Y O U R   C O O L I N G   T O W E R   P R O F E S S I O N A L S

A. BACKGROUND 

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A cooling tower is a specialized heat exchanger in which air and water are brought into direct contact with each other in order to reduce the water's temperature. As this occurs, a small volume of water is evaporated, reducing the temperature of the water being circulated through the tower.

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Water, which has been heated by an industrial process or in an air-conditioning condenser, is pumped to the cooling tower through pipes. The water sprays through nozzles onto banks of material called "fill," which slows the flow of water through the cooling tower, and exposes as much water surface area as possible for maximum air-water contact. As the water flows through the cooling tower, it is exposed to air, which is being pulled through the tower by the electric motor-driven fan.

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When the water and air meet, a small amount of water is evaporated, creating a cooling action. The cooled water is then pumped back to the condenser or process equipment where it absorbs heat. It will then be pumped back to the cooling tower to be cooled once again. Cooling Tower Fundamentals provides a level of basic cooling tower knowledge and is a great resource for those wanting to learn more.

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B. TYPES OF TOWERS 

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Not all towers are suitable for all applications. Cooling towers are designed and manufactured in several types, with numerous sizes available. Understanding the various types, along with their advantages and limitations, is important when determining the right tower for a project. The product list provides an overview of towers to help you determine which is right for your application.

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Crossflow cooling towers

In crossflow towers the water flows vertically through the fill while the air flows horizontally, across the flow of the falling water. Because of this, air does not have to pass through the distribution system, permitting the use of gravity flow hot water distribution basins mounted at the top of the unit above the fill. These basins are universally applied on all crossflow towers.

 

Counterflow cooling towers

Counterflow towers are designed so that air flows vertically upward, counter to the flow of falling water in the fill. Because of this vertical airflow, it is not possible to use the open, gravity-flow basins typical in crossflow designs. Instead, counterflow towers use pressurized, pipe-type spray systems to spray water onto the top of the fill. Since air must be able to pass through the spray system, the pipes and nozzles must be farther apart so as not to restrict airflow.

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Induced draft vs. forced draft

Induced draft cooling towers have fans that are typically mounted on top of the unit and pull air through the fill media. Conversely, air is pushed by blowers located at the base of the air inlet face on forced draft towers.

 

Factory-assembled (FAP) vs. Field-erected (FEP) towers

Factory-assembled towers (FAP) are rebuilt and shipped in as few sections as the mode of transportation will permit. A relatively small tower will ship essentially intact. A larger, multi-cell cooling tower is manufactured as modules at the factory, and shipped ready for final assembly. Factory-assembled towers are also known as "packaged" or "FAP" (factory-assembled product). Factory-assembled cooling towers can be crossflow or counterflow, induced draft or forced draft, depending on the application. While all applications are different, the factory-assembled Marley NC crossflow, induced draft tower is widely used for HVAC and light industrial applications.

Factory-assembled cooling towers can be crossflow or counterflow, induced draft or forced draft, depending on the application.

Field-erected cooling towers (FEP) Field-erected towers are primarily constructed at the site of ultimate use. All large cooling towers, and many of the smaller towers, are prefabricated, piece-marked, and shipped to the site for final assembly. The manufacturer usually provides labor and supervision for final assembly. Field-erected towers can be crossflow or counterflow, depending on the application. For power and heavy industrial applications, the field-erected Marley F400 counterflow tower can be customized to meet your exact specifications for performance, structure, drift and plume abatement.

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