Effects of ammonia and hydrogen on the sooting characteristics of laminar coflow flames of ethylene and methane

S.A. Steinmetz, H.A. Ahmed, Wesley Boyette, M.J. Dunn, William L. Roberts, A.R. Masri

Research output: Contribution to journalArticlepeer-review

41 Scopus citations


Hydrogen and its derivatives, including ammonia, are gaining increasing attention as carbon-neutral fuel alternatives. An intermediate step in the transition to hydrogen and ammonia is the blending of these fuels with hydrocarbons, introducing the challenge of soot formation. The impact of ammonia on soot formation has recently been the focus of several studies, but a complete understanding of its chemical effects is lacking. Hydrogen, by comparison, has received significant attention from the soot community. However, controversy remains with regards to hydrogen’s chemical impact, and the dependence of this impact on fuel and flame configuration. This work investigates the effect of both hydrogen and ammonia on soot formation in laminar coflow flames of both ethylene and methane. Hydrogen or ammonia are introduced either by addition or substitution, with parallel studies of helium and argon, in order to isolate their chemical effects. Time- and spectrally-resolved laser-induced emissions from UV and IR excitation are used to quantify differences in soot and soot precursor formation. Additionally, chemical kinetics calculations and analyses are used to elucidate the effects of ammonia introduction to ethylene flames. Ammonia is found to chemically inhibit soot when mixed with either ethylene or methane, with increasing effects on larger precursors. Calculations suggest that this suppression is due to carbon consumption in the formation of HCN and CN. Hydrogen is found to chemically enhance soot formation in both ethylene and methane flames.
Original languageEnglish (US)
Pages (from-to)121914
StatePublished - Sep 10 2021

Bibliographical note

KAUST Repository Item: Exported on 2021-09-13
Acknowledgements: This research was supported by the Australian Research Council and funding from King Abdullah University of Science and Technology (KAUST). Authors thank Prof. He Lin, from Shanghai Jiao Tong University, for providing the used chemical mechanism.

ASJC Scopus subject areas

  • Energy Engineering and Power Technology
  • Organic Chemistry
  • General Chemical Engineering
  • Fuel Technology


Dive into the research topics of 'Effects of ammonia and hydrogen on the sooting characteristics of laminar coflow flames of ethylene and methane'. Together they form a unique fingerprint.

Cite this