Addressing the Heat Exchange Question for Thermo-Electric Generators 2013-01-0550

The use of thermo-electric (TE) generation systems in internal combustion engines (ICEs) to reduce the carbon dioxide emission by harnessing the exhaust thermal energy is showing increasing promise. In addition, integration with after treatment devices is a development route for this technology that offers a great potential. Recent work on TE systems have shown that the overall efficiency of present TE generation systems are constrained by, the limitations of the conversion efficiency and operating temperatures of TE materials; fabrication quality, durability and thermal performance of the thermo-electric modules (TEMs); geometrical configuration and heat exchange efficiency of thermo-electric generator (TEG) and; conversion techniques of the TEG's electrical output to a form suitable for vehicle systems.

Therefore, this study is mainly focused on some previously unexplored aspects associated with the heat exchange process of TEGs that can be accommodated for planar TEMs in automotive applications. The analysis is supported by a theoretical modeling program as well as an experimental program to obtain the solutions for: selecting the optimum geometrical configuration for TEGs; analyzing the heat transfer process of TEGs; studying the fabrication feasibility of different TEGs; analyzing the quality of fabrication effect on the performance of the TEG and bonding of the TEMs to heat exchange surfaces to minimize the thermal resistances of the TEG.

The initial analysis shows that the overall performance of a TEG increases when the coolant of the TEG heat exchanger is directly exposed to TEMs due to the significant reduction of thermal resistance, while creating the same back pressure in the hot gas stream. The paper will present our experience of realistic solutions and, includes recommended approaches to a range of practical requirements.