Take the working process of [Tailing] circular counter-flow cooling tower as an example: hot water from the main engine room through the water pump at a certain pressure through the pipeline, horizontal throat, curved throat, and central throat to press the circulating water into the cooling tower's water distribution system , Sprinkle water evenly on the filler through the small holes on the water sowing pipe; the dry low-value air enters the tower from the bottom of the wind net under the action of the fan, and the hot water flows through the surface of the filler to form a water film and The air exchanges heat, and the hot air with high humidity and high value is drawn from the top, and the cooling water drops into the bottom basin, and flows into the host through the outlet pipe. Under normal circumstances, the air entering the tower is dry air with low wet bulb temperature. There is obviously a difference in the concentration of water molecules and a difference in kinetic energy pressure between water and air. When the fan is running, under the action of the static pressure in the tower, The water molecules continuously evaporate into the air and become water vapor molecules, and the average kinetic energy of the remaining water molecules will decrease, thereby reducing the temperature of the circulating water.

  It can be seen from the above analysis that evaporation cooling has nothing to do with air temperature (usually said dry bulb temperature) lower or higher than water temperature, as long as water molecules can continuously evaporate into the air, the water temperature will decrease.

  However, the evaporation of water into the air does not go on endlessly. When the air in contact with water is not saturated, water molecules continuously evaporate into the air, 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 that evaporate is equal to the number of water molecules returning from the air to the water, and the water temperature remains constant. It can be seen that the drier the air in contact with the water, the easier the evaporation is, and the water temperature is likely to decrease.