Reactive molecular dynamics study of the decomposition mechanism of the environmentally friendly insulating medium C3F7CN

Abstract

The extensive use of sulfur hexafluoride (SF₆) gas in the power industry has a strong greenhouse effect. Hence, many scholars are committed to studying SF₆ alternative gases to achieve green power development. In the past two years, C₃F₇CN (heptafluoroisobutyronitrile) has attracted the attention of many scholars due to its excellent insulation and environmental protection characteristics as a potential alternative gas. This study theoretically explores the decomposition characteristics of C₃F₇CN and the C₃F₇CN/CO₂ gas mixture based on the reactive molecular dynamics method and density functional theory. The main decomposition pathways of C₃F₇CN and the enthalpy of each path at different temperatures were analyzed. The yield of the main decomposition products was obtained under several temperature conditions. The decomposition of C₃F₇CN mainly produced CF₃, C₃F₇, CN, CNF, CF_2, CF, F, and other free radicals and a few molecular products, such as CF₄ and C₃F₈. The C₃F₇CN/CO₂ gas mixture has more excellent decomposition characteristics than that of the pure C₃F₇CN. The addition of CO₂ effectively ensures that the gas mixture has a low liquefaction temperature, which is considerably suitable for use as a gas insulation medium. The relevant research results provide guidance for the further exploration on the electrical properties and practical engineering application of the C₃F₇CN gas mixture.