Cooling tower
From Freepedia
Cooling towers are structures for cooling water or other working medium to near-ambient temperature. The primary use of cooling towers are to lower the temperature of power plant waste heat without causing heat pollution in nearby bodies of water. Though most laymen associate cooling towers with nuclear power plants, any type of steam generating power plant can utilize cooling towers. Many nuclear power plants, such as Seabrook Station nuclear power plant, do not use cooling towers.
Image:Didcot power station cooling tower zootalures.jpg With respect to the heat transfer mechanism employed the main types are:
- wet cooling towers operate on the priciple of evaporation, (see Swamp cooler)
- dry cooling towers operate by heat transmission through a surface that divides the working fluid from ambient air.
In a wet cooling tower the warm water can be cooled to a temperature lower than ambient, if the ambient air is relatively dry. (see: Dew point).
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 (or forced 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 a wet cooling tower (see image).
The cooling tower has been used in the media. On The Simpsons, at the Springfield Nuclear Power Plant, Lisa Simpson sung of the towers in a protest song.
...And we'll march day and night, by the big cooling towers- they've got the plant; but we've got the power
