The working principle of a cooling tower

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The working principle of a cooling tower is that ventilated air is blown at an appropriate angle towards the water droplets falling downward; as the air passes through these droplets, some of the water evaporates. The heat used to evaporate the water droplets lowers the temperature of the remaining water, thereby cooling it. The cooling effect of this method depends on the relative humidity and pressure of the air. When water droplets come into contact with air, evaporation occurs due, on the one hand, to direct heat transfer between the air and the water droplets, and on the other hand, due to the pressure difference between the surface of the water vapor and the air. This pressure difference drives the evaporation process; the latent heat of vaporization is released in this process, taking heat away from the water through evaporation-based heat transfer, thereby achieving a cooling effect. Working process of the cooling tower: Taking the circular counterflow cooling tower as an example, hot water from the machine room is pumped under certain pressure through pipes, cross nozzles, curved nozzles, and central nozzles to deliver the circulating water to the water distribution system of the cooling tower; from there, the water is evenly sprayed onto the packing material through small holes in the distribution pipes ； Dry air with a low specific humidity enters the tower through the air inlet at the bottom, driven by a fan. As hot water flows over the surface of the packing, a water film is formed to facilitate heat exchange with the air. Hot air with high humidity and high specific humidity is drawn out from the top. The cooling water drops into the bottom basin and then flows into the main unit through the outlet pipe. However, the evaporation of water into the air does not continue indefinitely. When the air in contact with water is unsaturated, water molecules continuously evaporate into the air. However, when the air at the water vapor interface becomes saturated, water molecules can no longer evaporate and remain in a state of dynamic equilibrium. The number of water molecules that evaporate is equal to the number of water molecules that return from the air back into the water, so the water temperature remains constant.