Plasma-assisted NH3/air flame : Simultaneous LIF measurements of O and OH
(2024) In Combustion and Flame 266.- Abstract
- In the emerging field of plasma-assisted ammonia (NH3) combustion, the evolution of key intermediate species has rarely been reported. This work establishes a simultaneous measurement system of laser-induced fluorescence (LIF) for hydroxyl (OH) and quantitative two-photon-absorption LIF for atomic oxygen (O), to explore the OH and O dynamics in an NH3/air flame affected by a nanosecond (ns) pulsed plasma discharge. Firstly, with the plasma on, the molar fraction of O is quantified to reach 8.7 × 10–3 in the burnt zone, about two orders of magnitude higher than that without plasma. In addition, the OH LIF signal intensity is four times higher, indicating a significant kinetic enhancement. Then, the spatial characteristics of OH and O are... (More)
- In the emerging field of plasma-assisted ammonia (NH3) combustion, the evolution of key intermediate species has rarely been reported. This work establishes a simultaneous measurement system of laser-induced fluorescence (LIF) for hydroxyl (OH) and quantitative two-photon-absorption LIF for atomic oxygen (O), to explore the OH and O dynamics in an NH3/air flame affected by a nanosecond (ns) pulsed plasma discharge. Firstly, with the plasma on, the molar fraction of O is quantified to reach 8.7 × 10–3 in the burnt zone, about two orders of magnitude higher than that without plasma. In addition, the OH LIF signal intensity is four times higher, indicating a significant kinetic enhancement. Then, the spatial characteristics of OH and O are discussed and compared, showing remarkable discrepancy. The discrepancy between them indicates that O production is dominated by plasma kinetics, however, the OH production, primarily stemming from reactions between O and NH3/H2O, still depends on parameters associated with combustion kinetics. We further study the temporal dynamics of O and OH. It is concluded that O and OH peaks at 1.75 μs are mainly attributed to the pathway of quenching of the excited species. After that, O and OH start to decay but show significant differences between unburnt and burnt zones, which are characterized by a single-exponential decay and a bi-exponential decay, respectively. In the unburnt zone, the OH decay is much slower than the O decay due to the diverse pathways for OH production. In the burnt zone, the bi-exponential decay of O and OH can essentially be regarded as a process in which the NH3/air reactive system reaches chemical equilibrium. At this stage, the impacts of the excited species from the plasma gradually diminish and combustion kinetics dominates alone. © 2024 The Author(s) (Less)
Please use this url to cite or link to this publication:
https://lup.lub.lu.se/record/adc97f8a-23e3-4410-af01-5514cd6f3d50
- author
- Sun, Jinguo
LU
; Bao, Yupan LU ; Ravelid, Jonas LU ; Konnov, Alexander A LU and Ehn, Andreas LU
- organization
- publishing date
- 2024
- type
- Contribution to journal
- publication status
- published
- subject
- in
- Combustion and Flame
- volume
- 266
- article number
- 113529
- pages
- 8 pages
- publisher
- Elsevier
- external identifiers
-
- scopus:85194500301
- ISSN
- 0010-2180
- DOI
- 10.1016/j.combustflame.2024.113529
- language
- English
- LU publication?
- yes
- id
- adc97f8a-23e3-4410-af01-5514cd6f3d50
- date added to LUP
- 2024-07-30 10:28:14
- date last changed
- 2024-08-13 08:29:25
@article{adc97f8a-23e3-4410-af01-5514cd6f3d50, abstract = {{In the emerging field of plasma-assisted ammonia (NH3) combustion, the evolution of key intermediate species has rarely been reported. This work establishes a simultaneous measurement system of laser-induced fluorescence (LIF) for hydroxyl (OH) and quantitative two-photon-absorption LIF for atomic oxygen (O), to explore the OH and O dynamics in an NH3/air flame affected by a nanosecond (ns) pulsed plasma discharge. Firstly, with the plasma on, the molar fraction of O is quantified to reach 8.7 × 10–3 in the burnt zone, about two orders of magnitude higher than that without plasma. In addition, the OH LIF signal intensity is four times higher, indicating a significant kinetic enhancement. Then, the spatial characteristics of OH and O are discussed and compared, showing remarkable discrepancy. The discrepancy between them indicates that O production is dominated by plasma kinetics, however, the OH production, primarily stemming from reactions between O and NH3/H2O, still depends on parameters associated with combustion kinetics. We further study the temporal dynamics of O and OH. It is concluded that O and OH peaks at 1.75 μs are mainly attributed to the pathway of quenching of the excited species. After that, O and OH start to decay but show significant differences between unburnt and burnt zones, which are characterized by a single-exponential decay and a bi-exponential decay, respectively. In the unburnt zone, the OH decay is much slower than the O decay due to the diverse pathways for OH production. In the burnt zone, the bi-exponential decay of O and OH can essentially be regarded as a process in which the NH3/air reactive system reaches chemical equilibrium. At this stage, the impacts of the excited species from the plasma gradually diminish and combustion kinetics dominates alone. © 2024 The Author(s)}}, author = {{Sun, Jinguo and Bao, Yupan and Ravelid, Jonas and Konnov, Alexander A and Ehn, Andreas}}, issn = {{0010-2180}}, language = {{eng}}, publisher = {{Elsevier}}, series = {{Combustion and Flame}}, title = {{Plasma-assisted NH3/air flame : Simultaneous LIF measurements of O and OH}}, url = {{http://dx.doi.org/10.1016/j.combustflame.2024.113529}}, doi = {{10.1016/j.combustflame.2024.113529}}, volume = {{266}}, year = {{2024}}, }