Abstract
A pilot injection has been used widely in diesel engines for the control of nitrogen oxide emissions and noise. However, very little information on the characteristics of particulate matter emissions with a pilot injection is available. In this paper, the non-volatile particle emissions of a light-duty common-rail production diesel engine under the impact of a pilot injection are studied in terms of the particle number concentration and the particle size distribution with the measurements taken with a scanning mobility particle sizer. For various key parameters such as the fuel quantity and the injection timing, the results illustrate how a pilot injection alongside a main injection could affect particulate matter emissions, which are also shown to be closely related to the engine mode and the exhaust gas recirculation level. It is revealed that advancing the pilot injection generally reduces the number and size of particles in both the accumulation mode and the nucleation mode. It is also found that an increase in the pilot fuel quantity increases the total number and size of particles, with a significant impact on the number of accumulation-mode particles, which overwhelms the decrease in the number of nucleation-mode particles.
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