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This paper investigates the design of a thermoelectric generator for exhaust gases from internal combustion engines. Experimentally validated CFD methodology was employed. Different issues are studied, such as the influence of the replacement of the exhaust pipe for the TEG, the recirculation produced, and the influence of fins. The results show that an enlarged inlet cone reduces the recirculation and the pressure drop of the TEG, but more heat is lost across the cone walls, reducing the heat available for the thermoelectric modules. Internal straight fins aligned with the flow achieved a 3% increase in heat transfer, did not significantly increase the pressure drop in this type of device, and reduced the effects on pressure of the recirculation, lowering the overall pressure drop by 10%. An energy production of 175.9 W with 16.2 W of pressure drop power losses resulted in a net energy production of 160.7 W. A comparison with a flat-type thermoelectric generator under the same hot source conditions is also provided. [ABSTRACT FROM AUTHOR]

Around a third of the energy input in an automotive engine is wasted through the exhaust system. Since numerous technologies to harvest energy from exhaust gases are accessible, it is of great interest to find time- and cost-efficient methods to evaluate available thermal energy under different engine conditions. Computational fluid dynamics (CFD) is becoming a very valuable tool for numerical predictions of exhaust flows. In this work, a methodology to build a simple three-dimensional (3D) model of the exhaust system of automotive internal combustion engines (ICE) was developed. Experimental data of exhaust gas in the most used part of the engine map in passenger diesel vehicles were employed as input for calculations. Sensitivity analyses of different numeric schemes have been conducted in order to attain accurate results. The model built allows for obtaining details on temperature and pressure fields along the exhaust system, and for complementing the experimental results for a better understanding of the flow phenomena and heat transfer through the system for further energy recovery devices. [ABSTRACT FROM AUTHOR]