- Author
- Linteris, G. T.
- Title
- Effect of Inhibitor Concentration on the Inhibition Mechanism of Fluoromethanes in Premixed Methane-Air Flames.
- Coporate
- National Institute of Standards and Technology, Gaithersburg, MD
- Book or Conf
- American Chemical Society. Halon Replacements - Technology and Science. National Meeting, 208th. Proceedings. ACS Symposium Series 611. August 21-25, 1994, American Chemical Society, Washington, DC, Washington, DC, Miziolek, A. W.; Tsang, W., Editors, 260-274 p., 1995
- Keywords
- chemical inhibition | flame chemistry | flame models | flame retardants | flame speed
- Abstract
- The mechanisms of inhibition premixed methane-air flames in the presence of difluoromethane, trifluoromethane, and tetrafluoromethane are studied. The chemistry of these agents is expected to be similar to that of agents which may be used as replacements for CF₃Br. The burning rates of premixed methane-air flames stabilized on a Mache-Hebra nozzle burner are determined using the total area method from a schlieren image of the flame. The three inhibitors are tested over an initial mole fraction from 0 to 8% at nominal values of the fuel-air equivalence ration, equal to 0.9, 1.0, and 1.1. The measured burning rate reductions are compared with those predicted by numerical solution of the mass, species, and energy conservation equations employing a detailed chemical kinetic mechanism recently developed at the National Institute of Standards and Technology (NIST). Even in this first test of the kinetic mechanism on inhibited hydrocarbon flames, the numerically predicted burning rates are in excellent agreement for CH₂F₂ and CF₄ and within 35% for CF₃H. The effects of inhibitor concentration on the decomposition pathway of the inhibitors and on the H, O, and OH radical production and consumption rates are discussed. The modified decomposition pathway and the reduced radical consumption explain the diminishing effectiveness of CF₃H and CH₂F₂ at higher concentrations.