Evaluation of Current and Next-Gen Diesel Particulate Filter Performance for US EPA MY27+ LD/MD Particulate Mass Emissions Regulation

Diesel particulate filters (DPF) have been part of vehicle after-treatment solutions in the US since being adopted in 2007 as the “go-to” solution for meeting particulate mass (PM) standards as set by the EPA for HD diesel engines. Within the highly popular LD/MD truck segment, defined as trucks weighing between 8501lb-14000lb, these limits have seen additional reduction in PM levels to 8 or 10 mg/mile as these vehicles have transitioned mostly over to chassis-based certification since 2014-2017. However, these reductions in PM requirements have been relatively minor allowing for the DPF technology used on these platforms to remain mostly unchanged over the same time period. With the finalization of MY27+ LD/MD vehicle emissions standards; PM limits are now set to make significant reductions down to 0.5 mg/mile, with phase-in to be completed by MY31. While the new limits present significant challenges for gasoline vehicles and most likely will require the use of gasoline particulate filter (GPF), this additional reduction of up to 95% for diesel vehicles may also require technology advancements of the DPF in order to meet compliance targets. The goal of this study was to evaluate the capability of current DPF technology along with other state-of-the-art DPF technologies to meet the new Tier 4 limits. Test conditions were run under both normal operation and active-regeneration certification-cycle conditions to be able to properly calculate a final PM result with IRAF (infrequent regeneration adjustment factor), as both test conditions have a tremendous impact on the final reported result. A combination of engine-based and vehicle-based (modern T3B170 HDV diesel truck) test measurements were used to complete the initial assessment for this evaluation. This report will show that advanced DPFs can deliver high PM filtration efficiency along with other system level improvements, positioning them well as one solution to meet the upcoming US EPA 0.5 mg/mile PM limit.