Cooling tower
Also known as: water cooling tower
Short definitionAn outdoor device that cools condenser water. It evaporates part of the water, the rest cools as a result and returns to the condenser; the temperature it can reach is limited by the wet-bulb temperature of the air.
Warm water from the condenser is spread over the fill while a fan draws air through it. The small amount of water that evaporates takes its heat from the rest; the cooled water drops into the basin below and is pumped back to the system. A good tower brings the water to within 3–5 K above the wet bulb. On a hot summer day this means a much lower condensing temperature and less compressor electricity than an air-cooled condenser.
A tower is a solution for large plants and is sized on the design wet-bulb temperature of the region. The customer should hear about the water bill from the start: rejecting 1 kW of heat evaporates about 1.5 litres of water an hour, and with blowdown the consumption reaches 1.3–2 times that. Softening, chemical treatment and automatic blowdown are included in the price. If basin cleaning and biocide dosing are neglected, legionella becomes a danger. In cold regions a basin heater or winter draining is planned.