摘要
三氟甲烷(CF_3H,HFC-23)是一种优良的哈龙替代物,在目前的气体灭火介质市场占据显著的位置。然而,在三氟甲烷和火焰作用的过程中产生的HF不仅对火灾现场设备具有严重的腐蚀,而且对灭火现场人员具有严重的伤害。首先采用κ-ε涡黏湍流模型,对CF_3H熄灭CH_4/O_2的二维稳态湍流非预混燃烧进行数值分析,讨论杯式燃烧器中CF_3H熄灭CH_4/O_2火焰过程中HF组分变化规律,通过改变初始参数分析CF_3H浓度、CH_4/O_2配比对HF生成量的影响;采用CHEMKIN 4.0程序模拟CF_3H熄灭CH_4/O_2火焰中温度、反应物、主产物和自由基浓度随火焰高度的变化关系。结果表明,火焰上方20~25cm的区域为HF富集区;H、CF:O为生成HF的重要中间产物,可以通过降低中间产物浓度降低HF。
This article is to present our study on reactions kinetics of HF formation during extinguishing fire by using CF_3H.To know the case that trifluoromethane(CF_3H,HFC-23),as one of important perfluoroalkanes,is used commonly in fire extinguishing agent market. However,when CF_3H is discharged into the fire protection place,HF will be produced by the interaction between the flame and CF_3H.HF not only has severe erosion to the metal apparatus,but also makes serious harm to the people in fire scene,so the production amount of HF in fire extinguishing protection is an important problem when CF_3H is applied.At present,there is lacking of in-depth insight of HF production in fire extinguishing process with CF_3H.In our study,detailed chemical kinetics and turbulent flow coupling method is applied to deal with mechanism of HF formation in Cup-burner. Firstly,κ-ε eddy viscosity turbulence model is employed to carry out the calculation on the two-dimensional steady state non-premixed combustion CH_4/O_2 fire with CF_3H;secondly,the HF formation influencing factors are discussed based on changing initial parameters, such as the CF_3H initial concentration or CH_4 initial concentration, while the rest parameters remain invariant;thirdly,in order to study the HF formation inner CF_3H/CH_4/O_2 flame,CHEMKIN 4.0 program is utilized to analyze temperature,reactant,the main product and free radical concentration with the variation of flame height.Conclusion: the rich HF height is 20 cm above the flame;H,CF:O is the key intermediate product during HF formation,so HF can be reduced by lowering the concentration of intermediate products H, CF:O.the research provides some references for developing new clean extinguishing media.
引文
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