Example of Cooling Tower Dimensioning

Cooling towers are commonly used for water cooling, but they can also be used for heat recovery from outlet air. If the water temperature is higher than the dewpoint of the air, water will cool in the tower. Cooling is caused by vaporization on the surface of the water drops. The vaporization energy comes from the inner energy of the water and in a certain phase, when the water temperature is lower than the dry bulb temperature of the air, also from the airflow. When the water temperature drops to near the air wet bulb temperature at the observation point, 

2 STATE VALUES OF HUMID AIR MOLLIER DIAGRAMS AND THEIR APPLICATIONS 

FIGURE 4.1 8 W ter drop cooling in the air flow. Point (I) represents the air state surrounding the water drop (2). 

If the air dewpoint is higher than the water temperature (or more accurately, the surface temperature of the drops), water vapor condenses from the air on the surface of the watet drops. Now the water warms up and the air cools down and at the same time dries up in other words, the cooling tower recovers heat from the outlet air. We will now consider the operation of a cooling tower more closely with the notations of Fig. 4.19. 

Alternatively, we can write the energy balance with the help of the enthalpy flows as 

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