Basic Concepts of Fan Power and Efficiency
Fan EC Motor Fan Permanent Magnet Synchronous Motor Selection Key Part 11-Basic Concepts of Fan Power and Efficiency
As we all know, fan EC motor/fan permanent magnet synchronous motor can improve the performance of the fan, how to embody it? We must first understand the basic concepts of fan power and efficiency before we can accurately evaluate fan EC motor.
Fan power includes effective power, shaft power and prime mover power.
1. Effective power: Effective power refers to the energy actually obtained by the fluid passing through the fan per unit time, and is called the output power (full pressure and flow rate) of the fan.
2. Axis power: Shaft power refers to the energy obtained from the prime mover through the rotating shaft of the fan per unit time, and is called the fan input power (fan and motor direct drive η=1.0, fan and motor coupling drive η=0.98, fan and motor delta drive η=0.9)
3. Power of prime mover: The power of the prime mover is the input power of the motor when the fan is running.
When the fan works, it will generate energy loss, mainly including mechanical loss efficiency, volume loss efficiency and flow loss efficiency, so the energy obtained by the fan cannot be completely transmitted to the fluid.
1. Mechanical efficiency: The mechanical loss is caused by the friction between the fan rotation and the static components, including the friction loss between the circumference and the bearing, the friction loss between the shaft and the shaft end seal, and the friction loss of the impeller.
2. Volume efficiency: The fluid in the high-pressure area flows to the low-pressure area through the gap between the transmission part and the prohibition part, or flows out of the energy damaged by the fan.
3. Flow efficiency: The energy lost by the flow through the fan to overcome the flow resistance is circulated.
To sum up, the improvement of fan efficiency should be done in these aspects: improving the quasi-exchange efficiency of fan impeller can improve the effective power of fan; Changing the transmission mode of fan and motive power can improve the efficiency of fan to a certain extent. Improving the motive power of the fan, that is, the efficiency of the motor, can improve the efficiency of the fan.
Fan mechanical optimization can reduce the loss of mechanical efficiency and improve fan efficiency. Optimization of fan structure and reduction of volume loss can improve fan efficiency. The efficiency of the fan can be improved by keeping the smooth finish of the fan wall and reasonable length of the fuselage and reducing the flow loss of the fan.