Liquefied hydrogen storage tank, and method for controlling temperature of liquefied hydrogen storage tank

A liquefied hydrogen storage tank acting as a storage container storing liquefied hydrogen, the liquefied hydrogen storage tank having an inner space comprising a lower space in which the liquefied hydrogen is stored and an upper space in which a gas is stored,

• wherein the liquefied hydrogen storage tank comprises a heat inflow prevention unit adjoining a surface of the liquefied hydrogen stored in the liquefied hydrogen storage tank or at least partially immersed in the liquefied hydrogen,
• wherein the heat inflow prevention unit comprises:
• one or more floating plates floating in the liquefied hydrogen stored in the liquefied hydrogen storage tank or adjoining the surface of the liquefied hydrogen;
• and
• a heat exchanger disposed and connected under the one or more floating plates,
• wherein the heat inflow prevention unit is variable in location depending of the level of the liquefied hydrogen, and
• wherein the heat exchanger is configured to cool a surface layer of the liquefied hydrogen and maintain the surface layer of the liquefied hydrogen in a temperature range in which the liquefied hydrogen is present in a solid-liquid mixed slurry state such that the surface layer is in the solid-liquid mixed slurry state to suppress evaporation of the liquefied hydrogen in the storage tank.