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Pirjola, Liisa
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Effect of Injection Parameters on Exhaust Gaseous and Nucleation Mode Particle Emissions of a Tier 4i Nonroad Diesel Engine

Metropolia Univ of Applied Sciences-Liisa Pirjola
Tampere Univ of Technology-Topi Rönkkö, Panu Karjalainen, Jorma Keskinen, Heino Kuuluvainen
Published 2013-10-14 by SAE International in United States
During the past few decades the exhaust emissions of diesel engines have significantly decreased due to efficient emissions regulation. Compared to the situation in the 1990s, the nitrogen oxide (NOx) and particulate matter (PM) emissions, the main challenges for diesel engines, are now reduced 80-95 % in many industrialized countries. To meet the demanding requirements, engine technologies have been updated and improved step by step. These improvements have also kept Specific Fuel Consumption (SFC) figures at a low level or they have even improved. The latter issue is of great significance for consumers (cost) and also for the environment (CO2).Nowadays many diesel engine fuel injection strategies rely on the use of exhaust after-treatment systems. Efficient and clean combustion is obtained by utilizing high injection pressure and advanced injection timing. The resulting high engine-out NOx is reduced to the target level by using an efficient NOx after-treatment system, possibly supported by an EGR system. In several applications no particulate filter is necessarily yet required for a nonroad engine to meet its emission limits. However, according to…
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The Effect of a Particle Oxidation Catalyst (POC®) on Particle Emissions of a GDI Car during Transient Engine Operation

Aristotle University of Thessaloniki-Theodoros Tzamkiozis
Ecocat Oy-Matti Happonen, Pekka Matilainen, Kauko Kanniainen, Toni Kinnunen
Published 2013-04-08 by SAE International in United States
Particle emissions have been generally associated to diesel engines. However, spark-ignition direct injection (SI-DI) engines have been observed to produce notable amounts of particulate matter as well. The upcoming Euro 6 legislation for passenger cars (effective in 2014, stricter limit in 2017) will further limit the particulate emissions from SI engines by introducing a particle number emission (PN) limit, and it is not probable that the SI-DI engines are able to meet this limit without resorting to additional aftertreatment systems.In this study, the solid particle emissions of a SI-DI passenger car with and without an installed Particle Oxidation Catalyst (POC®) were studied over the New European Driving Cycle (NEDC) on a chassis dynamometer and over real transient acceleration situations on road. It was observed that a considerable portion of particle number emissions occurred during the transient acceleration phases of the cycle. The application of the POC resulted in a reduction of those emission peaks and, as a conclusion, the car was able to meet the 2017 Euro 6 particle number emission limit with the POC.The…
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Reduction of Heavy-Duty Diesel Exhaust Particle Number and Mass at Low Exhaust Temperature Driving by the DOC and the SCR

SAE International Journal of Fuels and Lubricants

Finnish Meteorological Institute-Sanna Saarikoski, Minna Aurela, Risto Hillamo
Metropolia Univ of Applied Sciences-Aleksi Malinen, Liisa Pirjola
  • Journal Article
  • 2012-01-1664
Published 2012-09-10 by SAE International in United States
The effect of SCR on nanoparticle emissions has been a subject for some recent diesel particle emission related studies. In this study, the effect of after-treatment (DOC and SCR) on particle emissions was studied with a heavy-duty off-road diesel engine (emission level stage 3b with an SCR). A special “transient cold test cycle” (TCTC) was designed to describe the SCR system operation at low exhaust gas temperatures. The particle instrumentation made it possible to measure on-line the particle number concentration, particle size distribution and chemical composition of particles. The largest particle number concentrations were measured after the exhaust manifold. The exhaust after-treatment was observed to reduce the total particle number concentration by 82.5% with the DOC and 95.7% with the DOC+SCR. Also the mean particle composition was affected by the after-treatment; while the organics formed the main fraction of the particulate mass without exhaust after-treatment, after the DOC and especially after the DOC+SCR the organic particulate matter was reduced so that most significant particle fraction was soot. The effect of after-treatment was similar both on…
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A Novel Mobile Laboratory for “Chasing” City Traffic

Department of Physical Science, University of Helsinki-Kaarle Hämeri, Tareq Hussein
Department of Technology, Helsinki Polytechnic-Liisa Pirjola, Heikki Parviainen
Published 2004-06-08 by SAE International in United States
A mobile laboratory was designed and built in Helsinki Polytechnic, in close co-operation with the University of Helsinki, to measure traffic pollutants with high temporal and spatial resolution under real world conditions. The laboratory provides measurements of gaseous pollutants and particle size number distributions as well as meteorological and geographical parameters. Two inlet systems are employed to enable the “chasing” of different type of vehicles. This paper introduces the construction and technical details of the mobile laboratory, and presents the results from “chasing” experiments performed in the Helsinki metropolitan area during a field campaign in June, 2003. New particle formation was found while driving in the exhaust plume of vehicles. Approximately 75% of the total particle number concentration was due to particles smaller than 50 nm in size. The shorter the distance from the “chased” vehicle, the higher nuclei mode number concentration was recorded owing to the reduced potential dilution time. Typical modal mean particle diameters were 7-15 nm and 70 nm.
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