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

Type
Article

Authors
Al-Qurashi, Khalid
Zhang, Yu
Boehman, André Louis

KAUST Department
Clean Combustion Research Center

Online Publication Date
2012-09-20

Print Publication Date
2012-10-18

Date
2012-09-20

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.

Citation
Al-Qurashi, K., Zhang, Y., & Boehman, A. L. (2012). Impact of Intake CO2Addition and Exhaust Gas Recirculation on NOxEmissions and Soot Reactivity in a Common Rail Diesel Engine. Energy & Fuels, 26(10), 6098–6105. doi:10.1021/ef201120f

Publisher
American Chemical Society (ACS)

Journal
Energy & Fuels

DOI
10.1021/ef201120f

Permanent link to this record