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刘璐, 卢静圆, 王腾, 王太, 董新宇. 低压环境下固着盐水液滴蒸发特性研究[J]. 真空科学与技术学报. DOI: 10.13922/j.cnki.cjvst.202404015
引用本文: 刘璐, 卢静圆, 王腾, 王太, 董新宇. 低压环境下固着盐水液滴蒸发特性研究[J]. 真空科学与技术学报. DOI: 10.13922/j.cnki.cjvst.202404015
LIU Lu, LU Jingyuan, WANG Teng, WANG Tai, DONG Xinyu. Evaporation Characteristics of Sessile Brine Droplets Under Low Pressure[J]. CHINESE JOURNAL OF VACUUM SCIENCE AND TECHNOLOGY. DOI: 10.13922/j.cnki.cjvst.202404015
Citation: LIU Lu, LU Jingyuan, WANG Teng, WANG Tai, DONG Xinyu. Evaporation Characteristics of Sessile Brine Droplets Under Low Pressure[J]. CHINESE JOURNAL OF VACUUM SCIENCE AND TECHNOLOGY. DOI: 10.13922/j.cnki.cjvst.202404015

低压环境下固着盐水液滴蒸发特性研究

Evaporation Characteristics of Sessile Brine Droplets Under Low Pressure

  • 摘要: 本文开展低压环境下固着盐水液滴蒸发特性的实验和理论研究。实验方面,搭建了可视化实验系统,获得了固着盐水液滴在低压环境下蒸发过程的接触角、接触直径变化规律,使用称重传感器记录了液滴质量变化。理论方面,建立了低压环境下固着盐水液滴蒸发传热传质模型,该模型考虑了液滴的表面曲率及蒸发过程中的活度系数;通过与实验结果的对比,验证了该模型的可靠性。得出结论:当盐水液滴析出晶体形态不再变化时,还有部分水分在晶体缝隙中没有蒸发出来;随着蒸发进行盐水液滴接触角在不断减小,并且压力越低,接触角减小越快,析出的晶体会抑制接触线的铺展与收缩,使接触直径不再变化;液滴盐分浓度越大,蒸发速率越慢;环境压力越低,液滴蒸发速率越快;相比于平表面,凸面基底上液滴铺展面积更大,因此蒸发速率越快。

     

    Abstract: In this paper, the evaporation characteristics of sessile brine droplets in a low-pressure environment are studied experimentally and theoretically. Regarding the experiments, a visual system was established, and the contact angles and contact diameters of the sessile brine droplet during its evaporation process were obtained at low-pressure conditions. A weighing sensor was employed to record the changes in droplet mass. In terms of the theory, a heat and mass transfer model for the evaporation of sessile brine droplets at low-pressure conditions was established. The surface curvature of the droplet and the activity coefficient during its evaporation process were considered. By comparing with experimental results, the reliability of the model has been verified. The results showed that when the crystal morphology of the brine droplets no longer changed, there was still some water that did not evaporate from the crystal gaps. As evaporation proceeds, the contact angle of brine droplets decreases continuously, and the lower the pressure, the faster the contact angle decreases. The precipitated crystals will suppress the spreading and contraction of the contact line, causing the contact diameter to no longer change. The higher the salt concentration of the droplet, the slower the evaporation rate. The lower the ambient pressure, the faster the droplet evaporation rate. Compared to flat surfaces, droplets on convex substrates have a larger spreading area, resulting in a faster evaporation rate.

     

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