四氟乙烷对甲烷/空气爆炸特性的影响

Experimental study on the effects of R134a on the characteristics of methane/air explosion

通过实验来研究四氟乙烷(R134a)对甲烷/空气爆炸的影响。在自主搭建的小尺寸甲烷管道爆炸平台上,观测R134a的加入对甲烷爆炸过程及压力、火焰传播速度产生的影响,并对此进行定性、定量分析。结果表明:各次实验中,R134a的加入会延迟破膜时间,但破膜压力主要受泄爆膜自身影响,保持在8k Pa左右;当甲烷浓度一定时,随着管内R134a体积分数的增大,火焰传播速度逐渐变小;甲烷浓度接近当量比时,R134a量的改变对管内火焰传播时间延迟的影响减小,但对超压的抑制作用仍很大;在加入体积分数为2.67%的R134a后,9.0%、9.5%、10.0%浓度的超压峰值分别降低了25.34%、61.78%、38.73%,火焰传播时间延长至未加的1.28倍、1.423倍、1.17倍。R134a能够有效抑制爆炸的机理主要在于分解产生的自由基F?对碳氢燃料氧化链式反应具有很强的干扰和阻断作用。

In order to study the inhibitory effect of R134a(CH2FCF3)on methane/air explosion,the experimental tube system for explosion was set up.In the experiments,with and without R134a,the explosion processes were observed,and pressures and flame propagation velocities were measured.Then,the inhibitory effect of R134a was analyzed qualitatively and quantitatively.The results showed that the PVC film is broken by itself at the pressure about8kPa,uncorrelated with the amount of R134a.But the broken moment is delayed with the spraying amount of R134a.Under the same methane concentration,the flame propagation velocity decreases gradually in the tube with the increase of the R134a concentration.When the CH4concentration is close to the equivalent ratio,the influence of R134a to suppress the flame propagation becomes smaller,but the inhibitory effect on the overpressure is still great.When a volume fraction of2.67%R134a is added to initial methane/air mixtures with methane concentrations at9.0%,9.5%and10.0%,the peak values of overpressure reduce25.34%,61.78%,38.73%,respectively,and the average flame propagation velocities are slow down to1.28,1.423and1.17times respectively.The inhibition of R134a is mainly due to the mechanism that free radical F·produced by R134a strongly disturbs and impedes the normal oxidative chain of gas fuel and oxygen.