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Laser-induced fluorescence for studying the influence of potassium and sodium salts on PAH formation in sooting premixed flames

Mannazhi, Manu LU ; Bergqvist, Saga LU and Bengtsson, Per Erik LU orcid (2022) In Applied Physics B: Lasers and Optics 128(4).
Abstract

Previous studies have shown that alkali salts influence combustion processes and soot formation, although the effects seem to vary across systems. Moreover, fundamental studies on the effect of potassium and sodium salts on formation of polycyclic aromatic hydrocarbons (PAH), which are precursors in soot formation, are scarce. Here, we report a study in which the effects on PAH formation due to the addition of alkali metal salts (KCl, KOH, K2CO3, NaCl and NaOH) to premixed ethylene–air flames were investigated. Different size classes of PAHs were probed using both spectral and 2D measurements of laser-induced fluorescence (PAH-LIF) using the excitation wavelengths 266 nm and 532 nm, while detecting the fluorescence... (More)

Previous studies have shown that alkali salts influence combustion processes and soot formation, although the effects seem to vary across systems. Moreover, fundamental studies on the effect of potassium and sodium salts on formation of polycyclic aromatic hydrocarbons (PAH), which are precursors in soot formation, are scarce. Here, we report a study in which the effects on PAH formation due to the addition of alkali metal salts (KCl, KOH, K2CO3, NaCl and NaOH) to premixed ethylene–air flames were investigated. Different size classes of PAHs were probed using both spectral and 2D measurements of laser-induced fluorescence (PAH-LIF) using the excitation wavelengths 266 nm and 532 nm, while detecting the fluorescence emission at selected wavelength ranges. Elastic light scattering (ELS) measurements were also used to complement the fluorescence data. It was found that potassium and sodium salts do not significantly influence the formation of small PAHs (2–3 rings), while decreasing the concentration of larger PAHs at higher heights above burner (HAB). Another important result was that the anion in the salt (Cl, OH, CO32−) negligibly influences the PAH and soot formation processes after dissociation of the salts.

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type
Contribution to journal
publication status
published
subject
in
Applied Physics B: Lasers and Optics
volume
128
issue
4
article number
68
publisher
Springer
external identifiers
  • scopus:85126177939
ISSN
0946-2171
DOI
10.1007/s00340-022-07780-4
language
English
LU publication?
yes
id
ad0f3af8-4fb3-401a-8ebf-90c8ba8632d9
date added to LUP
2022-05-03 16:41:58
date last changed
2023-05-16 13:09:37
@article{ad0f3af8-4fb3-401a-8ebf-90c8ba8632d9,
  abstract     = {{<p>Previous studies have shown that alkali salts influence combustion processes and soot formation, although the effects seem to vary across systems. Moreover, fundamental studies on the effect of potassium and sodium salts on formation of polycyclic aromatic hydrocarbons (PAH), which are precursors in soot formation, are scarce. Here, we report a study in which the effects on PAH formation due to the addition of alkali metal salts (KCl, KOH, K<sub>2</sub>CO<sub>3</sub>, NaCl and NaOH) to premixed ethylene–air flames were investigated. Different size classes of PAHs were probed using both spectral and 2D measurements of laser-induced fluorescence (PAH-LIF) using the excitation wavelengths 266 nm and 532 nm, while detecting the fluorescence emission at selected wavelength ranges. Elastic light scattering (ELS) measurements were also used to complement the fluorescence data. It was found that potassium and sodium salts do not significantly influence the formation of small PAHs (2–3 rings), while decreasing the concentration of larger PAHs at higher heights above burner (HAB). Another important result was that the anion in the salt (Cl<sup>−</sup>, OH<sup>−</sup>, CO<sub>3</sub><sup>2−</sup>) negligibly influences the PAH and soot formation processes after dissociation of the salts.</p>}},
  author       = {{Mannazhi, Manu and Bergqvist, Saga and Bengtsson, Per Erik}},
  issn         = {{0946-2171}},
  language     = {{eng}},
  number       = {{4}},
  publisher    = {{Springer}},
  series       = {{Applied Physics B: Lasers and Optics}},
  title        = {{Laser-induced fluorescence for studying the influence of potassium and sodium salts on PAH formation in sooting premixed flames}},
  url          = {{http://dx.doi.org/10.1007/s00340-022-07780-4}},
  doi          = {{10.1007/s00340-022-07780-4}},
  volume       = {{128}},
  year         = {{2022}},
}