Calculate+the+output+in+(SI)+units+of+the+variable+speed+fan


 * Flow, Pressure and Power Output of the Variable Speed fan at a specific Frequency. **

To calculate a variable speed or frequency of the axial flow fan we must apply the Fan laws or “//Affinity laws//”:

1. Flow is proportional to the speed of the fan:

(Q1/Q2) = (N1/N2)

2. Pressure is proportional to the square of the speed of the fan:

(H1/H2) = (N1/N2)²

3. Power is proportional to the cube of the speed of the fan:

(P1/P2) = (N1/N2)³


 * Calculations **

According to the specifications provided by the manufacturer the following details are given:


 * Performance data of the FC071-4D Axial Fan: **


 * 3 Phase 400v 50Hz **


 * P ** = 2.9 Kw
 * Pressure ** = 280 Pa
 * Volumetric Flow ** = 14000 m³/h


 * Volumetric Flow conversion **

14000 * 0.000277777778 = **__3.89 m³/s__**


 * Apply the Affinity laws **

If we take for example the frequency of the fan is reduced to 40Hz via the variable speed drive:


 * 1) Flow decreases proportionally to the frequency:

(40/50) * 3.89 = **__3.112__** **__ m³/s __**


 * 1) Pressure is reduced to :

(40/50)² * 280 = **__179.2__** **__ Pa __**


 * 1) Power drops to :

(40/50)³ * 2.9 = **__1.485 Kw__**


 * Efficiency of the fan: **

Total fan Pressure * Flow 100 x - Absorbed Power 1

179.2 * 3.112 100 x - = **__37 %__** 1485 1