A fan is a machine that utilises input mechanical energy to increase gas pressure and discharge gas; it is a driven fluid-handling machine. In China, the term ‘fan’ is the customary abbreviation for gas compression and gas conveyance machinery; the term generally encompasses ventilators, blowers and wind turbines.
Fans are widely used for ventilation, dust extraction and cooling in factories, mines, tunnels, cooling towers, vehicles, ships and buildings; for ventilation and draught extraction in boilers and industrial furnaces; for cooling and ventilation in air-conditioning systems and domestic appliances; for drying and conveying grain; as air sources for wind tunnels; and for inflation and propulsion in hovercraft, amongst other applications.
The main structural components of a fan are the impeller, housing, inlet, support frame, motor, pulley, coupling, silencer and transmission components (bearings), amongst others.
Non-powered ventilators utilise natural wind and the thermal convection caused by temperature differences between indoor and outdoor environments to drive the impeller, thereby expelling stale, hot air from the interior through centrifugal force and negative pressure effects.
Fans have a significant impact on a system’s energy consumption during transmission and distribution, and are a crucial component of building energy efficiency. According to many years of fan testing conducted by the National Air-Conditioning Equipment Quality Supervision and Inspection Centre, numerous fans exhibit issues under rated operating conditions; therefore, fans must be manufactured in strict accordance with product standards.
