What limits the capacity of cooling towers that pass air over water to remove system heat?

The capacity of cooling towers that utilize the process of passing air over water to remove heat from a system is fundamentally influenced by the outside air wet bulb temperature. The wet bulb temperature represents the lowest temperature to which air can be cooled by the evaporation of water, serving as a crucial determinant in the cooling efficiency of the tower.

As water evaporates in the cooling tower, it absorbs heat from the water circulation within the system, effectively lowering the temperature. However, this cooling process is limited by the moisture content of the air; when the outside air wet bulb temperature is high, the potential for evaporation is reduced. Essentially, the cooler the wet bulb temperature, the more effective the cooling tower will be in dissipating heat.

This relationship between wet bulb temperature and cooling capacity is what establishes the limitations of performance for cooling towers. Higher wet bulb temperatures impede the tower's ability to achieve lower water temperatures, thereby capping the cooling capacity.

In contrast, outside air dry bulb temperature does not provide a complete picture of moisture and heat exchange efficiency in this context, while inside air parameters are not as relevant when determining the external limits of the cooling tower's operation. Understanding these thermodynamic principles helps ensure optimal design and operation of cooling systems, particularly in managing heat diss