Cryogenic system design for HTS power transmission cable cooling with sub-cooled liquid nitrogen

The cryogenic system that is being built will be supplied to the Institute of Electrical Engineering (IEE), CAS, for the cooling of the 3-phase HTS transmission cable. It consists of a centrifugal cryogenic pump, a vacuum pump, a sub-cooler, and a pressurization tank. The cryogenic system can continuously run in the temperature range of 66 K to 76 K because there are two 300L liquid nitrogen (LN2) storage tanks that alternate in use to supply LN2 to the sub-cooler and will yield the continuous cooling power. The design cooling power of the cryogenic system is 3 KW while the liquid nitrogen (@ 77 K, 0.1 MPa) consumed will be less than 80 liter per hour and the working pressures can also be regularly adjusted within the range between 0.1 MPa and I MPa. The Monitor and Control Generated System (MCGS) program is used to acquire the data and control the system to the demand state. The design, construction, cooling power and control system of the cryogenic system will be reported in this paper.