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The “low power-CO2 removal (LPCOR) system” is an advanced air revitalization system that is under development at NASA Ames Research Center. The LPCOR utilizes the fundamental design features of the ‘four bed molecular sieve’ (4BMS) CO2 removal technology of the International Space Station (ISS). LPCOR improves power efficiency by replacing the desiccant beds of the 4BMS with a membrane dryer and a state-of-the-art, structured adsorbent device that collectively require 25% of the thermal energy required by the 4BMS desiccant beds for regeneration. Compared to the 4BMS technology, it has the added functionality to deliver pure, compressed CO2 for oxygen recovery. The CO2 removal and recovery functions are performed in a two-stage adsorption compressor. CO2 is removed from the cabin air and partially compressed in the first stage. The second stage performs further compression and delivers the compressed CO2 to a reduction unit such as a Sabatier reactor for oxygen recovery.

This paper presents and discusses the results of an integrated 4-Bed Molecular Sieve (4BMS), Temperature Swing Adsorption Compressor (TSAC), and Sabatier Engineering Development Unit (EDU) test. Testing was required to evaluate the integrated performance of these components of a closed loop atmosphere revitalization system as well as to provide a better understanding of the practical inefficiencies and control issues, which are unavailable from a theoretical model.

CO2 removal, recovery and reduction are essential processes for a closed loop air revitalization system in a crewed spacecraft. Typically, a compressor is required to recover the low pressure CO2 that is being removed from the spacecraft in a swing bed adsorption system. This paper describes integrated tests of a Temperature-Swing Adsorption Compressor (TSAC) with high-fidelity systems for carbon dioxide removal and reduction assemblies (CDRA and Sabatier reactor). It also provides details of the TSAC operation at various CO2 loadings. The TSAC is a solid-state compressor that has the capability to remove CO2 from a low-pressure source, and subsequently store, compress, and deliver it at a higher pressure. TSAC utilizes the principle of temperature-swing adsorption compression and has no rapidly moving parts.

Continuous removal of carbon dioxide is one of the most critical processes in a spacecraft air revitalization system. Recovery of the waste carbon dioxide and its subsequent conversion to oxygen become essential for long-duration human space missions beyond Low-Earth orbit where re-supply of consumables such as oxygen is neither practical nor economical. The current CO2 removal technology employed in the United States Operating Segment (USOS) of the International Space Station (ISS) operates in an open loop mode where the waste CO2 is vented to space. A compressor is required to facilitate CO2 recovery capabilities. The CO2 removal process itself is one of the most energy-intensive processes in the life support system of the ISS due to the water vapor recovery method involved in the process. This paper discusses the design and development of a low-power CO2 removal system that has capabilities to recover and compress the CO2 for recycling oxygen.

This paper describes the results of an ongoing long-duration testing of a temperature-swing adsorption compressor (TSAC) that has application in closing the air revitalization loop of the International Space Station (ISS) and future spacecraft. The TSAC is a solid-state compressor that has the capability to remove CO2 from a low-pressure source, and subsequently store, compress, and deliver it at a higher pressure as required by a processor. The TSAC described in this paper was designed to function as an interface device for the CO2 removal and reduction units of the International Space Station (ISS). The air revitalization system of the ISS operates in an open loop mode and relies on the resupply of oxygen and other consumables from Earth for the life support of astronauts. A compressor is required for recovering the CO2 from the carbon dioxide removal assembly (CDRA) and delivering to a CO2 reduction unit of an oxygen recovery system and thereby closing the air-loop.