Uncertainty quantification of ion chemistry in lean and stoichiometric homogenous mixtures of methane, oxygen, and argon

Uncertainty quantification (UQ) methods are implemented to obtain a quantitative characterization of the evolution of electrons and ions during the ignition of methane–oxygen mixtures under lean and stoichiometric conditions. The GRI-Mech 3.0 mechanism is combined with an extensive set of ion chemis...

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Main Authors: Kim, Daesang, Rizzi, Francesco, Cheng, Kwok Wah, Han, Jie, Bisetti, Fabrizio, Knio, Omar Mohamad
Other Authors: School of Civil and Environmental Engineering
Format: Article
Language:English
Published: 2015
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Online Access:https://hdl.handle.net/10356/106367
http://hdl.handle.net/10220/34962
http://dx.doi.org/10.1016/j.combustflame.2015.03.013
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Institution: Nanyang Technological University
Language: English
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spelling sg-ntu-dr.10356-1063672019-12-06T22:09:59Z Uncertainty quantification of ion chemistry in lean and stoichiometric homogenous mixtures of methane, oxygen, and argon Kim, Daesang Rizzi, Francesco Cheng, Kwok Wah Han, Jie Bisetti, Fabrizio Knio, Omar Mohamad School of Civil and Environmental Engineering DRNTU::Engineering::Environmental engineering Uncertainty quantification (UQ) methods are implemented to obtain a quantitative characterization of the evolution of electrons and ions during the ignition of methane–oxygen mixtures under lean and stoichiometric conditions. The GRI-Mech 3.0 mechanism is combined with an extensive set of ion chemistry pathways and the forward propagation of uncertainty from model parameters to observables is performed using response surfaces. The UQ analysis considers 22 uncertain rate parameters, which include both chemi-ionization, proton transfer, and electron attachment reactions as well as neutral reactions pertaining to the chemistry of the CH radical. The uncertainty ranges for each rate parameter are discussed. Our results indicate that the uncertainty in the time evolution of the electron number density is due mostly to the chemi-ionization reaction CH + O ⇌ HCO+ + E− and to the main CH consumption reaction CH + O2 ⇌ O + HCO. Similar conclusions hold for the hydronium ion H3O+, since electrons and H3O+ account for more than 99% of the total negative and positive charge density, respectively. Surprisingly, the statistics of the number density of charged species show very little sensitivity to the uncertainty in the rate of the recombination reaction H3O+ + E− → products, until very late in the decay process, when the electron number density has fallen below 20% of its peak value. Finally, uncertainties in the secondary reactions within networks leading to the formation of minor ions (e.g., C2H3O+, HCO+, OH−, and O−) do not play any role in controlling the mean and variance of electrons and H3O+, but do affect the statistics of the minor ions significantly. The observed trends point to the role of key neutral reactions in controlling the mean and variance of the charged species number density in an indirect fashion. Furthermore, total sensitivity indices provide quantitative metrics to focus future efforts aiming at improving the rates of key reactions responsible for the formation of charges during hydrocarbon combustion. Accepted version 2015-07-14T01:09:27Z 2019-12-06T22:09:59Z 2015-07-14T01:09:27Z 2019-12-06T22:09:59Z 2015 2015 Journal Article Kim, D., Rizzi, F., Cheng, K. W., Han, J., Bisetti, F., & Knio, O. M. (2015). Uncertainty quantification of ion chemistry in lean and stoichiometric homogenous mixtures of methane, oxygen, and argon. Combustion and flame, 162(7), 2904-2915. 0010-2180 https://hdl.handle.net/10356/106367 http://hdl.handle.net/10220/34962 http://dx.doi.org/10.1016/j.combustflame.2015.03.013 en Combustion and flame © 2015 Elsevier. This is the author created version of a work that has been peer reviewed and accepted for publication by Combustion and Flame, Elsevier. It incorporates referee’s comments but changes resulting from the publishing process, such as copyediting, structural formatting, may not be reflected in this document. The published version is available at: [http://dx.doi.org/10.1016/j.combustflame.2015.03.013]. 49 p. application/pdf
institution Nanyang Technological University
building NTU Library
country Singapore
collection DR-NTU
language English
topic DRNTU::Engineering::Environmental engineering
spellingShingle DRNTU::Engineering::Environmental engineering
Kim, Daesang
Rizzi, Francesco
Cheng, Kwok Wah
Han, Jie
Bisetti, Fabrizio
Knio, Omar Mohamad
Uncertainty quantification of ion chemistry in lean and stoichiometric homogenous mixtures of methane, oxygen, and argon
description Uncertainty quantification (UQ) methods are implemented to obtain a quantitative characterization of the evolution of electrons and ions during the ignition of methane–oxygen mixtures under lean and stoichiometric conditions. The GRI-Mech 3.0 mechanism is combined with an extensive set of ion chemistry pathways and the forward propagation of uncertainty from model parameters to observables is performed using response surfaces. The UQ analysis considers 22 uncertain rate parameters, which include both chemi-ionization, proton transfer, and electron attachment reactions as well as neutral reactions pertaining to the chemistry of the CH radical. The uncertainty ranges for each rate parameter are discussed. Our results indicate that the uncertainty in the time evolution of the electron number density is due mostly to the chemi-ionization reaction CH + O ⇌ HCO+ + E− and to the main CH consumption reaction CH + O2 ⇌ O + HCO. Similar conclusions hold for the hydronium ion H3O+, since electrons and H3O+ account for more than 99% of the total negative and positive charge density, respectively. Surprisingly, the statistics of the number density of charged species show very little sensitivity to the uncertainty in the rate of the recombination reaction H3O+ + E− → products, until very late in the decay process, when the electron number density has fallen below 20% of its peak value. Finally, uncertainties in the secondary reactions within networks leading to the formation of minor ions (e.g., C2H3O+, HCO+, OH−, and O−) do not play any role in controlling the mean and variance of electrons and H3O+, but do affect the statistics of the minor ions significantly. The observed trends point to the role of key neutral reactions in controlling the mean and variance of the charged species number density in an indirect fashion. Furthermore, total sensitivity indices provide quantitative metrics to focus future efforts aiming at improving the rates of key reactions responsible for the formation of charges during hydrocarbon combustion.
author2 School of Civil and Environmental Engineering
author_facet School of Civil and Environmental Engineering
Kim, Daesang
Rizzi, Francesco
Cheng, Kwok Wah
Han, Jie
Bisetti, Fabrizio
Knio, Omar Mohamad
format Article
author Kim, Daesang
Rizzi, Francesco
Cheng, Kwok Wah
Han, Jie
Bisetti, Fabrizio
Knio, Omar Mohamad
author_sort Kim, Daesang
title Uncertainty quantification of ion chemistry in lean and stoichiometric homogenous mixtures of methane, oxygen, and argon
title_short Uncertainty quantification of ion chemistry in lean and stoichiometric homogenous mixtures of methane, oxygen, and argon
title_full Uncertainty quantification of ion chemistry in lean and stoichiometric homogenous mixtures of methane, oxygen, and argon
title_fullStr Uncertainty quantification of ion chemistry in lean and stoichiometric homogenous mixtures of methane, oxygen, and argon
title_full_unstemmed Uncertainty quantification of ion chemistry in lean and stoichiometric homogenous mixtures of methane, oxygen, and argon
title_sort uncertainty quantification of ion chemistry in lean and stoichiometric homogenous mixtures of methane, oxygen, and argon
publishDate 2015
url https://hdl.handle.net/10356/106367
http://hdl.handle.net/10220/34962
http://dx.doi.org/10.1016/j.combustflame.2015.03.013
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