Development of automotive thermoelectric generators at German Aerospace Center (DLR)

The German Aerospace Center is not only Germany`s research center for aeronautics and space, but also has a field of research “traffic and transportation”. Associated to this field the activities at the institute of vehicle concepts in Stuttgart contribute to a sustainable development of technological systems for future generations of vehicles, whereas waste heat recovery with thermoelectric generators is one of the topics in order to raise energy efficiency. Thermoelectric conversion of exhaust waste heat to electrical energy is attractive not only because of the lack of moving parts and the high steadiness of the technology but also due to the moderate r&d effort compared to other technologies, which is necessary to integrate it into the vehicle. The key aspects at the institute of vehicle concepts are the development of the component itself and its integration into the energy architecture of the vehicle. Thereby on the one hand computer aided development is done. A stationary thermodynamic model has been built up which can calculate beyond others the expectable temperature profiles, electrical power output and created backpressure in the fluid flows of the TEG. This model can be used to rate different TEG-designs at an early stage of development. Beyond that a dynamic TEG-model has been created in order to calculate the useful power output at different driving cycles and to show the retroactive effects to the vehicle system. After computer aided investigations the developments are also realized in hardware. E.g. in cooperation with BMW and DLR`s institute of material research a 200 W TEG has been integrated into a test vehicle of BMW 5 series and tested successfully. The current research focus area at the DLR has the goal of improving the manufacturing technique for the generators with a view to future standard production applications.