Particulate filter performance mapping for in-service conformity

The proposed Euro-7 regulations are expected to build on the significant emissions reductions that have already been achieved using advanced Euro VI compliant after treatment systems (ATS). The introduction of in-service conformity (ISC) requirements during Euro VI paved the way for enabling compliance during real-world driving conditions. The diverse range of applications and resulting operating conditions greatly impact ATS design and the ability of the diesel particulate filter (DPF) to maintain performance under the most challenging boundary conditions including cold starts, partial/complete regenerations, and high passive soot burn operation. The current study attempts to map the particle number (PN) filtration performance of different DPF technologies under a variety of in-use cycles developed based on field-data from heavy duty Class-8 / N3 vehicles. Access to such performance maps can allow original equipment manufacturers (OEMs) to select DPF technologies to suit different applications with a better understanding of underlying limitations. The potential inclusion of secondary emissions from diesel exhaust fluid (DEF) injection adds further uncertainty to ATS design including the likelihood of a secondary filter. Different secondary filter technologies were evaluated for DEF PN filtration performance and suitable candidates were identified for SCR systems with reasonable levels of DEF emissions and / or relaxed regulatory limits (>2E11 #/kWh). These results highlight the various product options available to OEMs to meet upcoming Euro-7 HD regulations with suitable safety margins.