TY - JOUR
T1 - Effects of exhaust gas recirculation and load on soot in a heavy-duty optical diesel engine with close-coupled post injections for high-efficiency combustion phasing
AU - O'Connor, Jacqueline
AU - Musculus, Mark
N1 - Funding Information:
Support for this research was provided by the US Department of Energy, Office of Vehicle Technologies. Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United State Department of Energy’s National Nuclear Security Administration under contract DE-AC04-94AL85000.
PY - 2014/6
Y1 - 2014/6
N2 - In-cylinder strategies to reduce soot emissions have demonstrated the potential to lessen the burden on, and likely the size and cost of, exhaust aftertreatment systems for diesel engines. One in-cylinder strategy for soot abatement is the use of close-coupled post injections. These short injections closely following the end of the main injection can alter soot-formation and/or oxidation characteristics enough to significantly reduce engine-out soot. Despite the large body of literature on post injections for soot reduction, a clear consensus has not yet been achieved regarding either the detailed mechanisms that affect the soot reduction, or even the sensitivity of the post-injection efficacy to several important engine operating parameters. We report that post injections reduce soot at a range of close-coupled post-injection durations, intake-oxygen levels, and loads in an optical, heavy-duty diesel research engine. Maximum soot reductions by post injections at the loads and conditions tested range from 40% at 21% intake oxygen (by volume) to 62% at 12.6% intake oxygen. From a more fundamental fluid-mechanical perspective, adding a post injection to a constant maininjection for conditions with low dilution (21% and 18% intake oxygen) decreases soot relative to the original main injection, even though the load is increased by the post injection. High-speed visualization of natural combustion luminosity and laser-induced incandescence of soot suggest that as the post-injection duration increases and the post injection becomes more effective at reducing soot, it interacts more strongly with soot remaining from the main injection.
AB - In-cylinder strategies to reduce soot emissions have demonstrated the potential to lessen the burden on, and likely the size and cost of, exhaust aftertreatment systems for diesel engines. One in-cylinder strategy for soot abatement is the use of close-coupled post injections. These short injections closely following the end of the main injection can alter soot-formation and/or oxidation characteristics enough to significantly reduce engine-out soot. Despite the large body of literature on post injections for soot reduction, a clear consensus has not yet been achieved regarding either the detailed mechanisms that affect the soot reduction, or even the sensitivity of the post-injection efficacy to several important engine operating parameters. We report that post injections reduce soot at a range of close-coupled post-injection durations, intake-oxygen levels, and loads in an optical, heavy-duty diesel research engine. Maximum soot reductions by post injections at the loads and conditions tested range from 40% at 21% intake oxygen (by volume) to 62% at 12.6% intake oxygen. From a more fundamental fluid-mechanical perspective, adding a post injection to a constant maininjection for conditions with low dilution (21% and 18% intake oxygen) decreases soot relative to the original main injection, even though the load is increased by the post injection. High-speed visualization of natural combustion luminosity and laser-induced incandescence of soot suggest that as the post-injection duration increases and the post injection becomes more effective at reducing soot, it interacts more strongly with soot remaining from the main injection.
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U2 - 10.1177/1468087413488767
DO - 10.1177/1468087413488767
M3 - Article
AN - SCOPUS:84903626452
SN - 1468-0874
VL - 15
SP - 421
EP - 443
JO - International Journal of Engine Research
JF - International Journal of Engine Research
IS - 4
ER -