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Basic principles of cooling tower operation and components of cooling tower

Author： Views: Time:2025-09-27

　　Working principle, installation, selection and fault analysis of cooling tower

　　Basic Principles of Cooling Tower Operation 1. Basic Principles of Cooling Tower Operation

　　Dry (low enthalpy) air is drawn by a fan and enters the cooling tower through the air intake network; High temperature water molecules with high partial pressure of saturated steam flow towards low-pressure air, while moist and hot (high enthalpy) water is sprayed into the tower through the self seeding water system. When water droplets come into contact with air, on the one hand, due to the direct heat transfer between air and water, and on the other hand, due to the pressure difference between the surface of water vapor and air, evaporation occurs under the action of pressure, taking away the latent heat of evaporation and the heat in water, thus achieving the purpose of cooling.

　　The working process of cooling tower

　　Taking the working process of a circular counter current cooling tower as an example:

　　The hot water in the main control room is pumped through pipes, horizontal pipes, curved pipes, and central pipes at a certain pressure to circulate water into the cooling tower's water distribution system. The water is evenly distributed on the packing material through small holes in the water distribution pipe; Dry low humidity air enters the tower through the bottom air inlet mesh under the action of the fan. When hot water flows through the surface of the packing, it forms a water film and exchanges heat with the air. High humidity and high humidity hot air is extracted from the top, and the cooling water drops into the bottom basin and flows into the main engine through the outlet pipe.

　　In general, the air entering the tower is dry and low humidity bulb temperature air. There is a significant concentration difference and kinetic energy pressure difference between water molecules and air. When the fan is running, under the action of static pressure in the tower, water molecules continuously evaporate into the air, becoming water vapor molecules. The average kinetic energy of the remaining water molecules will decrease, thereby reducing the temperature of the circulating water.

　　From the above analysis, it can be seen that evaporative cooling is not related to the temperature of the air (usually referred to as dry bulb temperature) being lower or higher than the 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 continue indefinitely.

　　When the air in contact with water is not saturated, water molecules continuously evaporate into the air. However, when the air on the water vapor contact surface reaches saturation, water molecules cannot evaporate and 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 constant. From this, it can be seen that the drier the air in contact with water, the easier it is for evaporation to occur, and the water temperature is more likely to decrease.

　　Composition of cooling tower

　　1. Watering filler:

　　Splash the water (hot water) that needs to be cooled multiple times into water droplets or form a water film to increase the contact area and time between water and air, and promote heat exchange between water and air. The cooling process of water is mainly carried out in the process of pouring water into the packing material.

　　2. Water distribution system:

　　Uniformly distributing hot water over the entire water filling material has a significant impact on the cooling effect. If the water distribution is uneven, it not only directly reduces the cooling effect, but also causes some cooling water droplets to splash and float outside the tower.

　　3. Ventilation equipment:

　　Utilize ventilation fans in mechanical ventilation cooling towers to generate the expected airflow to ensure the required cooling effect.

　　4. Air distribution device:

　　By utilizing devices such as air intakes, louvers, and air deflectors, the air is evenly distributed throughout the entire cross-section of the cooling tower.

　　5. Ventilation duct:

　　The function of a ventilation duct is to create good aerodynamic conditions, reduce ventilation resistance, and send the humid and hot air discharged from the cooling tower to high altitude to reduce the backflow of humid and hot air. The ventilation duct of a mechanical ventilation cooling tower is also known as an air duct. The ventilation duct of the naturally ventilated cooling tower plays a role in ventilation and sending humid and hot air to high altitude.

　　6. Dehydrator:

　　Separate the water droplets carried in the humid and hot air from the air, reducing the loss of water leakage and the impact on the surrounding environment.

　　7. Tower body:

　　The external enclosure structure of cooling towers, including mechanical ventilation cooling towers and naturally ventilated cooling towers with air ducts, is enclosed to support, maintain, and organize suitable airflow; The tower body of an open cooling tower is made open along the tower height to allow natural wind to enter the tower body.

　　8. Collecting pool:

　　Located at the lower part of the cooling tower, it collects the cooling water that falls from the sprinkler packing. Sometimes, the collection tank also has a certain reserve volume to regulate the flow rate.

　　9. Water delivery system:

　　The inlet pipe sends hot water to the water distribution system, and a valve is installed on the inlet pipe to adjust the water intake of the cooling tower. The outlet pipe sends the cooled water to the water equipment or circulating water pump. Supplementary water pipes, sewage pipes, overflow pipes, vent pipes, etc. are also installed in the collection tank, and if necessary, connecting pipes can be installed between multiple cooling towers.

　　10. Other facilities:

　　Including maintenance doors, maintenance ladders, walkways, lighting, electrical controls, lightning protection devices, and necessary flight obstacle signs, sometimes cooling tower testing components are also installed for testing purposes.

　　The different combinations of the above components constitute various forms and uses of cooling towers: open drip cooling towers, wind tube natural ventilation cooling towers, exhaust (or blast) counter current cooling towers, exhaust cross flow cooling towers, etc.

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