Authors
C. S. Sluder,
R. M. Wagner,
S. A. Lewis, Sr., and
J. M. E. Storey
Publication
Proceedings of the AFRC/JFRC International Combustion Symposium 2004.
Abstract
The integration of electronic controls into diesel engine systems has
resulted in substantial gains in efficiency and emissions control
during the last decade. This has also introduced the possibility of
exerting an increasing level of control over the combustion process
itself. In the past, lowering engine-out oxides-of-nitrogen
(NOx) and particulate matter (PM) emissions simultaneously
was not generally believed to be possible. Recently, however, several
organizations have begun to explore new combustion processes that do in
fact exhibit lower engine-out NOx and PM emissions. This
paper reports a study conducted using a modified Mercedes 1.7 liter
diesel engine. Increased exhaust gas recirculation (EGR) was used to
transition the engine into a clean-combustion mode. Fuel injection
parameters were then varied to recover the thermal efficiency that was
lost by operating at high EGR. NOx emissions were shown to
decrease by an order of magnitude with a simultaneous decrease of about
25% in PM emissions. The thermal efficiency was shown to be comparable
to baseline, despite a volumetric efficiency shortfall associated with
high EGR increasing the temperature of the fresh intake charge.
Analysis of the hydrocarbon emissions showed that the emissions were
trending towards shorter-chain hydrocarbons as the EGR was increased.
Aldehydes are an indicator of partial combustion and were found to
return to baseline levels once the thermal efficiency was
recovered. |
