Shock tube measurements of the rate constants for seven large alkanes+OH

Handle URI:
http://hdl.handle.net/10754/566166
Title:
Shock tube measurements of the rate constants for seven large alkanes+OH
Authors:
Badra, Jihad; Elwardani, Ahmed Elsaid ( 0000-0002-2536-2089 ) ; Farooq, Aamir ( 0000-0001-5296-2197 )
Abstract:
Reaction rate constants for seven large alkanes + hydroxyl (OH) radicals were measured behind reflected shock waves using OH laser absorption. The alkanes, n-hexane, 2-methyl-pentane, 3-methyl-pentane, 2,2-dimethyl-butane, 2,3-dimethyl-butane, 2-methyl-heptane, and 4-methyl-heptane, were selected to investigate the rates of site-specific H-abstraction by OH at secondary and tertiary carbons. Hydroxyl radicals were monitored using narrow-line-width ring-dye laser absorption of the R1(5) transition of the OH spectrum near 306.7 nm. The high sensitivity of the diagnostic enabled the use of low reactant concentrations and pseudo-first-order kinetics. Rate constants were measured at temperatures ranging from 880 K to 1440 K and pressures near 1.5 atm. High-temperature measurements of the rate constants for OH + n-hexane and OH + 2,2-dimethyl-butane are in agreement with earlier studies, and the rate constants of the five other alkanes with OH, we believe, are the first direct measurements at combustion temperatures. Using these measurements and the site-specific H-abstraction measurements of Sivaramakrishnan and Michael (2009) [1,2], general expressions for three secondary and two tertiary abstraction rates were determined as follows (the subscripts indicate the number of carbon atoms bonded to the next-nearest-neighbor carbon): S20=1.58×10-11exp(-1550K/T)cm3molecule-1s-1(887-1327K)S30=2.37×10-11exp(-1850K/T)cm3molecule-1s-1(887-1327K)S21=4.5×10-12exp(-793.7K/T)cm3molecule-1s-1(833-1440K)T100=2.85×10-11exp(-1138.3K/T)cm3molecule-1s-1(878-1375K)T101=7.16×10-12exp(-993K/T)cm3molecule-1s-1(883-1362K) © 2014 The Combustion Institute.
KAUST Department:
Clean Combustion Research Center; Physical Sciences and Engineering (PSE) Division; Mechanical Engineering Program; Chemical Kinetics & Laser Sensors Laboratory
Publisher:
Elsevier BV
Journal:
Proceedings of the Combustion Institute
Issue Date:
2015
DOI:
10.1016/j.proci.2014.05.098
Type:
Article
ISSN:
1540-7489
Sponsors:
We would like to acknowledge the funding support from Saudi Aramco under the FUEL-COM program and by the Clean Combustion Research Center (CCRC) at King Abdullah University of Science and Technology (KAUST).
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.authorBadra, Jihaden
dc.contributor.authorElwardani, Ahmed Elsaiden
dc.contributor.authorFarooq, Aamiren
dc.date.accessioned2015-08-12T09:30:47Zen
dc.date.available2015-08-12T09:30:47Zen
dc.date.issued2015en
dc.identifier.issn1540-7489en
dc.identifier.doi10.1016/j.proci.2014.05.098en
dc.identifier.urihttp://hdl.handle.net/10754/566166en
dc.description.abstractReaction rate constants for seven large alkanes + hydroxyl (OH) radicals were measured behind reflected shock waves using OH laser absorption. The alkanes, n-hexane, 2-methyl-pentane, 3-methyl-pentane, 2,2-dimethyl-butane, 2,3-dimethyl-butane, 2-methyl-heptane, and 4-methyl-heptane, were selected to investigate the rates of site-specific H-abstraction by OH at secondary and tertiary carbons. Hydroxyl radicals were monitored using narrow-line-width ring-dye laser absorption of the R1(5) transition of the OH spectrum near 306.7 nm. The high sensitivity of the diagnostic enabled the use of low reactant concentrations and pseudo-first-order kinetics. Rate constants were measured at temperatures ranging from 880 K to 1440 K and pressures near 1.5 atm. High-temperature measurements of the rate constants for OH + n-hexane and OH + 2,2-dimethyl-butane are in agreement with earlier studies, and the rate constants of the five other alkanes with OH, we believe, are the first direct measurements at combustion temperatures. Using these measurements and the site-specific H-abstraction measurements of Sivaramakrishnan and Michael (2009) [1,2], general expressions for three secondary and two tertiary abstraction rates were determined as follows (the subscripts indicate the number of carbon atoms bonded to the next-nearest-neighbor carbon): S20=1.58×10-11exp(-1550K/T)cm3molecule-1s-1(887-1327K)S30=2.37×10-11exp(-1850K/T)cm3molecule-1s-1(887-1327K)S21=4.5×10-12exp(-793.7K/T)cm3molecule-1s-1(833-1440K)T100=2.85×10-11exp(-1138.3K/T)cm3molecule-1s-1(878-1375K)T101=7.16×10-12exp(-993K/T)cm3molecule-1s-1(883-1362K) © 2014 The Combustion Institute.en
dc.description.sponsorshipWe would like to acknowledge the funding support from Saudi Aramco under the FUEL-COM program and by the Clean Combustion Research Center (CCRC) at King Abdullah University of Science and Technology (KAUST).en
dc.publisherElsevier BVen
dc.subjectAlkanesen
dc.subjectHydroxyl radicalsen
dc.subjectRate constantsen
dc.subjectShock tubeen
dc.subjectSite-specific ratesen
dc.titleShock tube measurements of the rate constants for seven large alkanes+OHen
dc.typeArticleen
dc.contributor.departmentClean Combustion Research Centeren
dc.contributor.departmentPhysical Sciences and Engineering (PSE) Divisionen
dc.contributor.departmentMechanical Engineering Programen
dc.contributor.departmentChemical Kinetics & Laser Sensors Laboratoryen
dc.identifier.journalProceedings of the Combustion Instituteen
kaust.authorBadra, Jihaden
kaust.authorElwardani, Ahmed Elsaiden
kaust.authorFarooq, Aamiren
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