Swamp coolers (also called "evaporative coolers" or "Air coolers") are air conditioners used to cool buildings in dry climates. The technique they use is evaporative cooling, of which two types exist: direct evaporative cooling and indirect evaporative cooling. Evaporative cooling is especially well suited where the air is hot and humidity is low. However, in higher humidity areas, there are many proven cost effective uses for evaporative cooling that make it the preferred choice. For example, industrial plants, commercial kitchens, laundries, dry cleaners, greenhouses, spot cooling (loading docks, warehouses, factories, construction sites, athletic events, workshops, garages, and kennels) and confinement farming (poultry ranches, hog, and dairy). [1] Water vapor condensing over a cup of hot tea Evaporation is one of the two forms of vaporization. ... Note: in the broadest sense, air conditioning can refer to any form of heating, ventilation, and air-conditioning. ... Evaporative cooling is a system in which latent heat of evaporation is used to carry heat away from an object to cool it. ...

History

Different civilizations throughout the ages have found ingenious ways to combat the heat in their region. An earlier form of air cooling was invented in Persia (Iran) thousands of years ago in the form of wind shafts on the roof, which caught the wind and passed it through water and blew the cooled air into the building [2]. Qajari era architecture of Hormozgan province. ... Motto: Persian: Esteqlāl, āzādÄ«, jomhÅ«rÄ«-ye eslāmÄ« (English: Independence, freedom, (the) Islamic Republic) Anthem: SorÅ«d-e MellÄ«-e Īrān Capital Tehran Largest city Tehran Official language(s) Persian Government Islamic Republic  - Supreme Leader Ali Khamenei  - President Mahmoud Ahmadinejad Revolution Overthrew Mohammad Reza Pahlavi   - Declared...

Evaporative cooler designs

Direct Evaporative Cooling (open circuit)

• used to lower the temperature of air by using latent heat of evaporation, changing water to vapor. In this process, the energy in the air does not change. Warm dry air is changed to cool moist air. Heat in the air is used to evaporate water.

Indirect Evaporative Cooling (closed circuit)

• similar to direct evaporative cooling, lowers the temperature of air by using latent heat of evaporation via some type of heat exchanger. The cooled moist air never comes in direct contact with products or environment.

A heat exchanger is a device built for efficient heat transfer from one fluid to another, whether the fluids are separated by a solid wall so that they never mix, or the fluids are directly contacted. ...

Typical

Evaporative cooler illustration

Typically, residential and industrial swamp coolers use direct evaporative cooling and can be described as an enclosed, metal or plastic box with vented sides containing a radial fan (also centrifugal or squirrel cage), fan motor with pulley wheels and a water pump to wet the cooling pads. They can be mounted on the roof (down draft) or exterior walls (side draft) of buildings. To cool, the fan draws ambient air through vents on the sides and through the damp pads. Heat in the air evaporates water from the pads which are constantly re-dampened to continue the cooling process. This cooled, moistened air is then delivered to the building via a vent in the roof or wall. Download high resolution version (879x620, 105 KB)Swamp cooler illustration, made by User:Buster2058. ... Download high resolution version (879x620, 105 KB)Swamp cooler illustration, made by User:Buster2058. ... Non-electric fan Household Electric Fan A fan has two purposes – to move air for creature comfort or for ventilation and to move air or gas from one location to another for industrial purposes. ... The expression centrifugal force is used to express that if an object is being swung around on a string the object seems to be pulling on the string. ...

Because the cooling air originates outside the building, a vent must exist to allow air to move from inside to outside. Air should only be allowed to cycle once through the system or cooling efficiency will fail. This is due to the air reaching the saturation point. Humidity is the concentration of water vapor in the air. ...

