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Chemical kinetic modelling of ammonia/hydrogen/air ignition, premixed flame propagation and NO emission

da Rocha, Rodolfo Cavaliere LU ; Costa, Mário and Bai, Xue Song LU (2019) In Fuel 246. p.24-33
Abstract


This work reports on a study of chemical kinetic modelling of ammonia/hydrogen/air ignition, premixed flame propagation and NO emission. A survey of chemical mechanisms available in the literature was first conducted, and the performance of 10 mechanisms was analysed in terms of the prediction of shock tube ignition delay times, laminar flame speeds and NO
x
concentrations for NH
3
/air and NH ... (More)


This work reports on a study of chemical kinetic modelling of ammonia/hydrogen/air ignition, premixed flame propagation and NO emission. A survey of chemical mechanisms available in the literature was first conducted, and the performance of 10 mechanisms was analysed in terms of the prediction of shock tube ignition delay times, laminar flame speeds and NO
x
concentrations for NH
3
/air and NH
3
/H
2
/air flames for a wide range of operating conditions. Then, three of these mechanisms were reduced and their performance compared against the behaviour of the original mechanisms. The results confirm that pure NH
3
flames have high ignition delay times and rather low flame speeds, and that the addition of H
2
to NH
3
flames increases exponentially the flame speed, and significantly the NO
x
emission. The currently available chemical kinetic mechanisms predict rather scattered ignition delay times, laminar flame speeds, and NO
x
concentrations in NH
3
flames, indicating that improvements in the sub-mechanisms of NH
3
and NH
3
/H
2
oxidation are still needed. Sensitivity analysis for NO formation indicates that NO formation in NH
3
flames is mainly produced through the NH
3
/O
2
chemical process, and sensitivity analysis for flame speed reveals that the differences among mechanisms are due to the relative importance of the reactions of the NNH and HNO sub-mechanisms. The reduced mechanisms show high fidelity when compared with the original ones, despite some discrepancies at high pressures.

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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Ammonia/hydrogen/air flames, Chemical kinetic modelling, Flame speed, Ignition, NO emission
in
Fuel
volume
246
pages
10 pages
publisher
Elsevier
external identifiers
  • scopus:85061982086
ISSN
0016-2361
DOI
10.1016/j.fuel.2019.02.102
language
English
LU publication?
yes
id
0f997bf7-fb59-4c26-84ec-1c92c78f1762
date added to LUP
2019-03-05 13:39:48
date last changed
2019-09-17 04:49:41
@article{0f997bf7-fb59-4c26-84ec-1c92c78f1762,
  abstract     = {<p><br>
                                                         This work reports on a study of chemical kinetic modelling of ammonia/hydrogen/air ignition, premixed flame propagation and NO emission. A survey of chemical mechanisms available in the literature was first conducted, and the performance of 10 mechanisms was analysed in terms of the prediction of shock tube ignition delay times, laminar flame speeds and NO                             <br>
                            <sub>x</sub><br>
                                                          concentrations for NH                             <br>
                            <sub>3</sub><br>
                                                         /air and NH                             <br>
                            <sub>3</sub><br>
                                                         /H                             <br>
                            <sub>2</sub><br>
                                                         /air flames for a wide range of operating conditions. Then, three of these mechanisms were reduced and their performance compared against the behaviour of the original mechanisms. The results confirm that pure NH                             <br>
                            <sub>3</sub><br>
                                                          flames have high ignition delay times and rather low flame speeds, and that the addition of H                             <br>
                            <sub>2</sub><br>
                                                          to NH                             <br>
                            <sub>3</sub><br>
                                                          flames increases exponentially the flame speed, and significantly the NO                             <br>
                            <sub>x</sub><br>
                                                          emission. The currently available chemical kinetic mechanisms predict rather scattered ignition delay times, laminar flame speeds, and NO                             <br>
                            <sub>x</sub><br>
                                                          concentrations in NH                             <br>
                            <sub>3</sub><br>
                                                          flames, indicating that improvements in the sub-mechanisms of NH                             <br>
                            <sub>3</sub><br>
                                                          and NH                             <br>
                            <sub>3</sub><br>
                                                         /H                             <br>
                            <sub>2</sub><br>
                                                          oxidation are still needed. Sensitivity analysis for NO formation indicates that NO formation in NH                             <br>
                            <sub>3</sub><br>
                                                          flames is mainly produced through the NH                             <br>
                            <sub>3</sub><br>
                                                         /O                             <br>
                            <sub>2</sub><br>
                                                          chemical process, and sensitivity analysis for flame speed reveals that the differences among mechanisms are due to the relative importance of the reactions of the NNH and HNO sub-mechanisms. The reduced mechanisms show high fidelity when compared with the original ones, despite some discrepancies at high pressures.                         <br>
                        </p>},
  author       = {da Rocha, Rodolfo Cavaliere and Costa, Mário and Bai, Xue Song},
  issn         = {0016-2361},
  keyword      = {Ammonia/hydrogen/air flames,Chemical kinetic modelling,Flame speed,Ignition,NO emission},
  language     = {eng},
  pages        = {24--33},
  publisher    = {Elsevier},
  series       = {Fuel},
  title        = {Chemical kinetic modelling of ammonia/hydrogen/air ignition, premixed flame propagation and NO emission},
  url          = {http://dx.doi.org/10.1016/j.fuel.2019.02.102},
  volume       = {246},
  year         = {2019},
}