Wind is the flow of gases on large scale. On the surface of the earth, wind consists of the bulk movement of air. In outer space, solar wind is the movement of gases and charged particles from the sun though space, while planetary wind is the outgassing of light chemical from a planet’s atmosphere into space. Wind by their spatial scale, their speed, the type of force that cause them, the region in which they occur and their effect. The strongest observed winds on planet in solar system occur on Neptune and Saturn. Winds have various aspects, an important one being its velocity, density of the gas involved and energy content of the wind.
Wind is almost entirely caused by the effects of the sun which, each hour, delivers 175 million watts of energy to the earth. This energy heats the planet’s surface, most intensively at the equator, which causes air to rise. This rising air creates an area of low pressure at the surface into which cooler air is sucked, and it is this flow of air that we know as “wind”. In reality atmospheric circulation is much more complicated and, after rising at the equator air travels pole wards. As it travels the air cools and eventually descends to the earth’s surface at about 30° latitude (north and south), from where it returns once again to the equator (a closed loop known as a Hadley Cell). Similar cells exist between 30° and 60° latitude (the Ferrell Cells) and between 60° latitude and each of the poles (the Polar Cells). Within these cells, the flow of air is further impacted by the rotation of the earth or the "Coriolis Effect". This effect creates a sideways force which causes air to circulate anticlockwise around areas of low pressure in the northern hemisphere and clockwise in the southern hemisphere
In summary, the origin of winds may be traced basically to uneven heating of the earth’s surface due to sun. This may lead to circulation of widespread winds on a global basis, producing planetary winds or may have a limited influence in a smaller area to cause local winds.
Wind power or wind energy is the use of wind to provide the mechanical power through wind turbines to turn electric generators and traditionally to do other work, like milling or pumping. Wind power is a sustainable and renewable energy, and has a much smaller impact on the environment compared to burning fossil fuels.
An Overview of Wind Power Generation and Design Aspects in Indiaijiert bestjournal
There is huge activity in wind power,pan-India with the instal led capacity increasing to 10,000MW. India today has the fifth largest installed capacity of wind power in the world w ith 11087MW installed capacity and potential for on-shore capabilities of 65000MW. However the plant load factor (PLF) in wi nd power generation is very low,often in the single digits. The increase in interest in wind energy is due to inves tment subsidies,tax holidays,and government action towards renewable energy playing a big part in nation�s energy system. T here is a need to generate environment friendly power that not only raises energy efficiency and is sustainable too. The time has come for moving to generation based subsidies and understanding the drawbacks associated with wind power in India. The capital cost of wind power is third higher than Conventional thermal power;further electrical problems like v oltage flicker and variable frequency affect the implementation of wind farm. However advances in technologies such as offshore construction of wind turbines,advanced control methodologies,and simulation of wind energy affecting over all grid performance are making a case for wind energy.
Wind power or wind energy is the use of wind to provide the mechanical power through wind turbines to turn electric generators and traditionally to do other work, like milling or pumping. Wind power is a sustainable and renewable energy, and has a much smaller impact on the environment compared to burning fossil fuels.
An Overview of Wind Power Generation and Design Aspects in Indiaijiert bestjournal
There is huge activity in wind power,pan-India with the instal led capacity increasing to 10,000MW. India today has the fifth largest installed capacity of wind power in the world w ith 11087MW installed capacity and potential for on-shore capabilities of 65000MW. However the plant load factor (PLF) in wi nd power generation is very low,often in the single digits. The increase in interest in wind energy is due to inves tment subsidies,tax holidays,and government action towards renewable energy playing a big part in nation�s energy system. T here is a need to generate environment friendly power that not only raises energy efficiency and is sustainable too. The time has come for moving to generation based subsidies and understanding the drawbacks associated with wind power in India. The capital cost of wind power is third higher than Conventional thermal power;further electrical problems like v oltage flicker and variable frequency affect the implementation of wind farm. However advances in technologies such as offshore construction of wind turbines,advanced control methodologies,and simulation of wind energy affecting over all grid performance are making a case for wind energy.
The design of Farm cart 0011 report 1 2020musadoto
This report describes the best designing of a 200cc FARM CART MACHINE which will be useful to the farm fields due to the fact that, the purchase, repair and maintenance are affordable to all level of income earners. Despite the cost effectiveness of the machine, the report also tries to justify that the machine can be used multipurposely as it serves the purposes of been used as farm transport, mowering machine, boom spraying and or mini planter with two rows. All these can be achieved as long as the implements are attached with respect to the power capacity of the farm cart.
The report tells only the design and testing of machine excluding its farm implements design. Some best reviews from other study projects done by other people in the world provided a good reference for designing and implementation of this project. The project is initially costly because it needs to develop a prototype and test the different first ideas.
The project report describes the important of choosing to use the designed farm cart machine compared to other farm machines at the market which are most efficiently to be used by farmers in their fields.
The challenges are inevitable in any project, here in designing of this 200cc farm machine, the major issue is the funding because the fund for this project is from the pocket which is always insufficient as it depends to the meals and accommodation money distribution sponsored from the HIGH EDUCATION STUDENTS LOAN BOARD (HESLB) thus it takes longer to accomplish the project by waiting another quarter of the semester to continue with the project which affects the other part of normal life(in terms of meals and accommodation).
The report recommends that, the department of engineering sciences and technology and Sokoine University of Agriculture as a whole should invest into this technology by utilizing fully the idea and funding the project for more better improvement so as to attain the desired standard that can with stand the different farm field factors. These when taken into consideration there is a possibility to achieve the industrialization policy in our country and thereafter it is a better approach to modern agriculture.
CONSTRUCTION [soil treatment, foundation backfill, Damp Proof Membrane[DPM] a...musadoto
With reference to a construction site visited recently, describe in details key features
that can be observed on site as follows
Foundations backfilling, hardcore, soil treatment, DPM and BRC works prior
to pouring oversite concrete
CONSTRUCTION [soil treatment, foundation backfill, Damp Proof Membrane[DPM] and BRC for engineers (civil)
BASICS OF COMPUTER PROGRAMMING-TAKE HOME ASSIGNMENT 2018musadoto
Self- Check 1
Which of the following are Pascal reserved words, standard identifiers, valid identifiers, invalid identifiers?
end ReadLn Bill
program Sues‟s Rate
Start begin const
Y=Z Prog#2 &Up
First Name „MaxScores‟ A*B
CostaMesa,CA Barnes&Noble CONST
XYZ123 ThisIsALongOne 123XYZANSWER
ANSWERS
Paschal reserved words:
begin, end, program, Start, CONST, const
Standard identifiers:
ReadLn, „MaxScores‟, Bill, Rate
Valid identifiers:
XYZ123, ThisIsALongOne, A*B, Y=Z, CostaMesa, CA, First Name
Invalid identifiers:
123XYZ, Sues‟s, &UpFirstName, Barnes&Noble, Prog#2
Self- Check 2
Which of the following literal values are legal and what are their types? Which are illegal and why?
15 „XYZ‟ „*‟
$25.123 15; -999
.123 „x‟ “X”
„9‟ „-5‟ True
ANSWER:
The following values are legal and their type
Legal
Type
Illegal
15
Integer literal
$25.123
„XYZ‟
String Literal
.123
„X‟
Character Literal
„9‟
True
Boolean Literal
15;
-999
Integer Literal
-„5‟
Operator literal
„*‟
TP- Lecture 4.2
Self- Checked 1
Which of the following are valid program headings? Which are invalid and why?
(i) Program program; - INVALID using reserved ID
(ii) program 2ndCourseInCS; -INVALID because starts with digit
(iii) program PascalIsFun;- VALID program heading
(iv) program Rainy Day; -INVALID – contains space
Self- Checked 2
Rewrite the following code so that it has no syntax errors and follows the writing conventions we adopted
(i) Program SMALL;
VAR X, Y, Z : real;
BEGIN
Y := 15.0;
Z := -Y + 3.5;
X :=Y + z;
writeln (x, Y, z);
END.
