green engineering systems
TRANSCRIPT
University JNTU Kakinada
Regulation R 16
Year III Year
Semester II Semester
Teaching Classes 3+1
Credits 3
Name of the Faculty Singuru Rajesh
Unit II – Wind Energy
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Green Engineering Systems
UNIT-2: WIND ENERGY
SYLLABUS
Sources and potentials, horizontal and vertical axis, wind mills, performance characteristics, betzcriteria, types of winds, wind data measurement
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Ancient Windmill in Iran
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WIND Energy
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The wind is a by-product of solar energy. Approximately 2% of the sun's
energy reaching the earth is converted into wind energy.
The surface of the earth heats and cools unevenly, creating atmospheric
pressure zones that make air flow from high-to low-pressure areas.
The wind has played an important role in the history of human
civilization.
The first true windmill, a machine with vanes attached to an axis to
produce circular motion, may have been built as early as 2000 B.C.
Water Pumping Windmill
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WIND Energy
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These too were used for milling grain. It was not until a few
hundred years later that windmills were modified to pump water
Until the diesel engine came along, many transcontinental rail routes
in the U.S. depended on large multi-vane windmills to pump water
for steam locomotives.
They are best suited for pumping ground water in small quantities
to livestock water tanks. These wind turbines provided electricity
to farms
Farm windmills
Water Pumping Windmill
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WIND Energy
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A typical modern windmill looks as shown in the following figure.
Because it is invisible, it is not easily measured without special
instruments.
Wind velocity is affected by the trees, buildings, hills and valleys
around us.
Wind is a diffuse energy source that cannot be contained or stored for use
elsewhere or at another time.
In India Tamil Nadu, Maharashtra, Karnataka, Rajasthan and Gujarat
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In India states having
potential of wind
energy are:
Tamilnadu,
Maharashtra,
Karnataka,
Andhra Pradesh
Rajasthan and Gujarat
Classification of Wind Mills
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Wind turbines are classified into two general types:
1. Horizontal axis
2. Vertical axis.
Horizontal axis machine has its blades rotating on an
axis parallel to the ground.
Vertical axis machine has its blades rotating on an axis
perpendicular to the ground.
Classification of Wind Mills
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Horizontal Axis Wind Turbines
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Horizontal axis machine has its blades rotating on an axis parallel to the
ground.
This is the most common wind turbine design.
In addition to being parallel to the ground, the axis of blade rotation is
parallel to the wind flow.
Some machines are designed to operate in an upwind mode, with the blades
upwind of the tower.
In this case, a tail vane is usually used to keep the blades facing into the
wind.
Horizontal Axis Wind Turbines
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Some very large wind turbines use a motor-driven mechanism that turns
the machine in response to a wind direction sensor mounted on the tower.
Commonly found horizontal axis wind mills are
1. Aero-turbine mill with 35% efficiency
2. Farm mills with 15% efficiency
Farm mills Aero-turbine mill
Vertical Axis Wind Turbines
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Vertical axis machine has its blades rotating on an axis perpendicular
to the ground.
Although vertical axis wind turbines have existed for centuries, they are
not as common as their horizontal counterparts.
The main reason for this is that they do not take advantage of the
higher wind speeds at higher elevations above the ground as well as
horizontal axis turbines.
Vertical Axis Wind Turbines
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The basic vertical axis designs are the
• Savonius, which uses scoops to catch the wind & the
efficiency of 30%.
• Darrieus, which has curved blades & efficiency of 35%,
• Giromill or H-Darrieeus which has straight blades &
efficiency of 35%
Vertical Axis Wind Turbines
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Vertical Axis Wind Turbines
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A vertical axis machine need not be oriented with respect to
wind direction.
Because the shaft is vertical, the transmission and generator
can be mounted at ground level allowing easier servicing
and a lighter weight, lower cost tower.
Although vertical axis wind turbines have these advantages,
their designs are not as efficient at collecting energy from
the wind as are the horizontal machine designs.
Components of Wind Turbine
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Components
1. Rotor
2. Blades
3. Hub
4. Main Rotating Shaft
5. Gear Box System
6. Generator
7. Housing
8. Anemometer
9. Pitching System
10.Yaw system
11.Tower
12.Grid Connection
13.Cables and
14.Foundation
Components of Wind Turbines
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Working of Wind Turbines
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Horizontal Axis Wind Turbines
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Specifications of Large Wind Machine, India
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Rated Capacity 2.1 MW
Rotor Diameter 88m
Hub Height 80m
Cut-in wind Speed 3-4m/s
Cut-out Speed 25m/s
Number of blades 3
Power control Active blade pitching
Generator Type Asynchronous
Location Pune
Working of Wind Turbines
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Types of Wind
Types of winds
1. Planetary winds or Permanent Winds
2. Periodic Winds
3. Local Winds
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Types of Wind
1. Planetary winds or Permanent Winds
These winds blow from high pressure belts to low pressure belts in the same direction throughout the year.
They blow over vast area of continents and Oceans.
1. Easterlies
2. Westerlies
3. Polar Easterlies
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Types of Wind
2. Periodic Winds
The direction of these winds changes with the change of seasons.
Monsoon winds are the important periodic winds
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Types of Wind
3. Local Winds
These winds are winds that affect the local weather on a small scale
• Land and Sea Breezes
• Mountain and Valley Breezes
• Hot Winds
• Cold Winds
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Wind Data
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Measurements of Wind Speed are made by using Anemometers.
The wind velocity at any location usually varies rapidly and continuously, the variation being irregular
both in terms of period and amplitude.
It is observed that there are turbulent fluctuations occurring continuously with occasional gusts causing
peaks and valley.
The no of hours in a month or in a year when the wind speed lies in a certain range.
This information can also be computed from hourly wind speed data.
Betz Criteria
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Betz's law indicates the maximum power that can be extracted from the wind,
independent of the design of a wind turbine in open flow.
According to Betz's law, no turbine can capture more than 16/27 (59.3%) of the kinetic
energy in wind.
The factor 16/27 (0.593) is known as Betz's coefficient.
Practical utility-scale wind turbines achieve at peak 75% to 80% of the Betz limit.
Betz Criteria
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It is the flow of air over the blades and through the rotor area
that makes a wind turbine function. The wind turbine extracts
energy by slowing the wind down.
The theoretical maximum amount of energy in the wind that
can be collected by a wind turbine's rotor is approximately
59.3%.This value is known as the Betz limit.
If the blades were 100% efficient, a wind turbine would not
work because the air, having given up all its energy, would
entirely stop.
Betz Criteria
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If all of the energy coming from wind movement through a turbine were extracted as useful
energy, the wind speed afterwards would drop to zero.
If the wind stopped moving at the exit of the turbine, then no more fresh wind could get in; it
would be blocked.
In order to keep the wind moving through the turbine, there has to be some wind movement,
however small, on the other side with some wind speed greater than zero.
Betz's law shows that as air flows through a certain area, and as wind speed slows from losing
energy to extraction from a turbine, the airflow must distribute to a wider area.
As a result, geometry limits any turbine efficiency to a maximum of 59.3%.
Thank You
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SINGURU RAJESHM.Tech (MD), PGDEEM, B.Tech (ME)
Assistant ProfessorRaghu Engineering College(Autonomous)
Dakamarri, Bhimunipatnam Mandal, Visakapatnam Dist, Andhra Pradesh