Oxygen chemisorption compressor study for cryogenic J-T refrigeration
Over twenty potentially reversible heat-powered oxide reactions have been studied and/or tested to determine their potential use as thermochemical oxygen compressors for cryogenic J-T LO2 refrigerators. One gas-solid compound family, Pr(1-n)Ce(n)O(x), 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 Pr(1-n)Ce(n)O(x) 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 K to 7 K minimum) are about three times less than any mechanical refrigerator, and spacecraft refrigeration weights are about twenty times less. Due to the lack of wear-related moving parts in sorption refrigerators, life expectancy is at least ten years, and there essentially no vibration.