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Low Temperature Solid State Refrigeration

Description:

OBJECTIVE: Develop a cryogenic, solid state, no-moving-parts thermal control system for use aboard spacecraft. DESCRIPTION: This solicitation seeks to develop a completely solid state, no-moving-parts refrigeration system that can be applied to cooling a focal plane array or other electronics in a space environment. The space environment for these purposes includes a heat reject temperature of nominally 300K and exposure to a vacuum. This entails cooling a flat surface roughly 25 square cm to less than 123K. The heat load for demonstration should be greater than 0.5W, though future real-world demands will be higher. Corresponding system specific power and specific mass should be on the order of 100 W/W and 1 kg/W. Current cryogenic refrigeration (i.e. cooling to temperatures less than 123K) technologies used to cool low temperature space-based EO/IR sensors use refrigeration cycles that depend on the expansion of a refrigerant gas, e.g. Brayton and Stirling type coolers. Though relatively efficient, these coolers rely on moving parts (compressors and expanders) which both create vibrations that can induce jitter into a telescope and reduce the expected lifespan of the system due to wear and fatigue. Additionally, the existing coolers require large masses for heat transfer components (e.g. recuperators and regenerators), compressors, and to contain high pressure gases. Solid state cooling, such as is done by thermoelectric devices and laser cooling, can overcome many of the mechanical coolers disadvantages by making a compact device that uses only electricity to produce a temperature gradient and transfer heat. While prior work has made substantial progress in optical cooling, only temperatures down to 155K have been accomplished in experimental settings with no method of heat rejection. Similarly, thermoelectric coolers require several stages to accomplish a large temperature gradient and, due to the number of stages, two-dimensional heat spreading becomes an issue because of the decreasing area a result of each subsequent stage having to compensate for the inefficiency of the previous stage. Both thermoelectric and optical cooling can theoretically cool well into the cryogenic regime, with modeling putting thermoelectric devices around 10K and optical cooling as low as 80K. The primary issue with these methods is the materials"performance. Though current focus has been on Peltier and optical cooling, other novel methods are encouraged, e.g. applying effects such as magnetocaloric, electrocaloric, thermotunneling, Ettingshausen, or a combination hybrid system constructed in such a way that there are no moving parts. PHASE I: Phase I SBIR efforts should concentrate on the development of the fundamental concepts for a low size, weight, and power solid state cryogenic refrigerator that is applicable to spacecraft. Determine expected performance through analysis and modeling efforts. Identify technical risks and develop a risk mitigation plan for Phase 2. PHASE II: Phase II SBIR efforts should take the innovation of Phase I and design/develop/construct a breadboard device to demonstrate the innovation. This device may not be optimized to flight levels but should demonstrate the potential of the prototype device to meet actual operational specifications. PHASE III: Military App: cryogenic sensing systems relate to infrared sensing, cryogen management, electronics cooling, and superconductivity. Commercial App: Medical applications such MRI machine magnet cooling, cooling of IR cameras, gas liquefaction and use in telecommunications cooling. REFERENCES: 1. Woochul Kim, et al.,"Thermal Conductivity Reduction and Thermoelectric Figure of Merit Increase by Embedding Nano-particles in Crystalline Semiconductors."PRL 96, 045901 2006. 2. Yucheng Lan, Austin Jerome Minnich, Gang Chen, and Zhifeng Ren,"Enhancement of Thermoelectric Figure-of-Merit by a Bulk Nanostructuring Approach."Adv. Funct. Mater. 2009, 19, 121. 3. M. S. Dresselhaus, et al."New Directions For Low Dimensional Thermoelectric Materials", DOI:10.1002/adma.200600527, Advanced Materials, 2007,19, 1-12. 4.J. R. Lukes and H. Zhong, 2007,"Thermal Conductivity of Individual Single-Wall Carbon Nanotubes,"Journal of Heat Transfer, Vol. 129, pp. 705-716. 5. D.V. Seletskiy, M.P. Hehlen, R.I. Epstein, and M. Sheik-Bahae, 2012,"Cryogenic optical refrigeration,"Adv. Opt. Photon. 4, 78-107.
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