Concept of a Thermoelectric Module and Generator for Automotive Applications Based on an Integrated Functional Design

Despite the ongoing electrification of vehicle propulsion systems, combustion engine vehicles will continue to bear the brunt of passenger and goods transport world-wide for the next several years. A major challenge of the automotive industry is the achievement of the required reduction of CO2 emissions for internal combustion engines. Therefore, it is necessary to investigate all potential technologies to improve efficiency. Regardless of whether a conventional or hybrid vehicle concept is used, up to approximately 40 percent of the fuels chemical energy is lost as waste heat in the exhaust system. As a result, the DLR Institute of Vehicle Concepts, the Institute of Technical Thermodynamics and the Institute of Materials Research focus on utilizing exhaust heat through thermoelectric generators (TEG) in the DLR project Next Generation Car (NGC). Their primary goals are the development of cost-efficient thermoelectric modules (TEM) and TEGs with long-term stability and a maximized energy yield. In addition to overall TEG system design, the development of long-term stable, efficient TEMs for high-temperature applications is a great challenge. This paper presents the results of internal development activities and demonstrates integrated functional designs of the TEM and TEG. The concept of contacting the TEMs on the surface of the heat exchanger of the TEG will be discussed. The thermodynamic boundary conditions are identified in this connection as well as the thermomechanical interactions. The connection is based on an innovative plasma-sprayed multilayer film. Moreover, the implemented thermodynamic, thermoelectric and thermomechanical models are described. The research results in an integrated functional design, which is primarily focused on high converter efficiency and low manufacturing complexity for the automotive applications.