ANSWER:
Program
ENGINEERING SYSTEM DYNAMICS-TAKE HOME ASSIGNMENT 2018musadoto
1. Read Chapter 4 – System Dynamics for Mechanical Engineers by Matthew Davies and Tony L. Schmitz and implement Examples 4.1 to 4.12 in Matlab.
2. Read Chapter 7 – System Dynamics for Mechanical Engineers by Matthew Davies and Tony L. Schmitz and implement Examples 7.1 to 7.11 in Matlab.
3. Read Chapter 9 – System Dynamics for Mechanical Engineers by Matthew Davies and Tony L. Schmitz and implement Examples 9.1 to 9.6 in Matlab.
4. Read Chapter 11 – System Dynamics for Mechanical Engineers by Matthew Davies and Tony L. Schmitz and implement Examples 11.1 to 11.7 in Matlab.
5. Read Chapter 2 - System Dynamics for Engineering Students: Concepts and Applications by Nicolae Lobontiu and attempt problem 2.18 (page 63).
6. Read Chapter 3 - System Dynamics for Engineering Students: Concepts and Applications by Nicolae Lobontiu and attempt problem 3.13 (pp 98 - 100).
7. Read Chapter 4 - System Dynamics for Engineering Students: Concepts and Applications by Nicolae Lobontiu and attempt problem 4.20 (page 146).
8. Read Chapter 5 - System Dynamics for Engineering Students: Concepts and Applications by Nicolae Lobontiu and attempt problems 5.15 (page 198), 5.21 (pp 199 - 200) and 5.27 (pp 201 – 202).
Hardeninig of steel (Jominy test)-CoET- udsmmusadoto
Controlling a material’s properties during processing is pivotal for any engineering field. A specific hardness for a metal is often a desirable characteristic for many applications, so controlling hardness is important during processing. To increase the hardness of steel, it is often quenched from a high temperature to form martensite, a hard yet brittle phase of iron. The extent of martensite formation, including hardness and depth of formation, is known as hardenability. This practical provides an experiment for measurement of hardenability in plain carbon steel and an alloyed steel according to, the Jominy End-Quench Test , (ASTM A255 – 10). The demonstration exercise involve quenching one end of a heated steel sample ,comparing and evaluating the hardness distribution using measurements obtained at different locations(distance interval) on the sample(specimens) surface.
1.1 The aim of the experiment
The aim of the experiment is to test the usefulness of the ultrasonic waves, by passing them through different
solids one can find out a lot of physical properties like young’s modulus , defects, Poisson ratio, Velocity of
sound in respective material this is due to the response of the received ultrasonic waves.
1.2 Theory of experiment
Ultrasonic testing (UT) is a family of non-destructive testing (NDT) techniques based on the propagation of ultrasonic waves in the object or material tested. In most common UT applications, very short ultrasonic pulse-waves with center frequencies ranging from 0.1-15 MHz, and occasionally up to 50 MHz, are transmitted into materials to detect internal flaws or to characterize materials. A common example is ultrasonic thickness measurement, which tests the thickness of the test object, for example, to monitor pipework corrosion.
Ultrasonic testing is often performed on steel and other metals and alloys, though it can also be used on concrete, wood and composites, albeit with less resolution. It is used in many industries including steel and aluminium construction, metallurgy, manufacturing, aerospace, automotive and other transportation sectors.
Ae 219 - BASICS OF PASCHAL PROGRAMMING-2017 test manual solutionmusadoto
Whether the Pascal program is small or large, it must have a specific structure. This
program consists mainly of one statement (WRITELN) which does the actual work
here, as it displays whatever comes between the parentheses. The statement is
included inside a frame starting with the keyword BEGIN and ending with the keyword
END. This is called the program main body (or the program block) and usually
contains the main logic of data processing.
1. The background of Fluid Mechanics
2. Fields of Fluid mechanics
3. Introduction and Basic concepts
4. Properties of Fluids
5. Pressure and fluid statics
6. Hydrodynamics
Fluid mechanics (a letter to a friend) part 1 ...musadoto
1. The background of Fluid Mechanics
2. Fields of Fluid mechanics
3. Introduction and Basic concepts
4. Properties of Fluids
5. Pressure and fluid statics
6. Hydrodynamics
Fluids mechanics (a letter to a friend) part 1 ...musadoto
1. The background of Fluid Mechanics
2. Fields of Fluid mechanics
3. Introduction and Basic concepts
4. Properties of Fluids
5. Pressure and fluid statics
6. Hydrodynamics
Fresh concrete -building materials for engineersmusadoto
CONCRETE
is a building Material made from a mixture of gravel ,sand ,cement,water and air ,forming a stone like mass on hardenning.
FRESH CONCRETE
It is a concrete that has not reached the final setting time.
Course Contents:
Introduction; Linear measurements; Analysis and adjustment of measurements, Survey methods: coordinate systems, bearings, horizontal control, traversing, triangulation, detail surveying; Orientation and position; Areas and volumes; Setting out; Curve ranging; Global Positioning system (GPS); Photogrammetry.
Fresh concrete -building materials for engineersmusadoto
General introduction
CONCRETE
is a building Material made from a mixture of gravel ,sand ,cement,water and air ,forming a stone like mass on hardenning.
FRESH CONCRETE
It is a concrete that has not reached the final setting time.
DIESEL ENGINE POWER REPORT -AE 215 -SOURCES OF FARM POWERmusadoto
The diesel engine (also known as a compression-ignition or CI engine), named after Rudolf Diesel, is an internal combustion engine in which ignition of the fuel which is injected into the combustion chamber is caused by the elevated temperature of the air in the cylinder due to mechanical compression (adiabatic compression). Diesel engines work by compressing only the air. This increases the air temperature inside the cylinder to such a high degree that atomised diesel fuel that is injected into the combustion chamber ignites spontaneously. This contrasts with spark-ignition engines such as a petrol engine (gasoline engine) or gas engine (using a gaseous fuel as opposed to petrol), which use a spark plug to ignite an air-fuel mixture. In diesel engines, glow plugs (combustion chamber pre-warmers) may be used to aid starting in cold weather, or when the engine uses a lower compression-ratio, or both. The original diesel engine operates on the "constant pressure" cycle of gradual combustion and produces no audible knock.
A diesel engine built by MAN AG in 1906
Detroit Diesel timing
Fairbanks Morse model 32
The diesel engine has the highest thermal efficiency (engine efficiency) of any practical internal or external combustion engine due to its very high expansion ratio and inherent lean burn which enables heat dissipation by the excess air. A small efficiency loss is also avoided compared to two-stroke non-direct-injection gasoline engines since unburned fuel is not present at valve overlap and therefore no fuel goes directly from the intake/injection to the exhaust. Low-speed diesel engines (as used in ships and other applications where overall engine weight is relatively unimportant) can have a thermal efficiency that exceeds 50%.[1][2
Farm and human power REPORT - AE 215-SOURCES OF FARM POWER musadoto
Farm is an area of land and its building, used for growing crops a rearing of animals or an area of land
that is devoted primarily of agricultural process with the primary objective of producing food and other
commercial crops. Or an area of water that is devoted primarily to agricultural process in order to
produce and manage such commodities as fibers, grains, livestock or fuel.
The process of working the ground, planting seeds and growing of planting known as farming.it can
described s raising of animals for milk and meat as farming.
ENGINE POWER PETROL REPORT-AE 215-SOURCES OF FARM POWERmusadoto
What is an Engine?
Before knowing about how the Petrol Engine works, let's first understand what an engine is. This is common for both petrol and diesel engines alike. An engine is a power generating machine which converts potential energy of the fuel into heat energy and then into motion. It produces power and also runs on its own power.
