Physicochemical properties of CF₃OCF = CF₂ in high-voltage switchgear: part 1. Decomposition characteristics and thermodynamic parameters

Abstract

Recently, perfluoromethyl vinyl ether (CF3OCF=CF2) has been proposed to have the potential to replace SF6, but its arc-extinguishing ability is still unknown. To provide the necessary basic parameters for further study of arc extinguishing characteristics, this series of papers focuses on the physical and chemical properties of CF3OCF=CF2 arc plasma. The research content of this paper is decomposition characteristics and thermodynamic parameters. The geometric configuration, rotational inertia, and vibration frequency characteristics of CF3OCF=CF2 and its decomposition products were obtained at the B3LYP/6-311G(d,p) level. The energy of each particle was calculated at the CCSD(T)/cc-pVTZ level. The most likely decomposition path was CF3OCF=CF2→CF3+CF2CFO→CF2+CFO. The equilibrium compositions of arc plasma were calculated by the mass action law model. The main components of pure CF3OCF=CF2 after arc were C3F8, C3F6, C2F6, CF4, and CO. When CO2 was mixed in CF3OCF=CF2, with the increase of CO2 content, the main components after arc gradually became CF2O, CF4, CO2, and CO. The thermodynamic parameters such as density, specific enthalpy, and specific heat at constant pressure were obtained by thermodynamic relationship. Through ρCp and ρh, it can be inferred that the radial heat transfer capacity of CF3OCF=CF2 is not as good as SF6, but the energy dissipation capacity of axial heat convection is stronger than SF6, and the arc presents the characteristics of large radius and long length.