Fan is a simple machine, which is used to create a flow within a liquid or a gas. The most common application of the fan is the ceiling fan in our homes. We use fans in different forms like the ceiling fan table fan, pedestal fans etc in our homes to help us cool down. Fan, as a cooling device was invented in India in around 500 BCE.
Contrary to the popular belief, the fan does not actually cool the air in our homes. However, it simply moves the air around and creates a circulatory flow of the air. This sets the air around us in motion and simulates the effect of a soft breeze. This soft breeze rubs against our skin, helps quickly evaporate the sweat and cools down our body.
When the blades of the fan rotate, it creates a vortex that pushes the surrounding air away from the fan. This creates a low pressure zone just below the blades of the fan. The air gets pushed and moves forward. Now since there a low pressure zone created just under the fan, air from the high pressure zones rushes towards it. This creates the circulatory effect in the air. In a closed room, with a fan on, the air constantly circulates around. This circulating air, also called breeze is very effective in creating a relaxed and comfortable atmosphere within room. However, it should be noted that in this process the fan does not cool the air at all. The temperature of the air within the room remains the same, yet it gives a cooling effect to those in the room.
The moving air helps to evaporate body sweat quickly. As the body sweat evaporates it cools down the body thus comforting the individual. It is thus widely mistaken that fans cools the air, whereas the fact is that the fan circulates the air, which in turn helps to cool individuals under the fan. It is a common myth that fan helps cool air.