The engine generates its power by burning the fuel in a self-regulated and controlled „Combustion‟ process. The combustion process involves many sub-processes which burn the fuel efficiently and results in the smooth running of the engine.
These processes include:
The suction of air (also known as breathing or aspiration).
Mixing of the fuel with air after breaking the liquid fuel into highly atomized / mist form.
Igniting the air-fuel mixture with a spark (petrol engine).
Burning of highly atomized fuel particles which results in releasing / ejection of heat energy.
How does an Engine work?
The engine converts Heat Energy into Kinetic Energy in the form of „Reciprocating Motion‟. The expansion of heated gases and their forces act on the engine pistons. The gases push the pistons downwards which results in reciprocating motion of pistons.
This motion of the piston enables the crank-shaft to rotate. Thus, it finally converts the reciprocating motion into the 'Rotary motion' and passes on to wheels.
A petrol engine (known as a gasoline engine in American English) is an internal combustion engine with spark-ignition, designed to run on petrol (gasoline) and similar volatile fuels.
In most petrol engines, the fuel and air are usually mixed after compression (although some modern petrol engines now use cylinder-direct petrol injection). The pre-mixing was formerly done in a carburetor, but now it is done by electronically controlled fuel injection, except in small engines where the cost/complication of electronics does not justify the added engine efficiency. The process differs from a diesel engine in the method of mixing the fuel and air, and in using spark plugs to initiate the combustion process. In a diesel engine, only air is compressed
TRACTOR POWER REPORT -AE 215 SOURCES OF FARM POWER 2018musadoto
A tractor is an engineering vehicle specifically designed to deliver a high tractive effort (or torque) at slow speeds, for the purposes of hauling a trailer or machinery used in agriculture or construction. Most commonly, the term is used to describe a farm vehicle that provides the power and traction to mechanize agricultural tasks, especially (and originally) tillage, but nowadays a great variety of tasks. Agricultural implements 0may be towed behind or mounted on the tractor, and the tractor may also provide a source of power if the implement is mechanised.
The word Tractor is derived prior to 1900, the Machine were known as traction motor (pulling-machine).After the year 1900 both the words are joined by taking ‘Tract’ from Traction and ‘Tor” from motor calling it a Tractor.
In our Country tractors were started manufacturing in real sense after independence and at present we are self-sufficient in meeting demand of country’s requirement for tractors. Our country is basically an agricultural country where 75% of our population is directly or indirectly connected with agriculture. This cannot be produced with our conventional bullock pulled agricultural implements. Tractor is one of the basic agricultural machines
used for speeding up agriculture production.
Water power or Hydropower is power derived from the energy of free falling water which may
be harnessed for useful purposes. Hydroelectricity is the term referring to electricity generated
by hydropower which implies the production of electrical power through the use of the
gravitational force of falling or flowing water. It is the most widely used form of renewable
energy, accounting for 16 percent of global electricity generation..The cost of hydroelectricity is
relatively low, making it a competitive source of renewable electricity. The average cost of
electricity from a hydro plant larger than 10 megawatts is 3 to 5 U.S. cents per kilowatthour.
Hydro is also a flexible source of electricity since plants can be ramped up and down very
quickly to adapt to changing energy demands. However, damming interrupts the flow of rivers
and can harm local ecosystems, and building large dams and reservoirs often involves displacing
people and wildlife. Once a hydroelectric complex is constructed, the project produces no direct
waste, and has a considerably lower output level of the greenhouse gas carbon dioxide (CO2)
than fossil fuel powered energy plants.
The Roman Empire A Historical Colossus.pdfkaushalkr1407
The Roman Empire, a vast and enduring power, stands as one of history's most remarkable civilizations, leaving an indelible imprint on the world. It emerged from the Roman Republic, transitioning into an imperial powerhouse under the leadership of Augustus Caesar in 27 BCE. This transformation marked the beginning of an era defined by unprecedented territorial expansion, architectural marvels, and profound cultural influence.
The empire's roots lie in the city of Rome, founded, according to legend, by Romulus in 753 BCE. Over centuries, Rome evolved from a small settlement to a formidable republic, characterized by a complex political system with elected officials and checks on power. However, internal strife, class conflicts, and military ambitions paved the way for the end of the Republic. Julius Caesar’s dictatorship and subsequent assassination in 44 BCE created a power vacuum, leading to a civil war. Octavian, later Augustus, emerged victorious, heralding the Roman Empire’s birth.
Under Augustus, the empire experienced the Pax Romana, a 200-year period of relative peace and stability. Augustus reformed the military, established efficient administrative systems, and initiated grand construction projects. The empire's borders expanded, encompassing territories from Britain to Egypt and from Spain to the Euphrates. Roman legions, renowned for their discipline and engineering prowess, secured and maintained these vast territories, building roads, fortifications, and cities that facilitated control and integration.
The Roman Empire’s society was hierarchical, with a rigid class system. At the top were the patricians, wealthy elites who held significant political power. Below them were the plebeians, free citizens with limited political influence, and the vast numbers of slaves who formed the backbone of the economy. The family unit was central, governed by the paterfamilias, the male head who held absolute authority.
Culturally, the Romans were eclectic, absorbing and adapting elements from the civilizations they encountered, particularly the Greeks. Roman art, literature, and philosophy reflected this synthesis, creating a rich cultural tapestry. Latin, the Roman language, became the lingua franca of the Western world, influencing numerous modern languages.
Roman architecture and engineering achievements were monumental. They perfected the arch, vault, and dome, constructing enduring structures like the Colosseum, Pantheon, and aqueducts. These engineering marvels not only showcased Roman ingenuity but also served practical purposes, from public entertainment to water supply.
Welcome to TechSoup New Member Orientation and Q&A (May 2024).pdfTechSoup
In this webinar you will learn how your organization can access TechSoup's wide variety of product discount and donation programs. From hardware to software, we'll give you a tour of the tools available to help your nonprofit with productivity, collaboration, financial management, donor tracking, security, and more.
Acetabularia Information For Class 9 .docxvaibhavrinwa19
Acetabularia acetabulum is a single-celled green alga that in its vegetative state is morphologically differentiated into a basal rhizoid and an axially elongated stalk, which bears whorls of branching hairs. The single diploid nucleus resides in the rhizoid.
Operation “Blue Star” is the only event in the history of Independent India where the state went into war with its own people. Even after about 40 years it is not clear if it was culmination of states anger over people of the region, a political game of power or start of dictatorial chapter in the democratic setup.
The people of Punjab felt alienated from main stream due to denial of their just demands during a long democratic struggle since independence. As it happen all over the word, it led to militant struggle with great loss of lives of military, police and civilian personnel. Killing of Indira Gandhi and massacre of innocent Sikhs in Delhi and other India cities was also associated with this movement.
A Strategic Approach: GenAI in EducationPeter Windle
Artificial Intelligence (AI) technologies such as Generative AI, Image Generators and Large Language Models have had a dramatic impact on teaching, learning and assessment over the past 18 months. The most immediate threat AI posed was to Academic Integrity with Higher Education Institutes (HEIs) focusing their efforts on combating the use of GenAI in assessment. Guidelines were developed for staff and students, policies put in place too. Innovative educators have forged paths in the use of Generative AI for teaching, learning and assessments leading to pockets of transformation springing up across HEIs, often with little or no top-down guidance, support or direction.
This Gasta posits a strategic approach to integrating AI into HEIs to prepare staff, students and the curriculum for an evolving world and workplace. We will highlight the advantages of working with these technologies beyond the realm of teaching, learning and assessment by considering prompt engineering skills, industry impact, curriculum changes, and the need for staff upskilling. In contrast, not engaging strategically with Generative AI poses risks, including falling behind peers, missed opportunities and failing to ensure our graduates remain employable. The rapid evolution of AI technologies necessitates a proactive and strategic approach if we are to remain relevant.
