Simulink Model of a Thermoelectric Generator for Vehicle Waste Heat Recovery

Abstract

More than 50% of the energy released through combustion in the internal combustion engine (ICE) is rejected to the environment. Recovering only a part of this energy can significantly improve the overall use of resources and the economic efficiency of road transport. One solution to recoup a part of this otherwise wasted thermal energy is to use thermoelectric generator (TEG) modules for the conversion of heat directly into electricity. To aid in development of this technology, this effort covers the derivation of a respectively simple steady-state Simulink model that can be utilized to estimate and optimize TEG system performance for ICEs. The model was validated against experimental data found in literature utilizing water cooling for the cold side. Overall, relatively good agreement was found with the maximum error in generated power around 10%. Following, it was investigated whether air can be used as a cooling medium. It was established that, at the same temperature as the water (18.4 °C), a flow velocity of 13.1 m/s (or 47.2 km/h) is required to achieve a similar cold junction temperature and power output. Subsequently using the model with air cooling, the performance of a TEG installed on a heavy-duty vehicle traveling at 50, 80, 90, and 120 km/h under different ambient temperatures was analyzed. It was determined that both a lower temperature and a higher flow velocity can improve power output. A further increase of the power output requires a larger temperature gradient across the module, which can be achieved by a higher heat input on the hot side.