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Effect of engine-out soot emissions and the frequency of regeneration on gasoline particulate filter efficiency.
ISSN: 0148-7191, e-ISSN: 2688-3627
To be published on April 14, 2020 by SAE International in United States
Gasoline particulate filters (GPFs) are an important aftertreatment system that enables gasoline direct injection (GDI) engines to meet current emission standards based on non-volatile particles > 23 nm in diameter. However, the filtration efficiency of GPFs may need to improve as emission regulations tighten, and possibly include non-volatile particles down to 10 nm. The filtration efficiency of GPFs is highly dependent on the amount of soot that accumulates on the GPF during engine operation. GPFs are often ‘passively’ regenerated during vehicle operation when the exhaust is sufficiently hot and it contains sufficient oxygen. This paper explores the effect that engine-out soot emissions and the frequency of GPF regeneration have on GPF filtration efficiency. Two GPF technologies were tested on two engine dynamometers as well as two production vehicles on a chassis dynamometer. The engines span a wide range of engine-out particle emissions (a range of almost one order of magnitude). The filtration efficiency of the GPFs were measured with a regulation-compliant particle number system (non-volatile particles > 23 nm), as well as with a particle counter with a lower cutoff of 2.5 nm, and with a differential mobility spectrometer. The results show that the GPFs regenerate regularly over the drive cycles and that drive cycle-averaged filtration efficiency of the GPFs are highly dependent on the engine-out particle emissions. The filtration efficiency of the GPF may increase significantly when the engine-out particle emissions increase by approximately one order of magnitude. These results show the importance of selecting an appropriate GPF technology based on engine-out particle emission rate.