Kinetic parameters, collision rates, energy exchanges and transport coefficients of non-thermal electrons in premixed flames at sub-breakdown electric field strengths

Handle URI:
http://hdl.handle.net/10754/563329
Title:
Kinetic parameters, collision rates, energy exchanges and transport coefficients of non-thermal electrons in premixed flames at sub-breakdown electric field strengths
Authors:
Bisetti, Fabrizio ( 0000-0001-5162-7805 ) ; El Morsli, Mbark
Abstract:
The effects of an electric field on the collision rates, energy exchanges and transport properties of electrons in premixed flames are investigated via solutions to the Boltzmann kinetic equation. The case of high electric field strength, which results in high-energy, non-thermal electrons, is analysed in detail at sub-breakdown conditions. The rates of inelastic collisions and the energy exchange between electrons and neutrals in the reaction zone of the flame are characterised quantitatively. The analysis includes attachment, ionisation, impact dissociation, and vibrational and electronic excitation processes. Our results suggest that Townsend breakdown occurs for E/N = 140 Td. Vibrational excitation is the dominant process up to breakdown, despite important rates of electronic excitation of CO, CO2 and N2 as well as impact dissociation of O2 being apparent from 50 Td onwards. Ohmic heating in the reaction zone is found to be negligible (less than 2% of peak heat release rate) up to breakdown field strengths for realistic electron densities equal to 1010 cm-3. The observed trends are largely independent of equivalence ratio. In the non-thermal regime, electron transport coefficients are insensitive to mixture composition and approximately constant across the flame, but are highly dependent on the electric field strength. In the thermal limit, kinetic parameters and transport coefficients vary substantially across the flame due to the spatially inhomogeneous concentration of water vapour. A practical approach for identifying the plasma regime (thermal versus non-thermal) in studies of electric field effects on flames is proposed. © 2014 Taylor & Francis.
KAUST Department:
Clean Combustion Research Center; Physical Sciences and Engineering (PSE) Division; Mechanical Engineering Program; Reactive Flow Modeling Laboratory (RFML)
Publisher:
Informa UK Limited
Journal:
Combustion Theory and Modelling
Issue Date:
2-Jan-2014
DOI:
10.1080/13647830.2013.872300
Type:
Article
ISSN:
13647830
Sponsors:
This work was supported by an Academic Excellence Alliance (AEA) grant awarded by the King Abdullah University of Science and Technology (KAUST) Office of Competitive Research Funds under the title 'Electromagnetically-enhanced combustion'.
Appears in Collections:
Articles; Physical Sciences and Engineering (PSE) Division; Mechanical Engineering Program; Clean Combustion Research Center

Full metadata record

DC FieldValue Language
dc.contributor.authorBisetti, Fabrizioen
dc.contributor.authorEl Morsli, Mbarken
dc.date.accessioned2015-08-03T11:45:53Zen
dc.date.available2015-08-03T11:45:53Zen
dc.date.issued2014-01-02en
dc.identifier.issn13647830en
dc.identifier.doi10.1080/13647830.2013.872300en
dc.identifier.urihttp://hdl.handle.net/10754/563329en
dc.description.abstractThe effects of an electric field on the collision rates, energy exchanges and transport properties of electrons in premixed flames are investigated via solutions to the Boltzmann kinetic equation. The case of high electric field strength, which results in high-energy, non-thermal electrons, is analysed in detail at sub-breakdown conditions. The rates of inelastic collisions and the energy exchange between electrons and neutrals in the reaction zone of the flame are characterised quantitatively. The analysis includes attachment, ionisation, impact dissociation, and vibrational and electronic excitation processes. Our results suggest that Townsend breakdown occurs for E/N = 140 Td. Vibrational excitation is the dominant process up to breakdown, despite important rates of electronic excitation of CO, CO2 and N2 as well as impact dissociation of O2 being apparent from 50 Td onwards. Ohmic heating in the reaction zone is found to be negligible (less than 2% of peak heat release rate) up to breakdown field strengths for realistic electron densities equal to 1010 cm-3. The observed trends are largely independent of equivalence ratio. In the non-thermal regime, electron transport coefficients are insensitive to mixture composition and approximately constant across the flame, but are highly dependent on the electric field strength. In the thermal limit, kinetic parameters and transport coefficients vary substantially across the flame due to the spatially inhomogeneous concentration of water vapour. A practical approach for identifying the plasma regime (thermal versus non-thermal) in studies of electric field effects on flames is proposed. © 2014 Taylor & Francis.en
dc.description.sponsorshipThis work was supported by an Academic Excellence Alliance (AEA) grant awarded by the King Abdullah University of Science and Technology (KAUST) Office of Competitive Research Funds under the title 'Electromagnetically-enhanced combustion'.en
dc.publisherInforma UK Limiteden
dc.subjectelectric fielden
dc.subjectelectron collisionsen
dc.subjectelectron mobilityen
dc.subjectnon-thermal plasmaen
dc.subjectpremixed flamesen
dc.titleKinetic parameters, collision rates, energy exchanges and transport coefficients of non-thermal electrons in premixed flames at sub-breakdown electric field strengthsen
dc.typeArticleen
dc.contributor.departmentClean Combustion Research Centeren
dc.contributor.departmentPhysical Sciences and Engineering (PSE) Divisionen
dc.contributor.departmentMechanical Engineering Programen
dc.contributor.departmentReactive Flow Modeling Laboratory (RFML)en
dc.identifier.journalCombustion Theory and Modellingen
dc.contributor.institutionInternational University of Casablanca, Casablanca, Moroccoen
kaust.authorBisetti, Fabrizioen
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