The Institute of Vehicle Concepts at the German Aerospace Center (Deutsches Zentrum für Luft-und Raumfahrt; DLR) is, together with the Japanese company Yamaha Corporation, developing special vehicle systems based on thermoelectric effects. The aim of the cooperation is to prototypically develop new modules for residual energy in road and rail vehicles. A promising area of application of this technology is, for example, the automotive sector. The Japanese company is mainly contributing its know-how in the procurement and manufacture of the thermoelectric modules made of semiconductor materials, and DLR is contributing its broad knowledge in design, vehicle concepts, as well as the design and optimisation of vehicle energy systems.
Using waste heat to generate electricity
The combustion engines of vehicles, for example, use only about one third of the potential energy in the fuel for propulsion – the remaining two thirds are lost as waste heat. Thermoelectric generators use this heat and convert it into electricity. The power can then be used in the vehicle for control units or convenience electronics and thus reduces the load on the alternator, which would otherwise have to generate this power itself. In hybrid and range-extender vehicles with internal combustion engines, the power obtained from such a thermoelectric generator can be fed directly to the battery. The goal of the DLR scientists is to reduce fuel consumption by three to five percent using thermoelectric generators.
Development of vehicle-compatible thermoelectric modules
Together with partners from industry and research, the Stuttgart-based DLR Institute of Vehicle Concepts has, in the last few years, already developed the first system integrations based on thermoelectric generators and successfully tested them in a car. Until now, industrially produced thermoelectric modules have only been available to a very limited extent. The engineers have therefore had to resort to modules that were not specially designed for this purpose. “Together with our Japanese partner, we are now developing vehicle-compatible modules for the next generation of our thermoelectric generators according to our design,” explains DLR researcher Mirko Klein Altstedde, who initiated the cooperation. “With regards to shape, thermal and electrical properties, maximum application temperatures and cycle stability, these have been specially developed to meet our requirements. At the same time, our partner also cares for the production technology, so that, in future, the modules can be produced as efficiently and economically as possible for the automotive industry,” says Klein Altstedde. At present, the first research demonstrators are being tested in the laboratory to further optimise details regarding the vehicle suitability and efficiency.