What type of heat transfer occurs on the exterior sides of a cooling tower?

The correct choice regarding the type of heat transfer that occurs on the exterior sides of a cooling tower is convective heat transfer.

Cooling towers operate by removing heat from water through a combination of evaporation and airflow. As water flows through the cooling tower, it comes into contact with the air moving across the outside surfaces. The warm air, having a lower density, rises and is replaced by cooler air. This process is driven by the natural convection caused by temperature differences, where warmer air rises and cooler air moves in, effectively cooling the water within the tower.

While evaporative heat transfer takes place inside the cooling tower as the water evaporates and cools down, the question specifically pertains to the exterior surfaces where convective heat transfer dominates due to the interaction of air with the surfaces. This helps facilitate the overall cooling process by drawing heat away from the structure and helps maintain efficient operation of the cooling tower.

Conductive heat transfer relates to heat transfer between materials that are in physical contact, which is not the primary mechanism occurring on the exterior of a cooling tower where the primary interaction is with the air. Radiation is the transfer of heat in the form of electromagnetic waves and does occur but is minimal in a cooling tower setting where airflow is the main heat transfer