Selecting Fog Harvesting Meshes for Environmental Conditioning Structures (original) (raw)
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Evaluating Mesh Geometry and Shade Coefficient for Fog Harvesting Collectors
Water Resources Management, 2023
The most valuable resource for sustaining life on earth is water. In dry and semi-arid areas, the problem of water scarcity can be resolved with the aid of fog collection techniques employing fog collectors. Fog collection is greatly influenced by a variety of factors. Some are design parameters, while others depend on ambient circumstances. Geometry and the mesh's shade coefficient are important design factors that can be modified and have an impact on the rate at which fog collects in fog collectors. The shape of the mesh holes and the process used to create the mesh serve to identify geometry and measure the shade coefficient. In this paper, a straightforward mathematical technique is proposed to make it easier to calculate the shade coefficient of various mesh shapes used in fog harvesting and to provide an approximation of the mesh volume and cost. Five alternative geometries were used: the rectangular mesh, square mesh, Raschel mesh, triangular mesh, and hexagonal mesh. The current simple method will facilitate the design of the fog mesh collector and can assist in achieving the ideal shade coefficient and most effective mesh geometry for fog harvesting. Rectangular meshes were solely used as an example to evaluate the results. Stainless steel rectangular meshes with various shade coefficients were tested for fog collection, and the amount of water collected by each mesh varied. It was concluded that the optimum shade coefficient ranged 50-60% for fog collection.
Experimental Study Of Fog Water Harvesting By Stainless Steel Mesh
International Journal of Scientific & Technology Research, 2017
The collection of fog water is a simple and sustainable technology to get hold of fresh water for various purposes. In areas where a substantial amount of fog can be obtained, it is feasible to set up a stainless steel as well as black double layer plastic mesh structure for fog water harvesting. The mesh structure is directly exposed to the weather and the fog containing air is pushed through the active mesh surface by the wind. Afterward fog droplets are deposited on the active mesh area which combines to form superior droplets and run down into a gutter to storage by gravity. Fog water harvesting rates show a discrepancy from site to site. The scope of this experimental work is to review fog collection at SCOE, Pune campus and to examine factors of success. This study is to synthesize the understanding of fog water harvesting in the institutional era and to analyze its benefits and boundaries for future development. The rate of fog water harvesting depends on the science of fog p...
Aerosol and Air Quality Research, 2018
Fog harvesting techniques for water collection have been implemented successfully worldwide for several decades. However, at locations with high wind speeds, traditional installations require high maintenance efforts endangering the sustainability of projects. Furthermore, the efficiency of fog collection meshes and the water quality in the field are key questions for the implementation of large-scale facilities. This study presents a novel, durable fog collector design and investigates the yield (fog + rain) and inorganic water quality of different potential collection meshes at a test site in Morocco. The pilot facility proved very reliable with only minimal maintenance required. Rankings of the efficiency of different fog nets were set up, with monofilaments and three-dimensional structures tending to show higher yields than woven fabrics such as the traditional 'Raschel' mesh. However, differences from fog event to fog event could be identified. Water quality was better than that of local wells and met WHO guidelines, except for the 'first flush' just after the start of fog events.
Novel Applications for Fog Water Harvesting
In a scenario of climate changes and increasing stress upon available fresh water resources like rivers, lakes and aquifers, collecting fog water is a promising yet relatively unexplored potentiality. Providing sufficient water and reducing water extraction's environmental impact at the same time can be a challenge with conventional ways, but fog harvesting technology presents itself as a powerful and efficient alternative. Water availability profoundly determined regional economic benefit, social relations and it also influenced environmental security and ecosystem services. Underdeveloped countries have been dealing with water scarcity issue for decades, but also wealthy countries will have to face the water crisis soon, due to unsustainable development processes. A review of the state of the art highlights the most relevant parameters to deal with when discussing about fog water harvesting. In regions with frequent fog events, this technology already proved to be a sustainable drinking water resource for rural communities and their low per capita water usage was provided by basic devices utilization. Nevertheless, in this paper, different fog water harvesting applications are investigated, besides the already existing freshwater collection, reforestation and agricultural use. Further options , such as building components, outdoor activities and domestic devices are considered, according to different parameters, such as economic benefits, possibility of standardized production, life cycle and market attractiveness. A desirable novel concept would become relevant in specific contexts, thanks to multiple functions, offering locals designed and customized solutions. Also noteworthy are the landscape impact of such devices and the effects of the project in terms of places regeneration, raising awareness and " green " conscience creation. The study of local climatic data and improvement in fog collector applications, integration with architectural and landscape design, will expand the regions where fog harvesting can be applied and its sustainable improvements.
Fog Water Collection Effectiveness: Mesh Intercomparisons
Aerosol and Air Quality Research
To explore fog water harvesting potential in California, we conducted long-term measurements involving three types of mesh using standard fog collectors (SFC). Volumetric fog water measurements from SFCs and wind data were collected and recorded in 15-minute intervals over three summertime fog seasons (2014-2016) at four California sites. SFCs were deployed with: standard 1.00 m 2 double-layer 35% shade coefficient Raschel; stainless steel mesh coated with the MIT-14 hydrophobic formulation; and FogHa-Tin, a German manufactured, 3-dimensional spacer fabric deployed in two orientations. Analysis of 3419 volumetric samples from all sites showed strong relationships between mesh efficiency and wind speed. Raschel mesh collected 160% more fog water than FogHa-Tin at wind speeds less than 1 m s-1 and 45% less for wind speeds greater than 5 m s-1. MIT-14 coated stainless-steel mesh collected more fog water than Raschel mesh at all wind speeds. At low wind speeds of < 1 m s-1 the coated stainless steel mesh collected 3% more and at wind speeds of 4-5 m s-1 , it collected 41% more. FogHa-Tin collected 5% more fog water when the warp of the weave was oriented vertically, per manufacturer specification, than when the warp of the weave was oriented horizontally. Time series measurements of three distinct mesh across similar wind regimes revealed inconsistent lags in fog water collection and inconsistent performance. Since such differences occurred under similar wind-speed regimes, we conclude that other factors play important roles in mesh performance, including in-situ fog event and aerosol dynamics that affect droplet-size spectra and droplet-to-mesh surface interactions.
