Effects of Injection Pressure on Diesel Engine Particle Physico-Chemical Properties

The effects of injection pressure on diesel particle physical and chemical properties were investigated on a heavy-duty diesel engine. Three injection pressures (600 bar, 800 bar, and 1000 bar) were selected at two engine loads (0.3 MPa BMEP and 0.9 MPa BMEP). The exhaust particle size distribution was measured by a scanning mobility particle sizer (SMPS). Consistent with previous studies, increasing injection pressure effectively removes accumulation mode particles, which results in a significant decrease in particle total mass concentration. The elemental carbon emission factors were then tested through organic carbon/element carbon (OC/EC) analysis. The emitted EC is decreased by 64% and 50% with increasing injection pressure from 600 bar to 1000 bar at the low and high engine loads, respectively. Particle morphology and oxidation reactivity were investigated by means of transmission electron microscope (TEM) imaging and thermogravimetric analysis (TGA) technology, respectively. Smaller primary particles with shorter and flatter graphene layer segments are observed at higher injection pressure conditions, and the particle oxidation reactivity is increased with injection pressure.