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Approximately a third part of the energy intake of a light-duty diesel engine is wasted through the exhaust system. Rising awareness of environmental issues together with fuel economy has encouraged research upon energy recovery in internal combustion engines. This article focuses on the application of thermoelectric generators in light-duty diesel vehicles. Most studies available in the literature tend to focus on maximizing the recovered electrical power, not always considering the increase in engine pumping work or testing conditions similar to those of a vehicle. The goal of this article is to evaluate the consequences of the modification of the cross-sectional area in the exhaust pipe that adding a thermoelectric generator implies and to compare them with the electrical power produced by the thermoelectric generator. The effect on the indicated and pumping parameters of the engine under common urban driving conditions is presented. From the results, it can be drawn that within the limits of engine speed and torque tested, the modification of the cross-sectional area does not have a significant negative effect on the engine pumping efficiency. This means that there is potential for the employment of this technique in energy recovery from light-duty vehicles. [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]