A counterflow diffusion flame study of branched octane isomers

Sarathy, S. Mani; Niemann, Ulrich; Yeung, Chuck; Gehmlich, Ryan K.; Westbrook, Charles K.; Plomer, Max; Luo, Zhaoyu; Mehl, Marco; Pitz, William J.; Seshadri, K.; Thomson, Murray J.; Lu, Tianfeng

doi:10.1016/j.proci.2012.05.106

Cited by 48 publications

(40 citation statements)

References 14 publications

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“…The present study on di-methylated alkane combustion builds upon previous experimental and modeling work performed by the authors on the combustion of branched alkanes [11][12][13][14][15][16] . The team has recently provided a wealth of experimental data spanning low-temperature auto ignition delay times to high-temperature premixed flame propagation rates for several octane isomers, together with chemical kinetic models capable of predicting the experimental data.…”

Section: Introductionmentioning

confidence: 93%

“…The proposed detailed chemical kinetic reaction mechanism includes high-temperature kinetic pathways for 2,5-dimethylhexane [13], plus low-temperature kinetic schemes for 2,5-dimethylhexane. The reactions were added to the recently developed 2-methylheptane and 3-methylheptane high-temperature oxidation schemes presented by LLNL [11,16,20].…”

Section: Chemical Kinetic Modelingmentioning

confidence: 99%

“…Recent comprehensive experimental and modeling studies on 2-methylheptane and 3-methylheptane [11][12][13]16,20] have shown that mono-methylated alkanes exhibit notably different combustion properties than their linear alkane counterparts (e.g., n-octane), including lower laminar flame speeds and decreased low temperature reactivity. Prior fundamental combustion studies on di-methylalkanes are limited.…”

Section: Introductionmentioning

confidence: 99%

“…Prior fundamental combustion studies on di-methylalkanes are limited. Sarathy et al [13] conducted an experimental and numerical study on counterflow diffusion flames of 2,5-dimethylhexane, and observed a decreased propensity for flame ignition and an increased propensity towards flame extinction when compared to mono-methyl and normal octane isomers. Liu et al [14] studied C 8 and C 10 dimethylated alkane ignition in non-premixed flames and found similar trends, wherein dimethylalkanes were found to be less reactive than isomeric normal and mono-methylated alkanes.…”

Section: Introductionmentioning

confidence: 99%

“…Ji et al [15] conducted experimental laminar flame speed measurements of five octane isomers (including 2,5-dimethylhexane) and compared them to chemical kinetic modeling predictions; both experimental and modeling results indicated that 2,5-dimethylhexane exhibits lower laminar flame speeds than mono-methylated octane isomers, thereby suggesting that increasing the number of methyl substitutions decreases reactivity. High-temperature combustion in flames is dominated by a fuel's ability to populate the hydrogen radical pool, and chemical kinetic modeling simulations [13,15] indicate that the decreased reactivity of 2,5-dimethylhexane in flames is due to its decreased ability to populate the H-atom radical pool.…”

Section: Introductionmentioning

confidence: 99%

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A comprehensive combustion chemistry study of 2,5-dimethylhexane

Sarathy

Javed

Karsenty

et al. 2014

Combustion and Flame

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Iso-paraffinic molecular structures larger than seven carbon atoms in chain length are commonly found in conventional petroleum, Fischer-Tropsch (FT), and other alternative hydrocarbon fuels, but little research has been done on their combustion behavior. Recent studies have focused on either mono-methylated alkanes and/or highly branched compounds (e.g., 2,2,4-trimethylpentane). In order to better understand the combustion characteristics of real fuels, this study presents new experimental data for the oxidation of 2,5-dimethylhexane under a wide variety of temperature, pressure, and equivalence ratio conditions. This new dataset includes jet stirred reactor speciation, shock tube ignition delay, and rapid compression machine ignition delay, which builds upon recently published data for counterflow flame ignition, extinction, and speciation profiles. The low and high temperature oxidation of 2,5-dimethylhexane has been modeled using a comprehensive chemical kinetic model developed using established reaction rate rules. The agreement between the model and data is presented, along with suggestions for improving model predictions. The importance of propene chemistry is highlighted as critical for correct prediction of high temperature ignition delay. The oxidation behavior of 2,5-dimethylhexane is also compared with oxidation behavior of other linear and branched octane isomers, in order to determine the effects of the number of methyl branches on combustion properties. Both experimental data and model predictions indicate that increasing the level of branching decreases fuel reactivity at low and intermediate temperatures. The model is used to elucidate the structural features and reaction pathways responsible for inhibiting the reactivity of 2,5-dimethylhexane. FUEL or CNF, Sarathy et al. submitted July 2013Introduction Detailed chemical kinetic models for transportation fuels have reached a level of fidelity where accurate predictions can be made of combustion phenomenon relevant to the operation of practical devices. Schofield [1] states that these large scale models are adequate as engineering tools for studying the combustion of new fuel molecules. A recent review paper by Pitz and Mueller [2] describing the development of diesel surrogate fuel models concluded that major research gaps remain in modeling high molecular weight (i.e., C 8 and greater) aromatics, alkyl aromatics, cyclo-alkanes, and lightly branched iso-alkanes. The present study is concerned with the combustion of branched alkanes, specifically 2,5-dimethylhexane, which has been reported as a component of petroleum combustion exhaust, smog, and tobacco smoke [3]. Branched alkanes are important components of conventional diesel and jet fuels derived from petroleum [2,4]; synthetic Fischer-Tropsch diesel and jet fuels derived from coal, natural gas, and/or biomass [5,6]; and renewable diesel and jet fuels derived from thermochemical treatment of bio-derived fats and oils (e.g., hydrotreated renewable jet (HRJ) fuels) [7,8]. Detailed com...

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