Cooling Tower

Fans can do a remarkable job.

Yes, its not natural ventilation its forced air.

Marley CT

Yes. Probably no heat exchange, where would it go?

With air movement, you still get evaporation

So, with air movement comes perpetual cooling?

Why do we need a refrigerant then?

so with air movement comes evaporation, with evaporation comes cooling.

You need a refrigerant, on other types of cooling not this type.

Each cooling tower is specified using your area weather

Using a specified performance conditions

• - 1800 GPM
• - 100 Degree F Enter Hot Water
• - 85 Degree F Exiting Cool Water
• - 75 Degree F WB

Then the tower is size from this.

There are other types of towers, this is just one type.

But the OP, never gave any other criteria. He may be spoon feeding info to us.

Agreed.

The air inside the tower can be considered as isolated from outside atmosphere, for the purposes of explaining draft in the tower.

Any warmer air within the tower would naturally rise to the upper parts of the tower.

At tower top there will be an exchange if any atmospheric air is lower in temperature, and air within the tower would then be replaced by the cooler external air which would decend into the tower to a balanced position. ( from the top, if the bottom were closed or restricted )

If the air in the tower was uniform in temperature, and that temperature was the same as external temperatures, the only action would be top stirring by wind action across the opening. ( if the bottom were closed or restricted )

The bottom of the cooling tower exposed to atmosphere may have a temperature lower than that of the air within the tower; this atmospheric air would not enter the tower unless air within the tower was warm enough to rise to the top and escape.

Some draw effect can be gotten from wind across the top opening, encouraging air at the top layer to move out of the tower due to a density change developed by the air stream. Similar to effects in airfoils creating lift, these currents may induce a mild vaccum. This air must be replaced into the pressure difference, either from the top or from the bottom. Air can also be forced into the tower base, from ground winds that are not present or not equivalent at the top of the tower.

If the entire system is at equilibrium and no external air movement is present then the system should be in a stasis situation. Note that other gases may be present in the tower which at any given temperature have densities lighter or heavier than ambient atmospere, and these gases will cause movements within the tower until equilibriums are achieved.

However, given the simple conditions described in the OP it could be expected that there would be little if any "draft" in the tower.

All of this ignores the possibility that warm soil could have a warming effect on the air at the base of the tower, through the tower foundation structure.

Your premise needs clarification. If there is no hot fluid flowing into the tower then on a still air day there will be nothing to change the density of the air inside and there will be little or no flow.

On the other hand as long as there's a fluid that is hotter than ambient flowing into the tower, the air inside the tower will be heated and start the bouyancy heat engine that powers a natural draft cooling tower.

Even a forced draft tower will exhibit this effect and provide some cooling, but it will be much lower than with the fans running. It can't be relied upon to provide adequate cooling except under very low load and/or low ambient temperature conditions.

Using a fan or blower? Yes, of course.

Remember that it is the difference between the dry-bulb temperature and the wet-bulb temperature that provides the actual cooling.

...In a dry tower?