In relation to cooling towers, what does "natural draft" refer to?

Natural draft in relation to cooling towers refers to the process of using the buoyancy effect of heated air to facilitate air circulation through the cooling tower. As water is cooled, it tends to be warmer than the ambient air surrounding the cooling tower. This temperature difference causes the warmer, lighter air to rise, creating a low-pressure area at the bottom of the tower. Consequently, cooler air from outside is drawn in from the bottom, allowing for effective heat exchange as air and water interact within the tower.

This method relies solely on the natural movement of air and does not require any mechanical assistance, such as electrical fans, to function. That's what differentiates natural draft from other cooling processes, making it an energy-efficient strategy for cooling in many industrial applications. The reliance on buoyancy is essential to how these systems operate, capitalizing on the principles of thermodynamics and fluid dynamics.