Temperature and pressure simulation of a high-temperature superconducting cable cooled by subcooled LN₂ with fault current

A computer simulation has been developed to estimate the transient temperature and pressure distributions in a high-temperature superconducting (HTS) power cable cooled by a forced flow of subcooled LN₂. This simulation is critical for assessing the effects of short-circuit accidents in practical HTS power cables. When a fault occurs, an excessive current of 31.5 kA may flow in a cable for 2 s, and it is important to understand the temperature and pressure profiles in a cable cooled by the forced flow of LN₂ when these faults occur until the disturbance flows out from a cable. The temperature profile of the LN₂ coolant and the cable cores was analyzed by solving heat conduction and heat transfer equations using the finite-difference method. The Cryodata GASPAK software package was used to estimate the fluid properties. The simulation results show a fairly good agreement with the experimental results. By employing a new model of the induction refrigeration system and the circulation pump, a small discrepancy is resolved in pressures between simulation and experiment. The analysis results show that the pressure in the cable significantly changes depending on the initial gas volumes in the terminals and the volume of the LN₂ gas that evaporates from the copper former in the cable.