What is atmospheric cooling tower?

Atmospheric cooling towers are similar to natural draft cooling towers in many ways. The main difference between the two lies in the mechanism of air movement. In an atmospheric cooling tower, natural wind currents provide the air supply. Louvers on the sides prevent water from being blown out, and allow air to enter in any direction. Hot, moist air rises in the tower, drawing in colder outside air.

DIAGRAM OF ATMOSPHERIC COOLING TOWER

Drift Eliminators : To stop water loss when wind velocity surges
Hot Water Return Line :
Water Distribution Header : Pipe or flume delivering water from inlet connection to lateral headers,troughs, flume or distribution basin
Makeup Water : Water added to the circulating water system to replace water lost from the system by evaporation, drift, blow-down, and leakage
Cold Water Out : Discharge of cold water
Splash Bars or Fill : Horizontal component of a fill deck, which constitutes the principal splash surface
Water Basin : Storage for water supply

Basic component of atmospheric cool and its functions:

How Does It Works??

- Hot water pump in from outside source and sprayed into the tower.

- Wind will moves air in and out of the tower. The tower is designed so that winds blow in horizontally, so the air moves in a crossflow direction.

- The airflow rates are determine by the wind velocity.

- As the air becomes heated, it will travels up and the cool water will fall down.

- Location of this tower is important because wind velocities of 4.5 to 6.5 mph are required in order for it to function properly.

- These tower have a 30% to 55% efficiency rating for cooling water.

- Very cost effective because the system does not require a fan.

- Efficiency can fluctuate greatly because it depends on an uncontrollable factor (wind velocity).

- Heat transfer drops significantly with the loss of airflow.

Advantages & Disadvantages

Low power requirement.
Typically lower initial and long-term cost, mostly due to pump requirements
Accepts variations in water flow without changing the distribution system
Easy maintenance access to vital parts.

Performance varies greatly due to its dependence on wind direction and velocity.
Moss formation due to water is distributed through open ducts means that sunlight comes into the tower through louvers causing serious biological formation.
Large air inlet surface makes icing difficult to control
Tendency of uneven air distribution through the infill due to the large inlet surface

Design

Tower Materials

Materials are chosen to enhance corrosion resistance, reduce maintenance, and promote reliability and long service life. Galvanized steel, various grades of stainless steel, glass fiber, concrete and also plastic including PVC, polypropylene, and other polymers are widely used in tower construction, as well as aluminum and plastics for some components.

Cooling Tower Design Consideration

Cooling range, approach to wet bulb temperature, mass flow rate of water, wet bulb temperature, air velocity through tower or individual tower cell, tower height, fan horsepower, pump horsepower, make-up water source, fogging abatement, and drift eliminator.

Atmospheric Cooling Tower