Closed circuit cooling towers are one of the methods of heat transfers. They are hybrids that pass the working fluid through a tube bundle, upon which clean water is sprayed and a fan-induced draft applied. The resulting heat transfer performance is much closer to that of a wet cooling tower, with the advantage provided by a dry cooler of protecting the working fluid from environmental exposure and contamination.

Application: 

Closed circuit cooling towers operate similar to open cooling towers, except that the heat load to be rejected is transferred from the process fluid to the ambient air through a heat exchange coil. This creates two separate fluid circuits an external circuit, in which spray water circulates over the coil and mixes with the outside air, and an internal circuit, in which the process fluid circulates inside the coil. The coil isolate the process fluid from the outside air, keeping it clean and contamination free. Heat is transferred from the internal circuit, through the coil to the spray water, and then to the atmosphere as a portion of the water evaporates.

Advantages: 

Costs Less to purchase & operate, Less Total HP required, Green solution, open towers use an efficient, simple, and economical design. This is accomplished by combining heat rejection equipment with a heat exchanger in a closed circuit tower