Atmospheric water generator
From Wikipedia, the free encyclopedia
An Atmospheric water generator (AWG), or atmospheric condenser, is a device that extracts water from humid ambient air. An AWG operates in a manner very similar to that of a refrigerated dehumidifier: air is passed over a cooled coil, causing water to condense. The rate of water production depends on the humidity, the volume of air passing over the coil, and the machine's capacity to cool the coil.
The device is very useful for locations where pure drinking water is difficult to obtain — such as in areas with heavy ground pollution — and the air is humid.
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[edit] Principle of operation
An AWG uses refrigeration which mimics conventional dehumidification techniques to condense water from air. A compressor circulates refrigerant through a coil or chiller array. A fan causes air to pass over the coil. If the coil's temperature is below the dew point, about 40% of the water in the air will condense on the surface of the coil, then drip into a holding tank. If the coil is too cold, ice will form and accumulate on the coil, spoiling the machine's ability to produce liquid water.
Optional AWG features
- An air filter can help prevent dirt from accumulating on the surface of the coil
- A level switch in the holding tank can shut the machine off when the tank is full
- Water can be pump-circulated through an UV light chamber to kill bacteria, and/or through high and low density charcoal filters to remove solids and oxygenate
The rate at which water can be produced depends on relative humidity and ambient air temperature. Relative humidity measures the amount of water vapor present in the air at a given temperature. AWGs become more effective as relative humidity and air temperature increase. As a rule of thumb, AWGs do not work efficiently when the temperature falls below (35°F), the relative humidity drops below 40%, or at high altitudes (above 4000 feet). If the ambient air has passed through an air conditioner, much of the water vapor has already been removed, leaving little for the AWG to work with.
[edit] Cost Details
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This section may require cleanup to meet Wikipedia's quality standards. Please improve this article if you can. (October 2008) |
The cost-effectiveness of an atmospheric water generator depends on the capacity of the machine as well as on humidity and temperature conditions.
The following is the cost per liter calculation for a typical 120 litres per day AWG with power consumption 2.6kW @ INR(Indian Rupee) 4.5 per kWh.
The cost of producing 1 liter of water will typically range from $US 0.12 (85-100% RH) to $US 0.25 (40-50% RH).
Total annual electric costs : 2.6kW × 24 hrs/day × 365 days/year ×INR 4.5 per kWh = Rs.1,02,492/year ≈ US$2,277.60/year (US$1 = INR45).......A
Total annual water production : 120 litres per day × 365 days/year = 43,800litres/year..........B
COST PER LITER = A ÷ B = US$0.15
[edit] Alternative methods
The methods listed below are not AWGs but other alternative methods of water making.
- One company is using the desiccant lithium chloride to pull water from the air, after which the water must be boiled off and distilled.[1]
- Another company is involved in making a machine that extracts water from car exhausts. Although the machine is in a prototype stage with a lot of problems with water quality, it is another non-conventional means of water making.[2]
- Another company has launched water-making fridges. Fridges & freezers that make pure drinking water from air.
- A Consortium company produces water from a precipitation process designed by Melvin M. Littrell and Prof. James D. Vagarasoto II and patented by Mr. Melvin M. Littrell in 1990.[3]
[edit] External links
- In popular culture: In the fictional Star Wars universe, atmospheric water generators were the source of livelihood for the Lars family.[4]
- Atmospheric Water Generators at the Open Directory Project - lists commercial sites
[edit] References
- ^ Sciperio Inc.
- ^ LexCarb LLC
- ^ Water precipitation in the next generation
- ^ http://www.starwars.com/databank/location/larsmoisturefarm/ Star Wars Databank, Lars Moisture Farm
