Controlling the thermal environment of underground cable lines using the pavement surface radiation properties

Abstract

The main purpose of this study is to show how the emissivity and absorptivity of a pavement surface aboveunderground cables affect their ampacity. The use of cool pavements whose surfaces absorb less heat from the Sun than theyemit to the ambient is considered as a novel method to control the thermal environment of underground cables. The methodpredicts that the trench along the entire length of a 110 kV cable line is completely filled with quartz sand and paved with a coolpavement. Quartz sand would provide good conduction of heat from the cables to the earth and pavement surfaces, while apaved surface of the trench would establish approximately unchangeable convection and radiation boundary conditions alongthe entire cable line route. It is assumed that the three-phase system is balanced and that the boundary conditions along theearth and pavement surfaces are the most unfavourable. The novel method is based on the results of experimental research,generalised and verified numerically using the finite-element method in COMSOL. Finally, it is established that the ampacity ofthe 110 kV cable line can be increased up to 26.7%