CFD optimization of a heat exchanger for energy recovery in a stationary single-cylinder diesel engine

Abstract

The implementation of thermoelectric generators (TEG) has been a promising response to the energy problem in internal combustion engines, which has motivated the study of the potential for energy recovery in the exhaust gas stream of a single-cylinder diesel engine using a thermoelectric generator, analyzing the importance of the heat exchanger geometry in the performance of the TEG. Considering many investigations, 3 different heat exchanger geometries were developed; the behavior of the exhaust gases was simulated with the OpenFOAM ® software, using a realizable  model, where a good quality mesh was established. In addition, a mesh independence study was performed, where stability was achieved from 1’000,000 elements. Experimental validation was carried out, and an average relative error of 2.23% was obtained, with which the results were classified as reliable. The simulations allowed the analysis of variables such as heat transfer, voltage, and current generated by thermoelectric modules, pressure drop, turbulence kinetic energy (TKE), and turbulence eddy dissipation rate (TEDR). Finally, it was obtained that the geometry with parallel paths had a better performance with respect to the analyzed variables, allowing a generation of 63.56 W, a pressure drop 92% lower than the other proposals, and better performance in the TKE and TEDR.