Heat Transfer Analysis of Different Conditions for SF$_{6}$/N$_2$ Gas-Insulated Transmission Lines

Considering that SF
₆
is a potent greenhouse gas, SF
₆
/N
₂
gas mixtures are preferred to serve as the insulating gas for its environmental friendliness and good insulation. Since heat transfer analysis is very useful for ascertaining the appropriate temperature rise range, which can ensure the safe operation and extension of remaining useful life of GIL, it is essential to study the thermal properties of SF
₆
/N
₂
gas mixtures. Nevertheless, very few studies investigate on the temperature field of SF
₆
/N
₂
gas mixtures under ideal conditions. To reflect the heat transfer characteristics accurately, in this paper, by using the finite-element method and multi-physics coupling, the heat transfer properties in the GIL is analyzed by using a three-dimensional (3-D) axisymmetric GIL model. By varying the SF
₆
/N
₂
mixing ratio and observing the corresponding heat transfer characteristics, the mapping between SF
₆
/N
₂
mixing ratio and the temperature rise is obtained by using the model. Furthermore, the mappings are studied under different gas pressures, line currents and ambient temperatures, which correspond to different real-life operating conditions. The proposed strategies can effectively give guidance of choosing proper SF
₆
/N
₂
mixing ratio for desired temperature rise, and thus having great values of practical applications.