Matsumoto, M., Mori, M., Haraguchi, T., Ohtani, M. et al., "Development of State of the Art Compact and Lightweight Thermoelectric Generator Using Vacuum Space Structure," SAE Int. J. Engines 8(4):1815-1825, 2015, doi:10.4271/2015-01-1691.
Exhaust heat recovery units that use a thermoelectric element generate electricity by creating a temperature difference in the thermoelectric element by heating one side and cooling the other side of the thermoelectric circuit (module). In this case, the general structure does not directly join the thermoelectric module with the heat sink, and instead presses the thermoelectric module against the heat sink using bolts or other means in order to prevent thermoelectric element damage due to the difference in linear expansion between the cooled and heated sides of the thermoelectric module. However, this poses the issues associated with a complex, heavy and expensive structure. Therefore, a new vacuum space structure was devised that houses the thermoelectric module in a vacuum chamber and presses the module against the heat sink using atmospheric pressure. The results of electric generation validation tests showed that the new vacuum space structure can provide electric generation performance equivalent to that of the conventional structure, and was also confirmed to effectively prevent thermoelectric element damage, enabling significant reduction of the thermoelectric generator size.