Macroeconomics- Movie Location
This will be used as part of your Personal Professional Portfolio once graded.
Objective:
Prepare a presentation or a paper using research, basic comparative analysis, data organization and application of economic information. You will make an informed assessment of an economic climate outside of the United States to accomplish an entertainment industry objective.
Francesca Gottschalk - How can education support child empowerment.pptxEduSkills OECD
Francesca Gottschalk from the OECD’s Centre for Educational Research and Innovation presents at the Ask an Expert Webinar: How can education support child empowerment?
Synthetic Fiber Construction in lab .pptxPavel ( NSTU)
Synthetic fiber production is a fascinating and complex field that blends chemistry, engineering, and environmental science. By understanding these aspects, students can gain a comprehensive view of synthetic fiber production, its impact on society and the environment, and the potential for future innovations. Synthetic fibers play a crucial role in modern society, impacting various aspects of daily life, industry, and the environment. ynthetic fibers are integral to modern life, offering a range of benefits from cost-effectiveness and versatility to innovative applications and performance characteristics. While they pose environmental challenges, ongoing research and development aim to create more sustainable and eco-friendly alternatives. Understanding the importance of synthetic fibers helps in appreciating their role in the economy, industry, and daily life, while also emphasizing the need for sustainable practices and innovation.
Biological screening of herbal drugs: Introduction and Need for
Phyto-Pharmacological Screening, New Strategies for evaluating
Natural Products, In vitro evaluation techniques for Antioxidants, Antimicrobial and Anticancer drugs. In vivo evaluation techniques
for Anti-inflammatory, Antiulcer, Anticancer, Wound healing, Antidiabetic, Hepatoprotective, Cardio protective, Diuretics and
Antifertility, Toxicity studies as per OECD guidelines
The French Revolution, which began in 1789, was a period of radical social and political upheaval in France. It marked the decline of absolute monarchies, the rise of secular and democratic republics, and the eventual rise of Napoleon Bonaparte. This revolutionary period is crucial in understanding the transition from feudalism to modernity in Europe.
For more information, visit-www.vavaclasses.com
How libraries can support authors with open access requirements for UKRI fund...
WIND ENERGY REPORT AE 215- 2018 SOURCES OF FARM POWER
1. NCE1 | P a g e
SOKOINE UNVERSITY OF AGRICULTURE
FACULTY OF AGRICULTURE
DEPARTMENT OF AGRICULTURAL ENGINEERING AND LAND PLANNING
BSc. IRRIGATION AND WATER RESOURCES ENGINEERING.
COURSE NAME: SOURCES OF FARM POWER
COURSE CODE: AE 215
TYPE OF ASSIGNMENT: GROUP WORK (GROUP NO 4.)
STUDENT NAME REGISTRATION
NUMBER
SIGNATURE
BIRUSYA, LILIAN MEDARD IWR/D/2016/0063
MBELWA JUSTA IWR/D/2016/0033
MUSHI, NOEL R. IWR/D/2016/0038
ZEITA, ROBERT JOHN IWR/D/2016/0060
MONYO, ISMAIL BAKARI IWR/E/2016/0084
YASSON, ANDREA BEZAEL IWR/D/2016/0059
LUHENDE,NTUGWA SAILENSA IWR/D/2016/0026
JORAM GEORGE IWR/D/2016/0066
MBAGO, MARTIN HABAKUKI IWR/D/2016/0032
PELLO RICKOYAN IWR/D/2016/0081
NDYAMKAMA, FIDELIS F IWR/D/2016/0044
FILBERT FRANK IWR/D/2016/0028
LWESHA, GABRIEL E. IWR/D/2016/0027
DAUDI SAID JAFARY IWR/D/2016/0010
KAIZA GEOFREY IWR/D/2016/0016
AMANZI ABUBAKARI IWR/D/2016/0003
KWEKA, DANIEL E. IWR/D/2016/0023
HENRY, PAULO B IWR/D/2016/0012
SAID, MOHAMED BAKARI IWR/D/2016/0052
MAYO AHMED IWR/D/2016/0070
DUE DATE: 15 MAY, 2018.
INSTRUCTOR NAME: HIERONIMO (Dr. PROCHES)
2. NCE2 | P a g e
WIND POWER
1. NATURE AND ORIGIN OF THE WIND
Introduction
Wind is the flow of gases on large scale. On the surface of the earth, wind
consists of the bulk movement of air. In outer space, solar wind is the
movement of gases and charged particles from the sun though space, while
planetary wind is the outgassing of light chemical from a planet’s atmosphere
into space. Wind by their spatial scale, their speed, the type of force that cause
them, the region in which they occur and their effect. The strongest observed
winds on planet in solar system occur on Neptune and Saturn. Winds have
various aspects, an important one being its velocity, density of the gas
involved and energy content of the wind.
Wind is almost entirely caused by the effects of the sun which, each hour,
delivers 175 million watts of energy to the earth. This energy heats the
planet’s surface, most intensively at the equator, which causes air to rise. This
rising air creates an area of low pressure at the surface into which cooler air is
sucked, and it is this flow of air that we know as “wind”. In reality atmospheric
circulation is much more complicated and, after rising at the equator air
travels pole wards. As it travels the air cools and eventually descends to the
earth’s surface at about 30° latitude (north and south), from where it returns
once again to the equator (a closed loop known as a Hadley Cell). Similar cells
exist between 30° and 60° latitude (the Ferrell Cells) and between 60° latitude
and each of the poles (the Polar Cells). Within these cells, the flow of air is
further impacted by the rotation of the earth or the "Coriolis Effect". This
effect creates a sideways force which causes air to circulate anticlockwise
around areas of low pressure in the northern hemisphere and clockwise in the
southern hemisphere
In summary, the origin of winds may be traced basically to uneven heating of
the earth’s surface due to sun. This may lead to circulation of widespread
winds on a global basis, producing planetary winds or may have a limited
influence in a smaller area to cause local winds.
4. NCE4 | P a g e
2. POWER CONTENT OF WIND.
The terms "wind energy" or "wind power" describe the process which the
wind is used to generate mechanical power or electricity. Wind power, as an
alternative to burning fossil fuels, is plentiful, renewable, widely distributed,
clean, produces no greenhouse gas emissions during operation, consumes no
water, and uses little land. The net effects on the environment are far less
problematic than those of nonrenewable power sources. Wind power has
been used as long as humans have put sails into the wind. For many years
wind-powered machines have ground grain and pumped water.
The kinetic energy in wind is utilized in form of electricity and mechanical
energy. This is done by using a large wind turbine usually consisting of
propellers; the turbine can be connected to a generator to generate electricity,
or the wind energy is transmitted through gears and shafts to mechanical
perform tasks such as pumping water or grinding grain. As the wind passes
the turbines it moves the blades, which spins the shaft. There are currently
two different kinds of wind turbines in use, the Horizontal Axis Wind Turbines
(HAWT) or the Vertical Axis Wind Turbines (VAWT). HAWT are the most
common wind turbines, displaying the propeller or ‘fan-style’ blades and
VAWT are usually in an ‘egg-beater’ style.
2.1. Kinetic Energy of The Undisturbed Wind Stream
Conservation Of Energy
The fundamental concept of wind kinetic energy is firstly to be considered.
