What types of cooling towers are used?
There are many types of cooling towers. The major types are wet and dry cooling towers. Wet cooling tower are more cost effective than dry cooling tower because of the high efficiency of direct heat contact between water and air. In a wet cooling tower, the cooled water can approach the wet bulb temperature of the air. In a dry cooling tower the cooled water temperature can only approach the dry bulb temperature of the air. The condenser temperature achievable with a wet cooling tower can be 20C lower than that achievable with a dry cooling tower resulting in a significant improvement in plant performance. The ultimate source of cooling in a wet cooling tower is evaporation of water into the air. About 4% of the water circulated is evaporated each time it goes though the tower, therefore wet cooling towers require a large make-up water supply. Dry cooling towers can be the only alternative where water is not available. Wet cooling type cooling towers are predominant.
