cooling tower

Cooling Towers
A tower offers an economical approach to cool large amounts of water with minimum energy requirements. A tower system is usually used to cool heat loads with 85°F water. This is the optimum operating temperature for hydraulic oil, chiller condensers (to cool refrigerants), and auxiliaries such as mold temperature controllers or air compressors. However the advantages and limitations of cooling towers must be understood before the equipment is selected for or applied to process cooling. Top

Cooling Tower Theory
The controlling principle of a tower system is water’s inherent nature to lower its own temperature as it evaporates. By evaporating a small part of the process water, the temperature of all process water is lowered.

Tower cells accomplish this by spraying fine water droplets in a contained environment. The droplets fall through a stream of upwardly moving air. The more contact time of the air and water, the greater the amount of evaporative and heat transfer. To significantly increase the amount of contact time, cells include “fill” material to reduce the free falling of water and enlarge the surface area of water to air. The result is greater exposure of water to air. With an increase in exposure, there is a corresponding increase in cooling capacity.

Air must absorb water for evaporation to occur. The higher the level of humidity, the less air is able to absorb water and, as a result, the less efficient the tower system in cooling. Typically, cooling tower systems capacity are rated to lower 95°F water to 85°F at 78°F wet bulb. Wet-bulb temperature of the air is the lowest temperature possible for evaporation due to ambient or surrounding environment so the temperature of the water cannot drop below the prevailing wet bulb temperature of the air.

Each tower system must be specifically sized for each geographic area’s prevailing summer wet bulb temperature. While some geographic areas may experience cold climates, a tower’s cooling capability is usually set at no colder than 70°F during winter months. High efficiency mechanical draft towers cool the water to within 5 or 6°F of the wet-bulb temperature, while natural draft towers cool within 10 to 12°F


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