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NCN concentration and interfering absorption by CH2O, NH and OH in low pressure methane/air flames with and without N2O

Klein-Douwel, R. J. H.; Konnov, Alexander LU ; Dam, N. J. and ter Meulen, J. J. (2011) In Combustion and Flame 158(11). p.2090-2104
Abstract
Absorption spectra in the wavelength region around 329 nm have been recorded with the cavity ring-down technique in various low pressure (200 hPa) CH4/air flames, two of which with N2O (nitrous oxide) addition. NCN (cyanonitrene) absorption appears to be significant only in N2O-enriched flames, which also reveal spectrally nearby absorption by NH. In a phi = 1.14, N2O oxidizer volume fraction = 57.0% flame, an upper limit for the NCN mole fraction of 4.0 x 10(-6) has been found. Absorption spectra have been recorded as a function of height and these clearly show the presence of CH2O (formaldehyde) and OH as well. In CH4/air flames, absorption by CH2O at and near the flame front is strong enough to mask any possible absorption signal due to... (More)
Absorption spectra in the wavelength region around 329 nm have been recorded with the cavity ring-down technique in various low pressure (200 hPa) CH4/air flames, two of which with N2O (nitrous oxide) addition. NCN (cyanonitrene) absorption appears to be significant only in N2O-enriched flames, which also reveal spectrally nearby absorption by NH. In a phi = 1.14, N2O oxidizer volume fraction = 57.0% flame, an upper limit for the NCN mole fraction of 4.0 x 10(-6) has been found. Absorption spectra have been recorded as a function of height and these clearly show the presence of CH2O (formaldehyde) and OH as well. In CH4/air flames, absorption by CH2O at and near the flame front is strong enough to mask any possible absorption signal due to NCN. OH absorption spectrally coincident with the maximum NCN absorption has been observed as well. CH2O absorption is present throughout the whole 327-331 nm range, which can severely affect the accuracy of NCN concentration measurements if both species are present in the measurement volume. This necessitates the acquisition of continuous spectra instead of absorption measurements at a few specific wavelengths. Absorption signals at wavelengths characteristic for NCN, CH2O, NH and OH are analysed as function of height in the flame. Probabilities that these signals may be assigned unambiguously to a single species are discussed. (C) 2011 The Combustion Institute. Published by Elsevier Inc. All rights reserved. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
NCN (cyanonitrene), CH2O (formaldehyde), NH, OH, Cavity ring-down, spectroscopy, N2O (nitrous oxide)
in
Combustion and Flame
volume
158
issue
11
pages
2090 - 2104
publisher
Elsevier
external identifiers
  • wos:000295424600002
  • scopus:80052923017
ISSN
0010-2180
DOI
10.1016/j.combustflame.2011.04.009
language
English
LU publication?
yes
id
d4abea03-2c74-4827-b73a-d2b05c4c3e0e (old id 2179517)
date added to LUP
2011-10-25 11:33:48
date last changed
2017-01-01 06:01:22
@article{d4abea03-2c74-4827-b73a-d2b05c4c3e0e,
  abstract     = {Absorption spectra in the wavelength region around 329 nm have been recorded with the cavity ring-down technique in various low pressure (200 hPa) CH4/air flames, two of which with N2O (nitrous oxide) addition. NCN (cyanonitrene) absorption appears to be significant only in N2O-enriched flames, which also reveal spectrally nearby absorption by NH. In a phi = 1.14, N2O oxidizer volume fraction = 57.0% flame, an upper limit for the NCN mole fraction of 4.0 x 10(-6) has been found. Absorption spectra have been recorded as a function of height and these clearly show the presence of CH2O (formaldehyde) and OH as well. In CH4/air flames, absorption by CH2O at and near the flame front is strong enough to mask any possible absorption signal due to NCN. OH absorption spectrally coincident with the maximum NCN absorption has been observed as well. CH2O absorption is present throughout the whole 327-331 nm range, which can severely affect the accuracy of NCN concentration measurements if both species are present in the measurement volume. This necessitates the acquisition of continuous spectra instead of absorption measurements at a few specific wavelengths. Absorption signals at wavelengths characteristic for NCN, CH2O, NH and OH are analysed as function of height in the flame. Probabilities that these signals may be assigned unambiguously to a single species are discussed. (C) 2011 The Combustion Institute. Published by Elsevier Inc. All rights reserved.},
  author       = {Klein-Douwel, R. J. H. and Konnov, Alexander and Dam, N. J. and ter Meulen, J. J.},
  issn         = {0010-2180},
  keyword      = {NCN (cyanonitrene),CH2O (formaldehyde),NH,OH,Cavity ring-down,spectroscopy,N2O (nitrous oxide)},
  language     = {eng},
  number       = {11},
  pages        = {2090--2104},
  publisher    = {Elsevier},
  series       = {Combustion and Flame},
  title        = {NCN concentration and interfering absorption by CH2O, NH and OH in low pressure methane/air flames with and without N2O},
  url          = {http://dx.doi.org/10.1016/j.combustflame.2011.04.009},
  volume       = {158},
  year         = {2011},
}