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Wet Bulb Temperature in Cooling Systems

Wet bulb temperature (WB) is the temperature air would have if cooled to 100% relative humidity by the evaporation of water into it, with the latent heat being supplied by the air. It is a critical factor in the performance of cooling systems, particularly evaporative cooling systems like cooling towers.

Evaporative Cooling

Evaporative cooling lowers the temperature of water or fluid by exploiting the natural process of evaporation. When hot water from industrial equipment enters the cooling tower, it exchanges heat with the air. This air, which initially has a lower wet bulb temperature, absorbs the heat and evaporates some water, thus cooling the remaining water. The efficiency of this process is significantly influenced by the wet bulb temperature.

Role of Wet Bulb Temperature in Cooling Efficiency

The wet bulb temperature reflects the lowest temperature to which water can be cooled by evaporation. The efficiency of a cooling tower is measured by how close the cooled water temperature can get to the wet bulb temperature. This temperature difference between the cooled water leaving the cooling tower and the wet bulb temperature is known as the approach temperature.

1. Approach Temperature :
   • The smaller the approach temperature, the more efficient the cooling tower.
   • Typically, the cooled water temperature is 3 to 6 degrees Celsius higher than the wet bulb temperature due to the imperfect heat exchange process.
2. Impact on Cooling Tower Size :
   • A larger cooling tower is needed when the cooling requirement is closer to the wet bulb temperature, indicating a more efficient cooling process.
   • Conversely, a smaller cooling tower suffices when the required temperature difference from the wet bulb temperature is larger.

Factors Influencing Wet Bulb Temperature

• Climate and Location: The wet bulb temperature is determined by the local climate, particularly the temperature and humidity. Different areas will have varying wet bulb temperatures, affecting the cooling efficiency and the selection of appropriate cooling towers.


• Humidity: Higher humidity levels can raise the wet bulb temperature, reducing the efficiency of evaporative cooling processes.

Practical Considerations for Cooling Tower Selection

1. Local Climate Data : To select and design an efficient cooling tower, it is essential to have accurate local temperature and humidity data to determine the wet bulb temperature.


2. Sizing the Cooling Tower : Depending on the wet bulb temperature and the required cooling efficiency, the cooling tower size will vary. Closer approach temperatures necessitate larger cooling towers for effective cooling.

Benefits of Using Linkcooling Closed Circuit Cooling Towers

We specializes in designing closed circuit cooling towers, which offer several advantages :

• Reduced Limescale Formation : Closed circuit systems prevent external impurities and limescale from entering the cooling water, maintaining efficiency and reducing maintenance costs.


• Energy and Water Savings : Optimized designs reduce water consumption through efficient evaporation and minimize splash and drift losses.


• Customized Solutions : With over 16 years of experience, Linkcooling provides tailored cooling solutions that meet specific environmental and operational needs.

Contact Information

• Phone: +886-4-26997836
• Email: [email protected]

Linkcooling's experienced team will assist in selecting and designing the most suitable cooling equipment for various industrial applications.