What is the primary function of cooling towers in a heat-rejection system?

The primary function of cooling towers in a heat-rejection system is to transfer process waste heat to the atmosphere. In industrial and power generation contexts, cooling towers are utilized to dissipate excess heat that is generated during various processes, such as steam generation or mechanical operations. They accomplish this by allowing warm water to flow through the tower, where it is cooled down through the evaporation process as ambient air is drawn in. As the water loses heat through evaporation, it is cooled and can be recirculated back into the system to absorb more heat. This mechanism is crucial for maintaining optimal operating temperatures and ensuring efficiency in the overall heat-rejection system.

The other options do not accurately capture the primary function of cooling towers. Condensing steam pertains to the process of converting vapor back to liquid, while pumping water relates more to the movement of fluids rather than heat transfer. Generating electricity is not a role of cooling towers, as their purpose is solely focused on heat management rather than power production.