The kinetic energy of an air flow of mass through a unit area is
perpendicular to the wind direction assuming a constant flow velocity
v(m/s) is
K.E=
Where v is the wind speed in (m/s)
m is the wind mass in kg
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The kinetic energy per unit volume V or energy density is thus
K.E =
=
Where V is the considered air volume in m3
The specific wind energy or kinetic energy per unit mass is given as
KE'=KE/m= [joules/kg]
The specific wind energy is proportional to the square of wind speed
Large wind farms consist of hundreds of individual wind turbines which are
connected to the electric power transmission network. Offshore wind is
steadier and stronger than on land, and offshore farms have less visual impact,
but construction and maintenance costs are considerably higher. The Haliade-
X 12 MW, is the most powerful offshore wind turbine in the world to date,
featuring a 12 MW capacity (the world’s first), 220-meter rotor, a 107-meter
blade designed by LM Wind Power, and digital capabilities. In addition, the
Haliade-X will also be the most efficient of wind turbines in the ocean. Best of
all, it’s capable of transforming more wind into power than any other offshore
wind turbine today.
Haliade-X Specifications
Rated Power 12 MW
Rotor Diameter 220m
Blade Length 107m
Rotor Swept Area 38,000m²
Total Height 260m
Capacity Factor 63%
Net AEP 67 GWh
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Fig. 2. Haliade Offshore Wind Farm
The main advantages of offshore wind farms are
a) Windmills can be built a lot bigger and taller allowing for more energy
collection from larger windmills.
b) Typically out at sea, there is a much higher wind speed/force allowing
for more energy to be created at a time.
c) There are no physical restrictions such as hills or buildings that could
block the wind flow.
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The disadvantages of offshore wind farms are:
a) The biggest disadvantage of an offshore wind farm is the cost. Offshore
wind farms are 90% more expensive than fossil fuel generators, and
50% more than nuclear. This is down to the fact that to build an
offshore farm, a whole platform has to be built to support the farm, but
also the cables required have to travel a long distance to get to an
onshore battery.
b) The long cables result in voltage drop off meaning that a loss of power
occurs the further the cable runs.
Small onshore (turbines located on land) wind farms provide electricity to
isolated locations. Utility companies increasingly buy surplus electricity
produced by small domestic wind turbine.
The advantages of onshore wind farms are:
a) The cost of onshore wind farms is relatively cheap, allowing for mass
farms of wind turbines.
b) The shorter distance between the windmill and the consumer allows for
less voltage drop off on the cabling.
c) Wind turbines are very quick to install, unlike a nuclear power station,
which can take over twenty years, a windmill can be built in a matter of
months.
Despite of the good of onshore wind farm, the following are their
disadvantages:
a) One of the biggest issues of onshore wind farms is that many deem them
to be an eye sore on the landscape.
b) They don’t produce energy all year round due to often poor wind speed
or physical blockages such as buildings or hills.
c) The noise that wind turbines create can be compared to as the same as a
lawn mower often causing noise pollution for nearby communities.
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Fig.3. German onshore wind farm
A unique feature of a wind turbine is that the energy extraction process uses a
change in the wind speed and not in the temperature like in the case of a heat
engine such as a steam or a gas turbine, a change in the head of a hydraulic
system or the change in potential of an electrical system. Wind speed and
direction are important design parameters in wind power systems. They vary
both in short and long terms.
2.2. Wind Power Density, Energy Flux Conservation Of Mass
For an air stream flowing through a cross sectional area A, the mass flow rate
is given
Mass flow rate=Density x Area x velocity
=ρ A v…… (1)
Since Power is kinetic energy per unit time
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P=
P=
Where by P=Power
ρ=Density
A=Area
V=Velocity
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3. WIND SPEED AND HEIGHT MEASUREMENT
3.1. Wind Speed Measurement
Wind speed is caused by air moving from high pressure to low pressure,
usually due to changes in temperature as seen in an introductory part of this
assignment. Wind speed is commonly measured with an anemometer. In the
absence of an anemometer, it is possible to estimate the wind speed through
the Beaufort wind scale which is based on people's observation of specifically
defined wind effects.
Anemometer
A simple type of anemometer was invented in 1845 by Dr. John Thomas
Romney Robinson, of Armagh Observatory. It consisted of four hemispherical
cups mounted on horizontal arms, which were mounted on a vertical shaft.
The air flow past the cups in any horizontal direction turned the shaft at a rate
that was roughly proportional to the wind speed. Therefore, counting the
turns of the shaft over a set time period produced a value proportional to the
average wind speed for a wide range of speeds.
Fig.4. Anemometer
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Beaufort scale
Beaufort scale is an empirical measure for describing wind intensity based on
on the sea or land. The scale was devised in 1805 by the Irish hydrographer
Francis Beaufort (later Rear Admiral Sir Francis Beaufort), a Royal Navy
officer, while serving on HMS Woolwich (Nine ships of Royal Navy) . The scale
was made in order to get common wind standards scales.
Wind speed on the 1946 Beaufort scale is based on the empirical relationship
V= 0.836 m/s where v is the equivalent wind speed at 10 meters above
the sea surface and B is Beaufort scale numbers correspond to 0.5, 1.5, 2.5, etc.
Beaufort Wind Scale
Developed in 1805 by Sir Francis Beaufort, U.K. Royal Navy
Force
Wind
(Knots)
WMO
Classification
Appearance of Wind Effects
On the Water On Land
0
Less
than 1
Calm
Sea surface smooth and
mirror-like
Calm, smoke rises
vertically
1 1-3 Light Air
Scaly ripples, no foam
crests
Smoke drift indicates
wind direction, still
wind vanes
2 4-6 Light Breeze
Small wavelets, crests
glassy, no breaking
Wind felt on face,
leaves rustle, vanes
begin to move
3 7-10 Gentle Breeze
Large wavelets, crests
begin to break,
scattered whitecaps
Leaves and small
twigs constantly
moving, light flags
extended
4 11-16
Moderate
Breeze
Small waves 1-4 ft.
becoming longer,
numerous whitecaps
Dust, leaves, and
loose paper lifted,
small tree branches
move
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5 17-21 Fresh Breeze
Moderate waves 4-8 ft
taking longer form,
many whitecaps, some
spray
Small trees in leaf
begin to sway
6 22-27 Strong Breeze
Larger waves 8-13 ft,
whitecaps common,
more spray
Larger tree branches
moving, whistling in
wires
7 28-33 Near Gale
Sea heaps up, waves
13-19 ft, white foam
streaks off breakers
Whole trees moving,
resistance felt
walking against
wind
8 34-40 Gale
Moderately high (18-25
ft) waves of greater
length, edges of crests
begin to break into
spindrift, foam blown in
streaks
Twigs breaking off
trees, generally
impedes progress
9 41-47 Strong Gale
High waves (23-32 ft),
sea begins to roll, dense
streaks of foam, spray
may reduce visibility
Slight structural
damage occurs, slate
blows off roofs
10 48-55 Storm
Very high waves (29-41
ft) with overhanging
crests, sea white with
densely blown foam,
heavy rolling, lowered
visibility
Seldom experienced
on land, trees broken
or uprooted,
"considerable
structural damage"
11 56-63 Violent Storm
Exceptionally high (37-
52 ft) waves, foam
patches cover sea,
visibility more reduced
12 64+ Hurricane
Air filled with foam,
waves over 45 ft, sea
completely white with
driving spray, visibility
greatly reduced
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3.2. Wind Height Measurement
Wind gradient, more specifically wind speed gradient or wind velocity
gradient, or alternatively shear wind, is the vertical gradient of the mean
horizontal wind speed in the lower atmosphere. It is the rate of increase of
wind strength with unit increase in height above ground level. In metric units,
it is often measured in units of meters per second of speed, per kilometer of
height (m/s/km), which reduces to the standard unit of shear rate, inverse
seconds (s−1).
In general, the wind speed increases with height from the surface to the upper
troposphere. There are several reasons that explain this tendency. First,
especially in the middle latitudes, the pressure gradient increases with height.
The height of the troposphere is taller in warmer air since warmer air is less
dense and thus occupies a greater volume. Going up in altitude, the pressure
gradient between the warm air and the cold air increases with height.
A second reason for the wind speed increasing with height, especially near the
ground, is due to surface friction. Surface objects such as trees, rocks, houses,
etc. slow the air as it collides into them. The influence of this friction is less
with height above the ground, thus the wind speed increases with height.
