Experimental and analytical investigation of a 0.3-mm-thick loop heat pipe for 10 W-class heat dissipation
Experimental and analytical investigation of a 0.3-mm-thick loop heat pipe for 10 W-class heat dissipation
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DOI：
10.1016/j.ijheatmasstransfer.2022.122950
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发表时间：
2022
影响因子：
5.2
通讯作者：
T. Mizutani;N. Watanabe;Shinobu Aso;Kazuki Sadakata;Shigeyuki Tanabe;H. Nagano
中科院分区：
文献类型：
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作者：
T. Mizutani;N. Watanabe;Shinobu Aso;Kazuki Sadakata;Shigeyuki Tanabe;H. Nagano
本文设计、制造了一种0.3 mm厚的超薄薄板型高热流密度环状热管(>；5×W/cm2)，用于冷却高性能移动设备，并对其换热特性进行了实验和分析评价。LHP的设计是在建立了专门针对超薄铜LHP的稳态数值模型之后进行的。热源尺寸为10×10 mm，LHP的整体尺寸设计为安装在智能手机上。在制造过程中，将两片铜片半刻蚀并焊接在一起，形成了LHP的原型模型。为了评价低温热泵的热传输性能，我们测量了低温热泵各部分的温度对热输入的响应。此外，在假设LHP安装在移动设备上的情况下，在五个方向(水平、横摇和俯仰)上进行了相同的测试，以验证操作方向对性能的影响。在水平工作状态下，低热泵的最大导热性能为10W(10W/cm2)，最小热阻为2.51W/W，有效导热系数为2438W/mK。取向变化试验结果表明，在大于6W的热负荷下，−轧辊的热阻发生了变化，在10W的热负荷下，轧辊90°取向的最小热阻为2.41W/W，有效导热系数为2538W/MK。另一方面，在相同的热负荷下，LHP在螺距+90°方向上的热阻为3.54W/W，有效导热系数为1728W/MK。另一方面，对蒸发器温度和热源温度的影响很小，可以预期所提出的LHP可以在任何方向的移动设备中实施。所建立的稳态数值模型与实验结果吻合较好，估算的LHP运行热损失和散热结果表明，71.3%的最大热负荷在水平方向上散失在冷凝器内，由于液体回流容易，蒸发效率随取向的变化而变化。
In this study, a 0.3-mm-thick ultra-thin sheet-type loop heat pipe (LHP) for high heat flux (>5 W/cm2) for cooling high-performance mobile devices was designed, fabricated, and its heat transfer characteristics were experimentally and analytically evaluated. The LHP was designed after a steady-state numerical model specialized for ultra-thin copper LHPs was developed. The heat source size was 10 × 10 mm, and the overall size of the LHP was designed to be mounted on smartphones. Two copper sheets were half-etched and soldered together to form a prototype model of the LHP during the fabrication process. To evaluate the LHP's heat transport performance, we measured the temperature of each part of the LHP in response to heat input. Furthermore, the same test was conducted in five orientations (Horizontal, Roll ± 90°, Pitch ± 90°) to verify the effect of operating orientation on performance, assuming that the LHP is mounted on a mobile device. In the horizontal operation, the fabricated LHP exhibited a maximum heat transport performance of 10 W (10 W/cm2) and a minimum thermal resistance and effective thermal conductivity of 2.51 K/W and 2438 W/mK, respectively. The orientation change test resulted in a change in the thermal resistance of the LHP under thermal loads greater than 6 W. At a 10 W heat load, the Roll −90° orientation obtained a minimum thermal resistance of 2.41 K/W and an effective thermal conductivity of 2538 W/mK. On the other hand, the LHP achieved a thermal resistance of 3.54 K/W and an effective thermal conductivity of 1728 W/mK at the Pitch +90° orientation under the same heat load. On the other hand, the effect on the evaporator temperature and the heat source temperature is small, and the proposed LHP can be expected to be implemented in mobile devices that take any orientation. The proposed steady-state numerical model agreed well with the experimental results, and the estimated heat loss and heat dissipation due to LHP operation showed that 71.3% of the maximum heat load was dissipated in the condenser in the horizontal orientation, and the evaporation efficiency changed with the change of the orientation due to the ease of liquid reflux.