Insights on decomposition process of c-C4F8 and c-C4F8/N2 mixture as substitutes for SF6

In recent years, many scholars have carried out studies on c-C4F8 and its gas mixture and found it has potential to be used as an environment-friendly insulating medium to replace SF6 in medium-voltage equipment. In this paper, the c-C4F8 and c-C4F8/N2 gas mixture models were built to study its decomposition process by the combination of reactive molecular dynamics method and density functional theory. The yield of the main decomposition products, the reaction pathways and enthalpy under different temperatures were explored. It was found that the decomposition of c-C4F8/N2 mainly produces CF2, F, CF3, CF, C, CF4 and C2F4. c-C4F8 can decompose to C2F4 by absorbing 43.28 kcal/mol, which is the main decomposition path and this process easily occurs under high temperature. There is a dynamic equilibrium process among the various produced radicals, which ensures the insulation performance of system to a certain extent. The decomposition performance of c-C4F8/N2 mixture is better than that of pure c-C4F8 at the same temperature. Relevant results provide guidance for engineering application of the c-C4F8/N2 gas mixture.

近年来，诸多学者针对八氟环丁烷（c-C4F8）及其混合气体开展了相关研究，发现其具备作为环保型绝缘介质替代中压电气设备中六氟化硫（SF6）的潜力。本文通过反应分子动力学方法与密度泛函理论相结合的手段，构建了八氟环丁烷（c-C4F8）及其与氮气（N2）的混合气体模型，以探究其分解过程。研究了不同温度下主要分解产物的产率、反应路径及反应焓变。结果表明，八氟环丁烷/氮气混合气体的分解产物主要包括CF2、F、CF3、CF、C、CF4与C2F4。八氟环丁烷可通过吸收43.28 kcal/mol的能量分解为四氟乙烯（C2F4），该路径为其主要分解通道，且在高温环境下易于发生。生成的各类自由基之间存在动态平衡过程，这在一定程度上保障了体系的绝缘性能。在相同温度下，八氟环丁烷/氮气混合气体的分解性能优于纯八氟环丁烷。相关研究结果可为八氟环丁烷/氮气混合气体的工程应用提供理论指导。