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Cup Burner Flame Extinguishment by Brominated Compounds.


pdf icon Cup Burner Flame Extinguishment by Brominated Compounds. (587 K)
Linteris, G. T.; Takahashi, F.; Katta, V. R.

HOTWC 2006;

Halon Options Technical Working Conference, 16th Proceedings. HOTWC 2006. May 16-18, 2006, Albuquerque, NM, 1-18 pp, 2006.

Keywords:

halon alternatives; halons; halon 1301; fire suppression; bromine compounds; flame extinguishment; burners; experiments; computation; fire extinguishing agents; methane; diffusion flames; flame structures; air; methane

Abstract:

Experiments and calculations have been performed for a methane-air cup-burner flame with added CF3Br or Br2. The time-dependent, two-dimensional numerical code, which includes a detailed kinetic model and diffusive transport, has predicted the flame extinction within 4% or 8% for each. Analysis of the flame structure has allowed the mechanisms of flame weakening in the base and trailing flame regions to be compared. The agents CF3Br and Br2 behave very similarly with regard to flame extinguishment: both raise the temperature in the flame everywhere, as well as lower radical volume fractions in the trailing diffusion flame or the reaction kernel. The mechanism of lowered radical volume fractions is shown to be primarily due to a catalytic cycle involving bromine species in both regions of the flame, with small contributions from radical trapping by fluorinated species in the trailing diffusion flame. In the trailing diffusion flame, the effectiveness of the agents is reduced because the hydrocarbon species, which are necessary for the regeneration of HBr, are scarce at the location of the peak radical volume fraction (i.e., at the flame zone).