Kinetics and Heat Exchanger Design for Catalytic Ortho‐Para Hydrogen Conversion during Liquefaction

A major challenge for hydrogen liquefaction is the required catalytic ortho‐para hydrogen conversion. Efficient liquefaction plants use catalyst‐filled plate‐fin heat exchangers for the conversion. Kinetics of the allotropic reaction are determined using raw literature data on common first‐order and a Langmuir‐Hinshelwood kinetics, including temperature and molar concentration dependencies. Evaluation and comparison of the obtained kinetics results in the first‐order approach as the most stable model. A one‐dimensional continuum reactor model of the counterflow‐cooled, catalyst‐filled plate‐fin heat exchanger is developed and tested combining correlations for heat, mass, and momentum transfer as well as a state‐of‐the‐art equation‐of‐state. Catalytic ortho‐para hydrogen conversion is a key challenge for hydrogen liquefaction. Several kinetic models for such conversion over hydrous ferric oxide are evaluated. Experiments from literature are combined to include pressure and temperature effects. The superior first‐order kinetic model is successfully applied on a counterflow‐cooled, catalyst‐filled plate‐fin heat exchanger model.