Cooling Tower

A cooling tower is a heat-rejection device that removes heat from a data center's chilled-water or condenser-water loop. It works by evaporating a small share of the water into the outside air. Because evaporation is far more effective than dry air exchange, towers let chiller plants run with lower energy use, which improves PUE, but they consume water continuously. US estimates put average data center water use near 1.8 litres per kWh of IT energy, most of it evaporated at the tower. Operators in water-stressed regions often swap towers for dry coolers or closed-loop systems, accepting higher power draw in hot weather. Tower performance depends on wet-bulb temperature, which sets the lowest water temperature the tower can reach, so the same design behaves very differently in Singapore and Stockholm.