Thermal Characteristics of Gaseous-Helium-Cooled HTS Cables With Practical Operating Conditions

High temperature superconducting (HTS) cables have the advantages of low loss and large capacity transmission. The cryogen used for HTS cable cooling is mainly liquid nitrogen. In some applications, using gaseous helium (GHe) as a cryogen has advantages. For example, it can reduce the weight of the system, remove the risk of frostbite of surrounding equipment and people caused by leakage of liquid nitrogen, and avoid suffocation due to evaporation of liquid nitrogen in confined spaces. Temperature is closely related to the performance of superconducting tapes. Therefore, it is of great significance to study the thermal characteristics of cables using GHe as cryogen under several important operating conditions. These conditions include cooling, carrying rated current, cryocooler fails, both cryocooler and cryogenic gas circulation pump fail, and local hot spot. In this article, a two-dimensional axisymmetric simulation model of a 50-m 4 kA HTS cable was built in COMSOL to study the thermal characteristics of GHe-cooled HTS cables. The range of mass flow rates of GHe suitable for operation of this cable was calculated considering different operating conditions.