Using Ducted Fuel Injection to Attenuate Soot Formation in a Mixing-Controlled Compression Ignition Engine
ISSN: 1946-3936, e-ISSN: 1946-3944
Published May 10, 2019 by SAE International in United States
Citation: Nilsen, C., Biles, D., and Mueller, C., "Using Ducted Fuel Injection to Attenuate Soot Formation in a Mixing-Controlled Compression Ignition Engine," SAE Int. J. Engines 12(3):309-322, 2019, https://doi.org/10.4271/03-12-03-0021.
Ducted fuel injection (DFI) has been proposed as a strategy to enhance the fuel/charge gas mixing within the combustion chamber of a direct-injection mixing-controlled compression ignition engine. The concept involves injecting each fuel spray through a small tube within the combustion chamber to facilitate the creation of a leaner mixture in the autoignition zone, relative to a conventional free-spray configuration (i.e., a fuel spray that is not surrounded by a duct). While previous experiments demonstrated that DFI lowers both soot incandescence and soot mass in a constant-volume combustion vessel with a single-component normal-alkane fuel (n-dodecane), this study provides the first evidence that the technology provides similar benefits in an engine application using a commercial diesel fuel containing ~30 wt% aromatics. The present study investigates the effects on engine-out emissions and efficiency with a two-orifice injector tip for charge gas mixtures containing 16 and 21 mol% oxygen. The result is that DFI is confirmed to be effective at curtailing engine-out soot emissions. It also breaks the tradeoff between emissions of soot and nitrogen oxides (NOx) by simultaneously attenuating soot and NOx with increasing dilution.