Cooling towers are heat removal devices used to transfer process waste heat to the atmosphere. Cooling towers
may either use the evaporation of
water to remove process heat and cool the working fluid to near the
wet-bulb air temperature or rely solely on air to cool the working fluid to near the dry-bulb air temperature. Common applications include cooling the circulating
water used in oil refineries, chemical plants, power stations and building cooling. The towers vary in size from small roof-
top units to very large hyperboloid structures that can be up to 200 metres tall and 100 metres in diameter, or rectangular structures that can be over 40 metres tall and 80 metres
long. Smaller towers are normally factory-built, while larger ones are constructed on site.