Threedimensional numerical simulation for heat and mass transfer of the evaporator in a flat miniature loop heat pipe
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摘要: 针对小型平板回路热管蒸发器内的流动与传热,建立了多区域耦合的数学物理模型,并应用FLUENT软件进行了三维数值模拟。结果表明:蒸发器传热特性在不同热负荷下呈现出较大的差异,其温度分布不仅取决于热负荷,更依赖于毛细芯表面发生的两种传热机制,即毛细蒸发和热传导。相比高热负荷(Q=120W)和低热负荷(Q=40W),中等热负荷(Q=80W)下蒸发器各个部位的温度均较低。三种不同热负荷下,毛细芯反向导热均大于侧壁漏热,补偿腔内与毛细芯相邻处易出现高温区。冷凝回流液在补偿腔内的流动形成两个涡,这种流动特点有利于降低毛细芯的温度。当热负荷与系统冷凝能力匹配时,整个系统流动与传热特性最优。Abstract: In order to analyse the heat and mass transfer of the evaporator in a flat miniature loop heat pipe, a multidomaincoupling mathematical model was developed and threedimensional numerical simulation was implemented using FLUENT software. According to the results, the evaporator heat transfer characteristics showed obvious difference at different heat loads. Evaporator temperature was not only determined by the heat load, but much affected by the two heat transfer mechanisms on the wick surface, i.e: capillary evaporation and heat conduction. Compared with high heat load (Q=120W) and low heat load (Q=40W) condition,all parts of the evaporator under medium heat load (Q=80W) condition were at lower temperature. For all of the three different heat loads, inverse heat conductions from the wick were larger than heat leak from the side walls, therefore the highesttemperature region in compensation chamber easily presented near the wick. Backflow from the condenser flowing into the evaporator formed two large eddies in compensation chamber. Such a flow characteristic is conducive to chilling wick. When the heat load added on the system matches its condensation capacity, the flow and heat transfer characteristics of the system is optimal.
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