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View by Category Toggle navigation. Products Sold on our sister site CrystalGraphics. Description: 1. Should desalination only be considered in areas that have water shortages? How can the energy required to run a desalination plant be used in the wet seasons?
Tags: desalination. Latest Highest Rated. MSF multi-stage flash. RO reverse osmosis. ED electrodialysis. VC vapour compression. MED multi-effect distillation. In areas with polluted waters, should clean-up be required prior to building a desalination plant? Would this be a reasonable request by a funding agency? Is desalination a useful technology in countries with extreme climatic changes, drought and flooding?
Most existing desalination plants discharge brine directly back into the ocean. It has been shown that this can harm the ecosystem around the area of discharge? How should this be factored into the desalination plant design in countries that are struggling financially already? Whose responsibility should it be to ensure minimal environmental damage?Solar desalination is a technique to produce water with a low salt concentration from sea-water or brine using solar energy.
There are two common methods of solar desalination. Either using the direct heat from the sun or using electricity generated by solar cells to power a membrane process. In the direct method, a solar collector is coupled with a distilling mechanism and the process is carried out in one simple cycle.
Water production by direct method solar distillation is proportional to the area of the solar surface and incidence angle and has an average estimated value of 3—4 litres per square metre 0. Many different plant arrangements have been theoretically analyzed, experimentally tested and in some cases installed. Indirect solar desalination systems using photovoltaic PV panels and reverse osmosis RO have been commercially available and in use since Methods of solar distillation have been employed by humankind for thousands of years.
From early Greek mariners to Persian alchemists, this basic technology has been utilized to produce both freshwater and medicinal distillates.
Solar stills were in fact the first method used on a large scale to process contaminated water and convert it to a potable form. It operated continuously for 40 years and produced an average of Solar desalination of seawater and brackish groundwater in the modern United States extends back to the early s when Congress passed the Conversion of Saline Water Act, which led to the establishment of the Office of Saline Water OSW in The OSW's main function was to administer funds for research and development of desalination projects.
Many of the projects were aimed at solving water scarcity issues in remote desert and coastal communities. There are two primary means of achieving desalination using solar energy, through a phase change by thermal input, or in a single phase through mechanical separation.
Single phase desalination is predominantly accomplished in a solar-powered desalination unitwhich uses photovoltaic cells that produce electricity to drive pumps, although there are experimental methods being researched using solar thermal collection to provide this mechanical energy. Multi-stage flash distillation is one of the predominant conventional phase-change methods of achieving desalination.
Can Solar Desalination Slake the World's Thirst?
Solar derivatives have been studied and in some cases implemented in small and medium scale plants around the world. In Kuwait a MSF facility has been built using parabolic trough collectors to provide the necessary solar thermal energy to produce m 3 of fresh water a day.
In order to achieve the highest efficiency MSF requires carefully controlled pressure drops across each stage and a steady energy input. As a result, solar applications require some form of thermal energy storage to deal with cloud interference, varying solar patterns, night time operation, and seasonal changes in ambient air temperature.
As thermal energy storage capacity increases a more continuous process can be achieved and production rates approach maximum efficiency. There are two inherent design problems facing any thermal solar desalination project. Firstly, the system's efficiency is governed by preferably high heat and mass transfer rates during evaporation and condensation. The surfaces have to be properly designed within the contradictory objectives of heat transfer efficiency, economy, and reliability.
Secondly, the heat of condensation is valuable because it takes large amounts of solar energy to evaporate water and generate saturated, vapor-laden hot air.Figure Source: Ahmed El Mekawy et. RO is the most widely used method for desalination that uses a semi-permeable membrane which resists salts passage.
In electrodialysis ED system, a direct current is passed through the water, which drives the ions not the water through membranes to electrodes of opposite charge. Source: John H Reif et. Desalination using Solar Energy.
Source: Solar desalination schematic Sustainable sanitation, water management, Output Known Specified. Modelling Problems Model Input Output.
