In-Cylinder Combustion and Output Performance and Emissions Influenced by Split Fuel Injection Input Parameters of Compression-Ignition Engines

Abstract

Split fuel injection is considered for liquid-fuel compression-ignition engines to improve the engine combustion, output performance and emissions. The influences of split injection primary input parameters on in-cylinder combustion and outputs of diesel engines in a single-split-injection case are studied and qualitatively investigated and predicted. Understanding the influences is importantly needed and can be beneficial in analysis and design of an engine of this type, especially before any engine experiments become available. The major split injection input parameters studied include the start timing of the pilot injection, the dwell duration between the pilot and second injection, and the mass fraction of the pilot injection in the total fuel injected per whole injection. The combustion and output parameters investigated include cylinder gas peak pressure and temperature, intake manifold air pressure, exhaust gas temperature, engine fuel efficiency, emission of NOx, emission of CO, and exhaust smoke. The overall effects, concerning interactions between the input parameters, are also studied and predicted. Understanding the influences with the consequent results can further be beneficial in a design optimization of split fuel injection in engine applications, as the split injection input parameters can be used as design variables, and the combustion and output parameters can be treated as requirements and/or constraints in the design optimization.