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Flame structure study of premixed NH3/O2/Ar flames using Raman spectroscopy

Zubairova, Alsu LU ; Chen, Jundie LU ; Konnov, Alexander A. LU and Brackmann, Christian LU (2025) In Combustion and Flame 280.
Abstract

While NH3 has gained a lot of interest as a potential carbon-free fuel, at present, there are notable disagreements when it comes to predictions of some of its combustion characteristics, such as burning velocity or species mole fractions, in particular of NOx, which have the potential to cause significant harm to both human health and the environment. Nevertheless, because the NH3 flame presents multiple challenges for experimental studies, there is a lack of data that could assist with the further development of kinetic models. In the present work, the authors demonstrate enhanced Raman spectroscopy with multiple laser beam passages that allows for non-intrusive sensitive detection and quantification of two... (More)

While NH3 has gained a lot of interest as a potential carbon-free fuel, at present, there are notable disagreements when it comes to predictions of some of its combustion characteristics, such as burning velocity or species mole fractions, in particular of NOx, which have the potential to cause significant harm to both human health and the environment. Nevertheless, because the NH3 flame presents multiple challenges for experimental studies, there is a lack of data that could assist with the further development of kinetic models. In the present work, the authors demonstrate enhanced Raman spectroscopy with multiple laser beam passages that allows for non-intrusive sensitive detection and quantification of two nitrogen oxide species, NO and N2O, in flame with detection limits of 600 and 500 ppm, respectively. All the datasets were acquired in NH3/O2/Ar flames, to only involve NOx reactions from fuel-bound nitrogen, at three equivalence ratios (Φ=0.8, 1.0, 1.2). The processed datasets were compared with predictions of four chemical kinetic mechanisms and possible reasons for disagreements in model predictions were discussed. While overall model performance varies between different flames, most of the models tested give acceptable predictions for the NO profiles, with predictions of all models being on the lower end of the experimental data range for rich flames. For N2O, the obtained peak mole fraction values of 1670 (Φ=0.8), 1060 (Φ=1.0) and 670 (Φ=1.2) ppm have been well reproduced by one of the models within the experimental error margins.

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author
; ; and
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Ammonia, Flame structure, Modeling, Nitrogen oxides, Raman Spectroscopy
in
Combustion and Flame
volume
280
article number
114382
publisher
Elsevier
external identifiers
  • scopus:105011969764
ISSN
0010-2180
DOI
10.1016/j.combustflame.2025.114382
language
English
LU publication?
yes
id
0af148fc-aefd-4d32-ab48-b359565115de
date added to LUP
2025-11-04 08:39:48
date last changed
2025-11-04 08:39:48
@article{0af148fc-aefd-4d32-ab48-b359565115de,
  abstract     = {{<p>While NH<sub>3</sub> has gained a lot of interest as a potential carbon-free fuel, at present, there are notable disagreements when it comes to predictions of some of its combustion characteristics, such as burning velocity or species mole fractions, in particular of NOx, which have the potential to cause significant harm to both human health and the environment. Nevertheless, because the NH<sub>3</sub> flame presents multiple challenges for experimental studies, there is a lack of data that could assist with the further development of kinetic models. In the present work, the authors demonstrate enhanced Raman spectroscopy with multiple laser beam passages that allows for non-intrusive sensitive detection and quantification of two nitrogen oxide species, NO and N<sub>2</sub>O, in flame with detection limits of 600 and 500 ppm, respectively. All the datasets were acquired in NH<sub>3</sub>/O<sub>2</sub>/Ar flames, to only involve NOx reactions from fuel-bound nitrogen, at three equivalence ratios (Φ=0.8, 1.0, 1.2). The processed datasets were compared with predictions of four chemical kinetic mechanisms and possible reasons for disagreements in model predictions were discussed. While overall model performance varies between different flames, most of the models tested give acceptable predictions for the NO profiles, with predictions of all models being on the lower end of the experimental data range for rich flames. For N<sub>2</sub>O, the obtained peak mole fraction values of 1670 (Φ=0.8), 1060 (Φ=1.0) and 670 (Φ=1.2) ppm have been well reproduced by one of the models within the experimental error margins.</p>}},
  author       = {{Zubairova, Alsu and Chen, Jundie and Konnov, Alexander A. and Brackmann, Christian}},
  issn         = {{0010-2180}},
  keywords     = {{Ammonia; Flame structure; Modeling; Nitrogen oxides; Raman Spectroscopy}},
  language     = {{eng}},
  publisher    = {{Elsevier}},
  series       = {{Combustion and Flame}},
  title        = {{Flame structure study of premixed NH<sub>3</sub>/O<sub>2</sub>/Ar flames using Raman spectroscopy}},
  url          = {{http://dx.doi.org/10.1016/j.combustflame.2025.114382}},
  doi          = {{10.1016/j.combustflame.2025.114382}},
  volume       = {{280}},
  year         = {{2025}},
}