Hydrogen production in protruded millisecond microchannel reactors by catalytically reforming methanol

Abstract

Flow of a fluid past a body is a very complicated phenomenon. Computational fluid dynamics is used for studying the characteristics of flow past an array of hemispherical protrusions that is disposed on the wall surfaces of a millisecond microchannel reactor. Protrusions can be used to improve the transport processes involved, but the causes of the phenomena are still incompletely understood. Parametric analyses are performed under different sets of circumstances to delineate the role of geometric features and operation conditions in reactor performance. Dimensionless quantities are used to simplify the characterization of the reactor system with multiple interacting transport phenomena. The mechanisms involved in the intensified processes are analysed, and performance improvement recommendations are presented. The results indicate that the protruded reactor behaves effectively and good yields can be obtained with only milliseconds residence of the mixtures within the channels. The reactor offers the unique advantage for hydrogen production from methanol in that process intensification is realized while preserving the energy balance between the exothermic and endothermic processes. However, the flow rates, feed compositions, and channel dimensions must be adjusted as needed to maximize production of hydrogen and minimize pressure drops. While the thermal diffusivity dominates the overall reactor behaviour, expectable compromises have to be made between hydrogen productivity and pressure drop. The results have implications for hydrogen production and beyond for the study of transport phenomena in microchemical systems.