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This research numerically investigated the combustion process and exhaust emissions from a light-duty Gasoline Compression Ignition (GCI) engine operating at low load as well as medium load conditions using a commercial computational fluid dynamic (CFD) software Converge. The fuel injection strategies and thermal boundary conditions effects were examined to produce locally stratified and globally lean partially premixed compression ignition (PPCI) combustion. The effects of fuel injection pressure, number of injections, and the quantity of fuel injected in each pulse were examined and optimized for emissions and fuel consumption (FC) under the design constraints of 180 bar peak cylinder pressure (PCP) and 10 bar/° CA maximum pressure rise rate (MPRR).

In common rail diesel fuel injector system, currently there are two kinds of servo-hydraulic type piezo-driven injector; 3-way and bypass-circuit type, in order to amplify the extension of the piezo stack. The pilot valve driven by piezo stack can control the flow of fuel at a pressure chamber, which is accurately regulated by 3-way or bypass-circuit mechanism. Even though fuel injection events are triggered electrically, the main actuation forces to move injector needle inside nozzle are hydraulic force which is the key object aimed to eliminate in this study. In this study, two experiments were carried out using a constant volume chamber and a single cylinder CR direct-injection diesel engine. The driving force for air-fuel mixing process in diesel diffusion combustion is the energy contained within the spray.