Session: 07-04: Experiments and Analyses - III

Paper Number: 135210

135210 - Experimental Study on Startup and Heat Transfer Performance of High Temperature Sodium Heat Pipe 

Abstract: 

The high temperature heat pipe with screen-wick is a highly effective passive device for transmitting heat that can operate under complex operating conditions. Heat transfer of high-temperature heat pipe involves several closely coupled heat and mass transfer processes such as heat conduction, phase change and two-phase flow.In order to study the startup and heat transfer performance of the high temperature heat pipe under different working conditions and to provide a reference for the operation of heat pipe in the heat pipe cooled reactor, sodium was used as the working fluid for the heat pipe, and a high-temperature heat pipe heat transfer performance experimental device was constructed. The startup process, steady-state heat transfer, and heat transfer limits of high-temperature heat pipes were experimentally studied using heating resistance wires and air-water cooling system.By analyzing the temperature change and axial temperature distribution of the heat pipe, the influence law and mechanism of the heating power, inclination angle, and cooling capacity on the heat transfer of the heat pipe have been discussed.The experimental results show that the increase of heating power can promote steam generation and propulsion, speed up the startup of heat pipe, increase the internal gas-liquid circulation rate and the temperature of condenser section, and enhance the heat pipe heat transfer capability. However, when the power is too high, insufficient reflux of liquid at the bottom of the heat pipe evaporator will cause overheating, and even local dry out, leading to the failure of heat pipe. The increase of inclination angle will help liquid return, but also aggravate the instability of liquid film and the accumulation of liquid at the bottom, leading to irregular change of heat transfer. The thermal resistance is the smallest under the horizontal inclination angle. Geyser boiling will occur in the bottom liquid pool within a heating power range under the positive inclination angle, resulting in significant temperature fluctuations. As the power and inclination angle increase, the fluctuation cycle shortened and the amplitude decreases even the fluctuation disappears. The increase of condenser length and heat transfer coefficient will improve heat pipe heat transfer capacity, and the critical startup power of the heat pipe is basically in a linear relationship with the length of the condenser. The excessive cooling of heat sink during startup may cause the heat pipe to fail to start completely or even fail to start. This research may provide valid experimental data support and references for the design optimization and operation of high temperature heat pipes.

Presenting Author: Shunli Jiang Nuclear Power Institute of China; Tsinghua University

Presenting Author Biography: Shunli Jiang (1996-), male, master's degree, doctoral student, currently mainly engaged in research on reactor thermal and hydraulic engineering

Authors:

Shunli Jiang Nuclear Power Institute of China; Tsinghua University
Huihui Zhou Nuclear Power Institute of China
Youjia Zhang Nuclear Power Institute of China
Dewen Yuan Nuclear Power Institute of China
Shanfang Huang Tsinghua University