SBIR-STTR Award

Mainstream proposes to develop a high-efficiency carbon removal system to safely collect and dispose of sub-micron carbon particulates generated from oxygen recovery systems. A cyclone separator reduces the total particulate matter loading while collecting larger particles (i.e., 1–10 µm, >10 µm). The remaining sub-micron particles (i.e. 0.1–1 µm) are then removed using an electrostatic precipitator (ESP), which drives particles entrained in the gas stream onto a collection electrode. Mainstream will optimize the geometry, electrode material, and key operational parameters to achieve a very high efficiency (>99%) for particles down to 0.1 µm. Collection electrodes can be regenerated in place through gas reaction or removed and scraped for safe storage and reuse or disposal, retaining all carbon particles. In Phase I, Mainstream will leverage our existing CFD and design toolsets to experimentally demonstrate sub-micron particulate separation with a combined cyclone and ESP system. Regeneration of electrodes would occur in-place or be used for safe disposal of carbon. Using process model designs and experimental data, Mainstream will design a carbon removal system and detail system size, weight, and power requirements. In Phase II, we will fabricate and validate a full-scale prototype system and advance system development for rapid integration. Potential NASA Applications (Limit 1500 characters, approximately 150 words): NASA applications for the proposed carbon removal system for sub-micron particulates separation include integration with oxygen recovery systems for future long-duration manned missions such as Gateway and Mars. Additionally, this technology is applicable for both general air purification of the main cabin of the manned spacecraft as well as the removal of planetary dust from main cabins and airlocks of the planetary habitat. Potential Non-NASA Applications (Limit 1500 characters, approximately 150 words): Non-NASA applications are numerous including automotive, thermal oxidizers, incinerators, industrial separators, commercial/medical/residential air purification, and particulate concentrators. With respect to additional manned spacecraft, non-government commercial entities such as Space-X, Blue Origin, Bigelow Aerospace, and others include space tourism as a future goal Duration: 6

Currently, oxygen in space is recovered through an advanced oxygen recovery system, which does not fully recover the oxygen. Future missions may use technologies such as the Plasma Pyrolysis Assembly (PPA) or Bosch process, both of which recover oxygen, but generate large amounts of carbon particulate (0.2 – 50 µm) that must be removed for proper operation and crew safety. In Phase I, Mainstream developed and demonstrated a high-efficiency carbon removal system (CRS) to safely collect, remove, and dispose of sub-micron carbon particulates that consists of a 1st-stage cyclone separator that removes 85% of the particulate (focused towards larger particles), a 2nd-stage electrostatic precipitator that removes another 8% (focused towards small particles), and a final porous metal filter which removes the remaining ~7% for a total removal efficiency of 99.93% at 0.3 µm and 99.69% from 0.3 µm to 10 µm. The CRS system was designed to operate in high-temperature steam (Bosch) or hydrogen (PPA) without issues. It is <0.1 ft3, 4 lb, and consumes <20 W of power with a pressure drop of <50 torr including all components and electronics. Phase I culminated in a final validation of operation independent of gravity (i.e., tested upside down), high loading (>10 g/min), and in high-temperature steam. In Phase II, Mainstream will iterate on the CRS prototype with our optimized computation fluid dynamics models, focus on practical carbon removal from the subsystems, and experimentally evaluate long-term CRS performance, pressure drop, and regeneration at relevant carbon loadings and operation conditions (e.g., reduced pressure, gravity, PPA, Bosch). The verified CRS undergo PPA and Bosch relevant lifetime testing and mature hardware delivered to NASA for evaluation. Anticipated

Benefits:
The developed technologies on this program are unique in that they provide HEPA-level filtration, with no consumable components and can reduce the need for consumables by 95%, all while requiring minimal increase in air pressure and a very low power consumption. This provides a direct and enabling technology for NASA for future moon and Mars missions where carbon particulate capture is necessary for full recovery of oxygen for long-term space flights and eventual bases. Mainstream sees many other dual-use applications in the industrial sector. We see the largest areas for this application in the large-scale industrial solid separation for air particulate and pollution control as well as in the specialty chemical manufacturing area, where recovery of expensive precious metal catalysts is a necessity.