Fans

Description

Fans are mechanical devices which produce air flow by means of electrical power. They can be considered as low-pressure air pumps which create a pressure difference to cause the airflow. Components of fans include impeller or rotor, a motor to rotate the blades, and a housing to cover the impeller and the motor. The rotor works on the air, imparts kinetic and static energy to it. The proportion of the energy imparted determines the type of fan.

Types

Fans are classified as follows:

• Axial or propeller fans (tube axial and vane axial fans)
• Centrifugal fans or radial fans (forward curved and backward curved centrifugal fans)
• Mixed flow fans -combination of axial and centrifugal fans
• Cross flow fans or tangential flow fans or squirrel cage fans

Domestic purpose fans such as table fans, portable fans, computer fans operate based on axial flow.

Advantages

• Fans provide trouble-free operation for years with low maintenance.
• Centrifugal fans are quieter in operation than axial fans
• Mixed flow fans have higher efficiency performance than centrifugal fans
• Cross flow fans distributes uniform flow over wide area without guiding vanes

Applications

• Fans are mainly needed for ventilation
• Axial fans find application in copy machines, computers, office equipment, vending machines, industrial control equipment; telephone equipment, audio and visual equipment, TV cameras, light projectors, and electrical equipment
• Cross flow fans are used to cool medium size equipment like photocopiers and are also employed in air conditioners, automobile ventilation systems
• Centrifugal fans are suited for air pollution control systems, inflatable structures, leaf blowers and air mattress inflators
• Mixed flow fans are designed to use for airborne system cooling (radar), electronics equipment cooling, avionics cooling, and are used as recirculation fans, and condenser fans