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Authors
R.M. Wagner ,
J.B. Green Jr.,
T.Q. Dam,
K.D. Edwards,
J.M. Storey
Publication
SAE Paper No. 2003-01-0262
Abstract
This paper describes the simultaneous reduction of nitrogen oxides
(NOx) and particulate matter (PM) in a modern light-duty
diesel engine under high exhaust gas recirculation (EGR) levels.
Simultaneous reduction of NOx and PM emissions was observed
under lean conditions at several low to moderate load conditions using
two different approaches. The first approach utilizes a throttle to
increase EGR rate beyond the maximum rate possible with sole use of the
EGR valve for a particular engine condition. The second approach does
not use a throttle, but rather uses a combination of EGR and
manipulation of injection parameters. A significant reduction in
particulate matter size and concentration was observed corresponding to
the reduction in particulate mass. This PM reduction was accompanied
by a significant shift in the heat release profile. In addition, there
were significant cylinder-to-cylinder variations in particulate matter
characteristics, gaseous emissions, and heat release. A fuel penalty
is associated with operating in the low NOx and low PM
regime when there are no modifications to the injection strategy.
Preliminary experiments indicate that the penalty can be eliminated or
reduced to a few percent while still maintaining a significant
reduction in NOx and PM. An improved understanding of this
combustion regime will lead to improved EGR utilization for lowering
the performance requirements of post-combustion emissions controls.
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