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A simple 1-dimensional filter model, with symmetric and asymmetric channels, has been developed to investigate the fundamental behavior and performance of ceramic partial diesel particulate filters (PFs). The governing equations of mass and momentum are similar to those of a full DPF [7, 15]. A standard DPF with the plugs at its inlet face removed has been referred to as a ‘rear-plugged PF’ while, one with the plugs at the outlet face removed has been referred to as a ‘front-plugged PF’ in the present study. Removal of some of the plugs from a standard ceramic DPF reduces the (i) overall pressure drop (ΔP) across the filter, (ii) filtration efficiency (FE) of the DPF, and (iii) manufacturing cost. Partial filters stand a high chance of being deployed in diesel exhaust after-treatment systems for the emerging markets (Brazil, Russia, India, China) that follow Euro 4 emission regulations.

Engine laboratory tests were conducted to assess the impact of B20 biodiesel on the performance of cordierite diesel particulate filters (DPFs). Test fuels included 20% soy based methyl ester blended into ultra low sulfur diesel fuel, and two ULSD on-road market fuels. B20 has a higher cetane number, boiling point and oxygen content than typical on-road diesel fuels. A comparative study was performed using a model year 2007 medium duty diesel truck engine. The aftertreatment system included a diesel oxidation catalyst (DOC) followed by a cordierite wall flow DPF. A laboratory-grade supplemental fuel doser was used in the exhaust stream for precise regeneration of the DPF. Tests revealed that the fuel dosing rate was higher and DOC fuel conversion efficiency was poorer for the B20 fuel during low exhaust temperature regenerations. The slip of B20 fuel past the DOC was shown to produce significantly higher exotherms in the DPF during regeneration.

Experimental and theoretical methods are presented to characterize the transient filtration efficiency (FE) behavior of Diesel Particulate Filters (DPFs) exposed to soot laden exhaust gas streams under laboratory and engine exhaust conditions. A (1+1) dimensional transient model, comprising a one dimensional channel model in combination with a one dimensional wall microstructure model is presented to study the sensitivity of the FE behavior on DPF microstructure and geometry properties, along with the impact of the hydrodynamic and aerosol flow conditions (flow rate, temperature, aerosol characteristics). The dynamic model also considers the dynamic soot oxidation by passive regeneration. The model has been validated through use of an extensive set of experimental data obtained under different operating conditions and with DPFs of different microstructure.

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 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.