Operational characteristics of the miniature loop heat pipe with non-condensable gases
Operational characteristics of the miniature loop heat pipe with non-condensable gases
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DOI：
10.1016/j.ijheatmasstransfer.2010.04.008
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发表时间：
2010-08
影响因子：
5.2
通讯作者：
Randeep Singh;A. Akbarzadeh;M. Mochizuki
中科院分区：
文献类型：
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作者：
Randeep Singh;A. Akbarzadeh;M. Mochizuki
实验研究了不凝性气体（NCGs）对微型环路热管（mLHP）热性能的影响。研究中使用了铜mLHP，其具有直径为30mm、厚度为10mm的扁平盘形蒸发器和长度为50mm、高度为10mm的翅片管式冷凝器，其位于150mm的距离处。该装置是为计算机微处理器的热控制而设计的，在保持电子设备蒸发器温度低于100°C极限的情况下，最大热负荷可达70W。水用作mLHP内的传热流体。所有的测试都是在蒸发器和冷凝器处于同一水平高度的情况下进行的。设计了简单的方法来检测和清除产生的NCG的环路热管，而不拆卸系统。对NCG生产和储存趋势进行分类的实验表明，大部分气体是在最初几次热运行中产生的，并积聚在补偿室中。灵敏度测试表明，NCG的总体效果是提高回路的稳态操作温度，并增加蒸发器所需的启动时间，以实现给定热负荷的稳定条件。作为研究工作的结果，可以得出结论，由于补偿室的存在，mLHP比传统热管更能耐受NCG，该补偿室可以积聚大部分释放的气体而不会导致主要性能下降。
The present paper experimentally investigates the effect of non-condensable gases (NCGs) on the thermal performance of the miniature loop heat pipe (mLHP). Copper mLHP with the flat disk shaped evaporator, 30mm diameter and 10mm thick, and fin-and-tube type condenser, 50mm length and 10mm height, located at a distance of 150mm was used in the study. The device which was designed for the thermal control of computer microprocessor was capable of transferring maximum heat load of 70W while maintaining evaporator temperature below 100°C limit for electronic equipments. Water was used as the heat transfer fluid inside the mLHP. All the tests were conducted with the evaporator and condenser at the same horizontal level. Simple methods were devised to detect and purge the generated NCG out of the loop heat pipe without disassembling the system. Experiments conducted to classify the trends in the NCG production and storage revealed that majority of the gas is generated in the first few thermal runs and is accumulated in the compensation chamber. Sensitivity tests show that overall effect of the NCG is to elevate the steady-state operating temperature of the loop and increase the start-up time required by the evaporator to achieve stable conditions for the given heat load. As an outcomes of the research work, it can be concluded that mLHPs are more tolerable to the NCGs than conventional heat pipes due to the presence of compensation chamber that can accumulate most of the released gas without major performance degradation.