Crossflow tower cooling diagram

A low air rate requires a large tower, while a high air rate in a smaller tower requires greater fan power. Limitations in air velocities are typically 300-500 fpm in counterflow towers, and 350-650 fpm in crossflow towers. 

Higher velocities are obtainable in crossflow towers because of larger air inlet and greater eliminator area. Also, the discharging air does not pass through the water distribution system. 

Cooling towers are capable of operating over a wide range of water rates, air rates and heat loads. Variations are reflected in the approach of the cold water to the wet-bulb temperature. The available tower coefficient is not a constant but varies with operating conditions. 

Cooling tower characteristics can only be deduced from actual field tests. Tower characteristics are generally presented in the form of an empirical correlation. This correlation defines the relationship between the available 

Common practice is to neglect the effect of air velocity and develop the tower correlation in the form of a power law relation  

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