An Experimental Study on the Heat Transfer Characteristics of a High-temperature Sodium Heat Pipe Depending on the Thermal Transport Conditions

고온 나트륨 히트파이프에서 열이송 조건에 따른 열전달 특성에 대한 실험 연구

Cylindrical stainless-steel/sodium heat pipe for a high-temperature application was manufactured and tested for transient and steady-state operations. Two layers of Stainless-steel screen mesh wick was inserted as a capillary structure. The outer diameter of the heat pipe was 12.7 mm and the total length was 250 mm. As thermal transport conditions, the effective transport length, the heat flux, the tilt angle and the operating temperature were varied. The heat was supplied by an electric furnace up to 1 kW and the cooling was performed by forced convection of air. The effective thermal conductivity and the thermal resistance were investigated as a function of heat flux, heat transport length, and vapor temperature. Typical range of the total thermal resistance was as low as $0.036^{\circ}C/W$ at $175.8\;kW/m^2$ of heat flux and $700^{\circ}C$ of operating temperature.