Simulation Problems Model Input Output? Known Known. Title Author s Remarks 1. Modeling and optimization of a solar Tzuc et. An artificial neural network inverse ANNi parabolic trough concentrator system model is applied to optimize the thermal using inverse artificial neural network. Optimal Design of a Solar Desalination Abidi et. Design to improve the yield of a solar Unit with Heliostats.
Modelling and simulation of Multi Maha et. Dynamic modeling and simulation of a de la Calle et. The model covers the whole operation range of solar-assisted multi-effect distillation the plant and used to study the plant plant performance in different scenarios and operating strategies to optimize future operating control strategies. Performance optimization study on an Liu et.
Performance simulation of a multi- Shim et. The accumulation of salt particles on the desalination plant components. Water being necessary for consumption, household usage, industry production, and agriculture, its demand will rise with economic and population growth. Desalination of seawater and brackish water is accepted as an alternative source to fulfil growing water demand.
The benefits of desalination are straightforward: more water. The drawback, unfortunately, is the cost and Environmental impact. Find alternatives to energy used for the desalination process: through the use of renewable energy such as solar or wind power. If technology continues to produce new methods and better solutions to the issues that exist today, there would be a whole new water resource for more and more countries that are facing drought, competition for water, and overpopulation.Introduction WHO: millions of human beings are suffering from acute lack of water.
Solar Thermal Methods Generation of heat energy from sun Use heat energy in a desalination process. Solar Thermal Methods Solar still Solar diffusion still Multi-effect evaporation Multi stage flash evaporation Humidification-dehumidification Freezing using absorption cooling process. A well-designed solar still can produce 2 to 4 liters or quarts of water per square meter of basin area.
Commissioned inwith an average. Sub-systems: the solar collector field, heat accumulator and evaporator. The performance of the collector field and evaporator sub-systems have not suffered in performance decline to any appreciable degree up to today. Location Amount of water to be produced Quality of water to be desalinated Quality of water to be produced. Learn more about Scribd Membership Home. Read Free For 30 Days.
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DESALINATION - PowerPoint PPT Presentation
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Effect of Various Absorbing Materials on the Thermal. Jump to Page. Search inside document. Solar Desalination Prof. There are several available solar systems for the production of fresh water from saline or brackish water.
Documents Similar To Solar Desalination. Chandra Reddy.Reducing salt water to its basic elements -- salt and water -- is so simple that it's become a science lesson for first-graders.
In fact, a "solar still" can turn salt water into fresh water in just a few days. Simply fill a large bowl with salt water and set an empty glass at the center. Then cover the bowl -- empty glass and all -- with plastic wrap that has a small hole poked in the middle. Place the contraption in direct sunlight, and watch the water cycle at work: The salt water evaporates, leaves salt crystals behind, and creates condensation that rises, gathers on the plastic membrane and drips into the empty glass.
The resulting fresh water is good enough to drink [source: Williams ]. But why remove salt in the first place? Turns out, drinking salt water can kill you. Ingesting salt signals your cells to flush water molecules to dilute the mineral.
Too much salt, and this process can cause a really bad chain reaction: Your cells will be depleted of moisture, your kidneys will shut down and your brain will become damaged. The only way to offset this internal chaos is to urinate with greater frequency to expel all that salt, a remedy that could work only if you have access to lots of fresh drinking water [source: Thompson ]. People -- especially those in water-starved parts of the world -- have been searching for fresh water solutions for centuries.
Turns out the same folks who built giant sphinxes and drove horse-drawn chariots also thirsted for clean, pure water [source: Jesperson ]. Even in modern times, entire populations struggle with a cruel irony; they are surrounded by salt water, but lack drinking water. The scarcity sometimes spurs deadly conflicts. Inonlookers killed a family in drought-ridden India for collecting water from a municipal well before it ran dry [source: Pacific Institute ].
But what if an abundant supply of fresh water could be created from salt water? A large-scale desalination operation -- using principles similar to a simple classroom project -- could change the world. On the next page, we'll explore why it's not always so easy to turn salt water into drinking water. How Water Works. About 70 percent of the world is water, but so little can actually be used because most of it is salt water. Up Next How Water Works.After you enable Flash, refresh this page and the presentation should play.
