Development and Testing of a Temperature-Swing Adsorption Compressor for Carbon Dioxide in Closed-Loop Air Revitalization Systems

The International Space Station's air revitalization system operates in an open loop mode and relies on the re-supply of oxygen and other consumables from earth for the life support of astronauts. A compressor is required to deliver the carbon dioxide from a removal assembly to a reduction unit to recover oxygen and close the oxygen loop. We have developed a temperature-swing adsorption compressor (TSAC) that is energy efficient, quiet, and has no rapidly moving parts for performing these tasks. The TSAC has the capability to remove carbon dioxide (CO₂) from a low-pressure source, and subsequently store, compress, and deliver it at a higher pressure as required by a processor. As such, the TSAC is an excellent candidate for interfacing CO₂ removal and reduction units in the air revitalization loop of a spacecraft for oxygen recovery. A TSAC that uses air as a cooling medium was developed and tested at NASA Ames Research Center. This paper discusses the TSAC prototype design, presents modeling results and functional performance tests, and describes the design improvements made. Approximately 30% reduction in mass and volume was achieved compared to the earlier prototype by modifying the heat transfer design and fabrication techniques. The compressor processed and produced compressed CO₂ at a rate of 4 kg/day at 1000 mm Hg, as per the design specifications.