Enhancing fog collection by optimizing wettability combination and fork-row collector arrangement: light and heavy fog

Abstract

Abstract Fog collection is essential to alleviate water scarcity in arid areas. However, the vast majority of existing fog collectors only work effectively in heavy fog. To broaden the fog concentration range for efficient work, an optimization strategy based on wettability combination and fork-row arrangement is proposed in this work. Single-layer experiment results show that a hydrophilic (HL) surface with high deposition capacity collects droplets at a faster rate in light fog (25–80 g h−1), while the collection rate of a hydrophobic (HB) surface with high drainage capacity is higher in heavy fog (220–500 g h−1). Double-layer experiment results show that in light fog, the best combination of double-layer collection electrodes is HL–HL, while HB–HL performs best in heavy fog. A 35% improvement in collection rate can be obtained simply by changing the arrangement from smooth-row (S) to fork-row (F), which is attributed to the increased effective collision area of droplets. In our series of experiments, at 50 g h−1, the collection rate of double-layer combination HL–HL(F) is 56.7% higher than that of single-layer HL. In particular, the collection rate of HB–HL(F) reaches 1434.7 mg cm−2 h−1 at 500 g h−1. Such a good performance is attributed to the force imbalance of hanging droplets caused by wettability differences, which tends to transport small droplets on HB towards HL directionally, resulting in a rapid droplet slippage. Therefore, the HB–HL accelerates drainage and refreshes capture points. Furthermore, fog collection performance is also influenced by layer spacing, which has an optimal distance. These findings provide a promising method for practical applications of fog collectors in a wide range of fog flow quantities, enhancing adaptability to variable environments.