A computational study of extinguishment and enhancement of propane cup-burner flames by halon and alternative agents

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.

Thermal decomposition and fire‐extinguishing mechanism of CF3I: A combined theoretical and experimental study

“…The reliability of our experimental measurement was verified [26] by comparing our measured MEC value for HFC‐125 (9.70 vol%) in extinguishing propane‐air flames with that tested by the standard of ISO 14520‐1‐2006 Part 8 (9.7 vol%). As listed in Table 2, CF 3 I exhibits the lowest MEC (3.61 vol%) for extinguishing the propane‐air flame among all the tested substances, and even lower than that of Halon 1301 (3.8–4.3 vol%) measured by Fumiaki [31]. In other words, the MEC performance of CF 3 I is much better than the three commonly used HFCs and HFO‐1336mzz(E).…”

Thermal decomposition and fire extinguishing mechanism of CF3I: a combined theoretical and experimental study

“…And the reliability of our experimental measurement was verified 14 by comparing our measured FEC value (9.70vol%) for propane-air flame with that tested by the standard ISO 14520-1-2006 Part 8 (9.7vol%). As listed in Table .2 , CF 3 I exhibits the lowest FEC (3.61vol%) for extinguishing the propane-air flame, even lower than that of Halon 1301 (3.8vol%-4.3vol%) measured by Fumiaki 18 . For propane-air flame, the FEC performance of CF 3 I is much better than three HFCs and HFO-1336mzz(E).…”

The fire-extinguishing performance and mechanism of fluorinated cyclobutane through experimental measurement and numerical calculation

“…These both indicate that C-318 can well inhibit the height of a propane flame. 40 There are two main reasons for the rise of the flame. Firstly, the diffusion of the agent from the bottom of the cup burner increases the buoyancy in the overall combustion system, leading to an enhanced positive effect on flame height.…”