C_(4)F_(7)N/CO_(2)/O_(2)混合气体交流电晕放电分解特性

Decomposition Characteristics of C_(4)F_(7)N/CO_(2)/O_(2) Gas Mixture in AC Corona Discharge

为研究环保型C_(4)F_(7)N/CO_(2)/O_(2)三元混合气体放电分解特性,开展了不同O_(2)体积分数的C_(4)F_(7)N/CO_(2)/O_(2)三元混合气体交流电晕放电分解试验,主要分解产物包括CF_(4)、C_(2)F_(6)、C_(3)F_(6)、C_(3)F_(8)、C_(6)F_(14)、CNCN和CF_(3)CN,CF_(4)、C_(2)F_(6)和C_(3)F_(8)等饱和类碳氟气体生成量较高,不饱和类碳氟气体C_(3)F_(6)生成量较低。O_(2)的加入能显著抑制气体分解,O_(2)体积分数为4%的混合气体在60 h电晕放电后的CNCN生成量仅为不含O_(2)时的22.1%。CNCN等分解产物生成速率随O_(2)体积分数增加呈现先快速下降后趋于稳定的典型特征,2%~8%体积分数的O_(2)对混合气体分解具有较好的抑制作用。基于密度泛函理论开展了分解过程仿真分析,发现O_(2)通过与CF_(3)、CN和CF_(3)CFCN等自由基的反应消耗了自由基,导致以这些自由基为反应物的主要分解产物的生成受到抑制,在O_(2)的作用下,主要分解产物生成速率随O_(2)体积分数增加呈现非线性变化特征。C_(2)F_(6)/CF_(4)比值较稳定,具备作为C_(4)F_(7)N/CO_(2)/O_(2)三元混合气体电晕放电识别指标的潜力。

To study the discharge decomposition characteristics of eco-friendly C_(4)F_(7)N/CO_(2)/O_(2) ternary gas mixture,the decomposition experiments of C_(4)F_(7)N/CO_(2)/O_(2) ternary gas mixture under corona discharge were carried out with different O_(2) volume fractions.The main decomposition products include CF_(4),C_(2)F_(6),C_(3)F_(6),C_(3)F_(8),C_(6)F_(14),CNCN and CF_(3)CN,in which the production of saturated fluorocarbon gases such as CF_(4),C_(2)F_(6) and C_(3)F_(8) is high,while the production of unsaturated fluorocarbon gases C_(3)F_(6) is low.The addition of O_(2) can significantly inhibit the gas decomposition,after 60 h corona discharge of the gas mixture with 4%O_(2) volume fraction,the production of CNCN is only 22.1%of that in the absence of O_(2).With the increase of O_(2) volume fraction,the formation rate of CNCN and other decomposition products decreases rapidly at first and then tends to be stable,and 2%to 8%volume fraction of O_(2) has good inhibitory effect on the decomposition of the gas mixture.Based on the density functional theory,the simulation analysis of the decomposition process was carried out.It is found that O_(2) will consume a large amount of free radicals by reacting with CF_(3),CN,CF_(3)CFCN and other radicals,resulting in the inhibition of the formation of the main decomposition products with these free radicals as reactants.Under the action of O_(2),the formation rate of main decomposition products shows a nonlinear variation with the increase of O_(2) volume fraction.The ratio of C_(2)F_(6)/CF_(4) is relatively stable,and it has a potential to be used as an indicator for corona discharge identification of C_(4)F_(7)N/CO_(2)/O_(2) ternary gas mixture.