Cup Burner Flame Extinguishment by Brominated Compounds.
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).
Building and Fire Research Laboratory
National Institute of Standards and Technology
Gaithersburg, MD 20899