OXYGEN-CHEMISORPTION COMPRESSOR STUDY FOR CRYOGENIC JOULE-THOMSON REFRIGERATION

Over 20 potentially reversible heat-powered oxide reactions have been studied and/or tested to determine potential use as thermochemical oxygen compressors for cryogenic Joule-Thomson (J-T) LO2 refrigerators. One gas-solid compound family, Pr1-nCenOx, proved to be completely reversible with fast kinetics for all pressure ranges tested below 650°C. With a heat-powered charcoal/methane physical adsorption upper stage and a Pr1-nCenOx chemisorption lower stage, temperatures should be attainable in the 55-80 K range for less power and over five times less weight than for charcoal/nitrogen sorption refrigeration systems. Total system power requirements with a hydride chemisorption lower stage (10-7 K minimum) are about three times less than any mechanical refrigerator, and spacecraft refrigeration weights are about 20 times less. Due to the lack of wear-related moving parts in sorption refrigerators, life expectancy is at least 10 years, and there is essentially no vibration.