Working process of cooling tower

Take the working process of circular countercurrent cooling tower as an example: the hot water main machine room will circulate the water pressure to the water sowing system of the cooling tower through the pipe, transverse throat, curved throat and central throat through the water pump at a certain pressure, and evenly sprinkle the water on the filler through the small hole on the water sowing pipe; The dry low Han value air enters the tower from the bottom air inlet network under the action of the fan. When the hot water flows through the filler surface, a water film is formed to exchange heat with the air. The hot air with high humidity and high Han value is extracted from the top, and the cooling water drops into the bottom basin and flows into the main engine through the outlet pipe.

Generally, the air entering the tower is the air with dry and low wet bulb temperature. There is an obvious concentration difference and kinetic energy pressure difference between water and air. When the fan is running, under the action of static pressure in the tower, water molecules continue to evaporate into the air and become water vapor molecules, and the average kinetic energy of the remaining water molecules will be reduced, Thus, the temperature of circulating water decreases.

From the above analysis, it can be seen that the evaporation cooling has nothing to do with the air temperature (commonly known as the dry bulb temperature) being lower or higher than the water temperature. As long as the water molecules can continuously evaporate into the air, the water temperature will decrease. However, the evaporation of water into the air will not continue endlessly. When the air in contact with water is unsaturated, the water molecules evaporate into the air continuously, but when the air on the water air contact surface reaches saturation, the water molecules cannot evaporate, but are in a state of dynamic equilibrium. The number of water molecules evaporated is equal to the number of water molecules returned from the air to the water, and the water temperature remains unchanged. It can be seen that the drier the air in contact with water, the easier evaporation will be and the easier the water temperature will be reduced.