Visualization Investigation on Temperature Oscillation and Two-Phase Behaviors of a Flat Loop Heat Pipe

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  • 1. College of Civil Engineering, Hunan University, Changsha 410082, China
    2. School of Civil Engineering, Hunan University of Technology, Zhuzhou 412007, China

Online published: 2023-11-27

Supported by

This work was supported by National Natural Science Foundation of China (NSFC) (Grant No. 51878254) and National Key R&D Program of China (Grant No. 2018YFE0111200), Key Research and Development Plan of Hunan Province (2020WK2012), Hunan    Provincial Science and Technology Department (2020GK4057).

Copyright

Science Press, Institute of Engineering Thermophysics, CAS and Springer-Verlag GmbH Germany, part of Springer Nature 2023

Abstract

To better analyzing the temperature oscillation and the two-phase behavior inside a flat loop heat pipe, visual studies were conducted. Under the 20°C water cooling and horizontal orientation, the effects of the filling ratio and heat loads on the temperature oscillation were analyzed. Based on the experimental data, the results indicate that owing to the increased system pressure, the temperature oscillation decays as the filling ratio increases from 34% to 58%. Meanwhile, during the startup process, temperature oscillation tends to occur during the boiling and steady stages due to the more violent two-phase behavior, while the temperature curves are smooth during the slow evaporation stage. Moreover, as the heat load increases, the evaporation becomes more intense at the active zone of evaporator, leading to a faster startup process and a higher oscillation frequency. Besides, owing to the synergistic effect of two-phase flow in the compensation chamber caused by heat leak and subcooled liquid backflowing, a “breathing” oscillation behavior of the vapor-liquid interface is observed at the compensation chamber, which further leads to the unstable operation behavior of the loop heat pipe system.

Cite this article

DU Sheng, ZHANG Quan, LING Li, ZOU Sikai, LIU Lijun, MENG Fanxi . Visualization Investigation on Temperature Oscillation and Two-Phase Behaviors of a Flat Loop Heat Pipe[J]. Journal of Thermal Science, 2023 , 32(4) : 1536 -1546 . DOI: 10.1007/s11630-023-1782-2

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