Exhaust system heat exchanger design for thermal energy recovery in passenger vehicle applications

The overall efficiency of internal combustion (IC) engines can be significantly improved by recovering the waste heat in exhaust gas. Use of thermoelectric (TE) waste heat recovery systems, has proved to be an attractive proposition when compared with other methods proposed in the literature. Recent investigations in TE waste heat recovery systems have highlighted the need for advanced heat exchanger (HE) designs to enhance the heat transfer rates across the thermo-electric generator (TEG). The objectives of this paper are (1) to present the results of an investigation into boundary layer development and heat transfer characteristics in such heat exchangers and (2) the analysis of the effect of back pressure development on both the heat exchanger behaviour and the overall engine performance.