Evaporative coolers are widely used in the western United States, southern Australia and Iran, where the climate is hot and air is dry. Also known as swamp coolers in the USA, they are cheaper than air conditioners and consume less electricity. Although they are becoming popular in recent years, evaporative cooling has been around for thousands of years. It was used widely in the ancient Persian Empire. In those days, the Persians used to construct air shafts on the roof of their house to pull in ir from outside, pass the same through water and flow the cooled air into the house. Modern day Iranians use the same technology in its more efficient form extensively to cool their houses.
Evaporative cooling is a natural phenomenon in which dry air cools down when it comes into contact with water. This can be explained by a simple law of physics: a liquid changes into gas in the presence of heat. To say this in another way, a liquid needs to absorb heat from the surrounding to change into gas. Water has the ability to turn into vapor at relatively low temperatures. Vapor is gaseous state of water. Although evaporation seems to take place only when the water it hot, the fact is that liquid water is always evaporating. Evaporative coolers take advantage of this property of water to cool down air.
While evaporative cooling has many industrial and commercial use, it is most commonly used at homes to chill the warm air inside the rooms. Modern evaporative coolers basically consist of a water container, a cooling pad made of excelsior (wood wool) or plastics and melamine paper, a pump to circulate the water through the cooling pad, and a fan to draw the air from outside the room. They can be set up on windows or ventilators. A typical home cooling system requires approximately 15 gallons of water a day. Today, you can buy solar powered evaporative coolers that use electricity generated by solar panels to run the fan and pump.
There are basically three types of evaporative coolers:
* Direct evaporative cooler (open circuit) draws outside air through a cooler pad which absorbs its heat to change liquid water into water vapor. The cooled moist air is then blown into the room.
* Indirect evaporative cooler (closed circuit) works similarly to the direct evaporative cooler. However, it uses some kind of medium to exchange heat so that the cooled moist air doesn't comes in direct contact with the air in the room.
* Two-stage evaporative cooler, or indirect-direct cooler, is a mixture of the above two systems. In this system pre-cooled air flows through the moistened pad. This way it produces less humidity than the above two and is good for areas with less dry air.
Evaporative coolers are different than air conditioners in the following ways:
* Evaporative coolers use water while air conditioners use chemical substances.
* Evaporating coolers are best suited for dry places as they add moisture to the air and make the place more humid and uncomfortable.
* An evaporative cooler draws air from outside the room, whereas in air conditioning the air is pulled from inside the room.
* Evaporative coolers require 4 times less electricity than air conditioners. They are also less costly to install than air conditioners.
* Evaporative coolers are by nature harmless to the environment, whereas the compounds (refrigerants) used in air conditioners are bad for the ozone.
Evaporative cooling is a natural phenomenon in which dry air cools down when it comes into contact with water. This can be explained by a simple law of physics: a liquid changes into gas in the presence of heat. To say this in another way, a liquid needs to absorb heat from the surrounding to change into gas. Water has the ability to turn into vapor at relatively low temperatures. Vapor is gaseous state of water. Although evaporation seems to take place only when the water it hot, the fact is that liquid water is always evaporating. Evaporative coolers take advantage of this property of water to cool down air.
While evaporative cooling has many industrial and commercial use, it is most commonly used at homes to chill the warm air inside the rooms. Modern evaporative coolers basically consist of a water container, a cooling pad made of excelsior (wood wool) or plastics and melamine paper, a pump to circulate the water through the cooling pad, and a fan to draw the air from outside the room. They can be set up on windows or ventilators. A typical home cooling system requires approximately 15 gallons of water a day. Today, you can buy solar powered evaporative coolers that use electricity generated by solar panels to run the fan and pump.
There are basically three types of evaporative coolers:
* Direct evaporative cooler (open circuit) draws outside air through a cooler pad which absorbs its heat to change liquid water into water vapor. The cooled moist air is then blown into the room.
* Indirect evaporative cooler (closed circuit) works similarly to the direct evaporative cooler. However, it uses some kind of medium to exchange heat so that the cooled moist air doesn't comes in direct contact with the air in the room.
* Two-stage evaporative cooler, or indirect-direct cooler, is a mixture of the above two systems. In this system pre-cooled air flows through the moistened pad. This way it produces less humidity than the above two and is good for areas with less dry air.
Evaporative coolers are different than air conditioners in the following ways:
* Evaporative coolers use water while air conditioners use chemical substances.
* Evaporating coolers are best suited for dry places as they add moisture to the air and make the place more humid and uncomfortable.
* An evaporative cooler draws air from outside the room, whereas in air conditioning the air is pulled from inside the room.
* Evaporative coolers require 4 times less electricity than air conditioners. They are also less costly to install than air conditioners.
* Evaporative coolers are by nature harmless to the environment, whereas the compounds (refrigerants) used in air conditioners are bad for the ozone.
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