The goal of this research is to investigate the physical parameters of stoichiometric operation of a diesel engine under a light load operating condition (6∼7 bar IMEP). This paper focuses on improving the fuel efficiency of stoichiometric operation, for which a fuel consumption penalty relative to standard diesel combustion was found to be 7% from a previous study. The objective is to keep NOx and soot emissions at reasonable levels such that a 3-way catalyst and DPF can be used in an aftertreatment combination to meet 2010 emissions regulation.The effects of intake conditions and the use of group-hole injector nozzles (GHN) on fuel consumption of stoichiometric diesel operation were investigated. Throttled intake conditions exhibited about a 30% fuel penalty compared to the best fuel economy case of high boost/EGR intake conditions. The higher CO emissions of throttled intake cases lead to the poor fuel economy. In comparison with the use of single-hole nozzles (SHN) GHN lowered the fuel consumption by 3% under throttled intake conditions, whereas it exhibited no significant improvement in ISFC in the high boost/EGR cases. In addition, while investigating the best fuel economy location from SOI sweeps, a sweet spot [1] was observed in exhaust CO and O2 measurements.
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