Thermal-Fluid Analysis of Coaxial Bipolar Superconducting DC Energy Pipeline

The superconducting DC energy pipeline is a promising technology to transmit electricity and fossil energy such as liquefied natural gas (LNG) at the same time, where LNG could serve as the refrigerant for the high-temperature superconducting (HTS) cables. The bipolar coaxial cable structure is compact and the outside diameter of the pipeline could be reduced. However, as the insulation layer is thickened, the heat generated in the inner conductor layer during the quench process would be difficult to be transferred to the LNG layer, which would lead to a high transient temperature rise and a long recovery time. In this paper, a ±100 kV/1 kA superconducting DC energy pipeline model with the bipolar coaxial cable structure is established in COMSOL Multiphysics. The steady state temperature rise per kilometer is simulated, which could decide the maximum distance between refrigeration stations. Moreover, the transient temperature rise of the conductor layers during DC fault and quench recovery process is evaluated, which could indicate the proper reclosing time after quench.