SBIR-STTR Award

The current Carbon Dioxide Removal Assembly (CDRA) onboard the International Space Station (ISS) is used to capture and compress CO2 from the cabin air and then deliver compressed CO2 to the Sabatier Reactor to make water and methane. The CDRA captures CO2 using a sorbent material, traditionally zeolite. The zeolite must be maintained at specific temperatures for successful adsorption (20°C) and desorption (200°C) of the CO2. The CDRA relies on cartridge heaters and solid conductive metal fins to generate and spread heat to the sorbent material. The cooling system connects to the main cooling system on the spacecraft. This thermal management system is employed to maintain the appropriate sorbent (i.e., zeolite) temperature for adsorption and desorption temperatures of the CO2. The current system has been used for over 30 years, and many problems have arisen during its lifetime including performance vs. resource usage, closed loop operation, zeolite dust causing leaks, and sensors failing due to thermal fatigue. The proposed thermal management system mitigates many of these issues by combining the heating and cooling modes, operating passively, and replacing the solid metal fins with a unique, two-phase heat transfer vapor chamber system. By using vapor chambers instead of solid metal fins, there is minimal temperature gradient along the heat transfer device which will increase the isothermality of the surrounding sorbent material. This allows for faster, and more even, heating and cooling of the sorbent bed, which will ultimately improve the CO2 adsorption and desorption rates. Anticipated

Benefits:
This novel vapor chamber thermal management system would be used for the current Carbon Dioxide Removal Assembly (CDRA) on board the International Space Station. It will allow for less power usage, combined heating and cooling mode, high isothermality in the sorbent material, and a more efficient carbon dioxide removal assembly. This concept can also be applied to future metal organic framework assemblies or liquid sorbent systems for carbon dioxide removal. This novel vapor chamber design can be applied to other CO2 capture systems that utilize a temperature sensitive zeolite. This includes direct air capture systems, systems capturing CO2 from truck exhaust, or systems filtering exhaust from manufacturing facilities. Theoretically, the vapor chamber can be retrofitted to suit the needs of any sized zeolite bed.

The Carbon Dioxide Removal Assembly (CDRA) is a subassembly of the Environmental Control and Life Support (ECLS) system on the International Space Station (ISS). The function of the CDRA is to remove CO2 from cabin air, ideally turning it into a useful resource such as water or methane. This is accomplished using a sorbent material, zeolite, to adsorb and desorb CO2. Zeolite has a highly porous molecular structure, and CO2 can favorably bond within these pores at certain temperatures and pressures. This molecular bonding process is exothermic during CO2 adsorption and endothermic during CO2 desorption. Thus, the zeolite material on the CDRA must be heated and cooled to very specific temperatures for the most efficient desorption and adsorption of CO2, respectively. The current CDRA operates most effectively when the sorbent bed is cooled to 20°C for adsorption and heated to 220°C for desorption. The zeolite material has poor heat transfer characteristics, making a well-designed thermal management system a priority on the CDRA. Advanced Cooling Technologies (ACT) has developed an additively manufactured (AM), titanium-water, vapor chamber to heat and cool the zeolite material in the CDRA. ACT’s proposed thermal management system is designed to heat and cool the zeolite to these specific temperatures at faster rates and more uniformly than the state-of-the-art design, which utilizes a cartridge heater and aluminum fin. ACT’s titanium water vapor chamber design has additional benefits over the state-of-the-art such as reduced size, weight, and power (SWaP) and adaptability to future sorbent materials. Anticipated

Benefits:
The proposed vapor chambers are applicable to the Carbon Dioxide Removal Assembly, which is a subset of the Environmental Control and Life Support System on the International Space Station. The vapor chambers will be used to heat and cool the sorbent material to sequester CO2 from the cabin air on the ISS. The vapor chambers may also be applicable to future manned missions to lunar or Martian surfaces, such as those proposed under NASA’s Space Launch System. These vapor chambers are designed to heat and cool sorbent material to adsorb/desorb CO2, thus can find non-NASA applications in any application using a similar sorbent material. This could be direct air capture systems, CO2 capture systems in coal and power plants, or certain air filtration systems.