Testing greenhouse shade nets in collection of fog for water supply
Journal of Water Supply: Research and Technology-Aqua, 2003
Fog is an important source of water for some inhabitants of arid regions where other sources of freshwater are scarce. Fog collection was carried out with polymeric greenhouse shade nets in order to investigate the feasibility of using similar shade cloths in fog water supply schemes in areas where the Raschel mesh that is used in standard fog collectors (SFC) is not available. The fog collectors were made from outdoor and indoor aluminet greenhouse shade nets of varying percent shade coefficient. The indoor weave is similar to that found in the Raschel mesh that is used in SFCs and proved to be more suitable for fog collection than the outdoor one. Fog collection with collectors made from the indoor weave mesh of varying percent shade coefficient indicates that the 40% shade coefficient is more appropriate for fog collection than the 60% and 90% mesh. The aluminet collectors appear to combine both fog and dew collection. The latter would make a 35% shade coefficient aluminet ('metal'-coated) collector more efficient than the plain polypropylene mesh that is used in fog collectors, particularly in low elevation areas where fog deposition is lower and therefore, the contribution of dew to the total collected volume is a significant one. The results of this study will enable prospective users of fog water to select the right weave and percent shade coefficient of a given mesh that is to be used for fog collection in areas where the Raschel mesh is not available.
Water harvesting from fog using building envelopes: part I
Water and Environment Journal
New sources of clean water are currently being researched and implemented, to face global water shortage. Techniques such as desalination or cloud seeding can have a high yield but present problems such as excessive energy consumption or consistent environmental impacts. Fog harvesting stands out for being considerably simpler and inexpensive compared to the previous. In the last decades researchers have developed detailed studies and numerical models, supported by a number of successful examples located mainly in arid or seasonally arid climates. This study surveys existing methods to collect water from fog, such as drop coalescence on vertically placed meshes, chemical absorption and desorption, and radiative condensers. Yields from different collectors are compared and some considerations on influencing climatic factors are discussed, suggesting that radiative systems may be applied on building envelopes as collection devices. A follow-up paper will present experimental results on applying radiative collection systems in buildings.
Feasibility and sustainability of fog harvesting
Sustainability of Water Quality and Ecology, 2015
Knowing that the fog harvesting is a non-conventional method for the production of freshwater, the sustainability of a fog collection project is studied. Sustainability and feasibility of fog harvesting collection projects is the focus of this Paper. A sustainable operation of fog harvesting projects which provides numerous sites worldwide with sufficient amounts of fresh water worldwide is presented. The key characteristics of fog harvesting system are considered including the physical process; the fog collectors; and the mesh types. Sustainability aspects of fog collection projects are investigated including fog water quantity and quality. The feasibility of fog harvesting collection projects is evaluated, compared with other sources for freshwater supply including the corresponding infrastructure; the cost of water; the operational costs; and the amortization periods for expenses. The vision of implementing a fog collection project including the decision-making criteria is presented as a logical process. The community involvement analysis and the social impact are analyzed in the light of the existing freshwater resources and needs. The most important environmental factors that affect the volume and the frequency of water are evaluated. The Paper concludes that prior to implementing a fog water harvesting program; a pilot-scale assessment of the collection system should be executed.
Aerosol and Air Quality Research
Scarcity of fresh water is one of the greatest obstacles to achieve the sustainable development in the Kingdom of Saudi Arabia. About thirty desalination plants are built to satisfy the Kingdom needs. The Kingdom is in need of new unconventional water resources such as fog water harvesting system which will complement the existing water resources in the Asir region. This region is facing major challenges due to the flourishing tourism, irrigation in agriculture and rising living standards. Passive mesh type fog collector is analyzed in the current study to predict the rate of fog water collection by combining a physically based impaction and aerodynamic models. The results indicate that the greater volumes of water can be harvested from the fog associated with higher wind speeds, bigger sizes of fog droplet and higher liquid water content in the fog-laden winds with the threshold mesh shade coefficient of about 0.56. It is found that the aerodynamic efficiency has a significant impact on the overall fog collection efficiency compared to the impaction efficiency. The model shows that for the fog droplet size of 30 µm with the wind speed of 4 m s-1 , it is possible to collect the fog water at the rate of 0.65 to 9.7 L m-2 per hour when the liquid water content (LWC) in the fog varies from 0.2 to 3 g m-3 , respectively.
E3S Web of Conferences
One of the sources of freshwater is groundwater, from below the ground. However, due to excessive human consumption and population growth, groundwater depletion has been a pressing problem all over the world, and it can lead to water scarcity in the future. In elevated areas where water scarcity is rampant due to its high elevation thus resulting in seasonal low surface and groundwater flow, the use of alternative water resources must be assessed. One of the alternative water resources is fog collectors which involves the use of fog harvesting technology. This paper aims to study the application of fog catchers in Atok, Benguet, Philippines by analyzing the fog water collected from standard fog catchers for one month. To determine the suitable fog catcher materials in the area, two types of mesh materials (Raschel mesh and Polypropylene) were installed and analyzed for their water collection ability, availability in the area, and strength to withstand environmental factors. An avera...