Study On Kinetic Decomposition Characteristics And Breakdown Strength Of C₄F₇N And C₅F₁₀O

Sulfur hexafluoride（SF₆）gas has been used in various electrical equipment because of its good insulation performance and arc extinguishing performance,but it has a significant disadvantage that the greenhouse effect potential is very high,while C₄F₇N and C₅F₁₀O as new environmental protection insulation gas,has the potential to replace SF₆ gas.However,due to the high liquefaction temperature of C₅F₁₀O,its practical application is limited to some extent.Obviously,C₄F₇N has more potential to replace SF₆ than C₅F₁₀O.Therefore,this paper takes C₄F₇N as the main object and C₅F₁₀O as the comparison object to carry out research,as follows:Firstly,the possible decomposition paths of C₄F₇N were calculated and analyzed by using CCSD（T）functional def2-TZVPP high order basis group based on density functional theory,and the decomposition mechanism was described in detail.At the same time,the rate constant of decomposition reaction with high energy barrier and low energy barrier were calculated based on the transition state theory and variational transition state theory in the temperature range of 300-30000K.The equilibrium constants of each reaction were also calculated to determine the highest concentration of particles in different temperature ranges.Meanwhile,10 eigen decomposition paths of C₅F₁₀O were comparatively analyzed by the same method.Secondly,the thermodynamic data of each particle in the C₄F₇N system were calculated and arrhenius fitting was carried out for all reaction rate constants.The Chemkin calculation program was used to simulate and analyze the dynamics of the C₄F₇N system as input data.The recombination process of decomposition products of C₄F₇N was considered.The reaction rate constant of the composite path was calculated and the kinetic analysis was carried out.Meanwhile,the kinetic characteristics of the related particles in C₅F₁₀O system were comparatively analyzed.Finally,the ionization energy,electron affinity energy,polarization and other insulation parameters of different particles were calculated,and the relative insulation strength prediction model was constructed.The relative insulation strength of C₄F₇N and C₅F₁₀O system particles was calculated with the prediction model.The results show that the concentration of CF₃ and CF₂CFCN in class I reaction is the highest in the temperature range of 300-30000K.The concentration of CF₂ and CF₂CN is the highest when the temperature is 300-2570K,and the concentration of CN and CF₂C is the highest when the temperature is 2570-30000K in class II reaction.The concentration of CF₃ and CF₂ should be the highest when the temperature is 300-4450K,and the concentration of CF₂ should be the highest when the temperature is 4450-30000K in class III reaction.The decomposition products of C₅F₁₀O is that CO and CF₃CFCF₃ have the highest concentration.According to the kinetic analysis,with the increase of temperature,the decomposition rate of C₄F₇N and C₅F₁₀O not only accelerates,but also becomes more intense,but the recombination degree decreases.The relative insulation strength of C₄F₇N and C₅F₁₀O systems is calculated by the relative insulation strength prediction model based on insulation parameters and the correlation between the experimental value and the relative insulation strength is 0.8068,and the relative insulation strength of C₄F₇N and C₅F₁₀O systems is obtained.The results of this paper can provide data guidance for the application of environmental insulating gas in practical engineering.