What is a cooling tower and what does it do?

In water-cooled chiller systems, the cooling tower is responsible for absorbing building heat from condenser water, and then rejecting that heat into the air through a fan. Specifically, water and captured heat from the condenser is pumped to the cooling tower, where it is sprayed over fill material. The tower fan pulls in air, which cools the condenser water and removes the building heat. The fan then blows this heat back out into the air. The pre-cooled condenser water is then pumped back to the condenser to absorb more heat, continuing the process.