Numerical Simulation of the Temperature, Humidity Field and Dew Condensation in Substation Equipment

Abstract

With the increasing level of electrical equipment manufacturing, the increasingly miniaturized structure of electrical equipment has been widely used, but with the gradual reduction of insulation levels, the internal insulation level of electrical equipment has been more severely tested. Based on the conservation laws of energy, momentum, mass and species, considering air as a mixture of ideal gases composed of water vapor and dry air, taking into account that the density of air changes relatively little during the flow, treating air as an incompressible fluid, and also considering that water vapor diffusion follows Fick's law, a mathematical model of the temperature and humidity field model of the outdoor terminal box under heat conduction, air convection and water vapor diffusion are constructed by computational fluid dynamics (CFD) technology with using the species transport model. This paper analyzes the effects of temperature, humidity, forced ventilation and internal heat source on the condensation phenomenon. The numerical calculation results show that the air temperature in the outdoor terminal box gradually rises under the condition of heat conduction and heat convection due to the self-heating of the conductor. The distribution of humidity shows that the humidity at the gas inlet is at the highest state, and the humidity at the higher temperature is relatively lower.