Magneto Hydrodynamic Generator and Wave energy

7/30/2019 Magneto Hydrodynamic Generator and Wave energy

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Magneto HydrodynamicGenerator and Wave

energy

Presented by

ABDUL JALEELROLL NO :9


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Magneto Hydrodynamic

Generator


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Contents

Introduction

Principle

Various System

Advantage


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Introduction

Eighty percentage of total electricityproduced in the world is hydal , while theremaining 20%

is produced from nuclear, thermal, solar,

geothermal energy and from Magnetohydrodynamic (MHD) Generator MHD Power generation is a new system of

electric power generation which is said tobe of high efficiency and low pollution. Inadvanced countries MHD generators arewidely used but in developing countries likeindia it is still under construction .Thisconstruction work is in progress in trichy attamilnadu under joint effort of BARC,BHEand ACC and Russian technologists


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As its name implies MHD isconcerned with flow of conductingfluid in the presence of magnetic

and electric field. The fluid may begas at elevated temperature or liquid

An MHD generator is a device for

converting heat energy of fueldirectly into electrical energywithout conventional electric

generator


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In this system an MHD convertersystem is a heat engine , in whichheat taken up at higher temperature

is partially converted to useful workand the remainder is rejected at atemperature like all heat engine

Thermal efficiency of MHD can beincreased by by supplying heat athighest practical temperature andrejecting it at lowest practical

temperature


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PRINCIPLES OF MHDGENERATOR

When an electric conductor is movedacross a magnetic field ,a voltage isproduced in it which produces anelectric current.

This is the principle ofconventionalgenerator wheretheconductor consistof copper strips

In MHD generator , the solid conductorsare replaced by an ionized gas . If sucha gas is passed at a high velocitythrough a powerful magnetic field, acurrent is generated and can be

extracted by placing electrodes in


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The principle can be explained asfollows, an electric conductor movingthrough magnetic field experience a

retarding force as well as an inducedelectric field and current


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this effect is a result of Faradayslaw of electromagnetic induction

The induced emf is given by

E=U x BThe induced current is given by

J= Electric conductivity x E

The retarding force on the conductoris Lorentz force is given by

F= J x B


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When a fluid is used for energyconversion it is calledMAGNETOHYDRODYNAMIC energy

conversion

If the flow direction is right angles tothe magnetic field an electromotive

force or electric voltage is induced inthe direction at right angles to bothflow and field directions


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An ionized gas is used as conductingfluid.

The ionization is produced by

thermal means ie by elevatedtemperature or by seeding with asubstance like ceisium or pottasiamvapours which ionize at relativelylower temperature

The atoms of seed element split offelectrons.

The presence of negatively charged


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MHD system can be broadly classified

1)Open cycle system

-Flue gas is released to theatmosphere

2)Closed cycle system

- Working fluid is circulated in thesystem


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Open Cycle System and ClosedCycle System

Fuel used may be oil or gasified coal The fuel is burned in the combustor or

combustion chamber The hot gases from combustor is then

seeded with a small amount of an ionizedalkali metal (ceisium or pottasium) toincrease electrical conductivity of gas

The seed material, generally pottassium

carbonate is injected into combustionchamber , the pottassium is then ionized bythe hot combustion gases at a temperatureof (2300-2700 oC)

The hot gases coming out of the combustor

is at high temperature and high pressure


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The working fluid is accelerated toalmost supersonic speeds indivergent portion of the duct.

The magnetic field coils are placed insuch a way that magnetic field is indirection perpendicular to the field

In Closed Cycle System working fluidis circulated again


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Advantages

The conversion efficiency of a MHDsystem can be around 50%.

Large amount of power is generated.

It has no moving parts, so morereliable

The closed cycle system producespower free of pollution.

It has the ability to reach the fullpower level as soon as started.


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Continue..

The size of plant (m2/kw) isconsiderably smaller thanconventional fossil plants.

Although the cost cannot bepredicted accurately, yet it has beenreported that capital cost of MHDplant s will be competitive with thoseof conventional steam plant.

It has been estimated that overalloperational cost in MHD plant would

be about 20% less than conventional


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Continue..

Direct conversion of heat intoelectricity permits to eliminate thegas turbine ( compared with gas

turbine power plant) or both boilerand turbine (compared with steampower plant) . This elimination

reduces loss of energy.


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Wave Energy


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Introduction

Waves are created by gravitationalaction of sun and the moon andinteraction of wind with surface of

the sea

It is a renewable energy source

Wave energy can be extracted andconverted into electrical energy bywave power machines. They can bedeployed either on the shoreline or

deeper water offshore


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Introduction

Wave energy fluxes against coastsmay vary from a few watts tokilowatts per meter. In favourablelocations, wave energy density canaverage 65 megawatts per mile ofcoastline.

The total power of waves breaking onthe worlds coastline is estimated toabout 2 to 3 million megawatts.


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Introduction

Wave motion consist of both verticaland horizontal movement of water.

They are smallest in summer andgreatest in winter


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APPROACHESTO CAPTURE

WAVE ENERGY


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1.Float or pitching device

The device floats on or just below thesurface of water.

A wave power machine needs to resistthe motion of the waves to generatepower: part of the machine needs tomove while another part remains still

In this type of device, the wave motionwill move only one part of the machine.

Electricity is generates from thepitching action of the floating objectwhich can be mounted to a floating raftor to a device fixed on the ocean floor


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2.Oscillating water column(OWC)

An oscillating water column ispartially submerged, hollow structurethat is installed in the ocean.

It is open to the sea below the waterline , enclosing a column of air aboveon top of column of water.

Waves cause the water column toraise and fall, which in turncompresses and depresses the aircolumn.


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Oscillating water column..

This trapped air is allowed to flow toand from the atmosphere via turbinewhich has the ability to rotate in the

same direction regardless of thedirection of the airflow . The rotationof the turbine is used to generate

electricity.


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3.Hinged contour device

Here the resistance to the waves iscreated by alternate motion of thewaves, which raises and lowers

different sections of machine relativeto each other pushing hydraulic fluidthrough hydraulic pumps to generate

. A hinged contour device is able to

operate at greater depth than float

device


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Continue..

These shoreline devices rely on shoremounted structure to channel andconcentrate the waves , driving them

to an elevated reservoir . Water flowout of this reservoir is used togenerate electricity, using standard

hydropower technology.


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ADVANTAGES AND

DISADVANTAGES


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Advantages

It produces no green house gases orother waste

It need no fuel

It produces electricity reliably

It is free and renewable energy

sources These devices are relatively pollution

free


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Disadvantages

The energy is available in ocean.Therefore extraction equipment mustoperate in a marine environment

which will have to be taken intoaccount during its construction ,lifetime and reliability should be

considered since energy may have tobe transported through greatdistance


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Continue

Wave energy conversion devices thathave been proposed are relativelycomplex.

Economic factors such as capitalinvestment, cost of maintenance,repair and replacement as well as

problems of biological growth ofmarine organisms which seem to bevery large are all relatively unknown.


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Continue.

Wave energy converters must becapable of withstanding very severepeak stresses in storm.


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Thank You

Documents

Magneto Hydrodynamic Generator and Wave energy