Potential for exhaust gas energy recovery in a diesel passenger car under European driving cycle

This work addresses the potential for waste energy recovery from exhaust gases in a diesel passenger car mounted in a chassis dynamometer. The New European Driving Cycle was followed, while recording relevant operating variables. Tests were performed under three temperature conditions, and exergy analysis was included to find the potential of exhaust gases to produce useful work at six points in the exhaust system. Results include mean temperature at each point, as well as the energy quality index, which was lower than 33%, meaning that less than one-third of the energy of exhaust gases can be converted into useful work in a recovery system. In general, the highest exergy losses were found in the muffler. Although the greatest recovery potential corresponds to the highest temperature of gases, environmental regulations for vehicles restrict waste energy recovery to be performed downstream after-treatment devices, which, in the present work, was the outlet of the diesel particle filter. Temperature of gases at this location varied in the range 115-320 °C, and potential fuel saving varied between 8% and 19% for the complete driving cycle.