Computational fluid dynamics study on concentration polarization in H2/CO separation membranes

Computational fluid dynamics (CFD) was applied to modeling the H2 selective extraction from an H2/CO gas mixture using a ceramic membrane, e.g. porous glass membrane and porous silica membrane, in the steam reforming process. The calculated separation factor and flux as a function of permeability and flow rate were compared with the result from the conventional plug flow (PF) model calculation. The result of CFD modeling agreed well with that of the PF model when lower permeability was assumed (permeability of H2 less than 10−7 mol m−2 s−1 Pa−1), where ideal flow dynamics were achieved. However, the CFD simulation gave a lower separation factor and flux for H2 than those by PFM for the condition where high H2 recovery was expected (the permeability of H2 is greater than 10−6 mol m−2 s−1 Pa−1). This shows the importance of considering non-ideal fluid dynamics in the design of a membrane module.