Toxicity Mitigating Single-Fluid Cooling System for Manned Spacecraft

Mainstream proposes a single-loop vapor compression thermal control system (VCTCS) to replace currently-used two-loop TCSs. NASA uses two-loop TCSs to mitigate crew toxicity risk whereby one loop collects heat within a crew module with a low-toxicity fluid and transfers the heat to a second loop in the external module that rejects heat through the radiators. This architecture is used for crew safety (most very low freezing point fluids are somewhat toxic or untested) but comes with a mass penalty due to the duplication of prime movers (pumps), mass of the intermediate heat exchanger, and extra radiator surface area to account for the additional temperature delta required for the intermediate heat exchange process. The two-loop mass penalty is a driving force toward reducing the TCS to a single working fluid. However, the toxicity risk must be mitigated for this architecture to be realized. Mainstream proposes to replace the two loop TCS architecture with a single loop TCS architecture that has toxicity mitigating technology. In Phase I, Mainstream demonstrated the performance of the lightweight and compact compressor, by far the most critical component in the single-loop system. In Phase II, Mainstream will refine the compressor design, and then will build and test a full-scale 8-kW capacity single-loop thermal system prototype.

NASA applications for the proposed toxicity mitigating thermal control system include future Orion-like manned missions, Deep Space Gateway and Transport missions, and lunar habitation modules. Any manned space vehicle would benefit from the expected weight and crew safety advantage offered by the innovative thermal control system proposed.

The compressor designed in Phase I expands our commercial compressor line. The compressors in this family can be used where size or mass are key requirements. Sub-ambient compressor operation further targets applications that involve close proximity or confined spaces. The negative-pressure VCTCS can also be downsized and integrated into a cooling system for personal protective equipment.

This is early/mid-stage (TRL 6) — the most realistic path in is NASA SBIR/STTR, which funds small businesses and research institutions to develop technology aligned with NASA's needs (equity-free, phased funding). Check whether a current SBIR/STTR solicitation topic overlaps with this project's technology area, or contact the project directly (above) to ask.

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