Investigation of Diesel Particulate Filter Design Parameters to Improve Filtration Performance under Various Test Cycles

Zhuqi  Wang, NGK Automotive Ceramics USA, INC.

CARB PM limit will be reduced 50% from 10mg/bhp-hr to 5mg/bhp-hr in 2024. PN limit in EU may be reduced to 1×1011 while measuring particle size down to 10nm in 2025. Those regulations will be challenging for conventional DPF technologies.  Next generation DPF needs to be able to capture particles more effectively while keeping pressure drop low. This presentation shows how we design a DPF to solve above-mentioned challenges. MD on-highway EPA 2013 certified diesel engine was utilized to conduct on-road cycles (FTP, WHTC/WHSC) and off-road cycles (NRTC/NRSC) for this DPF evaluation. EU OEMs may have engine out NOx to be higher and that will lead to lower engine out PN emissions, which will make it challenging for a filter to capture more particles during its initial status. Test condition was adjusted to high engine out NOx and low engine out PM/PN. The results show that all candidate DPFs can have PM emissions below the limit and more challenges are on PN performance.  Data were further analyzed to understand which DPF parameters (MPS, wall thickness, etc.) are affecting its performance on PN filtration. We also look at cycle difference to see how cycle’s characteristic is impacting DPF PN filtration performance. At the end, a design guideline is discussed to improve PN filtration efficiency and meet future regulation.

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