Cooling tower systems use the evaporation of water in order to remove process heat. Then they cool the working fluid to near the wet-bulb air temperature. When it comes to closed circuit dry cooling towers, the tower will rely only on air in order to cool the working fluid to near the dry-bulb air temperature. Cooling tower systems, specifically dry cooling towers operate through heat transfer with a surface that keeps the working fluid separate from ambient air, such as in a tube to air heat exchanger, utilizing convective heat transfer.

When it comes to cooling tower systems some common applications for cooling towers include cooling the circulating water that is used in petrochemical and other chemical plants, oil refineries, thermal power stations and HVAC systems for cooling buildings. They originated out of the development from the 19th century condensers used with the steam engine. The early cooling towers were placed on rooftops or as free standing structures, supplied with air from fans or relying on natural airflow.

An HVAC (heating, ventilating, and air conditioning) cooling tower can be used in order to dispose of unwanted heat from a chiller. Industrial cooling towers can remove heat from machinery or heated process material. Cooling tower systems are typically a large refinery that processes 40 thousand metric tons of crude oil a day and circulates around 80 thousand cubic meters of water per hour.