Question

an autobiography of a broken fan

Answer 1

A ceiling fan is a mechanical fan, usually electrically powered, suspended from the ceiling of a room, that uses hub-mounted rotating paddles to circulate air.

Ceiling fans typically rotate more slowly than other types of circulating fans, such as electric desk fans. They cool people effectively by introducing slow movement into the otherwise still, hot air of a room. Fans never actually cool air, unlike air-conditioning equipment, they in fact heat the air due to the waste heat from the motor and friction, but use significantly less power (cooling air is thermodynamically expensive). Conversely, a ceiling fan can also be used to reduce the stratification of warm air in a room by forcing it down to affect both occupants' sensations and thermostat readings, thereby improving climate control energy efficiency.

Answer 2

A mechanical fan is a powered machine used to create flow within a fluid, typically a gas such as air. A fan consists of a rotating arrangement of vanes or blades which act on the air. The rotating assembly of blades and hub is known as an impeller, a rotor, or a runner. Usually, it is contained within some form of housing or case.[1] This may direct the airflow or increase safety by preventing objects from contacting the fan blades. Most fans are powered by electric motors, but other sources of power may be used, including hydraulic motors, handcranks, internal combustion engines, and solar power.

Mechanically, a fan can be any revolving vane or vanes used for producing currents of air. Fans produce air flows with high volume and low pressure(although higher than ambient pressure), as opposed to compressors which produce high pressures at a comparatively low volume. A fan blade will often rotate when exposed to an air fluid stream, and devices that take advantage of this, such as anemometers and wind turbines, often have designs similar to that of a fan.

Further information: centrifugal compressor

Typical applications include climate control and personal thermal comfort (e.g., an electric table or floor fan), vehicle engine cooling systems (e.g., in front of a radiator), machinery cooling systems (e.g., inside computers and audio power amplifiers), ventilation, fume extraction, winnowing (e.g., separating chaff of cereal grains), removing dust (e.g. sucking as in a vacuum cleaner), drying (usually in combination with a heat source) and to provide draft for a fire.

While fans are often used to cool people, they do not actually cool air (if anything, electric fans warm it slightly due to the warming of their motors), but work by evaporative cooling of sweat and increased heat convection into the surrounding air due to the airflow from the fans. Thus, fans may become ineffective at cooling the body if the surrounding air is near body temperature and contains high humidity. During periods of very high heat and humidity, governments actually advise against the use of fans.