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An analysis on O2 usage, water contents in food, CO2 and H2 availability, water generation capability of CO2 reduction subsystems, water balance, etc. was conducted to evaluate the feasibility of integrating a CO2 reduction subsystem into an air revitalization system. The effects of CO2 reduction subsystem operating parameters on water recovery efficiencies and water generation capabilities were analyzed. Water mass balances for advanced missions were conducted for advanced missions. Equivalent system mass method was used to calculate payoff time for integrating the CO2 reduction subsystem into an air revitalization system. Decision criteria based on payoff time for integrating a CRS for advanced missions were developed.

The Shuttle Orbiter humidity control and carbon dioxide removal system for extended duration missions presently uses a solid amine called HS-C. This August, on board STS-62, a new solid amine called HS-C+ will be used. HS-C+ uses the same amine and the substrate material, but a different preparation process. Forty-seven breakthrough tests have been conducted to characterize the performance of HS-C+. CO2 partial pressure, bed temperature, and H2O partial pressure were varied. Eleven HS-C breakthrough tests were also run to provide a direct comparison. Under all conditions tested, HS-C+ outperformed HS-C. Both materials adsorb all CO2 and H2O available at the start of a test when the beds are fully desorbed. As the bed becomes partially loaded, the CO2 and H2O adsorption rates decrease rapidly. HS-C+ continues adsorbing all CO2 and H2O available for a longer time. Greater surface area on HS-C+ may cause the improved performance.