A third reason is due to air density. The density of the air is highest at the
surface and decreases with height. A force imparted on air will cause the air to
move more easily when the mass of the air is less. Dense air requires a greater
force to move it the same speed as less dense air. With air density decreasing
with height, it is easier to move the less dense air at a higher wind speed.
In wind energy studies, two mathematical models or 'laws' have generally
been used to model the vertical profile of wind speed over regions of
homogenous, flat terrain. The first approach, the log law, has its origins in
boundary layer flow in fluid mechanics and in atmospheric research. It is
based on a combination of theoretical and empirical research. The second
approach is the power law. Both approaches are subject to uncertainty caused
by the variable, complex nature of turbulent flows. (Manwell, J. F., Wind
Energy Explained, Wiley, 2003)
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Power Law
This calculator extrapolates the wind speed to a certain height by using the
power law.
Where by:
V1 = Velocity at height Z1
V2 = Velocity at height Z2
Z1 = Height 1 (lower height)
Z2 = Height 2 (upper height)
α = wind shear exponent it changes with different roughness, often assumed 0.14
over flat open terrain but can increase to 0.25 for area with forest or taller
building.
Log law
This is an approximation of wind speed at a certain height by using the log
law. The increase of wind speed with height in the lowest 100m can be
described by this logarithmic expression:
where:
V = velocity to be calculated at height z
Z = height above ground level for velocity v
Vref = known velocity at height Zref
Zref = reference height where vref is known
Z0 = roughness length in the current wind direction
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Fig.5 Graph of vertical profile (Height, m) with respect to wind speed (m/s)
A reliable prediction of the annual energy yield of wind farms is only possible
if it is based on accurate on-site wind speed measurements. Wind energy
applications require a higher standard of wind speed measurements than is
necessary for meteorological purposes. Particularly critical aspects are the
selection of the measuring site, the selection and calibration of anemometers,
and the installation of the sensors on met masts. The costs involved in high-
quality wind speed measurements are small in comparison to the reduction of
the financial risk of wind farm projects.
Therefore, responsible wind farm planning should be based on wind speed
measurements carried out by independent and recognized experts.
Apart from wind measurements there are other special wind measurements
such as site calibration, wind measurements for wind farm monitoring and
designing of special measuring set-ups, for example for determining the
turbulence characteristics by means of ultrasonic anemometers or wind
profile evaluations.
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4. COMPONENTS OF WIND POWER SYSTEM
Wind power is the use of air flow through wind turbines to mechanically
power generators for electricity. Wind power, as an alternative to burning
fossil fuels, is plentiful, renewable, widely distributed, clean, produces no
greenhouse gas emissions during operation, consumes no water, and uses
little land. Wind is caused by uneven heating of the earth from the sun making
wind a renewable and free source of energy. Wind turbines are an alternate
source of energy that harnesses this renewable wind power to make
electricity. Since wind turbines run solely on wind, they cause no pollution
making them environmentally friendly. Basically, wind turns blades that are
connected to a generator; the generator then makes electricity (more on this
later).
The wind power system made up by the following components which enable
the system in the process of collecting the energy through wind and
converting it for various appliance uses.
i) Batteries (For Off-Grid And Backup System): Provide energy storage
for periods of calm or during utility grid outages.
ii) A Charge Controller and/or Voltage Clamp: Take raw material energy
from a wind generator and condition it so it can charge batteries
safely and effectively.
iii) Disconnects And Over current Protection: Provide safety from
overloaded circuits and allow you to isolate different parts of the
system.
iv) A Dump Load: This is the place to divert excess energy in of-grid
system or when the utility grid is down, it’s windy and your batteries
are full.
v) An Inverter: This converts direct (DC) electricity to conventional
household alternating current (AC) electricity.
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vi) Metering: This gives you data display and logging so you can tell what
your system is doing and weather it’s performing well.
vii) A Tower: Support a wind generator getting it up into the smooth,
strong wind that is needed to generate meaningful amounts of
electricity. The following components makes up a tower
a) A rotor, consisting of blades with aerodynamic surfaces. When the
wind blows over the blades, the rotor turns, causing the generator
or alternator in the turbine to rotate and produce electricity.
b) A gearbox, which matches the rotor speed to that of the
generator/alternator. The smallest turbines (under 10 kW)
usually do not require a gearbox.
c) An enclosure, or nacelle, which protects the gearbox, generator
and other components of the turbine from the elements.
d) A tailvane or yaw system, which aligns the turbine with the wind.
viii) Transmission Wiring And Conduct: Allow you to transfer energy from
where it is made to where it is stored and used.
ix) Wind Generators: Collect the energy in the wind and use it to make
electricity. The whole system of wind power system is shown below;
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Fig. 6. Components of Wind power system
Fig.7. Components of a wind energy system. (Source: Natural Resources
Canada).
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5. WIND MACHINE (WIND TURBINES/ WINDMILL
CLASSIFICATION)
A. According to Design There are two kinds of wind turbines,
i) The Vertical axis wind turbine design, the vertical axis type is
designed like an egg-beater. Vertical Axis Wind Turbines are
designed to be economical and practical, as well as quiet and
efficient. There are two different styles of vertical wind turbines
out there. One is the Savonius rotor, and the second is the
Darrieus model ( Darrieus , a French man, invented it).
Advantages of Vertical Axis Wind Turbines:
They can operate even in area with wind obstruction such as hills as
they function better.
Since VAWT are mounted closer to the ground they make maintenance
easier, reduce the construction costs, are more bird friendly and does
not destroy the wildlife.
No need any mechanisms in order to operate the wind turbine
Lower wind startup speed
The main advantage of VAWT is it does not need to be pointed towards
the wind to be effective. In other words, they can be used on the sites
with high variable wind direction.
You can use the wind turbine where tall structures are not allowed.
VAWT’s are quiet, efficient, economical and perfect for residential
energy production, especially in urban environments.
They are cost effective when compare to the HAWTs. It is still best to
shop around and check prices before making a purchase, however.
Disadvantages of Vertical Axis Wind Turbines: There are also
disadvantages that come with the use of this type of wind turbine. While the
many advantages are certainly great, it is imperative that we must be aware of
its disadvantages.
Decreased level of efficiency when compared to the HAWT. The reason
for the reduced amount of efficiency is usually due to the drag that
occurs within the blades as they rotate.
You are unable to take advantage of the wind speeds that occur at
higher levels.
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VAWT’s are very difficult to erect on towers, which means they are
installed on base, such as ground or building.
Fig.8. Savonious Vertical Axis Wind Turbine
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Fig.9. Darrieus Vertical Axis Wind Turbine
ii) The Horizontal axis wind turbine design. A horizontal-axis wind
turbine (HAWT) is a wind turbine in which the axis of the rotor's
rotation is parallel to the wind stream and the ground. All grid-
connected commercial wind turbines today are built with a
propeller-type rotor on a horizontal axis (i.e. a horizontal main
shaft). The horizontal wind turbine, has two to three blades. This
type functions best when it is directly facing the wind. Farmers
with great land area found out another source of income. When
wind turbines became the newest source of electricity, these
farmers leased their lands to power developers. Wind farms
mushroomed all throughout the Midwest. HAWTs can be
subdivided into upwind wind turbines (The rotor faces the wind)
and downwind wind turbines (rotor is downwind which is the lee
side) of the tower.
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Advantages of Horizontal Axis Wind Turbines
Variable blade pitch, which gives the turbine blades the optimum angle
of attack. Allowing the angle of attack to be remotely adjusted gives
greater control, so the turbine collects the maximum amount of wind
energy for the time of day and season.
The tall tower base allows access to stronger wind in sites with wind
shear. In some wind shear sites, every ten meters up, the wind speed
can increase by 20% and the power output by 34%.
