Impact of intake CO 2 addition and exhaust gas recirculation on NO x emissions and soot reactivity in a common rail diesel engine

Khalid Al-Qurashi, Yu Zhang, André Louis Boehman

Research output: Contribution to journalArticlepeer-review

13 Scopus citations

Abstract

The impact of intake CO 2 addition and exhaust gas recirculation (EGR) on engine combustion characteristics, NO x emissions, and soot oxidative reactivity was studied in a common rail diesel engine equipped with a cooled EGR system. The engine test results and the heat release analysis show that the reduced flame temperature, induced by the reduction of the oxygen concentration (dilution effect) is the dominant mechanism via which CO 2 and EGR lower NO x emissions in diesel engines. On the other hand, the collected soot from the engine tests was examined for its oxidative reactivity using a thermogravimetric analyzer (TGA). Results show that EGR has a significant effect on soot reactivity and results in higher initial active sites compared to the CO 2 case. We conclude that the reduced flame temperature (thermal effect) which is a consequence of the dilution effect is responsible for the observed increase in soot reactivity. These results confirm observations from our past work on flame soot, which showed that the peak adiabatic flame temperature is the governing factor affecting soot reactivity. These findings imply that driving the combustion concepts toward low temperature is favorable to effectively control engine pollutants, including soot reactivity. © 2012 American Chemical Society.
Original languageEnglish (US)
Pages (from-to)6098-6105
Number of pages8
JournalEnergy & Fuels
Volume26
Issue number10
DOIs
StatePublished - Sep 20 2012

ASJC Scopus subject areas

  • Energy Engineering and Power Technology
  • Chemical Engineering(all)
  • Fuel Technology

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