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Experimental and modeling studies of a biofuel surrogate compound : laminar burning velocities and jet-stirred reactor measurements of anisole

Wagnon, Scott W.; Thion, Sébastien; Nilsson, Elna J.K. LU ; Mehl, Marco; Serinyel, Zeynep; Zhang, Kuiwen; Dagaut, Philippe; Konnov, Alexander A. LU ; Dayma, Guillaume and Pitz, William J. (2018) In Combustion and Flame 189. p.325-336
Abstract

Lignocellulosic biomass is a promising alternative fuel source which can promote energy security, reduce greenhouse gas emissions, and minimize fuel consumption when paired with advanced combustion strategies. Pyrolysis is used to convert lignocellulosic biomass into a complex mixture of phenolic-rich species that can be used in a transportation fuel. Anisole (or methoxybenzene) can be used as a surrogate to represent these phenolic-rich species. Anisole also has attractive properties as a fuel component for use in advanced spark-ignition engines because of its high blending research octane number of 120. Presented in the current work are new measurements of laminar burning velocities, jet-stirred reactor (JSR) speciation of... (More)

Lignocellulosic biomass is a promising alternative fuel source which can promote energy security, reduce greenhouse gas emissions, and minimize fuel consumption when paired with advanced combustion strategies. Pyrolysis is used to convert lignocellulosic biomass into a complex mixture of phenolic-rich species that can be used in a transportation fuel. Anisole (or methoxybenzene) can be used as a surrogate to represent these phenolic-rich species. Anisole also has attractive properties as a fuel component for use in advanced spark-ignition engines because of its high blending research octane number of 120. Presented in the current work are new measurements of laminar burning velocities, jet-stirred reactor (JSR) speciation of anisole/O2/N2 mixtures, and the development and validation of a detailed chemical kinetic mechanism for anisole. Homogeneous, steady state, fixed gas temperature, perfectly stirred reactor CHEMKIN simulations were used to validate the mechanism against the current JSR measurements and published JSR experiments from CNRS-Nancy. Pyrolysis and oxidation simulations were based on the experimental reactant compositions and thermodynamic state conditions including P = 1 bar and T = 675–1275 K. The oxidation compositions studied in this work span fuel-lean (ϕ = 0.5), stoichiometric, and fuel rich (ϕ = 2.0) equivalence ratios. Laminar burning velocities were measured on a heat flux stabilized burner at an unburnt T = 358 K, P = 1 bar and simulated using the CHEMKIN premixed laminar flame speed module. Ignition delay times of anisole were then simulated at conditions relevant to advanced combustion strategies. Current laminar burning velocity measurements and predicted ignition delay times were compared to gasoline components (e.g., n-heptane, iso-octane, and toluene) and gasoline surrogates to highlight differences and similarities in behavior. Reaction path analysis and sensitivity analysis were used to explain the pathways relevant to the current studies. Under pyrolysis and oxidative conditions, unimolecular decomposition of anisole to phenoxy radicals and methyl radicals was found to be important due to the relatively low bond strength between the oxygen and methyl group, ∼65 kcal/mol. Reactions of these abundant phenoxy radicals with O2 were found to be critical to accurately reproduce anisole's reactivity.

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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Biomass, Burning velocity, Kinetic mechanism, Methoxybenzene, Oxidation
in
Combustion and Flame
volume
189
pages
12 pages
publisher
Elsevier
external identifiers
  • scopus:85035064173
ISSN
0010-2180
DOI
10.1016/j.combustflame.2017.10.020
language
English
LU publication?
yes
id
66352f3c-d5b5-4b0d-8af3-f21cf293bce0
date added to LUP
2017-12-07 10:22:36
date last changed
2018-01-07 12:27:28
@article{66352f3c-d5b5-4b0d-8af3-f21cf293bce0,
  abstract     = {<p>Lignocellulosic biomass is a promising alternative fuel source which can promote energy security, reduce greenhouse gas emissions, and minimize fuel consumption when paired with advanced combustion strategies. Pyrolysis is used to convert lignocellulosic biomass into a complex mixture of phenolic-rich species that can be used in a transportation fuel. Anisole (or methoxybenzene) can be used as a surrogate to represent these phenolic-rich species. Anisole also has attractive properties as a fuel component for use in advanced spark-ignition engines because of its high blending research octane number of 120. Presented in the current work are new measurements of laminar burning velocities, jet-stirred reactor (JSR) speciation of anisole/O<sub>2</sub>/N<sub>2</sub> mixtures, and the development and validation of a detailed chemical kinetic mechanism for anisole. Homogeneous, steady state, fixed gas temperature, perfectly stirred reactor CHEMKIN simulations were used to validate the mechanism against the current JSR measurements and published JSR experiments from CNRS-Nancy. Pyrolysis and oxidation simulations were based on the experimental reactant compositions and thermodynamic state conditions including P = 1 bar and T = 675–1275 K. The oxidation compositions studied in this work span fuel-lean (ϕ = 0.5), stoichiometric, and fuel rich (ϕ = 2.0) equivalence ratios. Laminar burning velocities were measured on a heat flux stabilized burner at an unburnt T = 358 K, P = 1 bar and simulated using the CHEMKIN premixed laminar flame speed module. Ignition delay times of anisole were then simulated at conditions relevant to advanced combustion strategies. Current laminar burning velocity measurements and predicted ignition delay times were compared to gasoline components (e.g., n-heptane, iso-octane, and toluene) and gasoline surrogates to highlight differences and similarities in behavior. Reaction path analysis and sensitivity analysis were used to explain the pathways relevant to the current studies. Under pyrolysis and oxidative conditions, unimolecular decomposition of anisole to phenoxy radicals and methyl radicals was found to be important due to the relatively low bond strength between the oxygen and methyl group, ∼65 kcal/mol. Reactions of these abundant phenoxy radicals with O<sub>2</sub> were found to be critical to accurately reproduce anisole's reactivity.</p>},
  author       = {Wagnon, Scott W. and Thion, Sébastien and Nilsson, Elna J.K. and Mehl, Marco and Serinyel, Zeynep and Zhang, Kuiwen and Dagaut, Philippe and Konnov, Alexander A. and Dayma, Guillaume and Pitz, William J.},
  issn         = {0010-2180},
  keyword      = {Biomass,Burning velocity,Kinetic mechanism,Methoxybenzene,Oxidation},
  language     = {eng},
  month        = {03},
  pages        = {325--336},
  publisher    = {Elsevier},
  series       = {Combustion and Flame},
  title        = {Experimental and modeling studies of a biofuel surrogate compound : laminar burning velocities and jet-stirred reactor measurements of anisole},
  url          = {http://dx.doi.org/10.1016/j.combustflame.2017.10.020},
  volume       = {189},
  year         = {2018},
}