Ducted Fuel Injection vs. Conventional Diesel Combustion: Extending the Load Range in an Optical Engine with a Four-Orifice Fuel Injector
Journal Article
03-14-01-0004
ISSN: 1946-3936, e-ISSN: 1946-3944
Sector:
Topic:
Citation:
Nilsen, C., Biles, D., Yraguen, B., and Mueller, C., "Ducted Fuel Injection vs. Conventional Diesel Combustion: Extending the Load Range in an Optical Engine with a Four-Orifice Fuel Injector," SAE Int. J. Engines 14(1):47-58, 2021, https://doi.org/10.4271/03-14-01-0004.
Language:
English
Abstract:
Ducted fuel injection (DFI) is a technique to attenuate soot formation in
compression ignition engines relative to conventional diesel combustion (CDC).
The concept is to inject fuel through a small tube inside the combustion chamber
to reduce equivalence ratios in the autoignition zone relative to CDC. DFI has
been studied at loads as high as 8.5 bar gross indicated mean effective pressure
(IMEPg) and as low as 2.5 bar IMEPg using a
four-orifice fuel injector. Across previous studies, DFI has been shown to
attenuate soot emissions, increase NOx emissions (at constant charge
dilution), and slightly decrease fuel conversion efficiencies for most tested
points. This study expands on the previous work by testing 1.1 bar
IMEPg (low-load/idle) conditions and 10 bar IMEPg
(higher-load) conditions with the same four-orifice fuel injector, as well as
examining potential causes of the degradations in NOx emissions and
fuel conversion efficiencies. DFI and CDC are directly compared at each
operating point in the study. At the low-load condition, the intake charge
dilution was swept to elucidate the soot and NOx performance of DFI.
The low-load range is important because it is the target of impending,
more-stringent emissions regulations, and DFI is shown to be a potentially
effective approach for helping to meet these regulations. The results also
indicate that DFI likely has slightly decreased fuel conversion efficiencies
relative to CDC. The increase in NOx emissions with DFI is likely due
to longer charge gas residence times at higher temperatures, which arise from
shorter combustion durations and advanced combustion phasing relative to
CDC.