Electrostatic fog collection mechanism and design of an electrostatic fog collector with nearly perfect fog collection efficiency

Via a one-step gradient anodic oxidation, copper wire with a multi-scale structure and a multi-gradient was fabricated and controlled self-propelling of droplet was achieved.

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Enhancement of fog-collection efficiency of a Raschel mesh using surface coatings and local geometric changes

Colloids and Surfaces A Physicochemical and Engineering Aspects ◽

10.1016/j.colsurfa.2016.08.034 ◽

2016 ◽

Vol 508 ◽

pp. 218-229 ◽

Cited By ~ 22

Author(s):

Mithun Rajaram ◽

Xin Heng ◽

Manasvikumar Oza ◽

Cheng Luo

Keyword(s):

Collection Efficiency ◽

Surface Coatings ◽

Fog Collection ◽

Geometric Changes

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Fog harvesting from cooling towers using metal mesh: Effects of aerodynamic, deposition, and drainage efficiencies

Proceedings of the Institution of Mechanical Engineers Part A Journal of Power and Energy ◽

10.1177/0957650919890711 ◽

2019 ◽

Vol 234 (7) ◽

pp. 994-1014 ◽

Cited By ~ 1

Author(s):

Ritwick Ghosh ◽

Ranjan Ganguly

Keyword(s):

Fresh Water ◽

Cooling Tower ◽

Collection Efficiency ◽

Fluid Dynamic ◽

Tangential Velocity ◽

Cooling Towers ◽

Metal Mesh ◽

Computational Fluid Dynamic Analysis ◽

Fog Collection ◽

Energy Penalty

Fog harvesting is recognized as an important alternate source of fresh water. Industrial fog can supplement water for industrial requirement. Collection of fog (drift droplets) from cooling tower plumes is a viable mode of industrial fog harvesting. The present study delves deeper into the findings of our earlier pilot investigation, on cooling tower fog harvesting and unravels how the collection efficiency depends on interaction of the mesh with the oncoming flow and the deposited fog droplets. Herein, we quantify the fog collection and explain the rationale of the individual contributions of aerodynamic, deposition, and drainage efficiencies on the overall collection efficiency. The effect of the mesh orientations and the tangential velocity component of the cooling tower plume (arising out of the cooling tower-fan rotation) are considered. Aerodynamic efficiency of the mesh and pressure drop across is estimated through computational fluid dynamic analysis. Also, an analysis of the force interaction between the mesh wires, deposited droplet, and the fog stream is carried out to identify the salient deterring factors like re-entrainment, clogging, and premature dripping of collected water droplets, based on which the regime of collection is mapped. The best collection configuration is found at an inclination of 15° with the vertical, with an overall collection efficiency of about 16%. The best configuration would allow recovery of re-usable fresh water at a nominal energy penalty of ∼3.9 kWh/m3. Our results offer the design bases for developing full-scale fog harvesting setups for industrial cooling towers.

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Fog collection behavior of bionic surface and large fog collector: A review

Advances in Colloid and Interface Science ◽

10.1016/j.cis.2021.102583 ◽

2021 ◽

pp. 102583

Author(s):

Hao Yue ◽

Qinghong Zeng ◽

Jinxia Huanng ◽

Zhiguang Guo ◽

Weimin Liu

Keyword(s):

Fog Collection ◽

Bionic Surface ◽

Fog Collector

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Aerodynamics-assisted, efficient and scalable kirigami fog collectors

Nature Communications ◽

10.1038/s41467-021-25764-4 ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Jing Li ◽

Ranjiangshang Ran ◽

Haihuan Wang ◽

Yuchen Wang ◽

You Chen ◽

...

Keyword(s):

Collection Efficiency ◽

Three Dimensional ◽

Surface Characteristics ◽

Water Shortage ◽

Viscous Drag ◽

Flow Forming ◽

Low Wind Speed ◽

Fog Collection ◽

Outdoor Setting ◽

Structural Length

AbstractTo address the global water shortage crisis, one of the promising solutions is to collect freshwater from the environmental resources such as fog. However, the efficiency of conventional fog collectors remains low due to the viscous drag of fog-laden wind deflected around the collecting surface. Here, we show that the three-dimensional and centimetric kirigami structures can control the wind flow, forming quasi-stable counter-rotating vortices. The vortices regulate the trajectories of incoming fog clusters and eject extensive droplets to the substrate. As the characteristic structural length is increased to the size of vortices, we greatly reduce the dependence of fog collection on the structural delicacy. Together with gravity-directed gathering by the folds, the kirigami fog collector yields a collection efficiency of 16.1% at a low wind speed of 0.8 m/s and is robust against surface characteristics. The collection efficiency is maintained even on a 1 m2 collector in an outdoor setting.

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Importance of Body Stance in Fog Droplet Collection by the Namib Desert Beetle

Biomimetics ◽

10.3390/biomimetics4030059 ◽

2019 ◽

Vol 4 (3) ◽

pp. 59 ◽

Cited By ~ 1

Author(s):

Unmeelan Chakrabarti ◽

Roberto Paoli ◽

Souvick Chatterjee ◽

Constantine M. Megaridis

Keyword(s):

Gas Flow ◽

Volume Fraction ◽

Collection Efficiency ◽

Three Dimensional ◽

Stream Velocity ◽

Feedback Effects ◽

Carrier Fluid ◽

Microphysical Properties ◽

Fog Collection ◽

Biomimetic Approach

The fog-basking behavior of the Onymacris unguicularis, a beetle species living in the coastal regions of the Namibian desert, has recently caught the attention of the engineering community, as suggesting a viable biomimetic approach to address the problem of harvesting water in arid regions of the globe. Previous research has focused on observation and analysis of the beetle’s elytron properties and how these affect fog-collection rates. The head stance taken by the Onymacris unguicularis when fog basking is well documented. However, how this stance affects droplet collection has not been studied up to now. The present paper addresses this problem from a computational fluid dynamics perspective, where three-dimensional numerical simulations are used to characterize the fog flow properties around a simplified geometry mimicking the beetle’s body. The simulations employ two-way coupling between the gas flow and the dispersed fog phase to account for feedback effects of fog droplets on the carrier fluid (air), and assume that droplets are captured after hitting the elytron surface. The study considers several combinations of free-stream velocity and droplet volume fraction. The analysis reveals that there is a range of head-stance angles, corresponding to an inclination of the beetle between 35 deg and 45 deg with respect to the horizon, that maximizes water collection on the beetle’s back, in qualitative agreement with observations in nature and laboratory experiments. A rationale is proposed to explain this phenomenon, finding that the specific head stance corresponds to the maximum residence time of fluid particles above the beetle’s elytron surface. This, in turn, designates the maximum likelihood for water droplets to be captured in the boundary layer developing over the beetle and subsequently hit the surface where they get captured. The results reveal the importance of the fluid flow pattern around the beetle’s body in addition to the microphysical properties of the elytron when reliable predictions of the water droplet collection efficiency are sought.

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