Numerical study of heat transfer in underground power cable system

Underground power cable system has been wildly used as an effective transmission line. This paper presents the thermal analysis of the two formations (Flat and Trefoil) of buried system. Temperature-dependent thermal conductivity of soil was considered in the research and the Fluidized Thermal Backfill (FTB) was applied to increase the ability of heat dissipation of power cable system. Further, the influences of heat transfer performance and ampacity on power cable systems were studied when FTB was applied in two formations. Firstly, it is found that the geometric parameters have significantly effects on the heat transfer performance of underground power cable system. Secondly, considering the temperature-dependent thermal conductivity, the maximum temperature of cables will rise rapidly, the limited temperature is easy to reach. The application of FTB can enhance the heat transfer of the whole system, especially for trefoil formation. Finally, the analysis of ampacity shows that the FTB will ensure the higher loading current in a security condition with the temperature-dependent thermal conductivity.