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Measurements of the laminar burning velocities of NH3/H2/O2/CO2 mixtures and kinetic insights into CO2 and H2 effects

Lin, Qianjin LU ; Guo, Liqing ; Chen, Lijuan ; Wei, Bo ; Zou, Chun ; Wang, Jianjiang and Konnov, Alexander A. LU (2026) In International Journal of Hydrogen Energy 229.
Abstract

Combustion of NH3 with H2 addition can improve the combustion stability. In this study, the laminar burning velocities (LBVs) of NH3/H2/O2/CO2 mixtures were determined under atmospheric pressure and an initial temperature of 303 K by the heat flux method, spanning CO2 fractions of 0.50-0.75, H2 fractions of 0.20-0.70, and equivalence ratios of 0.6-1.5. Evaluations of three kinetic models (modified HUST, Shi et al. model from SJTU, and Zhu et al. model) by the new LBV data demonstrated that the modified HUST model well predicts the experimental data across all conditions, while the Shi et al. model notably underpredicts the LBVs under all equivalence... (More)

Combustion of NH3 with H2 addition can improve the combustion stability. In this study, the laminar burning velocities (LBVs) of NH3/H2/O2/CO2 mixtures were determined under atmospheric pressure and an initial temperature of 303 K by the heat flux method, spanning CO2 fractions of 0.50-0.75, H2 fractions of 0.20-0.70, and equivalence ratios of 0.6-1.5. Evaluations of three kinetic models (modified HUST, Shi et al. model from SJTU, and Zhu et al. model) by the new LBV data demonstrated that the modified HUST model well predicts the experimental data across all conditions, while the Shi et al. model notably underpredicts the LBVs under all equivalence ratios due to overestimation of NH2 + OH <=> NH + H2O, and the Zhu et al. model overpredicts LBVs on the fuel-rich side due to slight overestimation of NH2 + NH <=> N2H2 + H. Nonlinear variations of LBVs with CO2 and H2 amounts in the mixtures were observed in both simulations and experiments. Decoupling chemical, thermal, and transport effects indicated that the suppressing effects of CO2 on thermal and transport processes plateau with CO2 fraction, while the chemical inhibition of CO2 nonlinearly diminishes with CO2 concentration. This diminished inhibition results from the reaction flux ratio of NH2 + H <=> NH + H2 and NH2 + O <=> HNO + H versus NH2 + NO <=> NNH + OH being reduced (promoting flame propagation). Separating chemical, thermal, and transport effects indicated that the chemical promotion effect of H2 is remarkably significant, since the H2 addition increases concentrations of OH, H, and O radicals, which in turn promote the overall oxidation rates of both H2 and NH3.

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author
; ; ; ; ; and
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Heat flux burner, Kinetic model, Laminar burning velocity, NH/H/O/COmixtures
in
International Journal of Hydrogen Energy
volume
229
article number
154611
publisher
Elsevier
external identifiers
  • scopus:105034743335
ISSN
0360-3199
DOI
10.1016/j.ijhydene.2026.154611
language
English
LU publication?
yes
id
b5f31f8f-4c3d-4e9c-9add-17488cf16f93
date added to LUP
2026-06-08 11:59:07
date last changed
2026-06-08 11:59:40
@article{b5f31f8f-4c3d-4e9c-9add-17488cf16f93,
  abstract     = {{<p>Combustion of NH<sub>3</sub> with H<sub>2</sub> addition can improve the combustion stability. In this study, the laminar burning velocities (LBVs) of NH<sub>3</sub>/H<sub>2</sub>/O<sub>2</sub>/CO<sub>2</sub> mixtures were determined under atmospheric pressure and an initial temperature of 303 K by the heat flux method, spanning CO<sub>2</sub> fractions of 0.50-0.75, H<sub>2</sub> fractions of 0.20-0.70, and equivalence ratios of 0.6-1.5. Evaluations of three kinetic models (modified HUST, Shi et al. model from SJTU, and Zhu et al. model) by the new LBV data demonstrated that the modified HUST model well predicts the experimental data across all conditions, while the Shi et al. model notably underpredicts the LBVs under all equivalence ratios due to overestimation of NH<sub>2</sub> + OH &lt;=&gt; NH + H<sub>2</sub>O, and the Zhu et al. model overpredicts LBVs on the fuel-rich side due to slight overestimation of NH<sub>2</sub> + NH &lt;=&gt; N<sub>2</sub>H<sub>2</sub> + H. Nonlinear variations of LBVs with CO<sub>2</sub> and H<sub>2</sub> amounts in the mixtures were observed in both simulations and experiments. Decoupling chemical, thermal, and transport effects indicated that the suppressing effects of CO<sub>2</sub> on thermal and transport processes plateau with CO<sub>2</sub> fraction, while the chemical inhibition of CO<sub>2</sub> nonlinearly diminishes with CO<sub>2</sub> concentration. This diminished inhibition results from the reaction flux ratio of NH<sub>2</sub> + H &lt;=&gt; NH + H<sub>2</sub> and NH<sub>2</sub> + O &lt;=&gt; HNO + H versus NH<sub>2</sub> + NO &lt;=&gt; NNH + OH being reduced (promoting flame propagation). Separating chemical, thermal, and transport effects indicated that the chemical promotion effect of H<sub>2</sub> is remarkably significant, since the H<sub>2</sub> addition increases concentrations of OH, H, and O radicals, which in turn promote the overall oxidation rates of both H<sub>2</sub> and NH<sub>3</sub>.</p>}},
  author       = {{Lin, Qianjin and Guo, Liqing and Chen, Lijuan and Wei, Bo and Zou, Chun and Wang, Jianjiang and Konnov, Alexander A.}},
  issn         = {{0360-3199}},
  keywords     = {{Heat flux burner; Kinetic model; Laminar burning velocity; NH/H/O/COmixtures}},
  language     = {{eng}},
  publisher    = {{Elsevier}},
  series       = {{International Journal of Hydrogen Energy}},
  title        = {{Measurements of the laminar burning velocities of NH<sub>3</sub>/H<sub>2</sub>/O<sub>2</sub>/CO<sub>2</sub> mixtures and kinetic insights into CO<sub>2</sub> and H<sub>2</sub> effects}},
  url          = {{http://dx.doi.org/10.1016/j.ijhydene.2026.154611}},
  doi          = {{10.1016/j.ijhydene.2026.154611}},
  volume       = {{229}},
  year         = {{2026}},
}