Modeling Ignition of a Heptane Isomer: Improved Thermodynamics, Reaction Pathways, Kinetic, and Rate Rule Optimizations for 2-Methylhexane

Samah Mohamed, Liming Cai, Fethi KHALED, Colin Banyon, Zhandong Wang, Mariam El Rachidi, Heinz Pitsch, Henry J. Curran, Aamir Farooq, Mani Sarathy

Research output: Contribution to journalArticlepeer-review

52 Scopus citations


Accurate chemical kinetic combustion models of lightly branched alkanes (e.g., 2-methylalkanes) are important to investigate the combustion behavior of real fuels. Improving the fidelity of existing kinetic models is a necessity, as new experiments and advanced theories show inaccuracies in certain portions of the models. This study focuses on updating thermodynamic data and the kinetic reaction mechanism for a gasoline surrogate component, 2-methylhexane, based on recently published thermodynamic group values and rate rules derived from quantum calculations and experiments. Alternative pathways for the isomerization of peroxy-alkylhydroperoxide (OOQOOH) radicals are also investigated. The effects of these updates are compared against new high-pressure shock tube and rapid compression machine ignition delay measurements. It is shown that rate constant modifications are required to improve agreement between kinetic modeling simulations and experimental data. We further demonstrate the ability to optimize the kinetic model using both manual and automated techniques for rate parameter tunings to improve agreement with the measured ignition delay time data. Finally, additional low temperature chain branching reaction pathways are shown to improve the model’s performance. The present approach to model development provides better performance across extended operating conditions while also strengthening the fundamental basis of the model.
Original languageEnglish (US)
Pages (from-to)2201-2217
Number of pages17
JournalThe Journal of Physical Chemistry A
Issue number14
StatePublished - Mar 31 2016

Bibliographical note

KAUST Repository Item: Exported on 2020-10-01
Acknowledgements: This work was performed at the KAUST CCRC with funding from Saudi Aramco under the
FUELCOM program. The research at NUIG leading to these results has received funding from
the People Programme (Marie Curie Actions) of the European Union's Seventh Framework
Programme FP7/2007-2013/ under REA grant agreement n° 607214.


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