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Gasoline Particulate Filter Characterization Focusing on the Filtration Efficiency of Nano-Particulates Down to 10 nm
ISSN: 0148-7191, e-ISSN: 2688-3627
To be published on September 15, 2020 by SAE International in United States
With Euro 7 emission standards in discussion, stricter particulate number (PN) targets as well as a decreased PN cut-off size from 23 to 10 nm are expected. Sub-23 nm particulates are considered particularly harmful to human health, but are not yet taken into account in the current vehicle certification process. Former investigations on a gasoline direct-injection (GDI) engine equipped with a gasoline particulate filter (GPF) showed that the share of sub-23 nm particulates can reach up to 15% of the total PN emission during a worldwide-harmonized light-duty test cycle (WLTC). Not taking into account sub-23 nm particulates during the development process could lead to significant additional efforts for Original Equipment Manufacturers (OEM) to comply with future Euro 7 PN emission limits. It is therefore essential to increase knowledge about the formation and filtration of particles below 23 nm. In the present study, a holistic GPF characterization has been carried out on an engine test bench under varying boundary conditions and on a burner bench with a novel ash loading methodology. Moreover, vehicle tests were conducted and all relevant PN measurement systems available on the market were used during the measurement campaign. Measurement results are analyzed regarding particulate size distribution upstream of the Three Way Catalyst (TWC) and the GPF as well as at the tailpipe to determine the GPF filtration efficiency and the impact on the final PN emission results. Several complete engine map measurements show that for a simultaneous increase of engine speed and load, the filtration efficiency increases for sub-23 nm particulates. On the contrary, the filtration efficiency decreases significantly for larger particles with sizes up to 200 nm. A decrease in the GPF filtration efficiency is also observed for a decreasing airfuel ratio, whereas an increasing initial ash load results in an improved filtration efficiency. Furthermore, the PN size distribution shifts notably towards larger particulates over the TWC.
- Frank Dorscheidt - RWTH Aachen University
- Stefan Sterlepper - RWTH Aachen University
- Michael Görgen - FEV Europe GmbH
- Martin Nijs - FEV Europe GmbH
- Johannes Claßen - RWTH Aachen University
- Surya Kiran Yadla - FEV Europe GmbH
- Robert Maurer - RWTH Aachen University
- Stefan Pischinger - RWTH Aachen University
- Sascha Krysmon - RWTH Aachen University
- Abdelrahman Abdelkader - FEV Europe GmbH