Thermo-hydraulic analysis on long three-phase coaxial HTS power cable of several kilometers

A coaxial HTS (high temperature superconductor) power cable has advantage of using less amount of HTS wires than three-phases in one cryostat structure because it does not need each shielding layer. In the coaxial HTS power cable, thermo-hydraulic analysis such as pressure drop across a long cable and thermal characteristics in the cable is also required considering geographical feature of the installation site and the temperature distribution in the cable core, composed of three phases and insulation layers. The operating pressure and temperature are limited by the mechanical strength of a cryostat and the boiling temperature of liquid nitrogen. This paper describes a thermo-hydraulic analysis and design of the coaxial HTS power cable considering the operating temperature and circulation of subcooled liquid nitrogen over several kilometers. Through the analysis, the required specifications of a refrigeration system are determined considering the pressure drop and thermal analysis of cable core for heat losses such as AC loss and heat penetration. A 1-D node network analysis is conducted to investigate detail temperature distributions and variations of cable core in conjugation with computational fluid dynamics.