| 1. |
- Fomin, Alexey, et al.
(författare)
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Experimental and modelling study of 1CH2 in premixed very rich methane flames
- 2016
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Ingår i: Combustion and Flame. - : Elsevier BV. - 0010-2180. ; 171, s. 198-210
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Tidskriftsartikel (refereegranskat)abstract
- Stoichiometric and very rich (1.5 ≤ ɸ ≤ 1.9) laminar flat flames of methane have been investigated using nonintrusive laser diagnostics. Premixed CH4 + O2 + N2 flames were stabilized at a pressure of 30 ± 0.3 Torr. Temperature profiles were obtained using laser-induced fluorescence of OH. Absolute concentration profiles of singlet methylene, 1CH2, were measured by intracavity laser absorption spectroscopy. Uncertainties of the relative and absolute concentrations of singlet methylene were evaluated to be about ±10% and ±30%, respectively. These new experimental data were compared with predictions of three detailed kinetic mechanisms: GRI-mech. 3.0, Aramco mech. 1.3, and the model under development in Lund. In the last mechanism 78 rate constants of reactions along the pathway CH3 → 1CH2 → 3CH2 → CH were reviewed and updated. No adjustment or tuning of the rate expressions to accommodate experimental results was attempted. GRI-mech. significantly overpredicts singlet methylene concentrations in all flames. Aramco mech. and the present model are in good agreement with the measurements in stoichiometric flame, while in all rich flames only the present mechanism reproduces spatial profiles of 1CH2. Detailed analysis of the behaviour of these models revealed that omission of the reaction 1CH2 + M = 3CH2 + M is the main reason of the discrepancy between predictions of the Aramco 1.3 and GRI-mech. 3.0 and experimental 1CH2 concentrations in rich flames.
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| 2. |
- Fomin, Alexey, et al.
(författare)
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Fiber Laser Intracavity Spectroscopy of hot water for temperature and concentration measurements
- 2015
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Ingår i: Applied Physics B. - : Springer Science and Business Media LLC. - 0946-2171 .- 1432-0649. ; 121:3, s. 345-351
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Tidskriftsartikel (refereegranskat)abstract
- The feasibility of temperature and concentration measurements using near-IR (similar to 1.5 mu m) water spectra obtained by fiber laser intracavity spectroscopy was evaluated. The spectra were registered with water vapor heated in a tubular oven at temperatures between 1000 and 1300 K and in adiabatic flames where temperatures were above 1800 K. Adiabatic flames of methane were stabilized on the heat flux burner. For temperature and concentration evaluation, the observed spectra were fitted by simulated spectra calculated utilizing the HITEMP database. Several discrepancies between HITEMP data and the experiments leading to significant errors in evaluation were found. After small corrections to the database better, accuracy of the temperature (+/- 70 K) and concentration (+/- 20 %) measurements is obtained. A more precise spectroscopic assignment is needed to improve the accuracy of the results.
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| 3. |
- Fomin, Alexey, et al.
(författare)
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Intracavity Laser Absorption Spectroscopy Study of HCO Radicals during Methane to Hydrogen Conversion in Very Rich Flames
- 2015
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Ingår i: Energy & Fuels. - : American Chemical Society (ACS). - 0887-0624 .- 1520-5029. ; 29:9, s. 6146-6154
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Tidskriftsartikel (refereegranskat)abstract
- Stoichiometric and very rich flames of methane have been investigated using nonintrusive laser diagnostics. Absolute concentration profiles of HCO were measured by intracavity laser absorption spectroscopy, and temperature profiles were obtained with laser-induced fluorescence of OH. Premixed CH4 + O-2 + N-2 flames were stabilized at a pressure of 30 +/- 0.3 Torr. These new experimental data were compared with predictions of two models: GRI-mech. 3.0 and Aramco mech. 1.3. GRI-mech. performs better in a stoichiometric flame, whereas Aramco mech. is in better agreement with experiments in the rich flames. Detailed analysis of the behavior of these two models revealed that similar performance is essentially fortuitous and explained by balancing of different reactions involved in HCO formation and consumption.
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