A mechanical fan is a 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. Usually, it is contained within some form of housing or case. 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 and internal combustion engines and solar power. Fans produce air flows with high volume and low 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 stream, and devices that take advantage of this, such as anemometers and wind turbines, often have designs similar to that of a fan. Standalone fans are usually powered by electric motors, often attached directly to the motor’s output with no gears or belts. The motor is either hidden in the fan’s centre hub or extends behind it. For big industrial fans, three-phase asynchronous motors are commonly used, placed near the fan and driving it through a belt and pulleys. Smaller fans are often powered by shaded pole AC motors, or brushed or brushless DC motors. AC-powered fans usually use mains voltage, while DC-powered fans use low voltage, typically 24, 12, or 5V. Cooling fans for computer equipment always use brushless DC motors, which generate much less electromagnetic interference than other types. In machines with a rotating part, the fan is often connected to it rather than being powered separately. This is commonly seen in motor vehicles with internal combustion engines, where the fan is connected to the drive shaft directly or through a belt and pulleys. Compressors are similar to pumps: both increase the pressure on a fluid and both can transport the fluid through a pipe. As gases are compressible, the compressor also reduces the volume of a gas. Liquids are relatively incompressible; while some can be compressed, the main action of a pump is to pressurize and transport liquids. Compressors are often described as being either open, hermetic, or semi-hermetic, to describe how the compressor and motor drive is situated in relation to the gas or vapour being compressed. The industry name for a hermetic is hermetically sealed compressor, while a semi- is commonly called a semi-hermetic compressor. This book will give readers, and student community in particular a vivid picture of Fan and compressors technology.
AUTOR: Ravitz Wong
EDITORA: Auris Reference
DISPONIBILIDADE DO PRODUTO: Sob Encomenda - Até 40 dias ( Importação )