Design, Fabrication and Testing of a Novel Energy-Harvesting Thermoelectric Power Supply for Wireless Sensors

Abstract

A prototype energy-harvesting thermoelectric generator (TEG) was designed and fabricated and it is being tested to provide power for wireless sensors used in the health monitoring (monitoring of temperatures, vibrations, strains, etc) of Navy shipboard machinery. TEGs are rugged, reliable, solid-state devices that convert heat directly into electricity without any moving parts. The TEGs designed in this project utilize the heat transfer between shipboard waste heat sources and ambient air to generate electricity. To satisfy the required small design volume of less than one cubic inch, Hi-Z Technology, Inc. (Hi-Z) is using its innovative Quantum Well (QW) thermoelectric technology that provides a factor of four increase in the conversion efficiency, and a large reduction in the design volume over the currently used bulk bismuth-telluride thermoelectics. QWs are nanostructured multi-layer thin films. These wireless sensors can be used to detect cracks, corrosion, impact damage, and temperature and vibration excursions as part of the Condition Based Maintenance (CBM) of the Navy ship machinery. The CBM of ship machinery can be significantly improved by automating the process with the use of self-powered wireless sensors. These power-harvesting TEGs can be used to replace batteries as electrical power sources and to eliminate tethered wires and cables, thus significantly reducing the installation and maintenance costs. The very first QW TEG module anywhere was just successfully tested (it produced electricity from heat). It remains to package this module with thermal insulation in the housing and heat sink, and to test this entire TEG device in a simulated thermal environment of a Navy gas turbine. Following this test, it is planned to attach this device to the surface of a gas turbine on a Navy ship and to test it in its actual environment, in conjunction with a wireless sensor. This power supply for wireless sensors can also be used in health monitoring of equipment in the nuclear and conventional power plants, process plants, and the monitoring of temperatures, vibrations and pressures of steam lines, etc. Hi-Z has chosen this small power supply as the first practical application of its emerging QW TEG technology. However, this technology can also be used on a much larger scale in, for example, recovering the waste heat from the exhaust of the truck and automobile engines, where the generated electricity can be used to eliminate the alternator and thus reduce the load on the engine, improve overall efficiency and reduce fuel consumption.