Cryogenic recovery

Because of the low boiling temperature of cryogenic propellants to be used on the Space Shuttle, loss of cryogens from boiloff could become very costly. This paper describes how this shuttle problem is being solved at Kennedy Space Center. Cryogenic losses are categorized relative to the particular cryogenic involved, the Space Shuttle servicing operation causing boiloff and the magnitude of the loss. The techniques under consideration are discussed in detail. These techniques include reclaiming the boiloff by reliquefaction, upgrading the reclaimed boiloff by purification, and interim boiloff storage in metal hydride prior to reprocessing. One of the reliquefaction processes discussed in detail utilizes the cooling effect of venting some of the liquid hydrogen boiloff to provide a simple hydrogen reliquefaction unit. Possible future applications of these cryogenics recovery techniques to industry and transportation systems using liquid hydrogen for energy storage and fuel are also discussed.