Get the plugin now.MIT's passive solar-powered water desalination system achieves ultrahigh-efficiency
Toggle navigation. Help Preferences Sign up Log in. To view this presentation, you'll need to allow Flash. Click to allow Flash After you enable Flash, refresh this page and the presentation should play. View by Category Toggle navigation. Products Sold on our sister site CrystalGraphics. Title: Solar Desalination. Description: The raw water supply is distributed through the jet tube and the wicks in the soakage shield.
In the distillation reservoir the raw water is led through a Tags: desalination energy raw solar tube. Latest Highest Rated. What is Solar Water Desalination? Components of Solar Desalination The process of converting salt water to fresh water Specifications of Desalination plants Desalination using Membrane Distillation Where in the world is this used? Conclusions 3 Why Solar Water Desalination? Only 2. A float switch is the controller of the pump.
The control system leads the raw water to the distillation collector 'Flatmodel Rosendahl' The glass covering is 2. Solar energy radiation penetrates the glass and is transformed into thermal energy on the absorbing soakage sheet.Solar powered distillation of water can be defined as measures to separate and extract clean water by vaporization. This can be particularly useful to turn seawater, brackish or even contaminated water into clean water safe for drinking.
The history of solar powered water distillation started with Aristotle, already back in the 4 th century BC, described a technique of solar powered water distillation. However, it was not before late 19 th century, that the first large scale solar water distillation plant was built. This plant, located in Chile, supplied as much as 20 liters of safe water to nearby inhabitants. As mentioned above, solar distillation is separation of clean water by vaporization. Desalination refers to the process where salt and other minerals are removed from water.
While heat is necessary for distillation of water, electrical or mechanical driven systems can use reverse osmosis to desalinate water. Distillation of water with solar energy is quite simple. Think about how nature creates rain: The Sun heats and evaporates water, which at the same time is separated from salt, dirt or anything else for that matter.
When the temperature and pressure is right, the water molecules reforms and returns to liquid. Regardless of where in the World you are located, if you catch rain before it hits the ground, it is considered safe to drink. Devices that are built around the concept of solar distillation all mimic the natural process of rain formation and can be described in two simple steps:. A basin is covered by sloped glass or plastic where the evaporated water is condensed and lead into a rainwater channel.
The darker the color of the basin, the more sunlight is turned into heat.
Solar Desalination - PowerPoint PPT Presentation
The clean water output is higher in the evening due to greater temperature differences between warm water on the inside of the device and the outside ambient air. A stationary installation should be made out a glass basin to ensure longevity, but plastic would be better for a portable solar still. An emergency solar distillation is essentially the same thing as the single-basin still described above except it is simpler.
A mixing bowl can be used as the basin and plastic foil is put on top. A rubber holds the two together. Then a small stone is placed in the middle on top of the plastic foil and a cone shape forms. A cup and saltwater can be placed in the mixing bowl you have an emergency still. This is where it gets a little bit more advanced. Multi-stage flash distillation as well as multiple-effect distillation below is used in larger scales where distillation plants are made to supply clean water for hundreds if not thousands of people.
Multi-stage flash distillation is used to distill seawater by flashing water lowering pressure to induce vaporization in several stages. Another big one, as with multi-stage flash distillation above, multiple-effect distillation also consists of several stages effects. Seawater is heated by steam in tubes, leading to partial evaporation and more steam in the next stage.
The process is repeated several times. Every stage reuses some of the energy from the previous stages. Humans can go weeks or even months without food, but just after a few days without water, chances of survival are getting slim.
Water is absolutely essential. Most people take a supply of fresh and clean drinking water for granted, but in some places in the World or in emergency situations clean drinking water is not always readily available. Solar powered distillation of water can help to reduce these numbers. These are also common uses of solar-distilled water.
By using solar distillation of water, people are less dependent on rainwater to supply all their needs. As mentioned with the solar emergency distillation stills above, solar distillation is a good way to provide water in emergency situations. In places where hurricanes are likely to strike, and electricity and water supplies can be cut, solar distillation can be lifesaving. Lifeboats are often equipped with solar stills.