Performance analysis of a multilayer thermoelectric generator for exhaust heat recovery of a heavy-duty diesel engine

Thermoelectric generators can be used for low-grade energy conversion. However, the design of compact and highly efficient thermoelectric generators is difficult. In this study, the performance characteristics of a multi-layer thermoelectric generator are investigated for the exhaust heat recovery of a heavy-duty diesel engine. First, a mathematical model based on the finite volume method is established according to a designed thermoelectric generator. Subsequently, the working performance of the thermoelectric generator is analysed at the rated engine point. Next, the effects of some key parameters for the heat transfer process are evaluated, and the performance of the thermoelectric generator under various engine conditions is studied. Finally, the potential for the power output is estimated based on the world harmonised transient cycle. The results indicate that the output power increases with the engine load, whereas it is insensitive to the variation in the engine speed. The effects of the fin spacing and the fin height of the plain-fin heat exchanger are more significant compared with that of the fin thickness. The working parameters of the thermoelectric generator fluctuate significantly under transient conditions, and the thermoelectric conversion efficiency varies from 1.41% to 4.12%. The development of thermoelectric materials with high efficiency is critical. Furthermore, the results of this study indicate that the improvement in heat transfer between fluids and solid thermoelectric materials is important. The methodology and outcomes of this study can serve as a reference for the design and application of thermoelectric generators.