The Low-Power CO2 Removal and Compression System: Design Advances and Development Status

Abstract

Active resource recovery from metabolic CO2 facilitates long-duration missions by decreasing cost and increasing self-sustainability. To provide this capability, theLow-Power CO2 Removal � (LPCOR) closed- loop air revitalization system is under development at NASA Ames Research Center. The LPCOR system is designed to perform the same CO2 removal function as the four-bed molecular sieve (4BMS) system currently employed on the International Space Station (ISS), with the additional integrated ability to purify and thermally compress CO2 to supply downstream CO2 recovery units. The LPCOR design goals include decreasing cabin air CO2 concentration up to 60% while yielding a 50% power savings when compared to current ISS levels. The LPCOR system increases power efficiency by replacing the desiccant (packed) beds of the 4BMS with a passive, Nafion ® hollow-fiber membrane bulk dryer and a state-of-the-art engineered structured sorbent device that requires only 25% of the thermal energy required by the 4BMS desiccant beds. CO2 removal, purification, and compression functions are performed in an integrated 2-Stage adsorption canister. CO2 is removed from the cabin air and partially compressed in Stage 1. The CO2 is concentrated in a smaller Stage 2, where thermal desorption is then used to further compress the CO2 for delivery to a reduction unit (e.g., a Sabatier reactor) for oxygen recovery. This paper presents the ongoing design considerations and development status of the LPCOR system, including overall design principles, characterization tests, airflow distribution modeling, and potential design strategies for current and future components.