TECHNOLOGY AREAS: Air Platform, Ground/Sea Vehicles

ACQUISITION PROGRAM: PMA-262; Maritime Unmanned Aerial Vehicles
OBJECTIVE: Develop a highly efficient compact converter system used to produce electrical power from waste heat generated in ultra-high altitude Intelligence, Surveillance and Reconnaissance (ISR) UAVs operating at descending or low altitude cruise conditions.

DESCRIPTION: Current UAVs are experiencing a build up of excessive heat when all onboard systems are functioning at full capacity. Heat rejection issues are primarily at low altitude cruise under hot conditions when mission and flight systems are all operational. Currently, fuel is used as a coolant for the radar, avionics, and engine generated waste heat, and the wing tanks are used as a heat sink. Additionally, under certain conditions, power requirements can exceed what is available. An innovative solution is sought to convert the excess heat generated by the UAV systems into energy to power required onboard systems. The system should be on-demand, allowing the converter to function at only necessary points in the mission. In some instances, such as high altitude travel, heat is necessary in the UAV, however when the mission is low altitude, the converter should be actively converting excessive heat to power.

The resulting technology should consider size, weight, and power restrictions of UAVs without reducing fuel storage capacity. Initial design should allow flexibility so that it can be shaped to fit into a variety of spaces. Converting heat most closely to its generative source is desired. The converter system should produce electrical power in excess of the additional fuel energy required to operate.

Current and future UAVs would benefit from a system designed to convert excess heat into needed power.

PHASE I: Develop and prove feasibility of a concept model to convert waste heat to electrical power on board UAVs with heat source operating temperatures of 135 and 300 degrees Fahrenheit.

PHASE II: Based on the Phase I concept model and design, estimate the amount of electricity generated based on source heat surface temperatures of 135, 300, and 450 degrees Fahrenheit. Develop aircraft interfaces and perform a minimum of two iterations of component design; First demonstrate the feasibility of the technology to generate electricity from a heated surface at the three referenced temperatures in a laboratory bench test and second, redesign if necessary and in a scaled-up demonstration, characterize the design and report on component test results at the same referenced surface temperatures.

PHASE III: Transition developed technology to applicable military platforms as well as commercial aviation and other interested industries.

PRIVATE SECTOR COMMERCIAL POTENTIAL/DUAL-USE APPLICATIONS: The converter system could clearly be useful for any purpose where electricity is in limited supply, waste heat is plentiful, and conversion of heat to electricity is more constrained by size and weight, rather then efficiency. This would apply to any vehicle such as cars, commercial ships, aircraft and space exploration.

REFERENCES:
1. Wu1, D. M., Hagelstein , P. L. , Chen , P. , Sinha, K. P. & Meulenberg, A. (2009). Quantum-coupled single-electron thermal to electric conversion scheme. Journal of. Applied. Physics. 106, 094315
doi:10.1063/1.3257402

2. Choi, Wonjoon, Hong, Seunghyun, Abrahamson, Joel T., Han, Jae-Hee, Song, Changsik, Nair, Nitish, Baik, Seunghyun & Strano, Michael S. (7 March 2010). Chemically Driven Carbon-nanotube-guided Thermopower Waves. Nature Materials, Published online http://www.nature.com/nmat/journal/vaop/ncurrent/abs/nmat2714.html#a1#a1

3. Service, Robert F. (29 October 2004).Temperature Rises for Devices That Turn Heat Into Electricity. Science 306 806-807 http://www.sciencemag.org/cgi/content/summary/sci;306/5697/806?maxtoshow=&hits=10&RESULTFORMAT=&fulltext=heat+to+electricity&searchid=1&FIRSTINDEX=0&resourcetype=HWCIT

KEYWORDS: Electrical power; Unmanned Aerial Vehicle; excess heat; aircraft; energy harvesting; compact converter

** TOPIC AUTHOR (TPOC) **

DoD Notice:   Between July 20 and August 16, 2010, you may talk directly with the Topic Authors to ask technical questions about the topics. Their contact information is listed above. For reasons of competitive fairness, direct communication between proposers and topic authors is not allowed starting August 17, when DoD begins accepting proposals for this solicitation.

However, proposers may still submit written questions about solicitation topics through the DoD's SBIR/STTR Interactive Topic Information System (SITIS), in which the questioner and respondent remain anonymous and all questions and answers are posted electronically for general viewing until the solicitation closes. All proposers are advised to monitor SITIS (10.3 Q&A) during the solicitation period for questions and answers, and other significant information, relevant to the SBIR 10.3 topic under which they are proposing.

If you have general questions about DoD SBIR program, please contact the DoD SBIR Help Desk at (866) 724-7457 or email weblink.