Electrical Modelling and Mismatch Effects of Thermoelectric Modules on Performance of a Thermoelectric Generator for Energy Recovery in Diesel Exhaust Systems

Thermoelectric generators harvesting energy from exhaust gases usually present a temperature mismatch between modules, due to the gradual cooling of the gases along the flow direction. The way modules that produce unequal voltages are connected has a deep impact on the overall power output. A further step in the prediction of thermoelectric production is to consider the complete layout of the thermoelectric modules and not consider them as isolated systems. In this work, a model to predict the electric behavior of thermoelectric generators for automotive applications at different points of operation is presented. The model allows testing of serial-parallel connection configurations. The results present good agreement with experimental data. This model could be used on similar light duty vehicles with similar engines as the engine used in this work and using similar configuration of thermoelectric generators. Simulated scenarios considering realistic operating conditions in a light duty vehicle allow stating that thermoelectric modules interconnection under heterogenous thermal surface conditions has a significant negative effect (more than 17%) on electric energy production. Moreover, the proposed model shows the need to protect the electric circuit of the thermoelectric generator to avoid the negative effect of possible malfunction of some thermoelectric modules.