Experimental Study of DOC-on-Filter Using Next Generation Filter Solutions for Non-Road Applications

<div class="section abstract"><div class="htmlview paragraph">Upcoming California Tier 5 non-road limits mandate 90% and 75% reductions in NOx and PM respectively, from current Tier 4F emission standards. Similarly, lower NOx and PN/PM limits can be expected from a next round of European Non-Road regulations. To meet these limits, more SCR volume for greater NOx reduction, and better filtration efficiency filters for greater PN/PM reduction, may be required. The challenge is to accommodate larger SCR volume while maintaining oxidation (DOC) and filtration (DPF) functionality of the aftertreatment system within a limited packaging space on non-road machineries. Consolidating DOC and DPF into a single component as DOC-on-filter instead of separate DOC and DPF substrates to achieve space saving has been previously discussed in literature.</div><div class="htmlview paragraph">This study expands on the current understanding and explores various functional performance characteristics of the DOC-on-filter concept in comparison with DOC + bare DPF, DOC + PGM coated DPF. The three test configurations were evaluated for pressure drop, filtration efficiencies, active and passive regeneration performances. Relative advantages and challenges of each configuration were discussed. Along with a current Tier 4F filter, a next generation filter was introduced for performance understanding in non-road applications.</div><div class="htmlview paragraph">Pressure drop of DOC-on-filter was comparable to other test configurations within a given filter product. Significant improvements in filtration were achieved by the next generation filter compared to the current Tier 4F filter for bare, PGM coated, and DOC-on-filter coated filters. DOC-on-filter performance was found to be equivalent to other configurations in passive regeneration test conditions, however, it performed poorly in active regeneration test conditions. Better active regeneration efficiency of DOC-on-filter may be achieved by longer regeneration durations but that may lead to significant penalty in fuel economy. DOC-on-filter technology was found to be a viable technology pathway with certain limitations for applications which primarily depends on active regeneration of filters.</div></div>