低压环境固着盐水液滴蒸发析晶过程实验研究  

Experimental Study of Evaporation-Induced Crystallization Process of Sessile Saline Droplets under Low Pressure

作　　者：梁秀俊[1] 米梦龙 张凯祺 刘璐 孔淑贤 刘海艳 LIANG Xiujun;MI Menglong;ZHANG Kaiqi;LIU Lu;KONG Shuxian;LIU Haiyan(College of Science and Technology,North China Electric Power University,Banding 071003,China;Department of Power Engineering,North China Electric Power University,Banding 071003,China)

机构地区：[1]华北电力大学动力工程系,保定071003 [2]华北电力大学科技学院,保定071003

出　　处：《真空科学与技术学报》2021年第3期260-267,共8页Chinese Journal of Vacuum Science and Technology

基　　金：国家自然科学基金项目(51406055);河北省自然科学基金项目(E2019502183);中央高校基本科研业务费专项资金资助项目(2020MS108,2020MS144)。

摘　　要：实验研究了低压环境下固着盐水液滴在不同基底表面(铜、载玻片和聚四氟乙烯)的蒸发析晶过程,分析了表面性质和环境压力的影响。结果表明,低压环境下易在接触线处析出白色盐晶。铜表面由于表面能较大,接触面上覆盖盐晶体,液滴蒸发过程接触直径几乎不变,接触角逐渐减小。在载玻片表面,当环境压力较高时,液滴蒸发造成接触线收缩,伴随盐晶体的生长和移动接触角波动。在聚四氟乙烯表面,接触面处易产生气泡,气泡的生长和爆裂导致接触角明显波动。Pe数可以揭示液滴蒸发过程外部传质扩散和内部离子扩散的相对大小。研究成果有助于指导海水淡化的工业应用。The evaporation-induced crystallization process of sessile saline(NaCl solution) droplets on different substrates, including copper, slide glass, and polytetrafluoroethylene(PTFE),was experimentally studied under low ambient pressure.The effects of surface properties and ambient pressure were analyzed.The results showed that white salt crystals were easy to precipitate at the contact line under lower ambient pressure.Due to the large surface energy of copper, the contact surface was covered with salt crystal, the droplet contact diameter remained almost unchanged during evaporation, and the contact angle decreased gradually.On the slide glass, when the ambient pressure increased, the droplet evaporation caused a contraction, accompanied by the growth of salt crystal and the fluctuation of the droplet contact angle.On the surface of PTFE,bubbles were easy to form at the contact surface, and the growth and bursting of bubbles led to an obvious fluctuation of contact angle.The Pe number was introduced to analyze the influences of external mass transfer and internal ion diffusion.The research results are helpful to the industrial application of desalination.

关 键 词：液滴 蒸发 结晶 表面性质 环境压力 

分 类 号：TK121[动力工程及工程热物理—工程热物理]