Magnetothermoelectric mode of hydrogen refrigeration for spacecraft fuel storage

Limitations of the present state of magnetically enhanced thermoelectric progress in cryogenics is assessed, and anticipation of technology through the next decade of semimetals research is presented. There exists no published investigation on the thermoelectric (Peltier) or the thermomagnetic (Ettingshausen) cooling of fluids as cold as those of subcooled hydrogen or of slush hydrogen. To lead to the use of an electronic mode of refrigeration for spacecraft cryogens, certain research milestones are yet to be reached in solid-state physics. These goals are here viewed from a systems-engineering perspective. This appraisal extrapolates present advances in such means of cooling to applicable space-storage propellant requirements of a planetary-mission vehicle. A module arrangement of a cooling cascade of semimetal crystals is introduced for study, and feasibility is ascertained on the basis of projected research progress with semimetal figures-of-merit. Hypothetical coefficients of performance are calculated and correlated with tradeoffs on cascade efficiencies and isotopic power-supply weight penalties. Long-term space-storage requirements for hydrogen are shown to be distinctly suited to such advanced solid-state electronic mode of refrigeration, based on system effectiveness rather than on thermoelectric efficiency.