Cooler pads

Traditionally, swamp cooler pads consist of excelsior (wood wool) (aspen wood fiber) inside a containment net, but more modern materials, such as some plastics and melamine paper, are entering use as cooler-pad media. Wood absorbs some of the water, which allows the wood fibers to cool passing air to a lower temperature than some synthetic materials. The thickness of the padding media plays a large part in cooling efficiency, allowing longer air contact. For example, an eight-inch-thick pad with its increased interface will be more efficient than a one-inch pad. U.S. Patent 6,183,579 on a method of making cooling pads of excelsior, and illustrating such a pad Excelsior is a wood product made of aspen fibers, used in packaging, cushioning, stuffing of stuffed animals, and for the cooling pads in home evaporative cooling systems known as swamp... Species Populus adenopoda Populus alba Populus grandidentata Populus sieboldii Populus tremula Populus tremuloides Aspens are trees of the willow family and comprise a section of the poplar genus, Populus sect. ... A tree trunk as found at the Veluwe, The Netherlands Wood derives from woody plants, notably trees but also shrubs. ... Fiber or fibre[1] is a class of materials that are continuous filaments or are in discrete elongated pieces, similar to lengths of thread. ... Melamine Melamine is a strong organic base with chemical formula C3H6N6, with the IUPAC name 1,3,5-triazine-2,4,6-triamine. ...

Evaporative (wet) cooling towers

Didcot Power Station Cooling towers

Cooling towers are larger structures for cooling water or other working media to near-ambient temperature. Wet cooling towers operate on the evaporative principle and may be used in a swamp cooling arrangement. Cooling towers can be found on large buildings or on industrial estates. Image File history File links Download high resolution version (893x541, 103 KB)The cooling towers of Didcot Power Station taken from a train just outside of Didcot Parkway Station, 22/05/2004 by User:zootalures (Owen Cliffe) File history Legend: (cur) = this is the current file, (del) = delete this old... Image File history File links Download high resolution version (893x541, 103 KB)The cooling towers of Didcot Power Station taken from a train just outside of Didcot Parkway Station, 22/05/2004 by User:zootalures (Owen Cliffe) File history Legend: (cur) = this is the current file, (del) = delete this old... Cooling towers are structures for cooling water or other working medium to near-ambient temperature. ...

With respect to drawing air through the tower there are three types of cooling towers:

• natural draft, which utilizes a tall chimney,
• fan assisted natural draft, and
• mechanical draft which uses power driven fan motors to force or draw air through the tower.

If ambient conditions are right plumes (fog) can be seen rising out of evaporative (wet)cooling towers. A chimney is a system for venting hot gases and smoke from a boiler, stove, furnace or fireplace to the outside atmosphere. ...

Misting systems

Misting system work by forcing water via a high pressure pump and tubing through a brass and stainless steel mist nozzle that has an orifice of about 5 micrometres, thereby producing a micro-fine mist. The water droplets that create the mist are so small that they instantly flash evaporate. Flash evaporation can reduce the surrounding air temperature by as much as 35 °F (20 °C) in just seconds. For patio systems, it is ideal to mount the mist line approximately 8 to 10 feet above the ground for optimum cooling. Misting is used for many different applications including orchids, pets, livestock, kennels, insect control, odor control, zoos, veterinary clinics, produce cooling, greenhouses, etc. A micrometre (American spelling: micrometer), symbol µm, is an SI unit of length. ... The flash (or partial) evaporation is one of the simplest unit operations. ...

Performance

Understanding evaporative cooling performance requires an understanding of psychrometrics. Evaporative cooling performance is dynamic due to changes in external temperature and humidity level. Under typical operating conditions, an evaporative cooler will nearly always deliver air cooler than 80 °Fahrenheit (27 °Celsius). A typical residential swamp cooler in good working order should cool air to within 6°F - 8°F (3°C - 4°C) of the wet bulb temperature. Psychrometrics is the measurement of the heat and water vapor properties of air. ... Fahrenheit is a temperature scale named after the German physicist Gabriel Fahrenheit (1686–1736), who proposed it in 1724. ... A degree Celsius (°C) is a unit of temperature named after the Swedish astronomer Anders Celsius (1701-1744), who first proposed a similar system in 1742. ... The wet bulb globe temperature (WBGT) is used to measure the possible evaporation in natural ventilation conditions. ...

Some rough examples clarify this relationship.

• At 90 °F (32 °C) and 15% relative humidity, air may be cooled to nearly 60 °F (16 °C).
• At 90 °F (32 °C) and 50% relative humidity, air may be cooled to about 75 °F (24 °C).
• At 105 °F (40 °C) and 15% relative humidity, air may be cooled to nearly 70 ° (21 °C).

