Experimental Study on Startup and Heat Transfer Performance of High Temperature Sodium Heat Pipe

Abstract The screen-wick sodium heat pipe is a highly effective passive device for heat transfer that can operate under complex operating conditions. In this work, the startup process, steady-state heat transfer, and heat transfer limits of sodium heat pipe were experimentally studied and the influence law and mechanism of the heating power, inclination angle, and cooling condition on the heat transfer of the heat pipe have been discussed. The experimental results show that high heating power will cause overheating, and even local dry out, leading to the failure of heat pipe. The increase of inclination angle will lead to irregular change of heat transfer. Geyser boiling will occur within a heating power range under the positive inclination angle, resulting in the significant temperature oscillation. The increase of cooling capacity will improve heat transfer power, and the critical startup power of the heat pipe is basically in a linear relationship with the length of the condenser. However, the excessive cooling may cause the heat pipe to fail to start and the operation of heat pipe at low temperatures is restricted by the sonic limit. This research may provide valid experimental data support and references for the design optimization and operation of high temperature heat pipes.