Design of the Onboard Cryogenic System for High-Temperature Superconducting Maglev Vehicle

In the high-temperature superconducting (HTS) maglev system, the cryogenic system is used to eliminate the thermal load of the low-temperature unit in time to maintain the superconducting state of the superconductor, which is the prerequisite of the application. At present, liquid nitrogen (LN 2 ) immersion cryogenic system is used in HTS maglev vehicles, but the operation efficiency of the vehicles will be reduced because of the LN 2 replenishment. Therefore, according to the application environment of HTS maglev vehicles, an onboard LN 2 natural circulation cryogenic system based on the principle of thermosiphon is designed. This paper focuses on the design of the structure of the cryogenic box, including the design of the vacuum system, the selection of refrigerator, the design of heat exchanger, and the selection of materials. Finally, it is calculated that the thermal load of the cryogenic system during the normal operation of the HTS maglev vehicle is 25.09 W, which is less than the cooling capacity of 120 W when the cryogenic system is working at 65 K. The feasibility of the cryogenic system is verified, which will provide a reference for the design of the cryogenic system in the engineering of the HTS maglev vehicles.