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Ammonia/methane flame interaction and NOx emission in a double-swirler burner

Zhou, Yuchen LU ; Sjögren, Carl Otto Olsson LU orcid ; Xu, Leilei LU ; Hassan, Zubayr O. ; AlSuhaibani, Abduk Rahman ; Solami, Bandar H. ; Jamal, Aqil ; Siddiqui, Osamah ; Roberts, William L. and Bai, Xue Song LU , et al. (2026) In Fuel 414.
Abstract

A double-swirler ammonia/methane co-flame burner was developed to enhance flame stability and reduce NOx emissions in ammonia combustion. In this system, a premixed ammonia/air mixture is introduced through the inner swirler, while a lean premixed methane/air flame from the outer swirler stabilizes the ammonia/air flame. Experimental results highlight that the Reynolds number of the outer methane/air flame strongly affects flame stability and NOx emissions under fuel-lean ammonia/air conditions. Higher Reynolds numbers increase the fuel supply and combustion power of the methane/air flame but paradoxically destabilize the flame and lead to higher NOx emissions. Numerical simulations reveal the mechanisms underlying these observations.... (More)

A double-swirler ammonia/methane co-flame burner was developed to enhance flame stability and reduce NOx emissions in ammonia combustion. In this system, a premixed ammonia/air mixture is introduced through the inner swirler, while a lean premixed methane/air flame from the outer swirler stabilizes the ammonia/air flame. Experimental results highlight that the Reynolds number of the outer methane/air flame strongly affects flame stability and NOx emissions under fuel-lean ammonia/air conditions. Higher Reynolds numbers increase the fuel supply and combustion power of the methane/air flame but paradoxically destabilize the flame and lead to higher NOx emissions. Numerical simulations reveal the mechanisms underlying these observations. While higher Reynolds numbers increase energy and turbulence in the outer flame, they also intensify shear layer dynamics and turbulence-induced flame stretch. These effects promote localized flame quenching, disrupting the flame structure despite the additional energy in the system. Local extinction of the outer flame at high Reynolds numbers allows unburned methane/air to mix with the inner ammonia/air stream. This mixing raises the concentration of H and OH radicals in the reaction zones, promoting NO formation via the HNO pathway (e.g., HNO + H = NO + H2). To minimize NOx emissions in the double-swirler coflame burner, preventing local extinction and limiting partial mixing between the methane/air and ammonia/air streams are essential.

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organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Ammonia, Decarbonization, Double-swirl burner, Local flame extinction, NOx emission
in
Fuel
volume
414
article number
138356
publisher
Elsevier
external identifiers
  • scopus:105027554518
ISSN
0016-2361
DOI
10.1016/j.fuel.2026.138356
language
English
LU publication?
yes
additional info
Publisher Copyright: © 2026 Elsevier Ltd.
id
dc4d2ace-43db-4881-8389-efcdbfa3635b
date added to LUP
2026-03-10 13:30:48
date last changed
2026-03-12 15:45:19
@article{dc4d2ace-43db-4881-8389-efcdbfa3635b,
  abstract     = {{<p>A double-swirler ammonia/methane co-flame burner was developed to enhance flame stability and reduce NOx emissions in ammonia combustion. In this system, a premixed ammonia/air mixture is introduced through the inner swirler, while a lean premixed methane/air flame from the outer swirler stabilizes the ammonia/air flame. Experimental results highlight that the Reynolds number of the outer methane/air flame strongly affects flame stability and NOx emissions under fuel-lean ammonia/air conditions. Higher Reynolds numbers increase the fuel supply and combustion power of the methane/air flame but paradoxically destabilize the flame and lead to higher NOx emissions. Numerical simulations reveal the mechanisms underlying these observations. While higher Reynolds numbers increase energy and turbulence in the outer flame, they also intensify shear layer dynamics and turbulence-induced flame stretch. These effects promote localized flame quenching, disrupting the flame structure despite the additional energy in the system. Local extinction of the outer flame at high Reynolds numbers allows unburned methane/air to mix with the inner ammonia/air stream. This mixing raises the concentration of H and OH radicals in the reaction zones, promoting NO formation via the HNO pathway (e.g., HNO + H = NO + H<sub>2</sub>). To minimize NOx emissions in the double-swirler coflame burner, preventing local extinction and limiting partial mixing between the methane/air and ammonia/air streams are essential.</p>}},
  author       = {{Zhou, Yuchen and Sjögren, Carl Otto Olsson and Xu, Leilei and Hassan, Zubayr O. and AlSuhaibani, Abduk Rahman and Solami, Bandar H. and Jamal, Aqil and Siddiqui, Osamah and Roberts, William L. and Bai, Xue Song and Elbaz, Ayman M.}},
  issn         = {{0016-2361}},
  keywords     = {{Ammonia; Decarbonization; Double-swirl burner; Local flame extinction; NOx emission}},
  language     = {{eng}},
  month        = {{01}},
  publisher    = {{Elsevier}},
  series       = {{Fuel}},
  title        = {{Ammonia/methane flame interaction and NO<sub>x</sub> emission in a double-swirler burner}},
  url          = {{http://dx.doi.org/10.1016/j.fuel.2026.138356}},
  doi          = {{10.1016/j.fuel.2026.138356}},
  volume       = {{414}},
  year         = {{2026}},
}