Many factors determine how much energy a cooling tower can remove from a system. These include: the water flow rate and entering temperature, the spray pattern inside the tower and the available surface area for evaporation, the airflow through the tower and the ambient conditions — including temperature and humidity — (expressed as wet-bulb temperature).
With so many factors influencing the amount of energy the tower can remove, the tower’s cooling capacity will fluctuate as these parameters change. Therefore, the outlet water temperature from the tower varies as well.