Dry Cooler

A dry cooler is a heat-rejection unit that cools a closed water or glycol loop by passing it through finned coils over which fans blow outdoor air. The process involves no evaporation of water. It lets a data center reject heat with almost zero water use, which matters in water-stressed regions and is why dry coolers are common in liquid-cooled AI halls that run warm facility water of 30-45 degrees C. The trade-off is that capacity falls as outdoor temperature rises, so hot climates often add adiabatic assist or chillers on the hottest days, raising power use. A dry-cooler design can bring WUE close to 0 L/kWh, against roughly 1.8 L/kWh often cited for evaporative cooling towers, at the cost of a somewhat higher PUE.