Abstract.

The evaporation and crystallization process for sessile saline droplets during depressurization is experimentally studied. The relationship between ambient pressure and the crystallization pattern is primarily discussed. When the ambient pressure is low, salt particles are easily formed at the droplet contact line. In contrast, when the ambient pressure is similar to atmospheric pressure, it is more likely for cubic crystals to be formed inside the droplet. By analysing the contact angle fluctuation during crystallization, the experimental results show that the growth of a cubic salt crystal under high ambient pressure or low salt concentration leads to a greater deformation of the liquid-gas interface and a larger contact angle fluctuation. Finally, the Peclet number Pe is introduced to reflect the ratio of the rate of ion advection to the rate of diffusion. The Pe number is larger at lower ambient pressure, which means that the external mass transfer and convection effect is more significant under low pressure, with salt particles easily formed at the droplet contact line. The effect of concentration diffusion inside the droplet increases at higher ambient pressure, thereby, making it easy for cubic crystals to be formed inside the droplet.

Graphical abstract

中文翻译：

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减压过程中无盐盐水的蒸发和结晶过程。

摘要。

实验研究了无盐水滴在减压过程中的蒸发和结晶过程。首先讨论环境压力与结晶模式之间的关系。当环境压力低时，在液滴接触线上容易形成盐颗粒。相反，当环境压力类似于大气压时，在液滴内部形成立方晶体的可能性更大。通过分析结晶过程中的接触角波动，实验结果表明，在高环境压力或低盐浓度下立方盐晶体的生长导致液-气界面变形更大，接触角波动更大。最后，Peclet号Pe引入来反映离子对流速率与扩散速率之比。所述Pe的数目是在较低的环境压力，这意味着外部传质和对流效果低压力下更显著，与在液滴接触线很容易地形成盐颗粒较大。在较高的环境压力下，液滴内部的浓度扩散效果增加，从而易于在液滴内部形成立方晶体。

图形概要