Evaporative cooling towers are heat extraction devices that use the evaporation of a small amount of working fluid, typically water, to transfer heat into a moving air stream to cool the rest of the water stream close to the wet-bulb air temperature, a designed measurement of temperature reflecting the desired level of water vapor content of the cooling tower system.
Related Categories
Evaporative Cooling Towers
Offering reduced field costs, design flexibility and quiet operation, evaporative cooling towers use 40-60% less energy than air cooled chillers and provide cooler water temperatures than "air cooled" or "dry" heat removal devices. Common applications that evaporative cooling towers are used for include cooling hydraulic oil, refrigerator condensers, mold temperature controllers and chiller condensers as well as providing cooled air for air conditioning, electric power generation and manufacturing. Industries that benefit from the use of evaporative cooling towers include industrial, automotive, nuclear power, plastics, dry cleaning, petroleum refining, electrical generation and food processing. Also known as water cooling towers, they can be constructed from several construction materials, such as concrete, fiberglass, steel, and wood; each material presents its own advantages.
There are two main types of evaporative cooling towers: direct or open circuit and indirect or closed loop cooling towers. Direct evaporative towers have enclosed structures that distribute warm water through internal methods and feed it over a fill, a medium that is used to expand the amount of surface area between the air and water streams. The water is gravity-driven to descend through the fill while being cooled through direct contact with an air stream passing overhead. After the water is cooled it is collected in a cold water basin that is below the fill, from which it is pumped back to repeat the process. The heated air stream leaving the fill is released into the atmosphere. Indirect evaporative cooling towers have two separate fluid circuits; one is an external circuit that has recirculating water on the outside of the second, which consists of hot closed coils that connect to the evaporative process for the heated fluid to cool and return in a closed circuit. The only difference in the cooling process between direct and indirect evaporative cooling towers is that in indirect cooling towers the fluid to be cooled is enclosed within a circuit and is not in direct contact with either the atmosphere or the external recirculated water. In addition, air may be drawn through evaporative cooling towers in three distinct ways: natural draft, which makes use of the buoyancy provided by a tall chimney structure; mechanical draft, in which a power-driven fan motor is used; and induced draft, which places a fan at the discharge to pull air through the tower.
