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Influence of Soot Particle Aggregation on Time-Resolved Laser-Induced Incandescence Signals

Bladh, Henrik LU ; Johnsson, Jonathan LU ; Rissler, Jenny LU ; Adulhamid, H; Olofsson, Nils-Erik LU ; Sanati, Mehri LU ; Pagels, Joakim LU and Bengtsson, Per-Erik LU (2011) In Applied Physics B 104(2). p.331-341
Abstract
Laser-induced incandescence (LII) is a versatile technique for quantitative soot measurements in flames and exhausts. When used for particle sizing, the time-resolved signals are analysed as these will show a decay rate dependent on the soot particle size. Such an analysis has traditionally been based on the assumption of isolated primary particles. However, soot particles in flames and exhausts are usually aggregated, which implies loss of surface area, less heat conduction and hence errors in estimated particle sizes. In this work we present an experimental investigation aiming to quantify this effect. A soot generator, based on a propane diffusion flame, was used to produce a stable soot stream and the soot was characterised by... (More)
Laser-induced incandescence (LII) is a versatile technique for quantitative soot measurements in flames and exhausts. When used for particle sizing, the time-resolved signals are analysed as these will show a decay rate dependent on the soot particle size. Such an analysis has traditionally been based on the assumption of isolated primary particles. However, soot particles in flames and exhausts are usually aggregated, which implies loss of surface area, less heat conduction and hence errors in estimated particle sizes. In this work we present an experimental investigation aiming to quantify this effect. A soot generator, based on a propane diffusion flame, was used to produce a stable soot stream and the soot was characterised by transmission electron microscopy (TEM), a scanning mobility particle sizer (SMPS) and an aerosol particle mass analyzer coupled in series after a differential mobility analyzer (DMA-APM). Despite nearly identical primary particle size distributions for three selected operating conditions, LII measurements resulted in signal decays with significant differences in decay rate. However, the three cases were found to have quite different levels of aggregation as shown both in TEM images and mobility size distributions, and the results agree qualitatively with the expected effect of diminished heat conduction from aggregated particles resulting in longer LII signal decays. In an attempt to explain the differences quantitatively, the LII signal dependence on aggregation was modelled using a heat and mass transfer model for LII given the primary particle and aggregate size distribution data as input. Quantitative agreement was not reached and reasons for this discrepancy are discussed. (Less)
Please use this url to cite or link to this publication:
author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Applied Physics B
volume
104
issue
2
pages
331 - 341
publisher
Springer
external identifiers
  • wos:000293751800008
  • scopus:80052571838
ISSN
0946-2171
DOI
10.1007/s00340-011-4470-y
project
MERGE
language
English
LU publication?
yes
id
16c05954-5553-4fa7-9246-1ba54ebe8c7d (old id 1951410)
date added to LUP
2011-05-12 15:14:45
date last changed
2017-05-28 04:39:57
@article{16c05954-5553-4fa7-9246-1ba54ebe8c7d,
  abstract     = {Laser-induced incandescence (LII) is a versatile technique for quantitative soot measurements in flames and exhausts. When used for particle sizing, the time-resolved signals are analysed as these will show a decay rate dependent on the soot particle size. Such an analysis has traditionally been based on the assumption of isolated primary particles. However, soot particles in flames and exhausts are usually aggregated, which implies loss of surface area, less heat conduction and hence errors in estimated particle sizes. In this work we present an experimental investigation aiming to quantify this effect. A soot generator, based on a propane diffusion flame, was used to produce a stable soot stream and the soot was characterised by transmission electron microscopy (TEM), a scanning mobility particle sizer (SMPS) and an aerosol particle mass analyzer coupled in series after a differential mobility analyzer (DMA-APM). Despite nearly identical primary particle size distributions for three selected operating conditions, LII measurements resulted in signal decays with significant differences in decay rate. However, the three cases were found to have quite different levels of aggregation as shown both in TEM images and mobility size distributions, and the results agree qualitatively with the expected effect of diminished heat conduction from aggregated particles resulting in longer LII signal decays. In an attempt to explain the differences quantitatively, the LII signal dependence on aggregation was modelled using a heat and mass transfer model for LII given the primary particle and aggregate size distribution data as input. Quantitative agreement was not reached and reasons for this discrepancy are discussed.},
  author       = {Bladh, Henrik and Johnsson, Jonathan and Rissler, Jenny and Adulhamid, H and Olofsson, Nils-Erik and Sanati, Mehri and Pagels, Joakim and Bengtsson, Per-Erik},
  issn         = {0946-2171},
  language     = {eng},
  number       = {2},
  pages        = {331--341},
  publisher    = {Springer},
  series       = {Applied Physics B},
  title        = {Influence of Soot Particle Aggregation on Time-Resolved Laser-Induced Incandescence Signals},
  url          = {http://dx.doi.org/10.1007/s00340-011-4470-y},
  volume       = {104},
  year         = {2011},
}