In an induced draft cooling tower, what is the lowest temperature achievable?

In an induced draft cooling tower, the lowest temperature that can be achieved is the wet-bulb temperature. The fundamental principles of cooling tower operation hinge on the concept of evaporation and heat transfer within the ambient air.

The wet-bulb temperature, which measures the lowest temperature that can be attained through the evaporation of water, represents the cooling potential of the ambient air. When water is exposed to this air within the cooling tower, evaporation occurs, absorbing heat from the water and subsequently lowering its temperature.

If the dry-bulb temperature—referring to the actual air temperature—is higher than the wet-bulb temperature, it demonstrates that the air can hold more moisture and has the capacity to facilitate further evaporation, thus resulting in lower water temperatures.

Therefore, in an induced draft cooling tower, the operation is optimized by utilizing the wet-bulb temperature as a benchmark. The chilled water exiting the cooling tower cannot drop below this ambient wet-bulb temperature under normal operating conditions, making the dry-bulb temperature being higher than the wet-bulb the correct context for understanding the achievable temperature.