Role of Particles in the Inhibition of Counterflow Diffusion Flames by Iron Pentacarbonyl.
Role of Particles in the Inhibition of Counterflow
Diffusion Flames by Iron Pentacarbonyl.
Rumminger, M. D.; Linteris, G. T.
Combustion and Flame, Vol. 128, No. 1/2, 145-164,
diffusion flames; counterflow flames; fire suppression;
nanoparticles; flame inhibition; halon alternatives;
nucleation; iron pentacarbonyl; metal oxides
Laser light scattering and thermophoretic sampling have
been used to investigate particle formation in a
methane-air counterflow diffusion flames inhibited by
iron pentacarbonyl (Fe(CO)5) added to the fuel or the
oxidizer stream. Flame calculations which incorporate
only gas-phase chemistry are used to assist in
interpretation of the experimental results. In flames
with the inhibitor added to the oxidizer stream, the
region of particle formation overlaps with the region of
high H-atom concentration, and particle formation may
interfere with the inhibition chemistry. When the
inhibitor is added to the fuel stream, significant
condensation of metal or metal oxide particles is found,
and implies that particles prevent active inhibiting
species from reaching the region of high radical
concentration. As the inhibitor loading increases, the
maximum scattering cross section increases sharply, and
the difference between the measured and predicted
inhibition effect widens, suggesting that particle
formation is the cause of the deviation. Thermophoretic
sampling in low strain rate flames indicates that the
particles have diameters between 5 nm and 25 nm.
Thermophoresis affects the nanoparticle distribution in
the flames, in some cases causing particles to cross the
stagnation plane. The scattering magnitude in the
counterflow diffusion flames appears to be strongly
dependent on the residence time, and relatively
independent of the peak flame temperature.