Citation

Takahashi F, Katta V, Linteris G, Babushok V. Fire Safety J. 2017; 91: 688-694.

Affiliation

National Institute of Standard and Technology, 100 Bureau Drive Gaithersburg, MD 20899, USA.

Copyright

(Copyright © 2017, Elsevier Publishing)

DOI

10.1016/j.firesaf.2017.04.010

PMID

30983691

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 CF₃Br (halon 1301) and potential alternative fire-extinguishing agents (C₂HF₅, C₂HF₃Cl₂, and C₃H₂F₃Br). 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 H₂O formed in the inner zone is converted further, primarily in the outer zone, to HF and CF₂O through exothermic reactions most significantly with the C₂HF₅ addition. The total heat release of the entire flame decreases (inhibiting) for CF₃Br but increases (enhancing) for the halon alternative agents, particularly C₂HF₅ and C₂HF₃Cl₂. Addition of C₂HF₅ results in unusual (non-chain branching) reactions.

Language: en

Keywords

aircraft cargo-bay fire suppression; diffusion flame stabilization; halon 1301 replacement; numerical simulation; reaction kernel