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Title: A counterflow diffusion flame study of branched octane isomers

Conventional petroleum, Fischer–Tropsch (FT), and other alternative hydrocarbon fuels typically contain a high concentration of lightly methylated iso-alkanes. However, until recently little work has been done on this important class of hydrocarbon components. In order to better understand the combustion characteristics of real fuels, this study presents new experimental data for 3-methylheptane and 2,5-dimethylhexane in counterflow diffusion flames. This new dataset includes flame ignition, extinction, and speciation profiles. The high temperature oxidation of these fuels has been modeled using an extended transport database and a high temperature skeletal chemical kinetic model. The skeletal model is generated from a detailed model reduced using the directed relation graph with expert knowledge (DRG-X) methodology. The proposed skeletal model contains sufficient chemical fidelity to accurately predict the experimental speciation data in flames. The predictions are compared to elucidate the effects of number and location of the methyl substitutions. The location is found to have little effect on ignition and extinction in these counterflow diffusion flames. However, increasing the number of methyl substitutions was found to inhibit ignition and promote extinction. Chemical kinetic modelling simulations were used to correlate a fuel’s extinction propensity with its ability to populate the H radical concentration. In conclusion, speciesmore » composition measurements indicate that the location and number of methyl substitutions was found to particularly affect the amount and type of alkenes observed.« less
Authors:
 [1] ;  [2] ;  [3] ;  [2] ;  [1] ;  [4] ;  [4] ;  [1] ;  [1] ;  [2] ;  [3] ;  [4]
  1. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
  2. Univ. of California, San Diego, CA (United States)
  3. Univ. of Toronto, ON (Canada)
  4. Univ. of Connecticut, Storrs, CT (United States)
Publication Date:
OSTI Identifier:
1281687
Report Number(s):
LLNL-JRNL--521754
Journal ID: ISSN 1540-7489
Grant/Contract Number:
AC52-07NA27344
Type:
Accepted Manuscript
Journal Name:
Proceedings of the Combustion Institute
Additional Journal Information:
Journal Volume: 34; Journal Issue: 1; Journal ID: ISSN 1540-7489
Publisher:
Elsevier
Research Org:
Lawrence Livermore National Lab., Livermore, CA (United States)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; 29 ENERGY PLANNING, POLICY AND ECONOMY 3-methylheptane; 2,5-dimethylhexane; counterflow diffusion flame; ignition; extinction