ABSTRACT Heat transfer of a droplet and layer during evaporation of aqueous solutions of salts has been studied. The behavior of salt solutions on a smooth and microstructured surface is compared here. Evaporation rate of aqueous salt solutions is greater for a microstructured surface than for a smooth wall. The behavior of heat transfer coefficient α can be described by two time regimes: quasi-constant values of α and significant increase in heat transfer at a multiple decrease in the liquid layer height. Measurements made with application of the particle image velocimetry showed that the structured surface increases liquid speed inside the sessile drop. The largest value of the heat transfer coefficient α on the structured surface corresponds to water for the final stage of evaporation. For salt solutions, the heat transfer coefficient is lower than that for water in the entire period of evaporation on the structured surface. The maximal excess (20–30%) of α of the structured wall above the smooth surface corresponds to the maximal height of the liquid layer at the beginning of evaporation. With increasing time, the excess is reduced. A drop of heat transfer intensification with a decrease in the layer height relates to suppression of free convection (a multiple decrease in the average velocity in the drop).

中文翻译：

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微结构表面上盐溶液的非等温蒸发

摘要 研究了盐水溶液蒸发过程中液滴和层的传热。这里比较了盐溶液在光滑和微结构表面上的行为。微结构表面的盐水溶液的蒸发速率大于光滑壁的蒸发速率。传热系数 α 的行为可以用两个时间范围来描述：α 的准常数值和液体层高度多次降低时传热的显着增加。应用粒子图像测速仪进行的测量表明，结构化表面增加了固着液滴内的液体速度。结构化表面传热系数 α 的最大值对应于蒸发最后阶段的水。对于盐溶液，在结构化表面的整个蒸发过程中，传热系数低于水的传热系数。光滑表面上方结构壁的最大过量 (20-30%) α 对应于蒸发开始时液体层的最大高度。随着时间的增加，过量会减少。随着层高的降低，传热强化的下降与自由对流的抑制有关（下降中的平均速度的多次降低）。