Because swamp coolers perform best in dry conditions, they are widely used and most effective in arid, desert regions such as the southwestern USA and northern Mexico. Relative humidity is the ratio of the current vapor pressure of water in any gas (especially air), known as the absolute vapor pressure (AVP), to the equilibrium vapor pressure or saturation vapor pressure (SVP), at which the gas is called saturated at the current temperature, expressed as a percentage. ... Desert view in Saudi Arabia. ... The Southwest region of the United States is drier than the adjoining Midwest in weather; the population is less dense and, with strong Spanish-American and Native American components, more ethnically varied than neighboring areas. ...

(cooling examples extracted from the June 25, 2000 University of Idaho publication, "Homewise"). June 25 is the 176th day of the year (177th in leap years) in the Gregorian Calendar, with 189 days remaining. ... This article is about the year 2000. ...

Advantages vs. refrigerated air-conditioning

Less expensive to install

• Estimated cost for installation is 1/8 to 1/2 that of refrigerated air conditioning

Less expensive to operate

• Estimated cost of operation is 1/4 that of refrigerated air.
• Power consumption is limited to the fan and water pump vs. compressors, pumps, and blowers.

Fresh air A gas compressor is a mechanical device that increases the pressure of a gas by reducing its volume. ... A pump is a mechanical device used to move liquids or gases. ... Fan can mean the following: enthusiast or fanatic air-movement device This is a disambiguation page — a navigational aid which lists other pages that might otherwise share the same title. ...

• The constant stream of air from intake to vent through the building freshens the air in the building.

Disadvantages vs. refrigerated air-conditioning

Performance

• High temperature, high humidity outside conditions decrease the cooling capability of the swamp cooler.

Comfort

• The air supplied by the swamp cooler is nearly 100% humid (but typically is only 80-90%).
• Very humid air prevents the evaporative cooling of sweaty or wet skin.
• High humidity in air accelerates corrosion. This can considerably shorten the life of electronic equipment.
• High humidity in air may cause condensation (which can be extremely hazardous if it happens inside electrical equipment)

Water Rust, the most familiar example of corrosion. ...

• Swamp coolers require a constant supply of water to wet the pads.
• Water high in mineral content will leave mineral deposits on the pads and interior of the cooler. Water softeners, bleed-off and refill systems may relieve this problem, however.
• Water line needs protection against freeze bursting during off-season, winter temperatures.

Miscellaneous Minerals are natural compounds formed through geological processes. ... A water softener reduces calcium or magnesium concentration in hard water. ...

• Pollen, odors, and other outdoor contaminants may be blown into the building unless sufficient filtering is in place.
• The vents that allow air to exit the building may pose a physical security risk.
• Asthma patients may need to avoid evaporatively cooled environments.

SEM image of pollen grains from a variety of common plants: sunflower (Helianthus annuus), morning glory (Ipomoea purpurea), hollyhock (Sildalcea malviflora), lily (Lilium auratum), primrose (Oenothera fruticosa), and castor bean (Ricinus communis). ... Physical security describes measures that prevent or deter attackers from accessing a facility, resource, or information stored on physical media. ...

See also

• Air conditioning
• Cooling tower system
• Dew point
• Evaporation
• Humidity
• HVAC

Note: in the broadest sense, air conditioning can refer to any form of heating, ventilation, and air-conditioning. ... The primary use of large, industrial wet cooling towers is to lower the temperature of the cooling water used in power plants, petroleum refineries, petrochemical plants, natural gas processing plants and other industrial facilities. ... The dew point or dewpoint of a given parcel of air is the temperature to which the parcel must be cooled, at constant barometric pressure, for the water vapor component to condense into water, called dew. ... Water vapor condensing over a cup of hot tea Evaporation is one of the two forms of vaporization. ... Humidity is the concentration of water vapor in the air. ... HVAC (pronounced either H-V-A-C or, occasionally, H-VAK) is an initialism/acronym that stands for heating, ventilation and air-conditioning. This is sometimes referred to as climate control. ...

External links

• Swamp Cooler FAQ
• USA Today's Wonderquest