Microchannel structure design for hydrogen supply from methanol steam reforming

A methanol steam reforming-based microreactor is an extraordinary setup for hydrogen supply; nevertheless, the heat transfer capability and flow resistance of the microreactor may be restricted by each other, which calls for further structure design and investigation. To comprehensively improve the performance of a direct microchannel (DM) with the implementation of on-board hydrogen supply, the concepts of sinusoidal- and dimple-structured microchannels are synchronously introduced. Four types of microchannels for methanol steam reforming (MSR) are studied: direct microchannel (DM), direct microchannel with dimples (DMD), sinusoidal microchannel (SM), and sinusoidal microchannel with dimples (SMD). The influence of microchannel structure on the reformer's flow and heat transfer properties is evaluated by Nusselt number, resistance coefficient, and heat transfer efficiency factor using numerical simulation. Results show that the SMD is the optimal structure. Moreover, the effects of reaction temperatures, methanol feeding fluxes, and steam/CH₃OH mole ratios on the MSR performance are experimentally investigated. The effect of microchannel structures on the hydrogen production performance is also explored to validate the numerical simulation results. It is revealed that the integrated structure with both sinusoidal waves and dimples exhibited the best performance, demonstrating enhancements in heat and mass transportation as well as excellent H₂ production capacity.