Closed Cooling Tower With Internal And External Dual-Circuit System
Nov 14, 2025
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The closed cooling tower adopts a unique indirect evaporative cooling principle. The process fluid to be cooled circulates in fully enclosed coils, completely isolated from the outside air and spray water. The spray system uniformly sprays water onto the outer surface of the coils to form a water film. After the fan is activated, it drives the outside air to flow countercurrently with the spray water. During this process, the heat of the process fluid inside the coils is transferred to the spray water film through the tube wall, achieving the first sensible heat transfer.
Subsequently, some water molecules in the spray water film absorb heat and evaporate, carrying away a large amount of latent heat of vaporization-this is the second heat exchange process of the closed cooling tower, mainly based on latent heat transfer. Finally, the cooled process fluid in the closed cooling tower continues to return to the industrial system, while the humid and hot air that has absorbed heat and water vapor is discharged through the top of the tower. The unevaporated spray water flows back to the sump for recycling.
Introduction to the Circulation System
In the industrial production process, a large amount of waste heat is generated. Allowing this heat to cool naturally will waste a lot of production time and seriously affect the production progress. If the heat is not dissipated in a timely manner, it will damage the associated equipment and increase production costs. Therefore, timely and rapid heat dissipation is a crucial link.
Products Description
The traditional open cooling system has a relatively low purchase price. It sprays circulating water onto PVC fillings in the form of mist, conducts heat exchange through the contact between the circulating water and air, and finally expels the hot air after heat exchange between water and air out of the tower through a fan to achieve cooling. During such operation, the circulating water needs to be in direct contact with air, which inevitably generates many impurities and leads to unstable composition of the circulating water. For industries with high requirements for circulating media, the open cooling tower cannot achieve the ideal cooling effect. In addition, scaling is prone to occur during the entire cycle cooling process of the open cooling system, making the system vulnerable to damage and requiring frequent shutdowns for maintenance. Most importantly, the open cooling system consumes a large amount of water resources during the cycle cooling process, and the circulating system is prone to breeding bacteria, algae, crystals, etc., which significantly increases the production costs of enterprises.
The closed cooling system has a higher purchase price, approximately three times that of the open cooling tower. It consists of two separate internal and external cycle cooling systems, which are completely isolated from each other.
Internal Circulation System
It is connected to the target equipment to form a closed circulation system. The circulating medium circulates in a closed manner within the heat exchange coils without contacting the outside world. During the entire circulation process, the circulating medium is almost not consumed, no impurities are generated, and scaling is less likely to occur. It not only saves a large amount of water resources but also is environmentally friendly and safe, free from scaling and clogging. The system has an extremely low failure rate, eliminating the need for additional maintenance and repair costs, thus saving expenses.
External Circulation System
The external circulation system is used to cool the cooling tower itself. Start the spray pump, which collects water from the sump and delivers it to the upper part of the heat exchange coils. Through the nozzles, the water is uniformly sprayed onto the heat exchange coils to form a thin water film. The water film absorbs the heat of the circulating water inside the coils, reducing its temperature. In addition, the cold air and spray water undergo multiple heat and cold exchanges, which greatly lowers the temperature inside the tower. Finally, the high-temperature and high-heat gas is discharged out of the tower by the fan at the top.
These two circulation systems can be adjusted independently according to operating conditions. In spring and summer when the ambient temperature is high, both circulation systems need to be operated simultaneously. In autumn and winter when the ambient temperature is low, often only one circulation system needs to be activated to achieve the cooling effect.
Therefore
The closed cooling tower not only saves a large amount of water and electricity resources but also is less prone to clogging and scaling during the cooling process, eliminating the need for frequent shutdowns for maintenance. Its operating cost is much lower than that of the open cooling tower, and it has a long service life, making it suitable for the long-term development and use of enterprises.
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