Real-Time On-Board Indirect Light-Off Temperature Estimation as a Detection Technique of Diesel Oxidation Catalyst Effectiveness Level

Format:

Conference/Event

Author/Creator:

Sutjiono, Sutjiono, author.

Contributor:

Meckl, Peter

Tayal, Prateek

Zhou, Keqin

Conference Name:

SAE 2013 World Congress & Exhibition (2013-04-16 : Detroit, Michigan, United States)

Language:

English

Physical Description:

1 online resource

Place of Publication:

Warrendale, PA SAE International 2013

Summary:

The latest US emission regulations require dramatic reductionsin Nitrogen Oxide (NOx) emissions from vehicular diesel engines.Selective Catalytic Reduction (SCR) is the current technology thatachieves NOx reductions of up to 90%. It is typically mounteddownstream of the existing after-treatment system, id est, after theDiesel Oxidation Catalyst (DOC) and Diesel Particulate Filter(DPF). Accurate prediction of input NO₂:NO ratio is useful forcontrol of SCR urea injection to reduce NOx output and NH₃ slippagedownstream of the SCR catalyst. Most oxidation of NO to NO₂ occursin the DOC since its main function is to oxidize emissionconstituents. The DOC thus determines the NO₂:NO ratio as feedgasto the SCR catalyst. The prediction of NO₂:NO ratio varies as thecatalyst in the DOC ages or deteriorates due to poisoning. Thus,the DOC prediction model has to take into account the correlationof DOC conversion effectiveness and the aging of the catalyst.This research project is aimed at detecting the aging level inthe DOC in real time under actual operating conditions byestimating the light-off temperature for hydrocarbon conversion.The thermal energy balance used to compute indirect light-offtemperature includes a substrate heat rate storage term. Thisenergy balance equation is then applied to an instrumented DOC forlight-off temperature detection. Evaluation of the equation termsshows that heat loss analysis to surroundings is negligible whileuncertainty in the post-fueling quantity to the exhaust stream wasfound to have a significant impact on the estimated light-offtemperature. Ultimately, the light-off temperature can bedetermined with only 1 thermocouple inside the DOC rather than theoriginal 12 thermocouples. A comparison analysis for fresh and agedDOC's shows that clear light-off temperature shifts weredetected after the catalyst was thermally aged and the indirectestimation could roughly predict the aged DOC conversion. This isshown in detail in later sections of this paper. However, thetechnology is still preliminary and further work on datarepeatability and consistency needs to be done before thetechnology can be adopted for real-world application

Notes:

Vendor supplied data

Publisher Number:

2013-01-1517

Access Restriction:

Restricted for use by site license