Thermoelectric Generators for Heavy-Duty Vehicles: A Systemic Approach and Development

Abstract

At the automotive development the major challenges are the achievement of the required reduction of CO2 emissions and the reduction of the fuel consumption for internal combustion engines (ICE). Therefore, it is necessary to investigate all potential technologies to improve efficiency. Regardless of whether a passenger car or a heavy-duty truck concept with a modern conventional ICE is considered, approximately 2/3 of the fuels chemical energy dissipates as waste heat roughly in equal shares in the exhaust and coolant system. The heavy-duty market is expected to be dominated by ICE for a long-time period, due to the need for energy density in propulsion of larger vehicles and low Total Cost of Ownership (TCO). Specifically, the waste heat of the exhaust gas provides through its high temperature level and semi-stationary characteristics the highest potential as secondary energy source. The technology of thermoelectric generators (TEG) is very promising for automotive application and under investigation for several years in the research field of alternative energy converter at the DLR Institute of Vehicle Concepts (DLR-FK). It offers a low complexity without moving parts and provides advantages in terms of installation space, weight and a competitive cost to benefit ratio as an exhaust heat recovery system. In this work the methodical development of a TEG suitable for a modern Euro VI heavy duty vehicle is presented. The boundary conditions are analyzed by using real driving data of road tests and of a representative reference cycle. The necessary systemic approach is given which demonstrates the interactions and effects of a TEG with the vehicle engine, coolant and on-board electric system.