Entropy generation in concentric annuli of 400 kV gas-insulated transmission line

Abstract

The object of this study is entropy generation analysis in the concentric annuli of a gas insulation transmission line enclosure (GIL) loaded with air and SF6-N2 mixture gas. The inner and outer cylinders of the cavity are hot and cold, respectively. Because of symmetric conditions the ½ cylinder is considered for modeling. The standard k–ɛ turbulence model, the equation of entropy generation, and the conservation equations are transformed from dimensional form to non-dimensional form utilizing the definition of dimensionless parameters, stream function, and vorticity. Then dimensionless governing equations are solved by a finite volume method (FVM) using an innovative ANSYS Fluent non-dimensionalization scheme. Inflated layers applied to the fine grids to improve the simulation capability for turbulent modeling. The effects of the Rayleigh number at Ra = 2.5 × 106, 1.7 × 109, 2.1 × 109, 4.2 × 109 and 5.7 × 109 are investigated. The results demonstrate that the Nusselt number grows as the Rayleigh number grows and entropy generation number and the Bejan number decreases as the Rayleigh number increases. The GILs have a proper morphology in geometry that reducing the high irreversibility in higher Rayleigh numbers conditions.