Cooling configuration design considerations for long-length HTS cables

Recent successes in demonstrating high temperature superconducting (HTS) cable systems hundreds of meters in length have inspired even longer length projects. A compact and energy efficient cooling configuration can be achieved using a counterflow-cooling arrangement. This is particularly attractive when all three phases are contained in a single cryostat because of the elimination of the space and thermal requirements of a separate liquid nitrogen return line. Future cable projects will utilize second generation (2G) wire which is expected to become lower in cost but may have different thermal requirements than first generation (1G) BSCCO wire due to the lower critical temperature and to a lesser extent, the lower thermal conductivity of the wire. HTS cable configurations are studied with a numerical model to assess thermal hydraulic performance with AC and thermal losses; a summary of the results from the analysis will be presented. An analysis of the cable thermal-hydraulic response to over-current faults will be presented.