Anionic Effects in Hot Surface Combustions.
Anionic Effects in Hot Surface Combustions.
(573 K)
Bannister, W. W.; Donatelli, A.; Bonner, F.; Lai, F.;
Kurup, P.; Egan, J.; Jahngen, E. G. E.; Muanchareon, P.;
Paramasawat, W.; Sriseubsai, W.; Chiang, S. K.;
Kongkadee, V.; Sengupta, S.; Nagarajan, R.;
Euaphantasate, N.; Parma, V.; Cazeca, M.; Chen, E.;
Morales, A.
Paper 22; HOTWC 2005;
Halon Options Technical Working Conference, 15th
Proceedings. HOTWC 2005. Sponsored by: 3M Specialty
Materials, Boeing, Chemical Development Studies, Inc.,
DuPont Fire Extinguishants, Halon Alternative Research
Corp., Hughes Associates, Inc., Kidde-Fenwal, Inc.,
Sandia National Laboratories, SEVO Systems, Next
Generation Fire Suppression Technology Program. May
24-26, 2005, Albuquerque, NM, 1-13 pp, 2005.
Sponsor:
National Institute of Standards and Technology,
Gaithersburg, MD
Keywords:
halon alternatives; halons; halon 1301; combustion; hot
surfaces; equations; oxidation; ignition; hydrocarbons;
electrostatic charges
Abstract:
Hot surface oxidations are commonly thought to involve
initial free radical hydrogen atom abstraction. Our
evidence implicates initial Lewis base deprotonation by
O atomic oxygen radical anions to form negatively
charged carbanions. Subsequent rate determining electron
transfers generate free radicals which only then give
rise to combustion. Correlations regarding ignition
temperatures and hydrocarbon oxidation product identity
are consistent with carbanionic but not free radical
effects. Highly polarized surfaces (e.g., quartz and
corroded surfaces), and addition of polar compounds to
fuel/air mixtures facilitate ignitions. EFM confirms
increased electrostatic intensities at microscopic
surface defects. For seemingly uniformly hot surfaces
there are transient widely disparate high temperature
incandescent "red spot" zones due to flameless
oxidations induced by concentrated electrostatic
negative charges at surface defects. Isotope, ignition
temperatures and combustion trends are consistent with
Seebeck effects (ease of electron migration in unevenly
heated areas). There are preliminary though not yet
verified indications that electrostatic charges on hot
surfaces may facilitate combustion. Implications would
then involve fire mitigation and enhancement, and
industrial manufacture of many important organic
combustion products.
Building and Fire Research Laboratory
National Institute of Standards and Technology
Gaithersburg, MD 20899