Considering the total mass change of liquid nitrogen and heat capacity of tank

the mathematical model of vacuum cooling of liquid nitrogen based on the physico-chemical depression

heat transfer coefficient and mass transfer coefficient approach was built. The theoretical results were in satisfactory agreement with the experimental data of making subcooled liquid nitrogen

which indicated the mathematical model could well predict the phase change of liquid nitrogen. The physico-chemical depression of 1.21 K

heat transfer coefficient of 2 942.37 W/(m2·K) and mass transfer coefficient of 0.004 4 m/s respectively were also obtained.