KING FAHD UNIVERSITY OF PETROLEUM & MINERALS

ELECTRICAL ENGINEERING DEPARTMENT

EE 306 – Term 212

Course Design Project

(Due April 20, 2022 at 3:00PM)

Part I: Axial Fan Design

An axial flow fan is required to be installed for a large cooling tower. The fan needs to

deliver actual flow of 1.1 million cubic feet per minute (CFM) at actual static pressure of

0.477 +(0.your two-digit serial no., e.g., 0.01, 0.05, 0.12, 0.20, …etc) inch-H2O. To enhance

the operation of the fan, a velocity recovery (VR) stack is added.

You are required to design the fan and its driver (DC shunt motor) at the required operating

conditions.

Your design of the fan must consider the following:

 Temperature is set at 95o F

 Outlet-air temperature at sea level

 Total fan efficiency is in the range of 70%–85%

 Select the fan diameter based on your section number as follows:

Your Section Number Fan Diameter

3 20

6 22

7 24

8 26

9 28

10 30

 The VR stack will reduce the power of the fan so that the fan rated power equals to

the Air Horse-Power (AHP).

 The maximum feet per minute (FPM) is 18,000

 The fan is coupled with the motor via a gearbox with a ratio 1 to 4. Losses due to

gearbox could be neglected.

Your design for the fan should include the following calculations:

1. Velocity and total pressure

2. Selection of the diameter and number of blades for the fan

3. Air Horsepower (AHP) of the fan

4. Brake Horsepower (BHP) of the fan

5. Required pitch angle

Refer to the below document for guideline about axial fan design:

https://eurovent.eu/sites/default/files/field/file/PP%20-%202015-05-23%20-%20Attachment%20-

%20Hudson%20tip%20clearance%20example%20-%20page%2015%20-%20figure%206.pdf

Part II: DC Motor Design

Your design of the DC motor must consider the following:

 The efficiency of the motor must be between 85% to 90%.

 The brush losses in the machine is neglected

 The no load power should not exceed 7.5% of the output power.

 Speed regulation should not exceed 10%.

 The motor rated speed is available between 700 and 900 rpm.

 The supply voltage is 250V.

 The magnetization curve is linear and given as ϕ (Wb) =0.025If .

 The flux per pole should not exceed 25 mWb.

 The number of poles is up to 8 poles.

 The armature resistance is between (0.05 to 0.15) Ω.

Your design for the DC MOTOR should include the following calculations:

1. Output power, input power, copper losses, and rotational losses

2. Field current and field resistance

3. Armature current and motor input current

4. The machine constant Ka

5. Motor speed at no load and full load, and speed regulation