Investigation of Flow and Heat Transfer Characteristics Coupled with Ortho-Para Hydrogen Conversion in a Wall-Coated Catalyst Microchannel Reactor

Abstract This paper addresses the key technical challenges in the catalytic conversion of normal and medium-chain hydrocarbons during liquid hydrogen production. It systematically compares the catalytic performance, flow characteristics, and heat transfer efficiency of packed-bed and wall-mounted catalysts. Through a combination of experimental research and numerical simulation, it was found that wall-mounted catalysts significantly outperform traditional packed catalysts in terms of low pressure drop (pressure drop is only one-third of that of packed catalysts at flow rates of 5–10 m/s) and high hydrogen gas processing capacity (allowing for higher flow rates). The study also revealed the influence of the length-to-diameter ratio of the conversion column on catalytic performance: when the length-to-diameter ratio is between 1.5 and 5, the average conversion rate of secondary hydrogen increases by 4%, and the outlet temperature decreases by 37.6%. This study provides new insights for the efficient production of liquid hydrogen and lays the theoretical foundation for the large-scale application of wall-mounted catalysts in the field of cryogenic chemical engineering.