There are several main cooling tower categories, these are either:
And:
Cooling towers are a combination of these categories. For example, this 3D model shows a cross flow induced draft cooling tower although counter flow induced draft cooling towers and natural draft counter flow cooling towers are also common.
The below video is an extract from our Introduction to Cooling Towers Online Video Course.
Water enters the top of the tower and is distributed through spray nozzles to the fill. The fill may be of the film fill design or splash bar design. The water drips down through the fill and into the basin.
As the water drips through the fill, some of it evaporates and this cools the remaining water that did not evaporate (evaporative cooling). The cooled water remains in the basin until it is pumped to the process.
Some of the evaporated water is reclaimed by a drift eliminator whilst some is discharged through the top of the tower. This type of tower is an induced draft tower because the air passes over the heat exchanger before passing over the cooling tower fan.
cross flow cooling tower Cross-Section
This 3D model shows all major components associated with a typical induced draft cross flow cooling tower, these include:
https://en.wikipedia.org/wiki/Cooling_tower
http://spxcooling.com/pdf/AE-SK-18.pdf