With rising worldwide energy demands, there is a growing need for technologies which are able to utilize alternative forms and sources of energy as well as to reduce consumption. While energy storage technologies are rapidly advancing, they are not yet capable of matching the energy densities of combustible fuels. The internal combustion engine (ICE), coupled with a generator, is the predominant method of converting this chemical energy into electrical energy, yet the mechanical nature of this system presents performance limitations. An alternative being developed here is a combustion-powered thermoelectric generator (C-TEG) to directly convert the heat released from combustion into electricity. The solid-state nature of thermoelectric (TE) devices provides the attractive inherent benefits of reliability, fuel flexibility, controllability, and potential for power densities exceeding that of ICE/generator systems. While low material and device efficiencies have thus far limited the use of TEGs to niche applications, recently developed materials have more than doubled the TE figure of merit, a material parameter strongly influencing efficiency. The rapid rate of TE material advancements merits the parallel development of device technologies. Opportunities for a durable, multi-fuel, high power density generator make C-TEGs potential candidates for many consumer, industrial, and military power applications including automotive auxiliary power. Within the automotive field, C-TEGs may be applied in hybrid-electric vehicles to provide power during engine cycling or in conjunction with a TE waste heat recovery system to provide power on demand. With sufficient improvements in efficiency, C-TEGs may be used in plug-in hybrid-electric vehicles where the C-TEG serves as the range extender in lieu of an ICE/generator system. Another application is to provide auxiliary power in commercial vehicles. In this research, a baseline prototype was first constructed with a conventional heat exchange configuration, a commercial bismuth telluride module (maximum 225 °C), and a novel fuel atomizer. This prototype was used to develop and validate a computer simulator, identify the greatest opportunities for improvement, validate the use of the fuel atomizer with diesel fuel for TE power generation, and provide a baseline performance with which to compare system improvements. Subsequent improvements were made to increase combustion efficiency, reduce thermal losses, and characterize the heat exchangers at 500 °C for accurate simulation of the system performance with high performance lead telluride modules. In addition, multiple fuels were tested to verify multi-fuel capability and performance, and the use of a Pt/Pd combustion catalyst was tested to quantify improvements in heat exchange effectiveness.
- Aerospace Division
High Temperature Multi-Fuel Combustion-Powered Thermoelectric Auxiliary Power Unit
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Headings, LM, Washington, GN, Midlam-Mohler, S, & Heremans, JP. "High Temperature Multi-Fuel Combustion-Powered Thermoelectric Auxiliary Power Unit." Proceedings of the ASME 2009 Conference on Smart Materials, Adaptive Structures and Intelligent Systems. Volume 1: Active Materials, Mechanics and Behavior; Modeling, Simulation and Control. Oxnard, California, USA. September 21–23, 2009. pp. 123-130. ASME. https://doi.org/10.1115/SMASIS2009-1290
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