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On the role of excited species in hydrogen combustion

Konnov, Alexander LU (2015) In Combustion and Flame 162(10). p.3755-3772
Abstract
Recently updated hydrogen combustion mechanism was combined with ozone decomposition reactions and extended by reactions of excited species: O(D-1), OH((2)Sigma(+)), and O-2(a(1)Delta g). The reliability and the accuracy of the rate constants pertinent to these excited species were evaluated. Many reactions proposed in the literature and implemented in other kinetic schemes were found irrelevant or insignificant. The new mechanism for hydrogen combustion was then validated against commonly accepted sets of laboratory experiments. It was expected that new reactions incorporated into the model should not affect its predicting ability for "thermal" combustion of H-2, i.e. in the absence of excited species in the initial mixtures. The model... (More)
Recently updated hydrogen combustion mechanism was combined with ozone decomposition reactions and extended by reactions of excited species: O(D-1), OH((2)Sigma(+)), and O-2(a(1)Delta g). The reliability and the accuracy of the rate constants pertinent to these excited species were evaluated. Many reactions proposed in the literature and implemented in other kinetic schemes were found irrelevant or insignificant. The new mechanism for hydrogen combustion was then validated against commonly accepted sets of laboratory experiments. It was expected that new reactions incorporated into the model should not affect its predicting ability for "thermal" combustion of H-2, i.e. in the absence of excited species in the initial mixtures. The model validation showed that predictions of ignition, oxidation, flame burning velocities and flame structure of hydrogenoxygen-inert mixtures are indistinguishable or very close to those of the basic mechanism at all condition, except for hydrogen oxidation in a flow reactor close to explosion limit. It was further demonstrated that singlet oxygen formed in reaction H-2 + O-2(1 Delta) = H + HO2 at ppm levels may notably accelerate the process. Kinetic role of O(D-1) and OH((2)Sigma(+)) in the "thermal" combustion of H-2 was found negligible. In addition, hydrogen + air flame enhancement by singlet oxygen was modeled. It was demonstrated that the burning velocity increase with 1% of O-2(a(1)Delta g) seeded into the air is rather modest. Moreover, purely thermal effect due to additional enthalpy brought to the mixture exceeds chemical flame enhancement by the singlet oxygen. (C) 2015 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
Hydrogen, Ozone, Singlet oxygen, Kinetic mechanism, Ignition, Oxidation, Flame
in
Combustion and Flame
volume
162
issue
10
pages
3755 - 3772
publisher
Elsevier
external identifiers
  • wos:000361925600026
  • scopus:84946471161
ISSN
0010-2180
DOI
10.1016/j.combustflame.2015.07.014
language
English
LU publication?
yes
id
35afc0d0-7ec2-45ad-bcd4-28710e86f441 (old id 8221380)
date added to LUP
2015-11-30 13:52:29
date last changed
2017-04-09 03:48:10
@article{35afc0d0-7ec2-45ad-bcd4-28710e86f441,
  abstract     = {Recently updated hydrogen combustion mechanism was combined with ozone decomposition reactions and extended by reactions of excited species: O(D-1), OH((2)Sigma(+)), and O-2(a(1)Delta g). The reliability and the accuracy of the rate constants pertinent to these excited species were evaluated. Many reactions proposed in the literature and implemented in other kinetic schemes were found irrelevant or insignificant. The new mechanism for hydrogen combustion was then validated against commonly accepted sets of laboratory experiments. It was expected that new reactions incorporated into the model should not affect its predicting ability for "thermal" combustion of H-2, i.e. in the absence of excited species in the initial mixtures. The model validation showed that predictions of ignition, oxidation, flame burning velocities and flame structure of hydrogenoxygen-inert mixtures are indistinguishable or very close to those of the basic mechanism at all condition, except for hydrogen oxidation in a flow reactor close to explosion limit. It was further demonstrated that singlet oxygen formed in reaction H-2 + O-2(1 Delta) = H + HO2 at ppm levels may notably accelerate the process. Kinetic role of O(D-1) and OH((2)Sigma(+)) in the "thermal" combustion of H-2 was found negligible. In addition, hydrogen + air flame enhancement by singlet oxygen was modeled. It was demonstrated that the burning velocity increase with 1% of O-2(a(1)Delta g) seeded into the air is rather modest. Moreover, purely thermal effect due to additional enthalpy brought to the mixture exceeds chemical flame enhancement by the singlet oxygen. (C) 2015 The Combustion Institute. Published by Elsevier Inc. All rights reserved.},
  author       = {Konnov, Alexander},
  issn         = {0010-2180},
  keyword      = {Hydrogen,Ozone,Singlet oxygen,Kinetic mechanism,Ignition,Oxidation,Flame},
  language     = {eng},
  number       = {10},
  pages        = {3755--3772},
  publisher    = {Elsevier},
  series       = {Combustion and Flame},
  title        = {On the role of excited species in hydrogen combustion},
  url          = {http://dx.doi.org/10.1016/j.combustflame.2015.07.014},
  volume       = {162},
  year         = {2015},
}