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The Use of Proton Exchange Membrane Fuel Cell Technology to Recover Gaseous Helium from Rocket Testing Systems

Many rocket testing systems used by both the National Aeronautics and Space Administration (NASA) and commercial space agencies utilize liquid hydrogen (LH2) as a propellant. Subsequent to testing, significant quantities of LH2 and gaseous H2 (GH2) from boil-off may remain which must be removed through gas purging. This is accomplished with gaseous helium (GHe) because it is chemically inert and the boiling point of liquid helium (LHe) is lower than that of LH2. This ensures that the He will remain in the gaseous phase throughout the purging process. The resulting purge stream consists of a mixture of GHe and GH2 which must be sufficiently diluted and vented to the atmosphere or recaptured and separated.