MAGNETO HYDRO DYNAMICS (MHD)  power generation

1. MAGNETO HYDRO
DYNAMICS (MHD)
pOwER GENERATION

2. CONTENTS
1. What is MHD ?
2. Need of MHDs
3. Principle Of MHD Power Generation
4. Types of MHD SYSTEM
5. Open Cycle MHD System
6. Closed Cycle MHD System
7. Advantages OF MHD System
8. Disadvantages of MHD System
9. Applications

3. INTRODUCTION
 HEEE WITHOUT A CONVENTIONAL GENERATOR
 DIRECT CONVERSION FOR LARGE POWER GENERATION
 ENERGY IS GENERATED DUE TO THE MOVEMENT OF
CONDUCTING FLUID INSIDE A MAGNETIC FIELD
 η > 50%

4. NEED OF MHDS
At present a plenty of energy is needed to sustain
industrial and agricultural production, and the
existing conventional energy sources like coal, oil,
uranium etc are not adequate to meet the ever
increasing energy demands. Consequently, efforts
have been made for harnessing energy from several
non-conventional energy sources like Magneto
Hydro Dynamics(MHD) System.

5. HISTORY
• In 1932, Michael Faraday, demonstrated the
experiments that there is an electromagnetic
induction in a current carrying conductor moving
the earth magnetic field.
• In 1938, U.S scientist Bela Karlovitz is the first one
developed the Magneto hydrodynamic generator.
• In India, the MHD generator program is undergoing
in Thiruchirappalli in collaboration with Bharat
heavy electrical limited (BHEL).

6. PRINCIPLE OF MHD POWER
GENERATION
1.Faraday’s law of electromagnetic induction : When an
electric conductor moves across a magnetic field, an emf is
induced in it, which produces an electric current .

7. 2.Lorentz Force
Charged particle experience a
force when is moving in the
electromagnetic field. This
force can be explained as
F = q.(v × B)
where,
• v = velocity of the particle
(vector)
• q= charge of the particle
(scalar)
• B = magnetic field (vector)

8. Principle, construction and working of
Magneto hydrodynamic generator (MHD)
Principle
The principle of Magneto hydrodynamic generator is
based on Lorentz law and faraday's law.
 In this system, the hot ionized gaseous conductor
(working fluid) is passed into the high magnetic field
and thereby the current is produced. By placing
suitable electrodes (Anode and cathode) inside the
chamber, the output load is taken through the
external circuit.

10. CONSTRUCTION
S
N
combustion
Chamber
VIonized Gas
Working
fluid
Water cooler
Thermal resistance
sealing
Magnet
Stream
out
Load
output
Nozzle
Electrode
Inlet

11. WORKING
• The gaseous (fluid) conductor is passed into the combustion
chamber through inlet.
• By using a fuel like oil (or) natural gas (or) coal, the fluid
conductor is heated to a plasma state and hence it is ionized.
• The temperature in the combustion chamber is around 2000°K
to 2400°K.
• The heat generated in the combustion chamber removes the
outermost electrons in the fluid conductor.
• Therefore, the gas particle acquires the charge

12. • The charged gas particles with high velocity enters into the
generator chamber via nozzle.
• The positive and negative charge moves to corresponding
electrodes (anode and Cathode) and constitute the current.
• In generator chamber, based principles of Faraday’s law, the
high velocity ionized conducting gas particles experience the
magnetic filed at right angles to their motion of direction and hence
the potential (current) is produced.
• The direction of current (Potential) is perpendicular to both
the direction of moving gas particle and to the magnetic
field.

13. • The electrodes are connected to an external circuit to get a
load output.
• The current produced in the MHD generator are direct current
(DC)
• This DC current can be converted into alternative current (AC)
using an inverter attached with the external circuit.
• In MHD generator, the seeding materials such as potassium and
cesium are used to reduce the ionization temperature.
• These seeds are mixed with fuel material such as natural gas and
coal.
• The electrode are made generally using high temperature ceramic
materials such as carbides (SiC, ZrC, MbC), bromides (ZrB2, TiB2,
LaB2) and silicates (WS and MOSi2 ).

14. TYPES OF
MHD SYSTEMS
(1) Open cycle System
(2) Closed cycle System
(i)Seeded inert gas systems
(ii) Liquid metal systems

15. OPEN CYCLE MHD SYSTEM

16. CLOSED CYCLE MHD SYSTEM

17. DIFFERENCE BETWEEN OPEN CYCLE
AND CLOSED CYCLE SYSTEM
Open Cycle System
Working fluid after
generating electrical
energy is discharged to the
atmosphere through a
stack .
Operation of MHD generator
is done directly on
combustion products .
Temperature requirement :
2300˚C to 2700˚C.
More developed.
Closed Cycle System
Working fluid is recycled to
the heat sources and thus is
used again.
Helium or argon(with
cesium seeding) is used as
the working fluid.
Temperature requirement :
about 530˚C.
Less developed.

18. ADVANTAGES
Conversion efficiency of about 50% .
Less fuel consumption.
Large amount of pollution free power generated .
Ability to reach full power level as soon as started.
Plant size is considerably smaller than conventional fossil
fuel plants .
Less overall operational cost.
No moving parts, so more reliable .
 Suitable for peak power generation and emergency service

19. DISADVANTAGES
 Suffers from reverse flow (short circuits) of electrons through
the conducting fluids around the ends of the magnetic field.
 Needs very large magnets and this is a major expense.
 High friction and heat transfer losses.
 High operating temperature.
 Coal used as fuel poses problem of molten ash which may
short circuit the electrodes. Hence, oil or natural gas are
much better fuels for MHDs. Restriction on use of fuel
makes the operation more expensive.

20. APPLICATIONS
Power generation in space craft.
Hypersonic wind tunnel experiments.
 Defence applications.