Modeling and Design Optimization of a Thermoelectric Generator for Reducing Fuel Consumption in a Heavy-Duty Vehicle

Abstract

Heavy-duty vehicles are responsible for a large proportion of road traffic emissions in the European Union due to their high annual mileage and increasing freight traffic. For this reason, carbon dioxide limits will be introduced in this vehicle segment for the first time. Technological innovations are essential to meet these emission limits. Increasing the efficiency of modern heavy-duty vehicles is an important approach. Today, about 60% of the chemical energy of fuel is lost through waste heat. The use of a waste heat recovery system offers the potential to increase efficiency in order to reduce fuel consumption and thus emissions. The state of the art, however, was not convincing in terms of system efficiency and costs. Thermoelectric generators provide an attractive solution for a waste heat recovery system with low system complexity. Based on the Seebeck effect, they convert the existing thermal energy of the exhaust gas directly into electrical current. Integrated into the exhaust system of the current vehicle architecture, thermoelectric generators can convert part of the previously unused energy for supplying the vehicle electrical system or charging the battery and relieve the generator. The system advantages are low costs, low system weight and low installation volume. This paper presents a thermoelectric generator system for modern Euro VI heavy-duty vehicles. For this purpose, a novel approach is presented, which allows a holistic system modelling. Innovative segmented thermoelectric modules and heat exchanger structures will be used to demonstrate how efficiency can be increased. By optimizing the thermoelectric generator system, a significant fuel consumption of 1-2% under dynamic driving conditions is to be achieved. The challenge of optimizing a waste heat recovery system with regard to the total cost of ownership and amortization in 2 years of use is to be demonstrated.