressure Environment. W.H.Chen, P.C.Hsu, B.J.Lin: International Journal of Hydrogen Energy, 2010, 35[11], 5410-8