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Investigation of Extinguishment by Thermal Agents Using Detailed Chemical Kinetic Modeling of Opposed-Flow Diffusion Flames.


pdf icon Investigation of Extinguishment by Thermal Agents Using Detailed Chemical Kinetic Modeling of Opposed-Flow Diffusion Flames. (453 K)
Pitts, W. M.; Blevins, L. G.

Chemical and Physical Processes of Combustion, Fall Technical Meeting. Proceedings. Combustion Institute/Eastern States Section. October 10-13, 1999 Raleigh, NC, 184-187 pp, 1999.

Sponsor:

Deparment of Defense, Washington, DC

Keywords:

halon alternatives; diffusion flames; extinguishment; combustion; diluent gases; diluents; fire extinguishing agents; fire suppression; laminar flames; reaction kinetics; temperature effects

Abstract:

The manufacture of halons, which are widely used in fire extinguishing systems, was banned in 1984. The search for effective alternatives continues with a large effort known as the Next Generation Fire Suppression Technology Program (NGP). As part of the NGP, NIST is investigating whether highly effective thermal agents, which obtain their effectiveness solely by heat extraction and dilution, are feasible. The paper by Sheinson et al. provides a good introduction. Simple heating (i.e., heat capacity), phase changes, endothermic molecular decomposition (which is classified as a physical process as long as the initial agent and its products do not participate in the combustion chemistry), and simple dilution can modify flame temperatures and therefore contribute to flame extinction This paper summarizes the results of a detailed chemical kinetic modeling investigation of laminar opposed-flow methane/air diffusion flames designed to provide an improved understanding of the extinguishment of fires by thermal agents. A particular focus was to test the hypothesis that the effectiveness of a thermal agent depends on the location of heat absorption relative to the flame zone. An internal report has been prepared summarizing the kinetic modeling and also includes the results of an extensive data base search of potential thermal agents and modeling results for the effectiveness of thermal agents in cooling solid surfaces.