DESIGN, DEVELOPMENT AND TESTING OF LARGE DIAMETER HIGH TEMPERATURE ALKALINE METAL HEAT PIPE

Heat pipe is the most critical heat transfer element in the silent heat pipe reactor, which utilizes the phase change of the work material to carry out heat transfer work through gravity, centripetal force and capillary force, and works stably under high temperature conditions with high heat transfer efficiency. Large-diameter high-temperature heat pipe relies on a larger cross-sectional area of the vapor chamber and a larger amount of liquid filling, so that the heat transfer limit of the high-temperature heat pipe is greatly improved, increasing the heat transfer capacity of the heat pipe under the same length. In this paper, the design optimization and development test of large diameter high temperature heat pipe is carried out, the heat pipe shell material is stainless steel 310S, the length is 2 m, the diameter is 89 mm, and the wall thickness is 5 mm. The heat transfer medium is sodium and potassium. The filling of the heat pipe is carried out in the glove box using the hot state filling method to ensure the purity of the work material. The manufactured heat pipe is placed vertically for performance testing, utilizing electromagnetic induction to heat the evaporator section, and the condenser section is cooled under air-cooling conditions. It is found that the wick has a greater impact on the heat transfer performance of the heat pipe. Heat pipe #1 is a thermal siphon without the wick, the maximum heating power is 10 kW, due to the intermittent boiling of the large liquid pool at the bottom of the test process led to the existence of a violent vibration. The selection of the wick also has a great impact on the heat transfer performance of the heat pipe. Heat pipe #2 and heat pipe #3 are capillary core heat pipes with different mesh numbers of stainless steel wire mesh as the wick. The maximum electromagnetic power of heat pipe #2 is 12.3 kW, the cooling power is 3.72 kW, the maximum temperature of heat pipe is 903 ℃, and there is local high temperature in the evaporator section. The maximum electromagnetic power of the heat pipe #3 is 17 kW, the cooling power is 6.11 kW, the maximum temperature is 826.1 ℃, the heat transfer power is higher, and the overall temperature of the heat pipe is flattened, and no overheating phenomenon occurs. Compared with the small diameter heat pipes, the temperature fluctuation during the startup and steady state of the large diameter heat pipes is greater, and the temperature fluctuation in the condenser section reaches ± 10℃, and the entrainment phenomenon is more obvious. However, relying on a larger cross-sectional area of the vapor chamber and a larger amount of liquid filling, the heat transfer power of large diameter heat pipe is higher.