Intermediate species profiles in low-pressure methane/oxygen flames inhibited by 2-H heptafluoropropane: comparison of experimental data with kinetic modeling

Abstract

Experimental profiles of the intermediate species H, OH, CH, CF, CF 2 , and CHF are obtained in a 10 torr premixed flat flame of methane/oxygen in a 1:2 molar ratio, inhibited by a 4% mole fraction of 2-H heptafluoropropane (HFP, CF 3 CHFCF 3 ). These data are compared to calculations using a recently published kinetic mechanism describing the consumption of this fire suppression agent. The profiles in the flame inhibited by HFP are compared to previously published data for flames containing CHF 3 and CH 2 F 2 under the same conditions of stoichiometry and flux of fluorine atoms. The species profiles relative to the flames containing the fluoromethanes are accurately predicted and atmospheric pressure flame speeds are fairly well predicted by the kinetic mechanism. Under equal fluorine loadings, profiles of temperature and of H and OH mole fraction are virtually identical between the flames containing HFP and CHF 3 . The flame inhibited by HFP, however, has approximately twice as much CH* emission as the flame containing CHF 3 . The kinetic model predicts that thermal decomposition, rather than H atom abstraction, is the primary destruction mechanism for HFP under the conditions studied.

A Chemical Kinetic Mechanism for 2‐Bromo‐3,3,3‐trifluoropropene (2‐BTP) Flame Inhibition

“…mechanism [13], was used, including updates [15][16][17] and additions [3,9], as summarized in the work by Linteris et al [18]. Finally, the submodel for the reactions describing inhibition by Br-containing species (i.e., the decomposition products of 2-BTP) is based on the CF 3 Br flame inhibition model of Babushok et al [19], which has been updated [9].…”

Shock wave and modeling study of the thermal decomposition reactions of pentafluoroethane and 2-H-heptafluoropropane

“…[1][2][3][4][5] and work cited therein). The use of these substances is not unproblematic as they have long atmospheric lifetimes and even may enhance combustion (see ref.…”

“…As for C 2 F 5 H, there has been a single-pulse shock tube study 4 over the temperature range 1200-1500 K and at pressures between 16 and 18 atm. The flow system study of ref.…”

Comprehensive Theoretical and Experimental Studies on the CF3H Fire‐extinguishing Mechanism

“…Therefore, a large volume of HFCs needs to be collected in cylinders to suppress the fire successfully and more toxic hydrogen fluoride (HF) was produced in fire-extinguishing process. [6][7][8] In order to improve the fire suppression efficiency of HFCs, it is crucial to establish a fundamental understanding of the flame inhibition effects of fluorinated hydrocarbons. 9,10 As one of the most commonly used HFCs, the fire extinguishing reactions of CF 3 H have been continuously studied experimentally and theoretically.…”