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Results of this measurement campaign indicate that marine exhaust particles mostly consist of nanometer sized ash particles on which heavy volatile species condense during exhaust dilution and cooling.
Used exhaust sampling and dilution system was observed to have an influence especially to particle size distributions.
Particle emission characteristics for a medium-speed four-stroke marine diesel engine (Wärtsilä Wasa, 4R32) with different loads (25, 75%) were studied using a variety of sampling systems. Measurements were conducted employing a heavy fuel oil (HFO) and a lighter marine distillate oil. The measurements, especially with HFO, revealed that marine exhaust particles mostly consist of nanometer sized ash particles on which heavy volatile species condense during exhaust dilution and cooling. The soot mode number concentration was low with both fuels tested, in particular when HFO was used. Total particle number emissions were in the order of 5.2–6.9 x 1015 per kg of fuel and formed a monomodal size distribution when a porous tube diluter combined with an ageing chamber and operating at low dilution ratio was used for sampling. The levels and size distributions obtained in the lab using a porous tube diluter were similar to the ones reported in the literature studying ship plumes following atmospheric dilution. Lab measurements with ejector-type diluters mostly led to bimodal distributions that did not well resemble atmospheric size distributions. Moreover, the nucleation mode formed with the ejector diluters was variable in size and concentration. When used with dilution air at ambient temperature, ejector diluters were inappropriate for primary dilution due to clogging.
This research was done in Tekes funded project "Health relevant and energy efficient regulation of exhaust particle emissions (HERE)", coordinated by Tampere University of Technology (TUT). First author, Assoc. Prof. Leonidas Ntziachristos (Aristotle University Thessaloniki) is an invited FiDiPro fellow at TUT. In addition to TUT, VTT, Turku University of Applied Sciences and FMI collaboration partners in project are Wärtsilä Oyj, Agco Power, Pegasor, Dinex Ecocat, Dekati and Neste. The main target of the HERE project is to take into account the atmospheric transformation of exhaust emissions already in emission measurements. This enables more comprehensive understanding regarding the real effects of the exhaust emissions and emission mitigation techniques.
Researcher Hilkka Timonen, Hilkka.email@example.com
Article: Ntziachristos, L., Saukko, E., Lehtoranta, K., Rönkkö, T., Timonen, H., Simonen, P., Karjalainen, P., and Keskinen, J.: Particle emissions characterization from a medium-speed marine diesel engine with two fuels at different sampling conditions, Fuel, 186, 456-465, 10.1016/j.fuel.2016.08.091, 2016.
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