Role of Particles in the Inhibition of Premixed Flames by Iron Pentacarbonyl.
Role of Particles in the Inhibition of Premixed Flames
by Iron Pentacarbonyl.
Rumminger, M. D.; Linteris, G. T.
Combustion and Flame, Vol. 123, No. 1/2, 82-94, October
premixed flames; flame inhibition; flame chemistry; iron
pentacarbonyl; metal oxides; condensation; halon
alternatives; nucleation; nanoparticles
Laser light scattering has been used to investigate
particle formation in Fe(CO)5-inhibited premixed flames
in order to understand the influence of metal and metal
oxide condensation on flame inhibition. In premixed
CH4-air flames, particles form early in the flame zone,
nucleate and grow to a peak scattering cross section,
then disappear as the temperature increases its peak
value. Downstream in the post-combustion gases, the peak
scattering signal is several orders of magnitude larger
than the peak value near the main reaction zone of the
flame. Thermophoretic particle sampling and numerical
estimates indicate nanoparticles with diameters between
10 and 30 nm. The iron pentacarbonyl mole fraction above
which additional Fe(CO)5 no longer reduces the burning
velocity corresponds to the mole fraction at which the
in-flame particle nucleation begins to sharply increase.
A model of an ideal heterogeneous inhibitor shows that
radical recombination on particle surfaces alone cannot
account for the magnitude of the observed inhibition.
Measurements in three CO-H2 flames with similar
adiabatic flame temperatures but different burning
velocities demonstrate the importance of residence time
for particle formation in premixed flames.