A flow through behavior of gas across meso-porous membranes

A fractal permeability model for hydrogen diffusion across porous inorganic membranes is presented. The model accounts for the actual microstructures in terms of two fractal dimensions, one relating to the capillary flow pathways described by the pore area fractal dimension, Df and tortuosity of the capillary pathways described by tortuosity fractal dimension, Dt. From this, meso-porous titania membrane was found to contain less large pores (Df = 1.83) and less tortuous capillary pathways (Dt = 1.47) than titania–alumina (Dt = 1.51, Df = 1.76). The model was found to be consistent with the famous Kozeny–Carman equation for meso and micro porosity region, making the quantitative analysis of the gas diffusion into the media possible.

Meso-porous titania membrane has been found to contain less large pores (Df = 1.83) and less tortuous capillary pathways (Dt = 1.47) than titania–alumina (Dt = 1.51, Df = 1.76). Quantitative analysis of hydrogen diffusion into the media can be made possible using hydrogen permeability simulation based on fractal theories. The model is able to describe the observed datum well in the meso and micro-porosity region.Figure optionsDownload as PowerPoint slideHighlights
► Porous membranes have intricate microstructures that follow a fractal network.
► The level of pore size and tortuosity of the membranes can be quantified by fractal.
► Both models agree and become valid as the membrane becomes less porous.
► In meso and micro porosity, Knudsen flow mechanism is dominant.