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

Abstract

The variation in hydrogen concentration distribution on Pd/Ag membrane surface for permeation with H2/N2 mixture was investigated numerically, by varying the diameter of the mixture inlet. A 77wt.%Pd/23wt.%Ag purification membrane with thickness of 25μm and effective surface area of 3.14x10-4m2 was considered. The membrane temperature, total upstream pressure, and inlet H2 mole fraction were set to 623K, 0.25MPa and 0.75, respectively. Meanwhile, the downstream pressure was set at atmospheric. Mean mole flux (feed flow rate/effective membrane surface area) was varied between 0.19-0.95 mol.s-1.m-2. The hydrogen concentration distribution was investigated for various ratios of inlet radius to membrane radius (0.22:1, 0.50:1 and 0.75:1). It is found that hydrogen permeation flux obtained from various hydrogen concentration distributions are almost same, and quantitatively fit with analytical result based on the Sieverts’ equation with the effect of H2 permeation.