The primary task of a cooling tower is to reject heat into the atmosphere. It works on the principle of evaporation. In this process the sensible heat of hot water is converted to latent heat of vaporization.
Cooling tower types:
Cooling towers falls into two main categories: (1) Natural Draft and (2) Mechanical draft.
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| Difference between Natural Draft and Forced Draft Cooling towers |
Natural Draft Towers:
Natural draft towers use very large concrete chimney to introduce air through the media. Due to the large size of these towers, they are generally used for water flow rates above 45,000 m3/hr. These types of towers are used only by utility power plants.
Mechanical Draft Towers:
Mechanical draft towers utilize fans to force or suck air through circulated water. The water falls downwards over fill surfaces which help increase the contact time between the water and the air - this helps maximize heat transfer between the two. Cooling rates of Mechanical Draft Towers depends upon their fan diameter and speed of operation.
Mechanical draft cooling towers:
Mechanical draft towers are available in the following airflow arrangements:
Counter flow induced draft.
Counter flow forced draft.
Cross flow induced draft.
Components of cooling towers:
The basic components of evoparative tower are: Frame and Casing, Fill, Cold water basin, Drift eliminator, Air inlet, Louvers, Nozzles, and Fans.
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| Components of Different types of cooling towers |
Credits: Slideshare.net
Thermal control magazine
Kooldrop.com