A Pd-based membrane module for the capture of CO2 from a H2/CO2 binary gas mixture was considered, and computational fluid dynamics modeling was used to predict the module performance. Detailed models of momentum and mass balances, including local flux as a function of local linear velocity, satisfactorily described CO2 fraction in a retentate tube when compared to the experimental data under various feed flow rates. By using the model, several cases having different geometries, including the location and diameter of feed tube and the number and location of the feed and retentate tubes, were considered. Among tested geometries, the case of two feed tubes with each offset by an angle, θ, of 45o from the center line, and a feed tube diameter of 2.45mm showed the increase of the feed flow rate up to 11.80% compared to the reference case while a CO2 fraction of 90% in the retentate, which was the criterion for effective CO2 capture in the present study, was guaranteed. This would result in a plausible reduction in capital expenditures for the CO2 capture process.