The counterflow cooling configuration is a compact, efficient, and relatively low cost
thermal management approach for long-length HTS cable systems. In the counter-flow
cooling configuration the coolant flow, typically liquid nitrogen, is initially supplied
through the center of the cable turning around at the far end of the cable and returning
through the annular space between the cable and the inner cryostat wall, using a single
cryostat. The temperature distributions along the cable and the nitrogen flow streams are
extremely difficult to measure in an operating HTS cable because of the issues associated
with installing thermometers on high voltage components. A 5-meter long test loop has
been built that simulates a counter-flow cooled, HTS cable using a heated metal tube to
simulate the cable. The test loop contains calibrated thermometers to measure the
temperature distribution along the tube and the return liquid nitrogen stream. Measured
temperature distributions in the return flow stream and along the tube wall for varying flow
rates and heating conditions to simulate a HTS cable are presented and discussed.