The fluid dynamic effect on the driving force for a cobalt oxide silica membrane module at high temperatures

This work presents a computational fluid dynamic (CFD) model to investigate the effect of binary gas (H2/Ar) composition and fluid dynamics at high temperatures (from 200 up to 500 °C) for a reasonably sized membrane module containing two cobalt oxide silica membrane tubes in series for H2 separation. The model provided the local information of velocity, pressure and H2 fraction for the driving force analysis. The H2 molar fraction was found to be the most influential factor affecting the driving force, though the total pressure varied slightly along the axial length. In feed domain the H2 molar fraction showed a clear decline in the axial direction from feed inlet to retentate outlet by 45.34% (for the case of feed fraction 50% H2 and feed flow rate 100 N ml min−1). In permeate domain, H2 fraction showed the same trend but the decline slope was much less than feed domain being 2.22%. Concentration-polarizations in both feed and permeate domains were very weak with the concentration polarization degree less than 0.4% and can be ignored in cobalt-oxide-silica membrane module. High temperature promoted the performance of pure gas permeation, but had little impact on mixed gas separation as the driving force reduction at higher temperature is more significant.