Cooling system and method of cooling electronic device

A method of cooling an electronic device, comprising:

• disposing a housing having through-holes formed in a top portion and a bottom portion thereof, respectively, in a sealed immersion tank, and disposing an electronic device in the housing so that an inside of the immersion tank is filled with a liquid coolant;
• generating, by heat generated in the electronic device, natural convection of the coolant that is discharged out of the housing from the through-hole in the top portion of the housing, passes through a coolant flow path between an outer surface of the housing and an inner surface of the immersion tank, and returns to an inside of the housing from the through-hole in the bottom portion of the housing;
• and
• transporting, by a heat pipe, heat of the coolant that passes through the coolant flow path to an outside of the immersion tank,
• the heat pipe is arranged through a side wall of the immersion tank,
• the heat pipe is a hollow cylindrical member, opposite ends of which are closed,
• a hydraulic fluid is sealed in the heat pipe, and
• the hydraulic fluid transports heat of the coolant in the coolant flow path to an outside of the immersion tank.