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| Titel |
Effective density measurements of fresh particulate matter emitted by an aircraft engine |
| VerfasserIn |
Manuel Abegglen, Lukas Durdina, Amewu Mensah, Benjamin Brem, Joel Corbin, Theo Rindlisbacher, Jing Wang, Ulrike Lohmann, Berko Sierau |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250098669
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| Publikation (Nr.) |
 EGU/EGU2014-14367.pdf |
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| Zusammenfassung |
| Introduction
Carbonaceous particulate matter (commonly referred to as soot), once emitted into the
atmosphere affects the global radiation budget by absorbing and scattering solar radiation.
Furthermore, it can alter the formation, lifetime and distribution of clouds by acting as cloud
condensation nuclei (CCN) or ice nuclei (IN). The ability of soot particles to act as CCN and
IN depends on their size, morphology and chemical composition. Soot particles are
known to consist of spherical, primary particles that tend to arrange in chain-like
structures. The structure of soot particles typically changes in the atmosphere when the
particles are coated with secondary material, thus changing their radiative and cloud
microphysical properties. Bond et al. (Journal of Geophysical Research, 2013:
Bounding the Role of Black Carbon in the Climate System.) estimated the total
industrial-era (1750 to 2005) climate forcing of black carbon to be 1.1W/m2 ranging from
the uncertainty bonds of 0.17W/m2 to 2.1W/m2. Facing the large uncertainty
range, there is a need for a better characterization of soot particles abundant in the
atmosphere.
We provide experimental data on physical properties such as size, mass, density and
morphology of freshly produced soot particles from a regularly used aircraft engine and from
four laboratory generated soot types. This was done using a Differential Mobility Analyzer
(DMA) and a Centrifugal Particle Mass Analyzer (CPMA), a relatively new instrument that
records mass distributions of aerosol particles.
Experimental
Aircraft engine exhaust particles were collected and analysed during the Aviation Particle
Regulatory Instrumentation Demonstration Experiments (A-PRIDE) campaigns in a test
facility at the Zurich airport in November 2012 and August 2013. The engines were operated
at different relative thrust levels spanning 7% to 100%. The sample was led into a heated
line in order to prevent condensation of water and evolution of secondary organic aerosols.
The soot masses/densities were determined using a DMA-CPMA system as described in the
following.
The freshly generated soot particles were first charge equilibrated to account for multiple
charging and selected according to their mobility size (dm) by a DMA. The monodisperse
flow then entered the CPMA which measured the corresponding mass. A condensation
particle counter counted the particle number concentration. The effective density (Ïeff) can
be derived using the fractal relationship between mass and dm and the definition of the
effective density.
Additionally, we investigated four different laboratory-generated soot types at ETHZ. In
detail, a Combustion Aerosol Standard burner ((1) fuel-rich and (2) fuel-lean), a (3) PALAS
GFG aerosol generator and (4) carbon black (Cabot Regal Black) from an atomizer,
were used. The corresponding results are compared to the aircraft engine exhaust
measurements.
Results
The size, mass, effective density distributions, and the corresponding mobility based
fractal dimensions (Dfm) from fresh soot particles emitted by a common aircraft engine and
from four laboratory generated soot types were analysed. Dfm is used to describe aggregate
particles. It relates the number of primary particles to dm. In general, the effective
density decreases with increasing mobility diameter and depends on engine thrust. |
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