卤代烷对甲烷火焰抑制的物理化学作用机理研究

发布时间：2018-04-01 18:31

本文选题：卤代烷抑制剂　切入点：火焰抑制　出处：《中国科学技术大学》2017年硕士论文

【摘要】：卤代烷抑制剂是一类有着广泛应用前景的哈龙替代灭火剂,但是,相关研究表明,一些卤代烷在贫燃条件下会产生促进燃烧的效果,造成燃烧温度和压力的异常升高。卤代烷抑制剂的灭火机理包括化学阻燃机理和物理阻燃机理,这两种机理的共同作用导致了促燃或阻燃的效果。实验中难以实现对物理化学作用的解耦,使用计算机数值模拟的方法,可以有效的将化学作用和物理作用进行分离,对卤代烷的异常促燃现象进行深入分析。本文对反应动力学机理进行改动,实现对全氟己酮(C6F120)和五氟乙烷(C2HF5)化学反应活性的控制,通过人为开启或关闭相关反应,来区分这两种抑制剂对甲烷-空气层流火焰的物理和化学作用。研究表明,根据物理和化学作用之间的关系,可以将反应区域划分为协同效应区和非协同效应区。同时,数值模拟的结果也验证了 C6F12O和C2HF5的燃料效应,在贫燃区域,这两种物质充当燃料,从而增加反应的化学当量比,导致层流火焰速度的增加;在当量比大于1.10(或1.20)时,这两种物质的添加导致富燃效应,从而在物理上和化学上均降低层流火焰速度。初始温度和压力的变化也会导致C6F12O和C2HF5化学效应的变化,温度的升高会导致化学促燃效应的降低,而压力的升高会大幅度增加其化学促燃效果。CF3I是一种可以媲美CF3Br的卤代烷阻燃剂,其优点在于对环境的影响小,不会破坏臭氧层。本文利用对冲火焰实验装置,测量了 CF3I对甲烷-空气层流火焰速度的影响,获取了一系列详细的实验数据,并与模拟值进行了对比,实验值和模拟值吻合良好。和C6F12O和C2HF5不同,CF3I即使在贫燃条件下依然具有良好的阻燃效果,在当量比为0.6时,0.3%的CF3I添加就使得火焰速度降低为原来的52.4%。通过对CF3I的物理和化学效果进行分析发现,CF3I的化学效应在任何情况下均不会引起促燃效果,且随着当量比的增加呈现出先降低后增加的趋势。
[Abstract]:Haloalkane inhibitors are a kind of halon alternative fire extinguishers with wide application prospects. However, related studies have shown that some halogenated alkanes have the effect of promoting combustion under lean combustion conditions. Causing an abnormal increase in combustion temperature and pressure. The mechanisms of halogenated depressants include chemical flame retardation and physical flame retardation. The combined action of these two mechanisms leads to the effect of fire promotion or flame retardation. It is difficult to decouple the physicochemical action in experiments. The method of computer numerical simulation can effectively separate the chemical action from the physical action. In this paper, the mechanism of reaction kinetics was modified to control the chemical activity of perfluorohexanone C6F120) and pentafluoroethane C2HF5. To distinguish the physical and chemical effects of these two inhibitors on methane / air laminar flame. The study shows that according to the relationship between physical and chemical action, the reaction region can be divided into synergistic and non-synergistic regions. The results of numerical simulation also verify the fuel effect of C6F12O and C2HF5, which act as fuel in the lean combustion region, thus increasing the chemical equivalent ratio of the reaction, leading to the increase of laminar flame velocity, and when the equivalent ratio is greater than 1.10 (or 1.20), The addition of these two substances leads to the rich combustion effect, which decreases the laminar flame velocity both physically and chemically. The change of initial temperature and pressure also leads to the change of the chemical effect of C6F12O and C2HF5. The increase of temperature will lead to the decrease of chemical combustion promoting effect, and the increase of pressure will greatly increase its chemical flame promoting effect. CF3I is a halogenated flame retardant comparable to CF3Br, and its advantage is that it has little effect on the environment. The effect of CF3I on methane / air laminar flame velocity is measured, and a series of detailed experimental data are obtained and compared with the simulated data. The experimental values agree well with the simulated values. Different from C6F12O and C2HF5, CF3I still has a good flame retardant effect even under lean combustion conditions. The addition of 0.3wt% CF3I at the equivalent ratio of 0.6 reduced the flame velocity to 52.4% of the original flame velocity. By analyzing the physical and chemical effects of CF3I, it was found that the chemical effect of CF3I would not cause the combustion promotion effect under any circumstances. And with the increase of the equivalent ratio, it shows the trend of decreasing first and then increasing.
【学位授予单位】：中国科学技术大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TQ569

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