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Effects of ambient CO2 and H2O on soot processes in n-dodecane spray combustion using large eddy simulation

Zhang, Min ; Ong, Jiun Cai ; Pang, Kar Mun ; Bai, Xue Song LU and Walther, Jens H. (2022) In Fuel 312.
Abstract

In this study, large eddy simulations, coupled a two-equation soot model, are performed to investigate the effects of ambient carbon dioxide (CO2) and water (H2O) additions on the soot formation and oxidation processes in an n-dodecane spray flame. In the soot model, acetylene (C2H2) is soot precursor and surface growth species, while hydroxyl radical (OH) and oxygen (O2) are soot oxidizers. The effect of ambient CO2 and H2O additions on soot formation/oxidation can be separated into thermal and chemical effects. For the thermal effects, the ambient CO2 and H2O additions increase C2H2 but reduce OH formation by... (More)

In this study, large eddy simulations, coupled a two-equation soot model, are performed to investigate the effects of ambient carbon dioxide (CO2) and water (H2O) additions on the soot formation and oxidation processes in an n-dodecane spray flame. In the soot model, acetylene (C2H2) is soot precursor and surface growth species, while hydroxyl radical (OH) and oxygen (O2) are soot oxidizers. The effect of ambient CO2 and H2O additions on soot formation/oxidation can be separated into thermal and chemical effects. For the thermal effects, the ambient CO2 and H2O additions increase C2H2 but reduce OH formation by lowering the flame temperature. This leads to a higher soot mass formed. On the contrary to the thermal effects, the ambient CO2 and H2O additions reduce the soot formation due to their chemical effects. The reaction CH2∗+CO2↔CH2O+CO is found to be responsible for reducing C2H2 formation. The ambient H2O addition results in a higher OH but lower the C2H2 mass formed owing to the reverse reactions H2+OH↔H2O+H and OH+OH↔H2O+O. Furthermore, the chemical effects is more significant than the thermal effects under the tested conditions. This leads to a lower soot mass formed when adding ambient CO2 and H2O.

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author
; ; ; and
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
CO addition, HO addition, LES, Soot processes, Spray A
in
Fuel
volume
312
article number
122700
publisher
Elsevier
external identifiers
  • scopus:85121242637
ISSN
0016-2361
DOI
10.1016/j.fuel.2021.122700
language
English
LU publication?
yes
id
ae029540-1745-4131-a2e3-fd27c11c4b5a
date added to LUP
2022-01-25 14:19:29
date last changed
2022-04-19 19:23:35
@article{ae029540-1745-4131-a2e3-fd27c11c4b5a,
  abstract     = {{<p>In this study, large eddy simulations, coupled a two-equation soot model, are performed to investigate the effects of ambient carbon dioxide (CO<sub>2</sub>) and water (H<sub>2</sub>O) additions on the soot formation and oxidation processes in an n-dodecane spray flame. In the soot model, acetylene (C<sub>2</sub>H<sub>2</sub>) is soot precursor and surface growth species, while hydroxyl radical (OH) and oxygen (O<sub>2</sub>) are soot oxidizers. The effect of ambient CO<sub>2</sub> and H<sub>2</sub>O additions on soot formation/oxidation can be separated into thermal and chemical effects. For the thermal effects, the ambient CO<sub>2</sub> and H<sub>2</sub>O additions increase C<sub>2</sub>H<sub>2</sub> but reduce OH formation by lowering the flame temperature. This leads to a higher soot mass formed. On the contrary to the thermal effects, the ambient CO<sub>2</sub> and H<sub>2</sub>O additions reduce the soot formation due to their chemical effects. The reaction CH<sub>2</sub><sup>∗</sup>+CO<sub>2</sub>↔CH<sub>2</sub>O+CO is found to be responsible for reducing C<sub>2</sub>H<sub>2</sub> formation. The ambient H<sub>2</sub>O addition results in a higher OH but lower the C<sub>2</sub>H<sub>2</sub> mass formed owing to the reverse reactions H<sub>2</sub>+OH↔H<sub>2</sub>O+H and OH+OH↔H<sub>2</sub>O+O. Furthermore, the chemical effects is more significant than the thermal effects under the tested conditions. This leads to a lower soot mass formed when adding ambient CO<sub>2</sub> and H<sub>2</sub>O.</p>}},
  author       = {{Zhang, Min and Ong, Jiun Cai and Pang, Kar Mun and Bai, Xue Song and Walther, Jens H.}},
  issn         = {{0016-2361}},
  keywords     = {{CO addition; HO addition; LES; Soot processes; Spray A}},
  language     = {{eng}},
  publisher    = {{Elsevier}},
  series       = {{Fuel}},
  title        = {{Effects of ambient CO<sub>2</sub> and H<sub>2</sub>O on soot processes in n-dodecane spray combustion using large eddy simulation}},
  url          = {{http://dx.doi.org/10.1016/j.fuel.2021.122700}},
  doi          = {{10.1016/j.fuel.2021.122700}},
  volume       = {{312}},
  year         = {{2022}},
}