Electric fans, also known as fans or fans, are household appliances that use electric motors to drive the rotation of fan blades to accelerate air circulation. They are mainly used for cooling, relieving heat, and circulating air. Widely used in homes, classrooms, offices, shops, hospitals, and hotels. The common household electric fan essentially belongs to an axial flow fan, that is, the flow direction of the wind is parallel to the rotating axis of the fan blades. In addition, the application of small power motors such as DC motors and brushless DC motors in small electric fans is becoming increasingly widespread. When the electric fan is working (assuming there is no heat transfer between the room and the outside), the indoor temperature not only does not decrease, but also increases. Let's analyze the reason for the temperature increase: When the electric fan is working, due to the current passing through the coil of the fan and the resistance of the wires, it is inevitable to generate heat and release it, resulting in a natural increase in temperature. But why do people feel cool? Because there is a large amount of sweat on the surface of the human body, when the electric fan is working, the indoor air will flow, which can promote the rapid evaporation of sweat. Combined with the "evaporation needs to absorb a large amount of heat", people will feel cool