Abstract.

Gravity shedding of droplets is limited by droplet pinning, a major limitation for low condensation processes and in particular passive dew harvesting in its use as an alternative source of water. We present experiments showing that, paradoxically, a simple surface treatment increasing roughness (sand-blasting) favors droplet shedding compared to the original substrate, provided that sand-blasting does not increase too much the surface roughness. Sand-blasting ensures the high density of nucleation sites and enhances drops coalescence and growth at a sub-micron scale, thus lowering the lag-time to obtain drop sliding during condensation. Early nucleation indeed overcompensates the delay increase due to roughness. Edges of the substrate, where drops grow faster, also improve water collection, thanks to the early sliding of edge drops that behave as natural wipers. Combining the effects of sand-blasting and edges increases significantly the rate of collection of dew condensation on a substrate at a given time, gains of about 30% can be commonly obtained.

Graphical abstract

中文翻译：

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粗糙度提高了凝聚液滴的收集。

摘要。

水滴的重力脱落受到水滴钉扎的限制，水滴凝结是低凝结工艺的主要限制，尤其是在用作替代水源时被动收集露水。我们提出的实验表明，与原始基材相比，增加粗糙度（喷砂）的简单表面处理与原始基材相比更有利于液滴脱落，前提是喷砂不会增加太多的表面粗糙度。喷砂确保了高密度的成核位点，并增强了液滴的聚结和亚微米级生长，从而减少了在凝结过程中获得液滴滑动所需的滞后时间。早期成核确实补偿了由于粗糙度引起的延迟增加。基材边缘（液滴增长较快）还可以改善集水能力，得益于像自然刮水器一样的边缘滴的早期滑动。结合喷砂效果和边缘效果，可以显着提高给定时间在基材上结露的收集率，通常可获得约30％的增益。

图形概要