Effect of diluents on soot precursor formation and temperature in ethylene laminar diffusion flames

Ranjith Kumar Abhinavam Kailasanathan, Tiffany L Berry Yelverton, Tiegang Fang, William L. Roberts

Research output: Contribution to journalArticlepeer-review

73 Scopus citations


Soot precursor species concentrations and flame temperature were measured in a diluted laminar co-flow jet diffusion flame at pressures up to eight atmospheres while varying diluent type. The objective of this study was to gain a better understanding of soot production and oxidation mechanisms, which could potentially lead to a reduction in soot emissions from practical combustion devices. Gaseous samples were extracted from the centerline of an ethylene-air laminar diffusion flame, which was diluted individually with four diluents (argon, helium, nitrogen, and carbon dioxide) to manipulate flame temperature and transport properties. The diluted fuel and co-flow exit velocities (top-hat profiles) were matched at all pressures to minimize shear-layer effects, and the mass fluxes were fixed over the pressure range to maintain constant Reynolds number. The flame temperature was measured using a fine gauge R-type thermocouple at pressures up to four atmospheres. Centerline concentration profiles of major non-fuel hydrocarbons collected via extractive sampling with a quartz microprobe and quantification using GC/MS+FID are reported within. The measured hydrocarbon species concentrations are vary dramatically with pressure and diluent, with the helium and carbon dioxide diluted flames yielding the largest and smallest concentrations of soot precursors, respectively. In the case of C2H2 and C6H6, two key soot precursors, helium diluted flames had concentrations more than three times higher compared with the carbon dioxide diluted flame. The peak flame temperature vary with diluents tested, as expected, with carbon dioxide diluted flame being the coolest, with a peak temperature of 1760K at 1atm, and the helium diluted flame being the hottest, with a peak temperature of 2140K. At four atmospheres, the helium diluted flame increased to 2240K, but the CO2 flame temperature increased more, decreasing the difference to approximately 250K. © 2012 The Combustion Institute.
Original languageEnglish (US)
Pages (from-to)656-670
Number of pages15
JournalCombustion and Flame
Issue number3
StatePublished - Mar 2013

Bibliographical note

KAUST Repository Item: Exported on 2020-10-01
Acknowledgements: This material is based upon work supported by, or in part by, the U.S. Army Research Laboratory and the U.S. Army Research Office under Grant - W911NF-10-1-0118.

ASJC Scopus subject areas

  • Energy Engineering and Power Technology
  • General Physics and Astronomy
  • General Chemical Engineering
  • General Chemistry
  • Fuel Technology


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