Effects of diluents on soot surface temperature and volume fraction in diluted ethylene diffusion flames at pressure

Ranjith Kumar Abhinavam Kailasanathan, Ji Zhang, Tiegang Fang, William L. Roberts

Research output: Contribution to journalArticlepeer-review

16 Scopus citations


Soot surface temperature and volume fraction are measured in ethylene/air coflowing laminar diffusion flames at high pressures, diluted with one of four diluents (argon, helium, nitrogen, and carbon dioxide) using a two-color technique. Both temperature and soot measurements presented are line-of-sight averages. The results aid in understanding the kinetic and thermodynamic behavior of the soot formation and oxidation chemistry with changes in diluents, ultimately leading to possible methods of reducing soot emission from practical combustion hardware. The diluted fuel and coflow exit velocities (top-hat profiles) were matched at all pressures to minimize shear effects. In addition to the velocity-matched flow rates, the mass fluxes were held constant for all pressures. Addition of a diluent has a pronounced effect on both the soot surface temperature and volume fraction, with the helium diluted flame yielding the maximum and carbon dioxide diluted flame yielding minimum soot surface temperature and volume fraction. At low pressures, peak soot volume fraction exists at the tip of the flame, and with an increase in pressure, the location shifts lower to the wings of the flame. Due to the very high diffusivity of helium, significantly higher temperature and volume fraction are measured and explained. Carbon dioxide has the most dramatic soot suppression effect. By comparing the soot yield with previously measured soot precursor concentrations in the same flame, it is clear that the lower soot yield is a result of enhanced oxidation rates rather than a reduction in precursor formation. Copyright © 2014 Taylor & Francis Group, LLC.
Original languageEnglish (US)
Pages (from-to)815-828
Number of pages14
JournalCombustion Science and Technology
Issue number6
StatePublished - May 20 2014

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
  • Physics and Astronomy(all)
  • Chemical Engineering(all)
  • Chemistry(all)
  • Fuel Technology


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