Heavy duty off-road diesel engine low load particle number emissions and particle control

Tero Lähde (Corresponding Author), Annele Virtanen, Matti Happonen, Christer Söderström, Matti Kytö, Jorma Keskinen

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    24 Citations (Scopus)


    Exhaust gas particle and ion size distributions were measured from an off-road diesel engine complying with the European Stage IIIB emission standard. The measurements were performed at idling and low load conditions on an engine dynamometer. Nucleation-mode particles dominated the diesel exhaust particle number emissions at idle load. The nonvolatile nucleation-mode geometric mean diameter was detected at 10 nm or below. The nonvolatile nucleation-mode charge state implied that it has evolved through a highly ionizing environment before emission from the engine. The determined charging probabilities were 10.0 ± 2.2% for negative and 8.0 ± 2.0% for positive polarity particles. The nonvolatile nucleation particle concentration and size was also shown to be dependent on the lubricant oil composition. The particle emissions were efficiently controlled with a partial filter or with partial filter + selective catalytic reduction (SCR) combination. The particle number removal efficiencies of the aftertreatment systems were over 95% for wet total particle number (>3nm) and over 85% for dry particle total number. Nevertheless, the aftertreatment systems’ efficiencies were around 50% for the soot-mode particles. The low-load nonvolatile nucleation particle emissions were also dependent on the engine load, speed, and fuel injection pressure. The low load particle number emissions followed the soot-core trade-off, similar to medium or high operating loads.
    Original languageEnglish
    Pages (from-to)1186-1194
    JournalJournal of the Air and Waste Management Association
    Issue number10
    Publication statusPublished - 2014
    MoE publication typeA1 Journal article-refereed


    • diesel engines
    • diesel exhaust
    • particle emissions
    • idle load
    • low load


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