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Measuring Automotive Exhaust Particles Down to 10 nm - “DownToTen” Project
ISSN: 0148-7191, e-ISSN: 2688-3627
To be published on September 15, 2020 by SAE International in United States
Latest technology internal combustion engines may emit significant levels of sub-23 nm particles. The main objective of the Horizon 2020 “DownToTen” project was to develop a robust methodology and provide policy recommendations towards the particle number (PN) emissions measurements in the sub-23 nm region. In order to achieve this target, a new portable exhaust particle sampling system (PEPS) was developed, being capable of measuring exhaust particles down to at least 10 nm under real-world conditions. Three generations of the DownToTen sampling system were developed, as shown in Figure 1. The main design target was to build a system that is compatible with current PMP requirements and is characterized by minimized losses in the sub-23 nm region, high robustness against artefacts and high flexibility in terms of different PN modes investigation, i.e. non-volatile, volatile and secondary particles. This measurement setup was used for the evaluation of particle emissions from latest technology engine and powertrain technologies (including vehicles from other Horizon 2020 projects), different fuel types and a wide range of exhaust aftertreatment systems. Results revealed that in most cases (non-volatile) PN emissions down to 10 nm (SPN10) do not exceed the current SPN23 limit of 6×1011 p/km. However, there are some cases where SPN10 emissions exceeded the limit, although SPN23 were below that. An interesting finding was that even in the latter cases, the installation of a particle filter can significantly reduce PN emissions across a wide particle size range, fuels and combustion technology. Along with the above-mentioned investigation, DownToTen activities expanded to a wider scientific area through the development of several innovations. A few examples of these activities comprise the development and evaluation of a prototype counterflow denuder, the robustness testing of the DownToTen sampling system and instrumentation by means of a shaking system simulating acceleration profiles of real-world driving conditions, and the development of an aerosol simulation model which can simulate particle nucleation, condensation and coagulation mechanisms during exhaust dilution process. In addition, DownToTen developed a methodology and instrumentation for the on-line particle chemical characterization during transient engine operation. Finally, within the DownToTen context, a methodology for the evaluation of different PN modes was developed, including non-volatile, volatile and secondary aerosol. DownToTen results are being used to scientifically underpin the Euro 7/VII emission standard development in the EU. The method developed and the results obtained may be used to bring in the market clean and efficient vehicle technologies, improve engine and emission control performance with different fuels, and characterize size-fractionated particle chemistry to identify the formation mechanisms and control those in a targeted cost-effective fashion.
- Zissis C. Samaras - Aristotle University of Thessaloniki
- Jon Andersson - Ricardo Consulting Engineers, Ltd.
- Alexander Bergmann - Graz University of Technology
- Stefan Hausberger - Graz University of Technology
- Zisimos Toumasatos - Aristotle University of Thessaloniki
- Jorma Keskinen - Tampere University
- Christoff Haisch - Technical University of Munich
- Anastasios Kontses - Aristotle University of Thessaloniki
- Leonidas D. Ntziachristos - Aristotle University of Thessaloniki
- Lukas Landl - Graz University of Technology
- Athanasios Mamakos - AVL List GmbH
- Markus Bainschab - Graz University of Technology