By early 2007, all major manufacturers of light-duty diesel vehicles are marketing models equipped with diesel particulate filters (DPFs). However, there is still a lack of understanding of the particles emitted when the DPF undergoes regeneration. This paper focuses on measuring particle emissions of a representative light-duty diesel vehicle equipped with DPF and employing a fuel-borne catalyst (FBC) to aid regeneration.
Particulate Matter (PM) and non-volatile particle number emissions are measured throughout testing according to the Particle Measurement Programme (PMP) proposals. In addition, an Engine Exhaust Particle Sizer (EEPS) connected directly to the CVS is used to give real time size distributions of both volatile and non-volatile particles.
The paper focuses on particle emissions during regenerating New European Driving Cycles (NEDCs). In the first regeneration event a nucleation mode with peak at high diameters (∼35 nm) can be observed due to the purge of stored volatile material that combines with unburnt fuel and lubricant. In subsequent speed changes or regeneration events a smaller peak can appear (∼12 nm) due to the smaller amount of released volatiles. Particle number emissions during regenerating NEDCs are two orders of magnitude higher than those from non-regenerating cycles. However, non-volatile particle emissions stay at the same order as of non-regenerating cycles.
Differences between emissions before and after regeneration events are discussed for both PM and number. Based on NEDC emissions and two regeneration events during the 3000 km tests conducted, vehicle stabilization distances of 300 km are proposed. After this point particle number emissions are relatively constant.