The development of cryogenic liquid hydrogen (LH2) mobility solutions for land [R1], sea [R2] and air [R3] applications as a way to reduce the carbon emissions and its global warming effect is a technical and scientific endeavor rich of challenges and opportunities for innovation. Certainly, the widespread use of LH2 [R4] in a massive scale and tonnage will depend on the efficiency of the liquefaction process systems [R5, R6]. Plate and fin cryogenic heat exchangers filled with catalyst for ortho-para hydrogen conversion constitute one of the most critical components of the liquefaction process, particularly with respect to the exergy destruction [R7]. They also offer significant opportunities for improvement, both in fundamental understanding of the irreversibility processes and in terms of industrial manufacturability and scalability.
 
Within this framework, Alfa Laval Golbey and the CEA Low temperature department (DSBT) pursued a joint effort to improve the understanding of the thermal-hydraulic behavior of catalyst-filled cryogenic plate-and-fin heat exchangers. This work also aims to assess the performance of the ortho-para hydrogen catalyst under representative cryogenic conditions relevant to industrial processes. The study is part of the broader "HyGen" scientific project, sponsored by ADEME. Within the cryogenic scope, two cryogenic test facilities are developed. The first facility, PUMBAA [R8], is designed to characterize the Fanning and Colburn coefficients (Cf and Cj) of cryogenic plate-and-fin heat exchangers mockups when filled with commercially available catalyst. The experiments are conducted using cold (~100 K) pressurized gaseous nitrogen to reproduce representative Reynolds numbers. The second more challenging test facility, named PHYONA, is designed for the characterization of the conversion kinetics of ortho to para-hydrogen catalysts by means of Raman spectroscopy techniques under a broad range of representative conditions in terms of initial equilibrium composition (n-H2 50%p-H2), temperature (80 to 20 K), pressure (10 to 40 bar) and superficial velocities. The paper presents the main challenges, the current progress status of the two test facilities, and some preliminary qualification results.
 
[R1] Technology Pitch: Subcooled Liquid Hydrogen (sLH2). Available at: https://www.now-gmbh.de/wp-content/uploads/2021/05/Heavy-Duty-Event-Subcooled-Liquid-Hydrogen-sLH2-Schaefer-Linde-Maus-Daimler.pdf
 
[R2] Pratt J.W., Klebanoff L.E., “Feasibility of the SF-BREEZE: a Zero-Emission, Hydrogen Fuel Cell, High-Speed Passenger Ferry”. Report SAND2016-9719, Sandia National Laboratory, Livermore CA (2016). 89. NORLED, World’s first
 
[R3] “Airbus reveals new zero-emission concept aircraft”. Available at: https://www.airbus.com/en/newsroom/press-releases/2020-09-airbus-reveals-new-zero-emission-concept-aircraft
 
[R4] “Analysing future demand, supply, and transport of hydrogen”. Available at https://gasforclimate2050.eu/wp-content/uploads/2021/06/EHB_Analysing-the-future-demand-supply-and-transport-of-hydrogen_June-2021.pdf
[R5] “Proposal of an innovative, high-efficiency, large-scale hydrogen liquefier”, International Journal of Hydrogen Energy Volume 33, Issue 12, June 2008, Pages 3116-3121
 
[R6] Liquefaction plant by the IDEALHY consortium. Available at: https://www.idealhy.eu/index.php?page=publications
 
[R7] Wilhelmsen, Ø.; Berstad, B.; Aasen, A.; Nekså, P.; Skaugen, G. Reducing the exergy destruction in the cryogenic heat exchangers of hydrogen liquefaction processes. Int. J. Hydrogen Energy 2018, 10, 5033–5047.
 
[R8] Influence des conditions cryogéniques sur les performances hydrauliques et thermiques d’ondes remplies de catalyseur Becker Gaëtan et al., submitted to the 20th SFGP conference, 2026
 

Keywords
hydrogen|catalyst|heat exchangers|cryogenic|liquefaction