An atmospheric water generator ( AWG ) is a device that extracts water from moist ambient air. Water vapor in the air can be extracted by condensation - cooling air below its dew point, exposing air to the dryer, or by reducing air pressure. Unlike dehumidifiers, AWG is designed to make drinking water. AWG is useful where pure drinking water is difficult or impossible to obtain, since there is almost always little water in the extractable air. The two main techniques used are cooling and desiccants.
The extraction of atmospheric water may not be cost-free, since significant energy input is required to drive some AWG processes. Certain traditional AWG methods are entirely passive, dependent on natural temperature differences, and require no external energy source. Research has also developed AWG technology to produce beneficial water results with reduced energy costs (but not zero). Biomimicry studies show that Stenocara gracilipes has a natural ability to perform this task.
Video Atmospheric water generator
History
The Incas are able to defend their culture above the rain line by collecting dew and channeling it to the tank for later distribution. Historical records show the use of a water-fog haze fence. This traditional method is usually completely passive, requiring no external energy source other than the naturally occurring temperature variations.
Some inventors have developed an air well as a way to collect water from the air passively.
Maps Atmospheric water generator
Modern technology
Many atmospheric water generators operate in a way very similar to dehumidifiers: air is passed through a cooled coil, causing water to condense. The level of water production depends on the ambient temperature, humidity, the volume of air passing through the coil, and the engine capacity to cool the coil. This system reduces the air temperature, which in turn reduces the air capacity to carry water vapor. This is the most commonly used technology, but when powered by coal-based electricity it has one of the worst carbon footprints of any water source (exceeding the reverse osmosis seawater desalination by three orders of magnitude) and it demands more than four times more to water the supply chain given to the user.
Alternative technologies are available using liquids, or "wet" dryers such as lithium chloride or lithium bromide to draw water from the air through a hygroscopic process. The proposed similar technique combines the use of a solid dryer, such as silica gel and zeolite, with pressure condensation. Water-producing water quality devices directly using sunlight are also being developed.
It is said to take 310 Wh to make 1 liter of water.
Condensation cooling
In a cooling type of atmospheric water generator, the compressor circulates the refrigerant through the condenser and then an evaporator coil that cools the surrounding air. It lowers the air temperature to its dew point, causing the water to condense. The controlled speed fan pushes the filtered air over the coil. The resulting water is then passed to a storage tank with a purification and filtration system to help maintain pure water and reduce the risk posed by viruses and bacteria that can be collected from the surrounding air on the evaporator coil by condensing water.
The rate at which water can be produced depends on the relative humidity and ambient air temperature and compressor size. The atmospheric water generator becomes more effective because of the relative humidity and increased air temperature. As a rule of thumb, condensing cooling of atmospheric water generators does not work efficiently when temperatures fall below 18.3 ° C (65 ° F) or relative humidity drops below 30%. This means they are relatively inefficient when in an air-conditioned office. The cost effectiveness of the AWG depends on engine capacity, local humidity and temperature and cost conditions for turning on the unit.
New emerging technologies utilize the Peltier effect of a semi-conductor material in which one side of the semi-conductor material heats while the other side cools. In this application, air is forced through the cooling fins on the cooling side which lowers the air temperature to the dew point, causing the water to condense. The resulting water is then collected. Due to the solid-state properties of semi-conducting materials and low power usage, some of these new designs use solar energy panels as a power source.
The capacity of drinking water generation can be improved in low ambient air ambient conditions, first by using evaporative coolers with brackish water supply to increase air humidity close to dew point conditions. So drinking water is produced using brackish water without depending on the ambient air humidity by the water generator.
Desiccation wet
One form of wet dryer water generation involves the use of salt in a concentrated brine solution to absorb ambient moisture. The system then takes water from the solution and refines it for consumption. The version of this technology was developed as a portable device run on a generator. The large version, mounted in the trailer, is said to produce up to 1,200 US gallons (4,500 liters) of water per day, with a ratio of up to 5 gallons of water per gallon of fuel. The technology is contracted for use by the US Army and US Navy from Terralab and Federal Emergency Management Agency (FEMA).
Variations of this technology have been developed to be more environmentally friendly, especially through the use of passive solar energy and gravity. Salt water flows on the outside of the tower, where it absorbs water from the air. The salt water then enters the chamber and undergoes a partial vacuum and is heated. Water vapor is collected and condensed, while the renewed salt water is recirculated through the system. Because condensed water is removed from the system using gravity, it creates a vacuum that lowers the brine's boiling point.
A prototype system combining adsorption, cooling and condensation is also being developed.
In the greenhouse
A special case is the generation of water in greenhouses because the air inside the greenhouse is much hotter and more humid than outside. Particularly in climatic zones with water scarcity, greenhouses can greatly improve the conditions needed for water formation in the atmosphere. Examples are the seawaterhouses in Oman, and the proposed Integrated Biotourial System or IBTS-Greenhouse.
In a fuel cell car
The hydrogen fuel cell car produces one liter of quality drinking water for every 8 miles of significant travel in desert conditions.
In AC
In dehumidification-type air conditioners, waste water is a by-product, caused by air cooling and condensation, such as atmospheric water generators (AWG). Water, in this case, is not purified. AC cooling equipment usually reduces the absolute moisture of air processed by the system. The relatively cold coil of evaporator (below dewpoint) condenses water vapor from processed air, as cold drinks will condense water on the outside of the glass. Therefore, moisture is removed from the cooled air and the relative humidity in the room is lowered. Water is usually delivered to the drain or it may drip to the ground outside. The heat is rejected by the condenser that is located outside the room to be cooled.
Drinking water generator by solar power
The quality of drinking water is generated by the roof top solar hydro panels from the air using solar power and solar heat during daylight time.
See also
- Dehumidifier
- Well water (condenser)
- Dew Pool
- Fog collection
- Rainwater harvest
- Solar chimney
- Watermaker
- The sun is still
References
Source of the article : Wikipedia
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