For most industrial manufacturing, electric power generation and even air-conditioning needs, cooling towers are a critical element of the design. Cooling towers work on the principle of heat rejection: They extract heat to the atmosphere through evaporative cooling. The towers themselves are enclosed, steady-flow devices for cooling water by evaporation through direct contact with air. Cooling towers are used in water-cooled refrigeration, industrial process systems and commercial HVAC air-conditioning.

A simple way to appreciate how a cooling tower works is to consider the “beach effect.” On a 95°F (35°C) day with 95 percent humidity, a dip in the water is incredibly refreshing. When you get out of the water and are still damp, what happens when a breeze blows? You feel cool as the breeze evaporates the water on your skin. This is the basic premise behind evaporatively cooled equipment.