Windmill over view and its science windmill working and its application energy sources

windmill working and its application energy sources

1. Wind Power and its Science
As one of the powerful
energy sources

2. The first windmill / wind turbine
During 500–900 AD, windmills were
built in Persiafor pumping water and
grinding grains.
In 1888, Charles F. Brush used a
windmill to generate electricity in
Cleveland, Ohio, as is called a wind
turbine nowadays.

3. The advantages
Small environmental load
Little pollution
Equal to the efficiency of thermal
power with a best circumstance
Twice as much as that of solar cells
More secure than other energy
sources

4. Usage of wind energy
For charging batteries
Work saving
Pumping water to storing water when
wind is available, etc.
Hybrid generating system
Hybridized with other generators

5. The energy payback time (EPT)
With a 2000-kW class wind turbine,
7m/s of year-average wind velocity
It can create 7 million-kWh electricity a
year
The power consumed by 1,400
households
The average EPT is 3 to 4 months.

6. Measurement of wind velocity
Cup anemometer
World standard
Doppler LiDAR (Light Detection And
Ranging)
Using Doppler effect
Able to measure at 200-m height

7. Types of windmills / wind turbines
Horizontal Axis Wind Turbine (HAWT)
More common and commercialized
Dutch windmill
Propeller type, etc.
Vertical Axis Wind Turbine (VAWT)
Independent of directions of wind
Darrieus
Savonius
Giromill, etc.

8. Other wind turbines 1
Magnus wind turbine
From the effect discovered by Heinrich
Gustav Magnus
Using long cylinders instead of blades
Solar chimney wind turbine
Air heated by sun going up in the
chimney
The wind turbine installed in the chimney

9. Other wind turbines 2
Diffuser
With 10% increment of
wind velocity, 30%
increment of the power
generated
Tip vane
Removing vortex at the
tip of the blade

10. How a wind turbine rotates 1Low pressure
zone
High pressure
zone
Fluid resistance
Lifting force
Wind
velocity
Blade

11. How a wind turbine rotates 2Savonius-type
wind turbine Puddle type
The wind
for rotation
The wind against
rotation
Axis Savonius type
Axis
The wind
for rotation
The wind against
rotation
The net wind for
rotation

12. Types of wind turbines and the
power
A small number of blades
The power becomes larger, but the
torque is smaller.
A large number of blades
The power becomes smaller, but the
torque is larger.

13. The number of blades and usage of
wind turbines/windmills
One or two blades are capable of
generating the best power.
However, they get noise most.
Three-blade wind turbines are the
best balanced.
Multiple-blade windmills are used for
pumping water due to larger torques.

14. Theoretical efficiency of
windturbine
The maximum power
of windmill received
from wind 
The entire power from
wind covered by the
windmill 
The power coefficient C
P
(=P
MAX/P
0) becomes
16/27 = 0.593
(Lanchester-Betz limit)3
1max
2
1
27
16
SvP  3
10
2
1
SvP

15. Practical efficiency of windturbine
Fluid mechanical loss About 50%
Mechanic loss About 4%
Electrical loss About 6%
The practical energy efficiency is 40%.

16. Size of a windturbine and its power
The power of wind
where , A, vare the air density, the
area of windmill, and wind velocity,
respectively.
Therefore, the power is proportional to
the square of the wind velocity: 
322
2
1
2
1
2
1
AvvAvmvP   2
vP

17. How wind turbines distributed
(Making wind farms)
das the diameter of the wind
turbine
Space in the horizontal
direction
from 2dto 4d
Space in the vertical
direction
from 8dto 12dd
2d – 4d
8d – 12d
Wind