Study On The Influence Of O Atoms On The Local Superheated Decomposition Of C₄F₇N Gas Based On Density Functional Theory

Existing studies show that perfluorinated isobutyronitrile(C4F7N)is a new synthetic gas with good environmental performance and excellent insulation performance at the same time.As a substitute gas for SF6,it has great potential.Scholars at home and abroad have been studying C4F7N and its mixed gas from various aspects.But for C4F7N gas decomposition characteristics research is still in its infancy stage,the reaction mechanism is not clear,and the background gas such as O2,N2 and air interaction impact mechanism is not yet clear,also studied O atoms in the dry air on C4F7N gas insulation performance,the effects of C4F7N gas for the future application and the development of environmental protection equipment insulation has important theoretical and practical significance.In this paper,the C4F7N+O system was selected as the research object,and the decomposition mechanism of C4F7N+O was studied from the micro level based on density functional theory,in the first place in the Gaussian 16 C4F7N+O to molecular structure modeling,and optimize with stable C4F7NO molecular configuration,secondly by the potential energy surface scanning got C4F7NO decomposition reaction path,based on the DFT/B3LYP method calculated the energy of the particles involved in the reaction path,frequency and key geometric parameters,etc.,and the intrinsic reaction coordinate method is adopted for transient particles of the reaction R11 and R15 are verified,Finally,the decomposition system of C4F7N+O was constructed.Then on the basis of the microscopic parameters of particles is calculated,based on the traditional transition state theory to calculate the reaction rate constant of R11 and R15,for no obvious transition state structure of 19 other decomposition reaction,using variational transition state theory to modify velocity formula,finally the calculated the temperature range 300 K to 3500 K C4F7N+O system 21 decomposition reaction rate constant,and uses the Arrhenius formula fitting the reaction rate constant,the quantitative relationship between the reaction rate constant and temperature.Finally,the partial superheat decomposition test and gas component detection test were carried out to diagnose the decomposing components of C4F7N/CO2 mixed gas,and the variation rules of CF4 and C3F6 particles with the temperature and time of local superheat failure were emphatically analyzed.Relevant conclusions can provide theoretical basis and engineering guidance for fault diagnosis and state detection of C4F7N gas insulation equipment by analyzing C4F7N decomposition products and formation rate.