Study on Capillary Characteristics of High Temperature Liquid Sodium in Stainless Steel Wire Mesh Wick
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摘要: 碱金属高温热管吸液芯的毛细特性对于热管的正常运行具有重要意义。本文采用毛细上升法和称重法在手套箱中开展了高温液态金属钠(简称液钠)在不同目数的304不锈钢丝网吸液芯中毛细特性的实验研究。实验获得了不同温度阶段下吸液芯毛细性能的变化规律,结果表明:在低于460℃阶段,吸液芯毛细性能提升有限,这是由于不锈钢表面Cr2O3氧化膜对液钠润湿性影响决定的。温度高于460℃之后,液钠与Cr2O3发生腐蚀反应,吸液芯毛细性能明显增强。且液钠对不锈钢表面氧化膜的破坏是不可逆的,在后续加热周期的温度变化阶段将保持最佳浸润性,吸液芯毛细特性将主要受到表面张力物性的影响,呈现随温度升高吸液芯质量下降的变化趋势。根据毛细理论并结合吸液芯结构建立了吸液芯毛细抽吸模型,降温阶段模型预测吸钠质量与实验值的误差在12%以内。Abstract: The capillary characteristics of the alkali metal high temperature heat pipe wick are of great significance to the normal operation of the heat pipe. In this paper, the capillary rise method and the weighing method were used to carry out the experimental study on the capillary characteristics of the high temperature liquid metal sodium in the 304 stainless steel wire mesh wick with different mesh numbers in the glove box. The variation of the capillary performance of the wick at different temperature stages was obtained. The results show that the improvement of the capillary performance of the wick is limited below 460℃, which is due to the influence of Cr2O3 oxide film on the wettability of liquid sodium on the stainless steel surface. When the temperature is higher than 460℃, the liquid sodium reacts with Cr2O3, and the capillary performance of the wick is obviously enhanced. The damage of liquid sodium to the oxide film on the surface of stainless steel is irreversible, and the best wettability will be maintained in the temperature change stage of the subsequent heating cycle. The capillary characteristics of wick are mainly affected by surface tension and physical properties, showing a changing trend that the mass of wick decreases with the increase of temperature. According to the capillary theory and the structure of the wick, a capillary suction model of the wick is established. The error between the predicted sodium absorption mass and the experimental value in the cooling stage is within 12%.
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表 1 吸液芯工况表
Table 1. Working Condition of Wick
类型 100目 200目 400目 初始质量/g 140.046 242.555 341.635 -
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