Abstract An open capillary evaporator is proposed to study the evaporation heat transfer performance of porous wick. Both temperature and evaporating mass are measured in this system. Besides, the temperature and relative height of the supplied fluid can be adjusted. A composite porous wick is tested through the constant and variable heat load operation, and it reaches a maximum heat load of 320 W, which corresponds to a heat flux of 25.5 W/cm2. Two types of the evaporator wall temperature curve are observed, and the effect of the initial condition is considered. Intermittent fluid supply appears and causes a temperature overshoot of the evaporator wall. But continuous intermittent fluid supply and small amount of fast-replenishing fluid does not cause the temperature overshoot. The influence of adding water on temperature overshoot is also studied. The boiling and evaporation occur at different heat loads, and the two heat transfer modes coexist at moderate heat load. The transition in heat transfer modes leads to that the evaporation heat transfer coefficient first increases and then decreases with the increase of heat load. This study is helpful to analyze the evaporation heat transfer performance of porous wick and understand the operating characteristics of loop heat pipe.

中文翻译：

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开放式毛细管蒸发器中多孔毛细管的蒸发传热特性

摘要 为研究多孔毛细管的蒸发传热性能，提出了一种开放式毛细管蒸发器。在该系统中测量温度和蒸发质量。此外，可调节供应流体的温度和相对高度。复合多孔芯通过恒定和可变热负荷操作进行测试，其最大热负荷达到 320 W，对应于 25.5 W/cm2 的热通量。观察了两种类型的蒸发器壁温曲线，并考虑了初始条件的影响。出现间歇性流体供应并导致蒸发器壁温度过冲。但连续间歇供液和少量快速补液不会引起温度过冲。还研究了加水对温度超调的影响。沸腾和蒸发发生在不同的热负荷下，两种传热方式在中等热负荷下并存。传热方式的转变导致蒸发传热系数随着热负荷的增加先增大后减小。本研究有助于分析多孔芯的蒸发传热性能，了解环路热管的工作特性。