A fan does not cool the room at all. What a fan does is create a wind chill effect. When weather people talk about wind chill on a cold winter day, what they are referring to is how the wind increases convective heat loss (see How Thermoses Work for details on convection). By blowing air around, the fan makes it easier for the air to evaporate sweat from your skin, which is how you eliminate body heat. The more evaporation, the cooler you feel.
Fans simply work by increasing the rate of evaporation.
Ceiling fans utilize large, angled, rotating blades to push air down or pull air up, which creates currents that can stir things up and move stagnant air off the ceiling. Fan blades have a bend at the edge which, while moving, forces the air in the range downwards. The angled blades collide obliquely with the air particles in their path collision forces giving them a forward momentum (forward velocity), with the blades feeling a backwards reaction force. Behind a rotating blade is a region of reduced pressure because there are now less parlicles in this space. Surrounding air paricles move freely into this region and restore normal particle density before the next blade collides with them.
A fan does not cool the room at all. What a fan does is create a wind chill effect. When weather people talk about wind chill on a cold winter day, what they are referring to is how the wind increases convective heat loss (see How Thermoses Work for details on convection). By blowing air around, the fan makes it easier for the air to evaporate sweat from your skin, which is how you eliminate body heat. The more evaporation, the cooler you feel.Fans simply work by increasing the rate of evaporation.Ceiling fans utilize large, angled, rotating blades to push air down or pull air up, which creates currents that can stir things up and move stagnant air off the ceiling. Fan blades have a bend at the edge which, while moving, forces the air in the range downwards. The angled blades collide obliquely with the air particles in their path collision forces giving them a forward momentum (forward velocity), with the blades feeling a backwards reaction force. Behind a rotating blade is a region of reduced pressure because there are now less parlicles in this space. Surrounding air paricles move freely into this region and restore normal particle density before the next blade collides with them.
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