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Klemm O.,University of Munster | Schemenauer R.S.,FogQuest Sustainable Water Solutions | Lummerich A.,Alimon E.V | Cereceda P.,University of Santiago de Chile | And 12 more authors.
Ambio | Year: 2012

The collection of fog water is a simple and sustainable technology to obtain fresh water for afforestation, gardening, and as a drinking water source for human and animal consumption. In regions where fresh water is sparse and fog frequently occurs, it is feasible to set up a passive mesh system for fog water collection. The mesh is directly exposed to the atmosphere, and the foggy air is pushed through the mesh by the wind. Fog droplets are deposited on the mesh, combine to form larger droplets, and run down passing into a storage tank. Fog water collection rates vary dramatically from site to site but yearly averages from 3 to 10 l m-2 of mesh per day are typical of operational projects. The scope of this article is to review fog collection projects worldwide, to analyze factors of success, and to evaluate the prospects of this technology. © Royal Swedish Academy of Sciences 2012. Source

Bansal S.,Institute For Textil Und Verfahrenstechnik | von Arnim V.,Institute For Textil Und Verfahrenstechnik | Stegmaier T.,Institute For Textil Und Verfahrenstechnik | Planck H.,Institute For Textil Und Verfahrenstechnik
Journal of Hazardous Materials | Year: 2011

Separation of secondary emulsions of dispersed droplet size less than 10μm, by means of fibrous medium is a very complex but important process. The study investigates the influence of thin fibrous filter properties, i.e. surface energy, pore size and porosity on the separation performance of an isooctane in water emulsion (0.2%, mean drop size 2μm). Experiments were carried out on five different filter media with a wide variation in their pore size (2-51μm), surface energy (14-46. mN/m) and porosity (0.46-0.87) at similar process conditions. Filter media with different wettability are obtained by applying various hydrophobic and hydrophilic coatings. All the used coatings contain nanoparticles (25. nm) to impart nanoscale surface roughness at the single fiber surface. Besides emulsion properties and operating conditions, the phase separation mechanism and performance highly depends on pore size, surface energy and porosity of the filter media. More complete coalescence takes place at reduced pore size and at a surface preferentially wetted by the dispersed phase. Whereas when the pore size equals to the influent droplet size, then the surface wettability of filter is less effective and the separation mechanism is governed by inflow velocity. The emulsion inflow velocity and pressure drop are significantly affected by the filter media air permeability but do not depend on filter surface energy. © 2011. Source

Agarwal S.,Institute For Textil Und Verfahrenstechnik | Von Arnim V.,Institute For Textil Und Verfahrenstechnik | Stegmaier T.,Institute For Textil Und Verfahrenstechnik | Planck H.,Institute For Textil Und Verfahrenstechnik | Agarwal A.,Institute For Textil Und Verfahrenstechnik
Industrial and Engineering Chemistry Research | Year: 2013

Emulsions separation through porous fibrous media is a popular and complex process. This research investigates the influence of superficial velocity (0.6-1.8m/min), inflow direction (horizontal, radial), and sandwich filter structure on the phase separation performance of nanocoated coalescing filters. Experiments were performed using three different filters and their different sandwich combinations for 1% isooctane in water emulsions with mean droplet size 5 μm. These filters were coated with hydrophobic-oleophilic nanoparticle to impart suitable wetting and surface roughness functionality. With the increasing superficial velocity, the separation efficiency and quality factor decreases while the pressure drop across the filter increases. A rapid drop in the separation efficiency takes place above the superficial velocity of 1.0 m/min. The separation efficiency does not depend on the inflow direction, but the pressure drop across the filter is about half in the horizontal inflow direction than in radial inflow direction. For high droplet capture, the filter layer facing the influent stream should be made of the finest available fibers while its wettability does not affect the droplet capture. For effective separation of liquid droplets from a fluid stream, a vertically oriented gradient filter preferably wetted by dispersed phase and with increasing fiber size and permeability from influent to effluent is the most favorable structure. © 2013 American Chemical Society. Source

Sathis Kumar S.,Institute For Textil Und Verfahrenstechnik | Sathis Kumar S.,Indian Institute of Technology Delhi | Milwich M.,Institute For Textil Und Verfahrenstechnik | Deopura B.L.,Indian Institute of Technology Delhi | Plank H.,Institute For Textil Und Verfahrenstechnik
Procedia Engineering | Year: 2011

Composite sandwich structures were developed for the hydrofoil sail boat hull using biaxial carbon fabric/epoxy composite facing and agglomerated cork core. These ultra-light weight structures were tested through four point bending tests to characterize their flexural behavior. The material exhibited an initial linear elastic behavior followed by non-linear elastic-plastic behavior. Finite element analysis of the sandwich beams was performed to analyze the flexural behavior of the structure. It was found that the transition from linear elastic to non-linear elastic-plastic behavior is the result of compressive yielding of core material which leads to indentation in the beam. This also causes initiation of failure in the core. A shift in the centroid axis of the beam towards the tensile face was also observed. The sandwich structures made of cross-linked PVC and PMI foam cores were also analyzed for comparison. Further, a parametric study on the effect of areal density and ply angle of the facing fabric and core thickness were performed using finite element method. The parametric study revealed that the transition from linear to non-linear trend is caused by different mechanisms with the change in the mentioned parameters. © 2011 Published by Elsevier Ltd. Source

Agarwal S.,Institute For Textil Und Verfahrenstechnik | Von Arnim V.,Institute For Textil Und Verfahrenstechnik | Stegmaier T.,Institute For Textil Und Verfahrenstechnik | Planck H.,Institute For Textil Und Verfahrenstechnik | Agarwal A.,Institute For Textil Und Verfahrenstechnik
Separation and Purification Technology | Year: 2013

Droplet interaction with a surface placed in an immiscible liquid surrounding is very important for liquid-liquid separation. This study investigates the influence of filter surface energy (14-43 mN/m), micro- and nanoscale surface roughness on wetting, mobility and coalescence of isooctane droplets (5-10 μl) in immiscible water surrounding and explains their role in emulsion separation performance of nanoparticle coated filters. In water, coalescence among the oil droplets primarily takes place at filter surface. Despite different interfacial energies in air and water surrounding, the influence of substrate roughness on droplet mobility is same in both the surroundings. For effective separation of oil-in-water emulsion with a surface filter, it should be super hydrophilic, oriented vertically and have pore size smaller than the dispersed droplet size. In addition, the influent side of a surface filter should possess sufficient micro- and nanoscale surface roughness to provide high mobility, coalescence of the oil droplets and thereafter their easy detachment. For effective separation of oil from water a coalescing filter should be hydrophobic-oleophilic, oriented vertically with rough fibers surface to offer strong adhesion with the oil droplets and thereby high coalescence efficiency. © 2013 Elsevier B.V. All rights reserved. Source

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