Challenges and Solutions to Meeting Eu VII Particle Number Requirements during Aggressive Field Operation

The heavy duty (HD) Eu VII regulations, going into effect starting 2027, has aggressive particle number (PN) emissions limits under extended operating conditions compared to existing Eu VI framework. In addition to the proposed hot-start PN limit of 2.0E+11 #/kWh, which is a >65% reduction vs. Eu VI E, the particle size cut-off is being extended from 23nm+ to 10nm+ while also including nearly all field operating conditions such as regeneration events, wider ambient boundaries etc. The tighter limits coupled with a work-based window approach to evaluate emissions is driving the need for the next generation of ultra-high filtration efficiency (FE), diesel particulate filter (DPF) technologies. The current study evaluates the FE performance of different DPF solutions under development, over a range of challenging on-road conditions characterized by frequent high temperature events which are not actively triggered. The combination of higher temperatures and NO_x to Soot ratios (NSR) is expected to lead to partially regenerated DPF operation increasing the likelihood of high PN slip. The cycles were developed and tuned based on data from field operation of HD linehaul trucks. We demonstrate that some of the development DPF samples could maintain >99.9% filtration efficiency even during aggressive passive operation with high NSR. The results suggest that adoption of these DPF technologies can help HD vehicle manufacturers meet the extremely stringent Eu VII PN requirements under the most challenging field operating conditions.