The evaporation characteristics of liquid nitrogen coolant of HTS maglev in a low-pressure environment

•Evaporation characteristic of liquid nitrogen under different vacuum degree was studied.•Evaporation experiments were carried out in both vacuum drying oven and evacuated tube.•The effect of evacuation process on evaporation rate was discussed.•Evaporation rate of liquid nitrogen was found to decrease with the decreasing of pressure.

The evacuated tube provides a vacuum condition so that the high temperature superconducting (HTS) Maglev could run at an ultrahigh-speed. While inside the tube, the low-pressure environment could reduce air friction effectively, which is considered to be the main resistance to the Maglev. However, low-pressure would affect the evaporation state of liquid nitrogen (LN2), which is used as the coolant to ensure that the superconductor bulk could reach its superconducting state. This paper studied the evaporation characteristics of LN2 under different pressures, which influence the working time of the HTS Maglev vehicle directly. The results provide an important reference for the evacuated tube HTS Maglev.