Thermoelectric power for automobiles arrives in Europe

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by Prof. Rowe of the University of Wales

Exhaust waste heat recovery system attached to the underside of a Volkswagen. The Thermoelectric generating system is reproduced in artwork on the side of the vehicle. 

The first demonstration in Europe of a family sized Volkswagen car fitted with a thermoelectric generator was unveiled at the Thermoelektrik-Eine Chance Fur Die Atomobillindustrie  meeting held in Berlin, October 2008. Under motorway driving conditions a 600W(e) output is claimed. The additional electrical power serves to meet  around 30% of   the car's electrical requirement. This reduces the engine's mechanical load such as that due to the alternator and results in a reduction in fuel consumption of  more than 5%.

Also on show was an exhaust powered thermoelectric generator  developed  by BMW in co-operation with DLR( German Aerospace) which conference delegates could drive on a test run. It achieves 200 W maximum and has been  used successfully for more than 12,000 km road use.  In the BMW  the TG system consists of 24 BiTe modules between the hot exhaust side and the cold side which  is provided by an extra coolant loop. The cool loop operates at 60C and heat is dissipated by two extra radiators in the wheel housings.  The TEGs are prevented from overheating and  the engine  back pressure limited by locating the generator in an exhaust  bypass.



In automobiles thermal energy

In automobiles thermal energy is used at various energy scales. With regard to reduction of CO2 emissions, efficient generation of hot and cold temperatures and wise use of waste heat are of paramount importance for car manufacturers worldwide. Thermoelectrics could be a vital component in automobiles of the future. To evaluate the applicability of thermoelectric modules in automobiles, a Modelica model of a thermoelectric liquid–gas heat exchanger was developed for transient simulations. The model uses component models from the object-oriented Modelica library TIL (so called stone outdoor fireplaces). It was validated based on experimental data of a prototype heat exchanger and used to simulate transient and steady-state behavior. The use of the model within the energy management of an automobile is successfully shown for the air-conditioning system of a car.