A computational study of extinguishment and enhancement of propane cup-burner flames by halon and alternative agents. (July 2017)

• Record Type: Journal Article
• Authors: Takahashi, Fumiaki; Katta, Viswanath R.; Linteris, Gregory T.; Babushok, Valeri I.
• Is Part Of: Fire safety journal. Volume 91(2017:Jul.)
• Page Start: 688
• Page End: 694
• Publication Date: 2017-07
• Subjects: Aircraft cargo-bay fire suppression -- Halon 1301 replacement -- Numerical simulation -- Diffusion flame stabilization -- Reaction kernel; Fire prevention -- Periodicals; Incendies -- Prévention -- Recherche -- Périodiques; Fire prevention -- Research; Periodicals; 628.92205
• DOI: 10.1016/j.firesaf.2017.04.010
• Languages: English
• ISSNs: 0379-7112

Abstract

Abstract: Computations of cup-burner flames in normal gravity have been performed using propane as the fuel to reveal the combustion inhibition and enhancement by the CF3 Br (halon 1301) and potential alternative fire-extinguishing agents (C2 HF5, C2 HF3 Cl2, and C3 H2 F3 Br). The time-dependent, two-dimensional numerical code used includes a detailed kinetic model (up to 241 species and 3918 reactions), diffusive transport, and a gray-gas radiation model. The peak reactivity spot (i.e., reaction kernel) at the flame base stabilizes a trailing flame, which is inclined inwardly by a buoyancy-induced entrainment flow. As the volume fraction of agent in the coflow increases gradually, the premixed -like reaction kernel weakens, thus inducing the flame base detachment from the burner rim and blowoff-type extinguishment eventually. The two-zone flame structure (with two heat-release-rate peaks) is formed in the trailing diffusion flame. The H2 O formed in the inner zone is converted further, primarily in the outer zone, to HF and CF2 O through exothermic reactions most significantly with the C2 HF5 addition. The total heat release of the entire flame decreases (inhibiting) for CF3 Br but increases (enhancing) for the halon alternative agents, particularly C2 HF5 and C2 HF3 Cl2 . Addition of C2 HF5 results in unusual (non-chain branching) reactions. Highlights: Computation with full chemistry reveals the structure of propane cup-burner flames. Extinguishment occurs by destabilization processes of the premixed -like flame base. Two-zone flame structure and combustion enhancement occur in a trailing diffusion flame.