High efficiency, since the blades always move perpendicularly to the
wind, receiving power through the whole rotation. In contrast, all
vertical axis wind turbines, and most proposed airborne wind turbine
designs, involve various types of reciprocating actions, requiring airfoil
surfaces to backtrack against the wind for part of the cycle.
Backtracking against the wind leads to inherently lower efficiency.
Disadvantages of Horizontal Axis Wind Turbines
Taller masts and blades are more difficult to transport and install.
Transportation and installation can now cost 20% of equipment costs.
Stronger tower construction is required to support the heavy blades,
gearbox, and generator.
Reflections from tall HAWTs may affect side lobes of radar installations
creating signal clutter, although filtering can suppress it.
Mast height can make them obtrusively visible across large areas,
disrupting the appearance of the landscape and sometimes creating
local opposition.
Downwind variants suffer from fatigue and structural failure caused by
turbulence when a blade passes through the tower’s wind shadow (for
this reason, the majority of HAWTs use an upwind design, with the rotor
facing the wind in front of the tower).
They require an additional yaw control mechanism to turn the blades
toward the wind.
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Fig.10 Horizontal Axis Wind Turbine
B. According to Size Wind turbines vary not only with their designs but also
with their sizes.
Smaller turbines
They are usually lower than 100 kilowatts and they are most often
found in homes. They are associated with simple diesel generators and
water pumping needs.
Utility-scale wind turbines.
They start at 100 kilowatts and reach up to even a few megawatts.
There are also the really large turbines seen in wind farms. These
turbines serve as the primary source of electricity in the electrical grid.
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Parts of a Wind Turbine/Windmill
The nacelle contains the key components of the wind turbine, including the
Gear box, and the electrical generator.
The rotor blades capture wind energy and transfer its power to the rotor
hub.
The generator converts the mechanical energy of the rotating shaft to
Electrical energy.
The gearbox increases the rotational speed of the shaft for the
generator.
Blades: are the main electricity-generating parts of the turbine. Once
wind passes through it, they will rotate thereby causing a series of
reaction which will eventually lead to electricity production.
Brake: as with any other break, this is used to stop the turbines in
emergency cases. This could be a mechanical, electrical, or hydraulic
break.
Controller: this dictates the wind speed at which turbines start and stop.
It usually starts the machine when the wind hits 8 mph and stops it
upon reaching 55 mph. It is an important part of the machine since it
automatically stops any machine activity when wind speed is more than
55 mph because blades may easily be damaged.
Shaft: signals the generator to conduct electricity.
Tower: is a place where turbines may be placed to get more wind.
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Fig.11. Inside the wind turbine
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6. GENERATION OF ELECTRICAL ENERGY FROM WIND TURBINES
A wind turbine is in many ways the opposite of a fan. Instead of providing the
electricity to get the fan to rotate, wind rotates the turbine to generate
electricity.
Converting Wind to Mechanical Energy.
Wind is converted by the blades of wind turbines. The blades of the wind
turbines are designed in two different ways, the drag type and lift type.
Drag type: this blade design uses the force of the wind to push the blades
around. These blades have a higher torque than lift designs but with a slower
rotating speed.
The drag type blades were the first designs used to harness wind energy for
activities such as grinding and sawing. As the rotating speed of the blades are
much slower than lift type this design is usually never used for generating
large scale energy.
Lift type: most modern HAWT use this design. Both sides of the blade has air
blown across it resulting in the air taking longer to travel across the edges. In
this way lower air pressure is created on the leading edge of the blade, and
higher air pressure created on the tail edge. Because of this pressure
difference the blade is pushed and pulled around, creating a higher rotational
speed that is needed for generating electricity.
Mechanism of Creating Electricity from Wind
The Kinetic Energy in the wind is converted into rotation motion by the
turbine blades. This low rotation speed is transmitted to a gear box by the
main shafts. The gear box increases the rotation speed to the appropriate
rotation speed required by the generator. This increased speed of rotation is
transmitted to the generator by a fast rotation shaft. The generator uses the
turning motion of the shaft to rotate a rotor which has oppositely charge
magnets and is surrounded by copper wire loops. Electromagnetic induction
is created by the rotor spinning around the inside of the core, generating
electricity. The electric energy generated is transmitted to the grid by the
cable.
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Generation of electricity from the turbine is not as simple as it has been stated.
This can be pronounced as the wind is not blowing with the same speed and
with the same direction all the time. To overcome these problems, wind
turbine is usually equipped with several additional equipments.
Changes in the wind speed are measured by anemometer found at the top of
the turbine blades which sends data to a control computer inside the nacelle.
The control computer sends the signal to the control system which changes
the angle of attack of the blades (Pitch control action). Some small wind
turbines are designed for optimum wind condition and they don’t use pitch
control system. In these cases the price outweighs the efficiency.
Also the changes in wind direction affect the performance of the wind
turbines as they should always face to the wind. A change in wind direction
causes the wind vane, at the top of the turbine, to change direction in a similar
manner for a pitch control. Changes in wind direction are handled by an
internal computer and activates control motors to turn the nacelle in the
direction of the wind.
If the wind goes above the preset condition, things get tougher for the turbine
to handle it, so it needs to stop operating. This is achieved by combination of
two actions. First action is by turning the blades around their axis with pitch
control to minimize the area of blades exposed to the wind. The decreased
area reduces the rotation speed of the blades substantially. Secondly, the
breaking system on the fast rotating shaft is activated to stop the rotation of
the blades completely.
During the generation heat is generated inside the generator and the gearbox
and this should be handled by cooling system installed inside the nacelle.
In summary, the rotor blade on a wind turbine catches the kinetic energy in the
wind and transfers it via a rotor shaft to the generator. The wing blades can be
rotated and adjusted to the wind direction and strength, for maximum
utilization of energy. When the rotor spins, the power is transferred via the drive
shaft and gearbox. Then, the generator converts the kinetic energy from the
turbine into electrical energy. The electricity is sent to the substation, where it is
converted and then transported out on the network.
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Distribution of Electricity
The electricity generated by harnessing the wind’s mechanical energy must go
through a transformer in order increase its voltage and make it successfully
transfer across long distances. Power stations and fuse boxes receive the
current and then transform it to a lower voltage that can be safely used by
business and homes.
7. PUMPING OF WATER USING WIND POWER
Introduction
Wind pump is the type of windmill which is used to pump water. Wind pumps
were used to pump water since the 9th century. Wind Water Pumping by
windmills is possibly one of man’s earliest inventions with wind energy
historically being used for a wide range of applications, ranging from grinding
grain to sawing wood, with many other applications as well. About one million
windmills are pumping water in the world today. The most common
application is to install a windmill directly over a drilled or dug well. Pumping
water from an aboveground source is also an easy task for a windmill. If you
need to pump water on your property and the site has access to reliable
winds, a water-pumping windmill may be a good option.
Sitting wind mill
To avoid turbulence caused by surrounding objects, the blades of water-
pumping windmills should be at least 9m (30 feet) above any obstructions
such as trees or buildings in a 90m (300-feet) radius. Access to “clean wind”
helps the windmill operate smoothly, ensures a more effective operation, and
extends its life. This often means installing a tall tower, so you can get well
above nearby buildings, trees, and land features. Although you can select and
site a windmill without using local wind-speed data, correctly sizing the
windmill and pump cylinder (see How Much Will it Pump?) using real data
will remove much of the guesswork about how much the ‘mill will pump. A
well-selected and well-suited windmill should start pumping water at wind
speeds between 9.5 and 13km/h. Most windmill manufacturers rate a
windmill’s pumping capacity for winds in the 16 to 32km/h range.
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Fig. 12. Wind mill pump at the site
How the Windmill pump works:
Water-pumping windmills are simple devices that use mechanical advantage
in multiple ways. It’s a direct-drive device that transfers energy via gears,
rods, simple valves, and a piston in a cylinder—and uses high torque to move
water.
