On-road chasing and laboratory measurements of exhaust particle emissions of diesel vehicles equipped with aftertreatment technologies (DPF, urea-SCR)

A mobile emission laboratory was applied to measure particle number size distributions of exhaust emissions for base diesel, plasma-assisted burner type-DPF, and urea-SCR equipped vehicles during on-road driving and laboratory measurements using chassis dynamometer. The measurement of total particle number concentrations revealed that the base diesel had the highest concentrations, while the DPF system effectively reduced particle numbers during all operation conditions. The particle reduction rate during idling and constant speed conditions was 60-99.9% for the DPF and 10-25% for the urea-SCR. The size distributions of particles showed that the dilution ratio significantly affected the nanoparticle formation and growth, and that laboratory measurement, in general, tended to underestimate the nucleation mode (NM) (< 50 nm) particles compared to on-road results. The NM fraction during on-road measurements was the highest at low vehicle speed (20 km/h) with values of 94% for the base diesel, 96% for the DPF, and 94% for the urea-SCR equipped vehicles, and it was the lowest at increased vehicle speed (80 km/h) with values of 59% for the base diesel, 61% for the DPF, and 65% for the urea-SCR.