Description: Spacecraft environmental and thermal control systems make use of a variety of heat exchangers and condensers to provide clean water and maintain component temperatures at acceptable levels. In many cases these heat exchangers and condensers are fabricated using passivated stainless steel to retard corrosion and fouling processes, representing a significant weight penalty even for heat exchangers with minimal solid material. Leveraging extensive experience in the design and fabrication of ultra-compact heat exchangers, evaporators, and condensers using photochemically etched thin metal laminates, microVection has developed a concept for fabricating ultra-lightweight compact microfinned heat exchangers using 3-D printing technology. The concept involves 3-D printing a frame using relatively low-cost resins, followed by fully-dense plating of the frame to produce the desired heat exchanger feature dimensions. Heat exchanger fabrication is completed through heating in a furnace to remove the frame. The result is a heat exchanger that possesses all of the benefits of a laminated microfinned heat exchanger without the design constraints of continuous load paths through the structure. The proposed effort supports the NASA goal of reducing the mass and increasing the efficiency of heat acquisition components (per the 2015 NASA Technology Roadmap, TA 14.2.1 Heat Acquisition). Specific goals of the program are to design a heat exchanger with a performance metric below 0.4 kg/kW-K, eliminate the need for bonded/brazed joints, and demonstrate the ability to fabricate the concept.

Benefits: The reduction in weight and volume, coupled with increased thermal performance, provides significant improvement to the effectiveness of heat exchangers, while reducing the heat exchanger's impact in terms of system integration. Potential benefits include reduced fuel burn and improved system performance, in alignment with NASA's goals. This technology would be applicable to any NASA application where heat exchangers are required and where weight has a significant impact on system performance. NASA programs the concept could impact include ASCENDS (Active Sensing of CO2 Emissions over Nights, Days, and Seasons), DRM 5 (Asteroid Redirect), DRM 6 (Crewed to Near Earth Asteroid), DRM 7 (Crewed to Lunar Surface), and DRM 8 & 9 (Crewed to Mars).

Lightweight and compact heat exchanger units have uses across a wide range of applications. The impact of such an advancement in heat exchanger technology cannot be overstated, as the applicability to the military and commercial sectors is vast. Improving the thermal performance of the heat exchangers enables process and performance improvements throughout the potential usage scenarios, reduction in weight has cascading impacts on such things as fuel consumption and system performance, while reduction in volume improves system integration and packaging considerations. It is not difficult to envision the multitude of positive impacts such technology could have across a wide array of industries, and these attractive features offer a compelling value proposition to companies.