Visualization study of a loop heat pipe with two evaporators and one condenser under gravity-assisted condition
Visualization study of a loop heat pipe with two evaporators and one condenser under gravity-assisted condition
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DOI：
10.1016/j.ijheatmasstransfer.2019.01.121
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发表时间：
2019-06-01
影响因子：
5.2
通讯作者：
Nagano, Hosei
中科院分区：
文献类型：
--
作者：
Chang, Xinyu;Watanabe, Noriyuki;Nagano, Hosei
本文对两蒸发一冷凝回路热管的热流体行为进行了实验研究。丙酮被用作工作流体。为了直接研究流动模式和汽液分布，在具有各种热负荷的MLHP的冷凝器、蒸发器芯和补偿室（CC）中进行可视化测试。实验在重力辅助条件下进行（即，冷凝器的位置比蒸发器高360 mm）。在正常操作模式下，两个蒸发器都被加热;对于热负荷分担模式，只有一个蒸发器被加热。为了进行可视化测试，MLHP的冷凝管使用透明塑料管制造。在MLHP的每个CC中，安装玻璃管。这些试验研究了温度变化、压降、汽液分布和两相流区域的组合。在正常运行模式和热负荷分配模式下，确定了冷凝器漏热与两相长度的关系。研究了重力水头对冷凝管内流动形态和热漏的影响。在热负荷分配模式下，采用可视化实验研究了各蒸发器芯和CC内的汽液分布。在重力驱动模式下，发现并研究了热负荷分担的不足。在重力-毛细管协同驱动模式下，在无动力蒸发器芯中观察到核态沸腾。(C)2019爱思唯尔有限公司版权所有。
In this work, the thermofluid behavior of a loop heat pipe (LHP) with two evaporators and one condenser was experimentally investigated. Acetone was used as the working fluid. To directly investigate the flow patterns and vapor-liquid distribution, visualization tests were conducted in the condenser, evaporator cores, and compensation chambers (CCs) of the MLHP with a variety of heat loads. The experiments were conducted under a gravity-assisted condition (i.e., the condenser was positioned 360 mm higher than the evaporators). Under the normal operating pattern, both evaporators were heated; for the heat load sharing pattern, only one of the evaporators was heated. To conduct visualization tests, the condensing tube of the MLHP was fabricated using a transparent plastic pipe. In each CC of the MLHP, a glass tube was installed. These tests investigated a combination of temperature variations, pressure drops, vapor-liquid distribution and two-phase flow regions. In the normal operating pattern and heat load sharing pattern, the relation between heat leak and two-phase length in the condenser was confirmed. The effect of gravitational head on flow patterns in the condensing tube and heat leak were also investigated. In the heat load sharing pattern, visualization experiments were used to study the vapor-liquid distribution in each evaporator core and CC. In the gravity-driven mode, a lack of heat load sharing was discovered and investigated. In the gravity-capillary codriven mode, nucleate boiling was observed in the unpowered evaporator core. (C) 2019 Elsevier Ltd. All rights reserved.