Generally speaking, wet cooling towers are small in size, high in efficiency, and inexpensive. In contrast, dry cooling towers are bulky, low in efficiency, and expensive.
(1) The heat is taken out by the cooling liquid and dissipated in the air through conduction and evaporation, which is called a wet cooling tower. The cooling gas or air takes heat out and transfers it into the air through conduction, which is called a dry cooling tower. The cooling tower that completes the wet cooling method is a wet cooling tower, and the cooling tower that implements the dry cooling method is a dry cooling tower. While the wet and dry cooling tower is actually a combination of a closed cooling tower, cooler and wet cooling tower.
(2) One of the heat exchange methods between water and air in the cooling tower is that the air flowing through the surface of the water is in direct contact with the water, and the heat in the water is transferred to the air through contact heat transfer and evaporation. It is called a wet cooling tower.
(3) The heat exchange efficiency of the wet cooling tower is high, and the limit temperature at which the water is cooled is the wet bulb temperature of the air. However, water is lost due to evaporation; evaporation also increases with the salinity of the circulating cooling water. In order to stabilize the water quality, part of the water with higher salinity must be drained; wind blowing can also cause water loss. These water losses must be continuously replenished with enough new water. Therefore, the wet tower must have a source of make-up water.
(4) In water-deficient areas, when it is difficult to replenish water, only dry cooling towers can be used. The heat exchange between air and water in the dry tower is to transfer heat through the surface of the radiator composed of metal pipes, and transfer the heat of the water or steam in the pipe to the air flowing outside the radiator. The heat exchange efficiency of the dry tower is lower than that of the wet tower, and the limit temperature of cooling is the dry bulb temperature of the air.