A great site showing the contribution of Muslim scientists to the modern world. Work of Muslim scientists formed the foundation of modern world inventions we see around us today. This period has been forgotten in the history as ‘The Dark Ages’. But actually it was a golden era in which many important inventions were done.
Power available in wind is calculated by formula
Power Available = ½* air density * swept area * wind velocity3
Air density at sea level is 1.23kg/m3
I will consider it as 1kg/m3 at Faisalabad (Pakistan).
Swept area is in m2. It is calculated by formula πr2.
Where r is radius of the rotor. Diameter of the rotor is 2r.
Wind velocity is in m/s.
Therefore, at a wind velocity of 5 m/s and rotor diameter of 1m,
Power available in wind is 196.25 Watts.
If we double the wind speed power increases by a factor of 8. i.e. at 10m/s
Power available in wind is 1570 Watts.
When the diameter of rotor is doubled power increases by factor of 4.
If wind velocity is 5 m/s and diameter is 2m, then the power available is 785 Watts.
But it is not possible to extract all the Power available in wind.
In 1919 Betz calculated the limit to how much a wind turbine can extract from wind.
This limit is called Betz limit.
Betz Limit = 59.26%
It is the maximum amount of power that can be extracted from wind.
An ideal wind machine will work at Betz limit. But in practice there is no ideal machine.
There are power losses because
- No blades are 100% efficient
- No alternator/ generator is 100% efficient.
- Friction losses
- Magnetic drag and resistance losses
Mike Klemen calculated a co-effient of Power= 35%
A good turbine extract about 35% of energy available in wind.
You can take a look at Mike Klemen work here
http://www.ndsu.nodak.edu/ndsu/klemen/Perfect_Turbine.htm
|
Data on power available in wind |
|||||
|
Wind Speed ( m/s ) |
Rotor Diameter ( m ) |
Area ( m2 ) |
Power Available ( Watts) |
Betz limit ( Watts ) |
Good Turbine ( Watts) |
|
1 |
1 |
3.14 |
1.57 |
0.930382 |
0.5495 |
|
5 |
1 |
3.14 |
196.25 |
116.2978 |
68.6875 |
|
10 |
1 |
3.14 |
1570 |
930.382 |
549.5 |
|
1 |
2 |
12.56 |
6.28 |
3.721528 |
2.198 |
|
5 |
2 |
12.56 |
785 |
465.191 |
274.75 |
|
10 |
2 |
12.56 |
6280 |
3721.528 |
2198 |
The Beaufort Wind Scale is named after Sir Francis Beaufort, an admiral in the British Navy. He developed the scale in 1805 in order to estimate wind speed by noting how sails move in the wind. It turned out to be a great help and was later adapted for use on land.
Strength: Calm
Speed: Less than 1 mile per hour (mph), less than 2 kilometers per hour (kph)
Observations: Tree leaves don’t move, smoke rises vertically, sea is calm
Strength: Light Air
Speed: 1-3 mph, 2-6 kph
Observations: Tree leaves don’t move, smoke drifts slowly, sea is lightly rippled
Strength: Slight Breeze
Speed: 4-7 mph, 7-11 kph
Observations: Tree leaves rustle, flags wave slightly, small wavelets or scale waves
Strength: Gentle Breeze
Speed: 8-12 mph, 12-19 kph
Observations: Leaves and twigs in constant motion, small flags extended, long unbreaking waves
Strength: Moderate Breeze
Speed: 13-18 mph, 20-29 kph
Observations: Small branches move, flags flap, waves with some whitecaps
Strength: Fresh Breeze
Speed: 19-24 mph, 30-39 kph
Observations: Small trees sway, flags flap and ripple, moderate waves with many whitecapes
Strength: Strong Breeze
Speed: 25-31 mph, 40-50 kph
Observations: Large branches sway, flags beat and pop, larger waves with regular whitecaps
Strength: Moderate Gale
Speed: 32-38 mph, 51-61 kph
Observations: Whole trees sway, large waves (“heaping sea”)
Strength: Fresh Gale
Speed: 39-46 mph, 62-74
Observations: Twigs break off trees, moderately high sea with blowing foam
Strength: Strong Gale
Speed: 47-54 mph, 75-87 kph
Observations: Branches break off trees, shingles blown from roofs, hight crested waves
Strength: Whole Gale
Speed: 55-63 mph, 88-101 kph
Observations: Some trees blown down, damage to buildings, high churning white sea
Strength: Storm
Speed: 64-74 mph, 101 kph-119 kph
Observations: Widespread damage to trees and buildings, mountainous waves
Strength: Hurricane
Speed: 75 mph or greater, 120 kph or greater
Observations: Severe and extensive damage
The source of this material is Windows to the Universe, at http://www.windows.ucar.edu/ at the University Corporation for Atmospheric Research (UCAR). © The Regents of the University of Michigan. Windows to the Universe® is a registered trademark of UCAR.
There is lot of loadshedding these days in Pakistan. The prices of
energy are also increasing, so i decided to make an experimental wind energy system.
Which I plan to upgrade to a bigger one.
For my convinience I divided it into parts
1. Generator: for making electricity.
2. Rotor : wings for moving the generator.
3. A controller: to control charging of battery.
4. Batteries : to store energy.
5. Inverter: To convert DC voltage to AC.
I shall make or get these parts one by one and assemble them into a power generating system.
My site will be updated regularly with the project details. So stay tuned if you are interested.
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