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| Titel |
Model studies of volatile diesel exhaust particle formation: are organic vapours involved in nucleation and growth? |
| VerfasserIn |
L. Pirjola, M. Karl, T. Rönkkö, F. Arnold |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7316
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 15, no. 18 ; Nr. 15, no. 18 (2015-09-23), S.10435-10452 |
| Datensatznummer |
250120045
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| Publikation (Nr.) |
 copernicus.org/acp-15-10435-2015.pdf |
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| Zusammenfassung |
| A high concentration of volatile nucleation mode particles (NUP) formed in
the atmosphere when the exhaust cools and dilutes has hazardous health
effects and it impairs the visibility in urban areas. Nucleation mechanisms
in diesel exhaust are only poorly understood. We performed model studies
using two sectional aerosol dynamics process models AEROFOR and MAFOR on the
formation of particles in the exhaust of a diesel engine, equipped with an
oxidative after-treatment system and running with low fuel sulfur content
(FSC) fuel, under laboratory sampling conditions where the dilution system
mimics real-world conditions. Different nucleation mechanisms were tested.
Based on the measured gaseous sulfuric acid (GSA) and non-volatile core and
soot particle number concentrations of the raw exhaust, the model simulations
showed that the best agreement between model predictions and measurements in
terms of particle number size distribution was obtained by barrier-free
heteromolecular homogeneous nucleation between the GSA and a semi-volatile
organic vapour combined with the homogeneous nucleation of GSA alone. Major
growth of the particles was predicted to occur due to the similar organic vapour at
concentrations of (1−2) × 1012 cm−3. The pre-existing core
and soot mode concentrations had an opposite trend on the NUP formation, and
the maximum NUP formation was predicted if a diesel particle filter (DPF) was
used. On the other hand, the model predicted that the NUP formation ceased if
the GSA concentration in the raw exhaust was less than 1010 cm−3,
which was the case when biofuel was used. |
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