The capacity of an open cooling tower is controlled by which air temperature?

The capacity of an open cooling tower is primarily influenced by the wet bulb temperature. This measurement reflects the lowest temperature that can be achieved through evaporative cooling when air passes over water. In an open cooling tower, water is cooled by evaporation, and as air moves over the surface of the water, some of that water evaporates, absorbing heat from the remaining water and thus lowering its temperature.

The wet bulb temperature accounts for both the temperature and the moisture content of the air, making it more relevant for assessing the cooling tower's performance. When the wet bulb temperature is lower, the potential for evaporative cooling is higher, resulting in greater cooling capacity. This relationship is essential for understanding the design and operation of cooling towers, as it indicates how effectively the system can remove heat from a fluid.

The dry bulb temperature, while informative about the air temperature, does not offer insight into the humidity conditions that significantly impact the cooling efficiency within the tower. Other metrics like relative humidity and dew point relate to moisture content and air saturation but are less directly connected to the cooling capacity than wet bulb temperature. Thus, recognizing the importance of wet bulb temperature in cooling tower operations is crucial for proper system management.