1. Centrifugal fan
Depending on the input mechanical energy, it is a kind of driven fluid machinery to increase the pressure of gas and to discharge the gas side by side.
Centrifugal fans are widely used in:
①Ventilation, dust removal and cooling of factories, mines, tunnels, cooling towers, vehicles, ships and buildings;
②Ventilation and induced air of boilers and industrial kilns;
③Cooling and ventilation in air conditioning equipment and household appliances;
④Drying and transporting of grains;
⑤Wind tunnel wind source and hovercraft aeration and propulsion, etc.
2, axial fan
It is the air flow in the same direction as the axis of the wind blade, such as an electric fan, and the fan in the air conditioner is an axial flow fan. It is called "axial flow" because the gas is parallel to the flow of the wind shaft.
Axial flow fans are usually used in situations where the flow rate is high and the pressure is low. The axial flow fan fixed the position and moved the air.
Small axial fan: low power consumption, fast heat dissipation, low noise, energy saving and environmental protection. Because of its small size, it is widely used.
Large axial fan: simple structure, stable and reliable, low noise, large volume of air, wide range of function selection and so on.
3, inclined flow fan / mixed flow fan
Between the axial fan and centrifugal fan, the impeller of the inclined flow fan makes the air move both centrifugal and axial. The movement of the air in the shell is a mixture of axial flow and centrifugal movement.
Features of axial and centrifugal fans are combined, although they look more like traditional axial fans. Weld the curved blade to the conical steel hub. Change the flow rate by changing the blade angle in the upstream inlet shell of the impeller. The housing can have an open inlet, but more commonly, it has a right-angle bending shape that allows the motor to be placed outside the pipe. The discharge shell expands slowly to slow down the flow of air or gas and convert kinetic energy into useful static pressure.
Mainly used for mine ventilation and tunnel ventilation.
1. Centrifugal fan changed the flow direction of the medium in the air duct, while the axial fan did not change the flow direction of the medium in the duct;
2, the former installation is more complex.
3, the former motor and fan are generally driven by the belt rotating wheel connection, the latter motor is generally in the fan;
4, the former is often installed in the inlet and outlet of the air conditioning unit, the boiler drum, the induced draft fan and so on. The latter is often installed in the duct or at the front end of the duct outlet.
5, the former is the air income after pressurization, the latter is positive pressure drive.
Inclined flow (mixed flow) fan:
1. The wind pressure coefficient is higher than the axial flow fan, and the flow coefficient is larger than the centrifugal fan.
2, fill the gap between axial flow fan and centrifugal fan.
3.The installation is simple and convenient.
The difference between centrifugal fan and axial flow fan at startup:
The running power of centrifugal fan increases with the increase of air flow, so the valve of centrifugal fan should be completely closed when starting, and then gradually open to avoid excessive fan current and destroy the motor.
The operating power of the axial fan decreases with the increase of the air volume, so when the axial fan starts up, the air valve should be fully opened, and then gradually closed to the required wind value.