Evolutionary computation for maximizing CO₂ and H₂ separation in multiple-tube palladium-membrane systems

Membrane separation is a promising method to separate CO₂ and H₂ from hydrogen-rich gases. This simultaneously achieves H₂ recovery and CO₂ enrichment. The latter is conducive to subsequent carbon capture and storage, and thereby the development of negative emission technologies. In this study, single-, double-, triple-, and quadruple-tube systems with palladium (Pd) membranes and cross-flow configuration are considered, while the Reynolds number (Re) is in the range of 1–50. To maximize H₂ recovery and CO₂ enrichment in the systems, the systems are designed using a two-stage optimization in which the parametric sweep technology followed by the evolutionary computation of the Nelder-Mead simplex method is applied to find the best configuration and the exit H₂ concentration is chosen as the objective function. On account of the scavenging waves stemming from the upstream tubes, the goals of the optimization is to diminish the concentration polarization effect of the upstream tubes upon the downstream ones. The predictions indicate that an increase in the number of tubes raises the optimization efficiency. Compared to the tubes in tandem, the optimized configuration at Re = 10 can improve the hydrogen recovery up to 12.2%, while the CO₂ enrichment can be intensified by up to 7%.