Session: 04-07: SMRs, Advanced Reactors and Fusion

Paper Number: 137029

137029 - Numerical Investigation of High-Temperature Heat Pipes With Different Wick Structures Under Non-Uniform Heating Boundary Conditions 

Abstract: 

High-temperature heat pipe is an ideal technical solution for microreactors applied for space missions, planet surface, and the small electricity markets on the ground. By using heat pipes, fission heat can be transferred passively and the structure of microreactor is highly simplified as the pumps, pipelines and coolant system are no longer needed in reactor system. For space reactors, because there is no gravity to drive working fluid in the heat pipe, wick structure is used to provide capillary force to generate driving head. However, for the microreactors operating on planet surface or on the earth, high temperature heat pipe is proved to have different thermal behavior compared to weightless environment. Due to gravity, the heat transfer characteristics varies from operation positions, including horizontal, vertical, and inclined positions. The internal wick structure of high-temperature heat pipes provides the driving force for fluid reflux. However, the internal fluid flow state and the effects of key parameters such as permeability, porosity, and capillary force of wick structure on the distribution of working fluid inside the heat pipe are difficult to measure experimentally. In this study, a general CFD model for heat pipe with wick structure that can predict the thermal behavior at different steady-state conditions was carried out. The thermal conduction through heat pipe shell, liquid film on the inner surface, and the formation of liquid reservoir at the bottom of heat pipe were considered in this model. A high-temperature heat pipe model considering the flow of liquid working fluid inside the wick structure was developed based on the Star-CCM+ numerical simulation software. The model used a combination of the liquid film model and the Volume of Fluid (VOF) model to simulate the effects of fluid flow and collection behavior inside the wick structure on the heat transfer characteristics of the heat pipe. The method included models for flow resistance and capillary driving force under steady-state conditions, centrifugal force and time-varying gravitational field under motion conditions, and mixed convective heat transfer caused by motion conditions. The accuracy of the numerical simulation was validated using typical potassium high-temperature heat pipe experiments. The effects of different permeability, porosity, and capillary force characteristics of the wick structure on heat transfer and internal fluid distribution in the heat pipe were studied. Based on the current method, high-temperature heat pipes with different inclinations (0°, 90 °and 45°) were investigated. Additionally, non-uniform heating boundary conditions were added to the high-temperature heat pipe evaporator section to investigate its heat transfer performance under real reactor axial power input. This investigation lays the foundation for the design and analysis of the heat transfer characteristics of high-temperature heat pipes.

Presenting Author: Kailun Guo Xi'an Jiaotong University

Presenting Author Biography: Kailun Guo, PhD, assistant professor at Xi'an Jiaotong University. Dr. Guo’s research interests span various topics, including advanced nuclear reactor thermal-hydraulics, new concept reactor design, high-temperature heat pipes, and meshless particle numerical simulations. He conducted a research visit to the Massachusetts Institute of Technology for two years. Dr. Guo is currently leading two programs of the national natural science foundation of China and more than ten research projects. His scholarly contributions encompass over 50 journal publications with more than 350 citations. He is a recipient of China's "Postdoctoral Innovative Talents Support Program" and won the special award of Science and Technology Award in Shaanxi Province Higher Education Institutions.

Authors:

Kailun Guo Xi'an Jiaotong University
Qishi Sun Xi'an Jiaotong University
Hao Sun China nuclear power technology research institute
Chenlong Wang Xi'an Jiaotong University
Kang Chen SHANGHAI NUCLEAR ENGINEERING RESEARCH & DESIGN INSTITUTE CO., LTD.
Wenxi Tian Xi'an Jiaotong University
Guanghui Su Xi'an Jiaotong University
Suizheng Qiu Xi'an Jiaotong University