1065Cooling Towers

Cooling towers use atmospheric air to cool the water from a condenser or coil through evaporation. In general there are three types of cooling tower, named for the relationship between the fan-powered airflow and the flow of water in the tower: counterflow induced draft, crossflow induced draft and counterflow forced draft.

The use of variable-speed, two-speed or three-speed fans is one way to optimize the control of the cooling tower in order to reduce power consumption and provide adequate water cooling capacity. As the required cooling capacity increases or decreases the fans can be sequenced to maintain the approach temperature difference. For most air-conditioning systems this usually varies between 5 and 12 degrees F (3 to 7 degrees C).

When operated in the winter, the quantity of air must be carefully controlled to the point where the water spray is not allowed to freeze. In cold climates it may be necessary to provide a heating element within the tower to prevent freeze-ups. Although electric resistance heaters can be used for this purpose it is far more efficient to utilize hot water or steam as a heat source if available.

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