Speaker
Description
Cryogenic boil off from liquid hydrogen can harness the endothermic para- to orthohydrogen quantum state conversion for refrigeration. Ferrimagnetic catalysts such as Fe2O3 are utilized to accelerate the rate of parahydrogen conversion to maximize the rate of cooling. However, the extent of conversion and amount of cooling deliverable is limited by the size of the catalytic converter in the cryogenic cold box. Externally applied magnetic fields can augment catalyst activity to deliver larger cooling loads with smaller parahydrogen catalytic converter sizes. The degree of magnetic enhancement is highly sensitive to the catalyst material, temperature and magnetic field strength and requires experimental measurement to refine the underlying mechanism. This study investigated the influence of an externally applied magnetic field on the conversion rate of para- to orthohydrogen at cryogenic temperatures. The rate of conversion was measured at magnetic fields of 0.25 T and 0.5 T and conducted over a Fe2O3 catalyst. Further experiments assessed the reversibility of the magneto-catalytic effect by measuring the impact of an applied magnetic field on the ortho- to parahydrogen conversion, which is encountered during hydrogen liquefaction. The results contribute to understanding the basic physics of ortho-parahydrogen conversion catalysts.
