Effect of Feed Flow Rate of Hydrogen Mixture on Hydrogen Permeation for Flat Sheet Pd/Ag Membrane with Stagnating Flow

Abstract

The effect of feed flow rate of hydrogen mixture on the H 2 permeation for a flat sheet Pd/Ag membrane with stagnating flow at the upstream side was investigated experimentally and theoretically. A 77wt.% Pd/23wt.% Ag flat sheet membrane with 25μm thickness and 0.02m diameter was used. The permeation rate of H 2 was investigated under various feed flow rates (1.489 × 10 -5 -2.976 × 10 -4 mol/s), for pressures of 0.20-0.30MPa and reference membrane temperatures of 523-723K. Experimental results demonstrated that when the feed flow rate is decreased, the H 2 permeation rate decreases. This is supposed to be due to the phenomena of hydrogen concentration decrease at the membrane surface of the upstream side, as a result of the effect of H 2 permeation itself. When a theoretical equation that takes into account the effect of H 2 permeation is used, the H 2 permeation mole flux can be predicted quantitatively by using the concentration of H 2 of the feed mixture. This shows that the diffusive transport effect plays an important role as well as the convective transport effect when determining H 2 concentration at the membrane surface. In addition, the normalization of the theoretical results shows that the trend of the decrease in the H 2 permeation mole flux with respect to the feed mole flux follows the first order lag function, regardless of the inlet H 2 partial pressures.

Initial Study on Hydrogen Permeation with Flat Sheet Pd/Ag Membrane for Mixture of Hydrogen and Carbon Dioxide

“…The estimation was performed by Eqs. ( 1) and ( 2), which represent Sieverts' equation without and with [9] the effect of permeation, respectively.…”

“…This mixture was selected because our focus was mainly on the overall reaction of methanol steam reforming reaction. The experimentally obtained hydrogen permeation flux is then compared with the analytical result based on Sieverts' equation with the effect of permeation [9].…”

Numerical Investigation on Hydrogen Permeation with Flat Sheet Pd/Ag Membrane for Various Geometries

“…Several researchers have introduced the estimation method for such condition, such as modification of original equation of mass transport coefficient [6] and manual polarization map [7]. The authors also have introduced a new method, by taking into account the effect of permeation itself in the Sieverts' equation [8].…”