Radiative properties and numerical modeling of C4F7N-CO2 thermal plasma

Abstract

C4F7N and C4F7N − CO2 mixtures are considered as alternatives to SF6 for use in medium voltage gas insulated switchgear applications (GIS), due to the low global warming potential and good dielectric properties of C4F7N. Current work is focused on the calculation of radiative properties (absorption coefficients) of C4F7N − CO2 thermal plasma and computational fluid dynamics (CFD) simulations of free burning C4F7N − CO2 arcs that are stabilized by natural convection. Absorption coefficients of C4F7N − CO2 plasma used in the CFD model are derived from spectral absorption coefficients by Planck averaging. An optimization procedure has been applied to find the optimal number of spectral bands as well as spectral band interval boundaries. Radiation and flow model results for C4F7N − CO2 in comparison to SF6 and air are provided and discussed.