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Harvesting Thermal Energy for Novel Power Sources in Long Range Precision Fired Artillery

Description:

TECHNOLOGY AREA(S): Materials 

OBJECTIVE: Investigate and develop innovative solutions for harvesting and converting heat generated during aerodynamic flight into electrical energy and power for precision guided munitions. The technology should be capable of surviving typical artillery gun launch loads and should conform to fit within an artillery projectile. 

DESCRIPTION: The Army’s Long Range Precision Fires mission expands the current portfolio of conventional artillery to advanced munition technologies with extended range capability (>70km). Extended range requires the projectile to fly to higher velocities and altitudes as well as longer flight times. At high Mach speeds the projectiles may be exposed to high temperatures and heat fluxes up to 3500°C and 1000 W/cm2 respectively. Additionally, due to extended flight times, the electronics required for precision guidance require more power in order to maintain operation throughout the flight. The presence of high heat fluxes results in waste heat into the projectile which could potentially damage critical electronics. This coupled with the need for new power sources to sustain operational capability of onboard electronics systems creates a new opportunity for the investigation of novel energy harvesting technologies that can remove the excess heat from the airframe via conversion to electrical energy. The new source of electrical energy can thus be used to power fuzes, guidance, navigation, and control technologies, actuation systems, and staging technologies. The Army is currently looking for novel thermoelectric materials and thermoelectric generators (TEG) that extend the current state of the art in thermal limits (>1500F) and thermoelectric effectiveness (ZT>2). Materials of interest include, but are not limited to, low dimensional materials, nanocrystalline and nanocomposite materials, organics (conducting polymers), inorganics (tellurides, oxides, Half Heusler alloys, skutterudites, silicides, etc.,), and organic-inorganic composites. 

PHASE I: During the Phase I contract, successful proposers shall conduct a proof of concept study that focuses on thermal energy harvesting materials and energy conversion technologies that can withstand and operate within varying thermal loads ranging from 5 W/cm2 to 700 W/cm2 and temperatures ranging from ambient to 2000°F (objective). Investigations should include analysis of material performance under transient thermal loading, potential power output (threshold of 100W and objective 250W), and generator efficiency (ZT>2). A final proposed concept design, including a detailed description and analysis of potential candidate electronics packages for the new power source, is expected at the completion of the Phase I effort. 

PHASE II: Using the data derived from Phase I, in Phase II the proposer shall fabricate and integrate a prototype of the technology into a nominal projectile form-factor. Specifically the TEG shall conform to a volume = 1 in3. The proposer shall further their proof of concept design by demonstration that the technology can sustain power to a representative electrical component or system under thermal loading up to 15 minutes (objective) and by performing mechanical and thermal testing on the proposed materials and power generator architecture. Upon evaluation of the design through a critical design review, the prototype hardware’s survivability shall be demonstrated via high G testing in an air launched munition and aerothermal ground testing. Information and data collected from these tests will be used to validate operational performance. 

PHASE III: Phase III selections shall ruggedize the final design, identify large scale production alternatives, and fabricate 20 prototypes that can be integrated into a nominal projectile form-factor to be identified by the SBIR: Army 20 Topics and Concepts Government. Live fire tests will be conducted and the prototype integrated with projectile form-factor will have to withstand shock loads approaching 35,000g’s. Phase III selections will develop of a cost model of expected large scale production to provide estimates of non-recurring and recurring unit production costs. Production concept for commercial application will be developed addressing commercial cost and quality targets. Phase III selections might have adequate support from an Army prime or industry transition partner identified during earlier phases of the program. The proposer shall work with this partner (TBD) to fully develop, integrate, and test the performance and survivability characteristics of the design for integration onto the vendor’s target platform. COMMERCIALIZATION: High efficiency energy harvesting and conversion technologies are continually in demand by the aerospace and automotive industries. Commercial and dual applications of this technology include electrical power supplies for satellites, fuel cells and combustion engines such as for aircraft and ground transportation. 

REFERENCES: 

1: Ali Shakouri, Thermoelectric, thermionic, and thermophotovoltaic energy conversion, Baskin School of Engineering, University of California, 2005, https://apps.dtic.mil/dtic/tr/fulltext/u2/a458490.pdf

KEYWORDS: Energy Harvesting, Energy Conversions, Thermoelectric Efficiency, Seebeck Effect 

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