Experimental and kinetic modeling study of laminar burning velocity enhancement by ozone additive in NH3+O2+N2 and NH3+CH4/C2H6/C3H8+air flames
(2023) In Proceedings of the Combustion Institute 39(4). p.4237-4246- Abstract
Ammonia (NH3) is regarded as a promising future carbon-free fuel but needs to overcome drawbacks including extremely low burning velocity in practical combustion apparatus. In this study, ozone (O3) additive is used to elucidate one of the mechanisms of potential flame enhancement method based on plasma-assisted combustion. The effects of ozone addition on the laminar burning velocity of premixed NH3/(35%O2/65%N2) and NH3+ CH4/C2H6/C3H8+air flames over a wide range of equivalence ratios were investigated experimentally and numerically. Blending NH3 with hydrocarbons can decrease the ignition energy and... (More)
Ammonia (NH3) is regarded as a promising future carbon-free fuel but needs to overcome drawbacks including extremely low burning velocity in practical combustion apparatus. In this study, ozone (O3) additive is used to elucidate one of the mechanisms of potential flame enhancement method based on plasma-assisted combustion. The effects of ozone addition on the laminar burning velocity of premixed NH3/(35%O2/65%N2) and NH3+ CH4/C2H6/C3H8+air flames over a wide range of equivalence ratios were investigated experimentally and numerically. Blending NH3 with hydrocarbons can decrease the ignition energy and increase the burning velocities of the whole mixture, which may contribute to developing ammonia co-fired mechanisms with varied complex fuels and validating the feasibility of NH3 using strategies in real applications. Measurements were conducted at atmospheric conditions using the Heat Flux method. For NH3/(35%O2/65%N2) flames, a significant increase was found on the fuel-lean side. Experimental data showed that maximum enhancement reaches 15.34% at π=0.6 with 5000 ppm O3 additive. For NH3+CH4/C2H6/C3H8+air blended flames, the enhancement effect was much more profound under off-stoichiometric conditions, being 1.5-4 times higher than that under near-stoichiometric conditions. A 28-step O3 related kinetic sub-mechanism was integrated with five selected NH3-oxidation mechanisms to simulate the burning velocities of NH3/(35%O2/65%N2) flames and CEU-Mech for NH3+CH4/C2H6/C3H8+air flames. Simulation results show improved agreement with the experimental data, especially for fuel-rich conditions as NH3 blending ratio xNH3 increases from 0 to 0.9. Each of the NH3/CH4/air, NH3/C2H6/air and NH3/C3H8/air cases fits well between experimental data and numerical results with varied NH3-fuel blending ratios. Detailed kinetic analyses adopting the CEU-NH3-Mech integrated with O3 sub-mechanism were carried out and revealed that active radicals such as HNO, which are rapidly produced due to high O concentration from O3 decomposing in the pre-heating zone, interfered with the ammonia-fuel chemistry and thus evidently promoted the overall combustion process.
(Less)
- author
- Chen, Chenlin ; Wang, Zhihua ; Yu, Zuochao ; Han, Xinlu LU ; He, Yong ; Zhu, Yanqun and Konnov, Alexander A. LU
- organization
- publishing date
- 2023
- type
- Contribution to journal
- publication status
- published
- subject
- keywords
- Ammonia flame, Combustion enhancement, Heat flux method, Laminar burning velocity, Ozone
- in
- Proceedings of the Combustion Institute
- volume
- 39
- issue
- 4
- pages
- 4237 - 4246
- publisher
- Elsevier
- external identifiers
-
- scopus:85135822512
- ISSN
- 1540-7489
- DOI
- 10.1016/j.proci.2022.07.025
- language
- English
- LU publication?
