RESUMEN
Water shortages are currently becoming more and more serious due to complicated factors such as the development of the economy, environmental pollution, and climate deterioration. And it is the best solution to the problems faced by people in today's world to investigate the bionic structure of nature and explore effective methods for fog collection. Herein, we've illustrated the bionic structures of the Namib desert beetle, cactus spines, and spider silk, and we imitate and further modify the respective bionic structures, as well as construct multifunctional bionic structures to improve fog collection. In addition, we also expound the fog collection behavior of a large fog collector, and an excellent fog capture effect was achieved through studying the mesh structure, the surface modification of the mesh, and the construction of the fog collector. The advantages and limitations of fog collection by a harp fog collector were also explored. We hope that through this review, relevant researchers can have a deeper understanding of this field and thus promote the development of fog collection.
Asunto(s)
Biónica , Cactaceae , Humanos , AguaRESUMEN
It has recently been demonstrated that harps harvest substantively more fog water than conventional mesh nets, but the optimal design for fog harps remains unknown. Here, we systematically vary key parameters of a scale-model fog harp, the wire material, wire pitch, and wire length, to find the optimal combination. We found stainless steel to not only be the best hydrophilic wire material but also nearly be as effective as Teflon-coated wires. The best choice for the wire pitch was coupled to the wire length, as the smallest pitch collected the most water for short harps but was hampered by tangling for taller harps. Accordingly, we use an elastocapillary wire tangling model to successfully predict the onset of tangling beyond a critical length for any given wire pitch. Combining what we learned, we achieved a water harvesting efficiency of 17% with an optimized stainless-steel harp, over three times higher than that of the current standard of a Raschel mesh. These results suggest that an optimal fog harp should feature high-tension, uncoated wires within a large aspect ratio frame to avoid tangling and promote efficient and reliable fog harvesting.
RESUMEN
In arid yet foggy regions, fog harvesting is emerging as a promising approach to combat water scarcity. The mesh netting used by current fog harvesters suffers from inefficient drainage, which severely constrains the water collection efficiency. Recently, it was demonstrated that fog harps can significantly enhance water harvesting as the vertical wire array does not obstruct the drainage pathway. However, fabrication limitations resulted in a very low shade coefficient of 18% for the initial fog harp prototype and the field testing was geographically confined to light fog conditions. Here, we use wire-electrical discharge machining (wire-EDM) to machine ultrafine comb arrays; winding the harp wire along a comb-embedded reinforced frame enabled a shade coefficient of 50%. To field test under heavy fog conditions, we placed the harvesters on a closed-circuit test road and inundated them with fog produced by an array of overlying fog towers. On average, the fog harps collected about three times more water than the mesh netting. During fog harvesting, the harp wires were observed to tangle together due to the surface tension of water. We developed a rational model to predict the extent of the tangling problem for any given fog harp design. By designing next-generation fog harps to be anti-tangling, we expect that even larger performance multipliers will be possible compared to the current mesh harvesters.
RESUMEN
Fog harvesting is a useful technique for obtaining fresh water in arid climates. The wire meshes currently utilized for fog harvesting suffer from dual constraints: coarse meshes cannot efficiently capture microscopic fog droplets, whereas fine meshes suffer from clogging issues. Here, we design and fabricate fog harvesters comprising an array of vertical wires, which we call "fog harps". Under controlled laboratory conditions, the fog-harvesting rates for fog harps with three different wire diameters were compared to conventional meshes of equivalent dimensions. As expected for the mesh structures, the mid-sized wires exhibited the largest fog collection rate, with a drop-off in performance for the fine or coarse meshes. In contrast, the fog-harvesting rate continually increased with decreasing wire diameter for the fog harps due to efficient droplet shedding that prevented clogging. This resulted in a 3-fold enhancement in the fog-harvesting rate for the harp design compared to an equivalent mesh.