Development of a Para-Orthohydrogen Catalytic Converter for a Solid Hydrogen Cooler

Abstract

Various spaceborne systems are under study which utilize liquid or solid hydrogen1,2 for long-term instrument cooling. For these systems, efficient utilization of the vent gas in vapor-cooled shields or supports is necessary to minimize cryo-gen losses and extend system lifetimes. If the 99.9% parahydro-gen vent gas can be converted to its equilibrium ratio of paraortho at an increased temperature, then a substantial heat absorption will take place and the vent gas can be further utilized for instrument cooling or reductions of the parasitic heat loads. Spontaneous conversion of the vented hydrogen vapor is quite slow and would not occur to any extent in a venting system without utilization of a catalyst.