- yes
- id
- ee1bf11d-b71c-4735-8481-e273adb87d61
- date added to LUP
- 2022-10-18 15:42:24
- date last changed
- 2023-11-06 17:10:04
@article{ee1bf11d-b71c-4735-8481-e273adb87d61,
abstract = {{<p>Ammonia (NH<sub>3</sub>) is regarded as a promising future carbon-free fuel but needs to overcome drawbacks including extremely low burning velocity in practical combustion apparatus. In this study, ozone (O<sub>3</sub>) additive is used to elucidate one of the mechanisms of potential flame enhancement method based on plasma-assisted combustion. The effects of ozone addition on the laminar burning velocity of premixed NH<sub>3</sub>/(35%O<sub>2</sub>/65%N<sub>2</sub>) and NH<sub>3</sub>+ CH<sub>4</sub>/C<sub>2</sub>H<sub>6</sub>/C<sub>3</sub>H<sub>8</sub>+air flames over a wide range of equivalence ratios were investigated experimentally and numerically. Blending NH<sub>3</sub> with hydrocarbons can decrease the ignition energy and increase the burning velocities of the whole mixture, which may contribute to developing ammonia co-fired mechanisms with varied complex fuels and validating the feasibility of NH<sub>3</sub> using strategies in real applications. Measurements were conducted at atmospheric conditions using the Heat Flux method. For NH<sub>3</sub>/(35%O<sub>2</sub>/65%N<sub>2</sub>) flames, a significant increase was found on the fuel-lean side. Experimental data showed that maximum enhancement reaches 15.34% at π=0.6 with 5000 ppm O<sub>3</sub> additive. For NH<sub>3</sub>+CH<sub>4</sub>/C<sub>2</sub>H<sub>6</sub>/C<sub>3</sub>H<sub>8</sub>+air blended flames, the enhancement effect was much more profound under off-stoichiometric conditions, being 1.5-4 times higher than that under near-stoichiometric conditions. A 28-step O<sub>3</sub> related kinetic sub-mechanism was integrated with five selected NH<sub>3</sub>-oxidation mechanisms to simulate the burning velocities of NH<sub>3</sub>/(35%O<sub>2</sub>/65%N<sub>2</sub>) flames and CEU-Mech for NH<sub>3</sub>+CH<sub>4</sub>/C<sub>2</sub>H<sub>6</sub>/C<sub>3</sub>H<sub>8</sub>+air flames. Simulation results show improved agreement with the experimental data, especially for fuel-rich conditions as NH<sub>3</sub> blending ratio x<sub>NH3</sub> increases from 0 to 0.9. Each of the NH<sub>3</sub>/CH<sub>4</sub>/air, NH<sub>3</sub>/C<sub>2</sub>H<sub>6</sub>/air and NH<sub>3</sub>/C<sub>3</sub>H<sub>8</sub>/air cases fits well between experimental data and numerical results with varied NH<sub>3</sub>-fuel blending ratios. Detailed kinetic analyses adopting the CEU-NH<sub>3</sub>-Mech integrated with O<sub>3</sub> sub-mechanism were carried out and revealed that active radicals such as HNO, which are rapidly produced due to high O concentration from O<sub>3</sub> decomposing in the pre-heating zone, interfered with the ammonia-fuel chemistry and thus evidently promoted the overall combustion process.</p>}},
author = {{Chen, Chenlin and Wang, Zhihua and Yu, Zuochao and Han, Xinlu and He, Yong and Zhu, Yanqun and Konnov, Alexander A.}},
issn = {{1540-7489}},
keywords = {{Ammonia flame; Combustion enhancement; Heat flux method; Laminar burning velocity; Ozone}},
language = {{eng}},
number = {{4}},
pages = {{4237--4246}},
publisher = {{Elsevier}},
series = {{Proceedings of the Combustion Institute}},
title = {{Experimental and kinetic modeling study of laminar burning velocity enhancement by ozone additive in NH<sub>3</sub>+O<sub>2</sub>+N<sub>2</sub> and NH<sub>3</sub>+CH<sub>4</sub>/C<sub>2</sub>H<sub>6</sub>/C<sub>3</sub>H<sub>8</sub>+air flames}},
url = {{http://dx.doi.org/10.1016/j.proci.2022.07.025}},
doi = {{10.1016/j.proci.2022.07.025}},
volume = {{39}},
year = {{2023}},
}