Characteristic of temperature oscillation during the operation of loop heat pipe enhanced by pressure head of evaporation

Author(s):  
Xueqiang Li ◽  
Zhongyao Zhang ◽  
Yabo Wang ◽  
Kai Zhu ◽  
Shengchun Liu
2010 ◽  
Author(s):  
D. X. Gai ◽  
Z. C. Liu ◽  
W. Liu ◽  
B. Liu ◽  
J. G. Yang ◽  
...  

2019 ◽  
Vol 163 ◽  
pp. 114281 ◽  
Author(s):  
Takuya Adachi ◽  
Koji Fujita ◽  
Hiroki Nagai

Author(s):  
Dong-chuan Mo ◽  
Guan-sheng Zou ◽  
Shu-shen Lu

Loop heat pipes are high efficient heat transfer loops/devices. Compared to the typical loop heat pipe with cylinder evaporator, loop heat pipe with flat evaporator (flat loop heat pipe, FLHP) can reduce the thermal resistance between the evaporator and the heat loads. In order to remove the heat leak from the evaporator to the compensation chamber to reduce the operation temperature, a new type of FLHP coupling the compensation chamber and the condenser has been developed. Experiments have been conducted to compare the heat transfer characteristics between the normal type and the new type of FLHP. Part of the heat lead from the evaporator to the compensation chamber can be removed in the new type of FLHP, so it gives better heat transfer performance than the normal one. Results show that, the temperatures in the loop of the new type of FLHP are much more stable than the normal one. The evaporator temperatures and the total thermal resistances of the new type are much lower than those of the normal type. For the normal type of FLHP, it may be failed to start up under low power, and usually the larger temperature oscillation will happen. With the power increasing, the frequency of the oscillation is increasing. When the applied power is large enough, the loop can keep running in the design way, and the large temperature oscillation will disappear.


Author(s):  
Dongchuan Mo ◽  
Guansheng Zou ◽  
Shushen Lu ◽  
L. Winston Zhang

This paper presents a flow visualization study on the temperature oscillations inside a loop heat pipe in order to gain a better understanding of its heat transfer characteristics. A flat loop heat pipe (FLHP) with a flat evaporator instead of a typical cylindrical evaporator was built using copper as the shell and water as the working fluid. An experimental setup was designed by using the transparent material instead of copper in some parts of the FLHP. The experiment results showed that there were at least three different flow patterns in the vapor line as the heating power increased. The temperatures in different locations of the loop oscillated even when the heating power was kept constant. The largest amplitude of the temperature oscillation in the loop was located at the condenser outlet. It was found that the temperature oscillation at the condenser outlet could be divided into two types, one with smaller amplitudes and the other with larger amplitudes. The smaller amplitude temperature oscillations were always there when the heating power was increased step by step, while the larger amplitude temperature oscillations would disappear initially and show up later. Finally, the location of the vapor/liquid interface inside the condenser varied with the temperature oscillations, resulting in liquid/vapor interface motion in the compensation chamber.


2021 ◽  
Vol 198 ◽  
pp. 117450
Author(s):  
Xiaochen Lv ◽  
Yongqi Xie ◽  
Hongxing Zhang ◽  
Yanmeng Xu ◽  
Hongwei Wu ◽  
...  

2021 ◽  
Vol 185 ◽  
pp. 116455
Author(s):  
Xueqiang Li ◽  
Bingqing Xu ◽  
Guodong Zhang ◽  
Yabo Wang ◽  
Baomin Dai ◽  
...  

2011 ◽  
Vol 71-78 ◽  
pp. 3806-3809
Author(s):  
Xian Feng Zhang ◽  
Shuang Feng Wang

The present work experimentally investigated the operating characteristics of a miniature loop heat pipe (LHP) under different power cycle. The miniature LHP with flat evaporator of 8mm thick is made of copper. The evaporator with sintered copper power wick is in series structure with compensation chamber. Water is working fluid. It is found that the LHP can start up at heat load of 15W with temperature oscillation and the maximum heat load is 160W with Rl=0.068°C/W. The LHP operates unstably under low heat load. The oscillating frequency of temperature rises with heat load increased. The operating performance of the LHP is affected by the power cycle.


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