The blades of the windmill wheel catch the wind which turns the wheel
(rotor). The wheel is attached to a shaft by long arms. The shaft has small
pinion gears at the other end, inside a gearbox. The pinion gears drive larger
bull gears, which move pitman arms. The pitman arms push a sliding yoke up
and down, above the bull gears (much like a crankshaft, connecting rod, and
piston in a standard vehicle engine). The moving yoke lifts and drops the
pump rod to do the work down below.
The pump rod goes down the tower through a watertight seal at the top of the
well’s drop pipe, and to the pump cylinder, the part that moves the water. The
cylinder is attached to the bottom of the drop pipe below the water level, and
has a simple piston and two check valves.
As the piston rises, water moves up the pipe above it. At the same time, water
is sucked through a screen and the lower check valve below the piston, into
the lower section of the pump cylinder. When the pump rod reverses and
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begins to descend, the lower check valve closes and the piston check valve
opens. This allows water in the cylinder to pass through, and the water that is
trapped above the piston to be pushed up out of the cylinder and ultimately to
its final delivery height. One might think of the pump as a cup with a trap door
in the bottom that opens when the cup falls and shuts when the cup rises. This
cycle is constantly repeated as the wind wheel turns to move the pump rod up
and down.
If the wind wheel is moving, the pump piston is moving. As the wind speed
increases, the speed and frequency of the piston stroke increases, so more
water is pumped. But the windmill’s efficiency drops because the airfoil is not
optimized for higher wind speeds—it doesn’t make as much use of the cubic
effect of wind power as a wind generator does. (The power available in the
wind is proportional to the cube of the wind speed.) But then, water needs do
not increase in proportion to the wind speed either, so this is not a major
impediment. In fact, water pumpers do the job they are designed for
efficiently and well.
Block Diagram Of Windmill Pump
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Fig. 12. Internal Parts Of The Wind Mill Pump
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8. REPAIR AND MAINTENANCE OF WIND POWER SYSTEM
Wind power system can be repaired or maintained. The repair and
maintenance can be done on any part of the wind system including the turbine
as whole or simple repair on small parts of the turbine such as Foundation,
Connection to the electric grid, Tower, Access ladder, Wind orientation control
(Yaw control), Nacelle, Generator, Anemometer, Electric or Mechanical Brake,
Gearbox, Rotor blade, Blade pitch control, Rotor hub
Methods of repairing will differ depending on the type of turbine itself
whether it is onshore turbine or offshore turbine.
Two types of maintenance can be done which are either Preventive
maintenance or Corrective maintenance
Preventive maintenance (PM)
The care and servicing by personnel for the purpose of maintaining
equipment in satisfactory operating condition by providing for
systematic inspection, detection and correction of incipient failures
either before they occur or before they develop into major defects.
The work carried out on equipment in order to avoid its breakdown or
malfunction. It is a regular and routine action taken on equipment in
order to prevent its breakdown
Maintenance including tests, measurements, adjustments, parts
replacement, and cleaning, performed specifically to prevent faults from
occurring.
The primary goal of maintenance is to avoid or mitigate the consequences of
failure of equipment. This may be by preventing the failure before it actually
occurs which Planned Maintenance and Condition Based Maintenance help to
achieve. It is designed to preserve and restore equipment reliability by
replacing worn components before they actually fail.
Corrective maintenance is a maintenance task performed to identify, isolate,
and rectify a fault so that the failed equipment, machine, or system can be
restored to an operational condition within the tolerances or limits
established for in-service operations.
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Corrective maintenance can be subdivided into "immediate corrective
maintenance" (in which work starts immediately after a failure) and "deferred
corrective maintenance" (in which work is delayed in conformance to a given
set of maintenance rules
Predictive and preventive maintenance
Laser alignment
Vibration and Modal Analysis
Thermography
Bore Scoping
Aims For Repair And Maintenance Of Wind Power System
The repair and maintenance of wind power system is done so that to ensure
the following;
Increase efficiency and energy delivery (kWh/kW)
Decrease downtime (hours/year)
Ensure safety and reduce risk
Extend system lifetime
Often required in financing and warranty
General Wind Power Services and Capabilities
The following are the general wind power services that should be done where
necessary so that to ensure the proper performance of the wind power
system.
Wyes ring replacement
Generator shaft repair
Rotor lead change outs
Bearing change outs and upgrades
Slip ring change outs, upgrades & turning
Brush holder upgrades
Wind generator and gearbox repair
Gearbox oil changes
Grounding system upgrades
Housing and component rebuilds
General labor and maintenance
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Scheduled and emergency repair and maintenance
Fig. 13. Wind Generator Bearing Changeout
Fig. 14. Wind Turbine Main Shaft Repair
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Pre end-of-warranty wind turbine inspections to detect and address:
Imbalance
Misalignment
Mechanical looseness
Shaft bends
Lubrication condition
Abnormal slip ring wear
Bearing condition
Generator faults
Winding issues
Natural frequency and resonance
Offshore Turbine Maintenance
Offshore wind power or offshore wind energy is the use of wind farms
constructed in bodies of water, usually in the ocean on the continental shelf, to
harvest wind energy to generate electricity. Higher wind speeds are available
offshore compared to on land, so offshore wind power’s electricity generation
is higher per amount of capacity installed.
Turbines are much less accessible when offshore (requiring the use of a
service vessel or helicopter for routine access, and a jackup rig for heavy
service such as gearbox replacement), and thus reliability is more important
than for an onshore turbine. Some wind farms located far from possible
onshore bases have service teams living on site in offshore accommodation
units.
A maintenance organization performs maintenance and repairs of the
components, spending almost all its resources on the turbines. The
conventional way of inspecting the blades is for workers to rappel down the
blade, taking a day per turbine. Some farms inspect the blades of three
turbines per day by photographing them from the monopile through a 600mm
lens, avoiding to go up. Others use camera drones.
Because of their remote nature, prognosis and health-monitoring systems on
offshore wind turbines will become much more necessary. They would enable
better planning just-in-time maintenance, thereby reducing the operations
and maintenance costs. According to a report from a coalition of researchers
from universities, industry, and government (supported by the Atkinson
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Center for a Sustainable Future), making field data from these turbines
available would be invaluable in validating complex analysis codes used for
turbine design. Reducing this barrier would contribute to the education of
engineers specializing in wind energy.
Fig. 15. Offshore Wind Turbine
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9. SELECTION OF WIND POWER COMPARED TO OTHER ENERGY
SOURCE
a) Wind energy does not produce any toxin, greenhouse gases, waste or by
product.
b) The fire risk at wind farm is very low. The flammable part are located
high above the ground, away from the vegetation and high voltage
connections are underground. They are equipped with comprehensive
lighting production system that transfers voltage and currents safely to
the ground.
c) Wind farm have minimal local environmental impacts. The land can still
be used for other purpose like farming and grazing, this is because
livestock appears an affected by presence of wind farm
d) Wind power is the good method of supplying electricity to remote areas
e) Wind power uses less water in cooling.
f) Wind power blows day and night; hence the wind allows the wind mill
to produce electricity throughout the day.
g) Wind power does not require any fuel.
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REFERENCES
NES Global Talent. https://www.nesgt.com/blog/2016/07/offshore-and-onshore-wind-farms
Katabatic power. https://websites.pmc.ucsc.edu/~jnoble/wind/extrap/
Royal Meteorological. https://www.rmets.org/weather-and-climate/observing/beaufort-scale
The weather Prediction. https://www.theweatherprediction.com/habyhints3/749/
David Darling. http://www.daviddarling.info/encyclopedia/H/AE_horizontal-
axis_wind_turbine.html
Azo CleanTech. https://www.azocleantech.com/article.aspx?ArticleID=191