Magnetic refrigeration system SEMINAR PPT.pptx 2.pdf

Seminar ppt on magnetic refrigeration. A novel technique to carry out the process of refrigeration. It can be used for lower load applications. Economic than conventional vcrs system. COP if the System is far better than household system. It can be used widely than vapour absorption System.

1. GUIDED BY

DEEPU RJ
SUBMITTED BY
ADHEELA S
ROLL NO - 46
MAGNETIC REFRIGERATION
TECHNOLOGY

2. CONTENT
v Introduction
v Objective
v Magneto Caloric Effect
v Thermodynamic Cycle
v Comparison
v Construction
v Requirements For Pratical Applications
v Benefits
v Future Applicatios
v Advantages
v Disadvantages
vConclusion

3. INTRODUCTION
•Magnetic refrigeration is a cooling technology based on the magneto caloriki. This technique
can be used to attain extremely low temperatures (well below 1 Kelvin), as well as the
ranges used in common refrigerators, depending on the design of the system.
•It is a physical process that exploits the magnetic properties of certain solid materials to
produce refrigeration.
•The refrigerant is often a paramagnetic salt, such as cerium magnesium nitrate.
•It gives cooling nearest to absolute zero than any other method hence it made liquidification
of gases easier.
•At the same time it does not emit any CFC or HCFC compounds hence it never affects our
environment specially OZONE layer.

4. OBJECTIVE
•To develop more efficient and cost-effective small-scale H, liquefiers as an
alternative to vapour-compression cycles using Magnetic refrigeration
(adiabatic magnetization)
•To understand the Principle and mechanism for generating cooling effect
using the magnet.

5. Magneto Caloric Effect
•MCE is a magneto-thermodynamic phenomenon in which a reversible
change in temperature of a suitable material is caused by exposing the
material to changing magnetic field.
•All magnets bears a property called Currie effect i.e. If a temperature of
magnet is increased from lower to higher range at certain temperature
magnet looses the magnetic field.
•Currie temperature Depends on individual property of each material.
•As Energy input to the magnet is increased the orientation of the magnetic
dipoles in a magnet starts loosing orientation. And vice a versa at curie
temperature as magnet looses energy to the media it regains the property.

6. WORKING PRINCIPLE

7. THERMODYNAMIC CYCLE

8. •Process is similar to gas compression and
expansion cycle as used in regular
refrigeration cycle
•Steps of thermodynamic Cycle :-
•Adiabatic Magnetization
•Isomagnetic Enthalpy Transfer
•Adiabatic demagnetization
•Isomagnetic Entropic Transfer

9. ADIABATIC MAGNETIZATION
•Substance placed in insulated environment
•Magnetic field +H increased
•This causes the magnetic dipoles of the atoms to align
•The net result is that total Entropy of the item is not reduced and item heats
up (T+ ΔΤ)

10. ISOMAGNETIC ENTHALPY TRANSFER
•Added heat removed by a fluid like water or helium (-Q)
•Magnetic Field held constant to prevent the dipoles from reabsorbing the
heat.
•After a sufficient cooling Magnetocalric material and coolant are
separated(H=0)

11. ADIABATIC DEMAGNETIZATION
•Substance returned to another adiabatic(insulated) condition
•Entropy remains constant
•Magnetic field is decreased
•Thermal Energy causes the Magnetic moments to overcome the field and sample
cools(adiabatic temperature change)
•Energy transfers from thermal entropy to magnetic entropy(disorder of the magnetic dipoles)

12. ISOMAGNETIC ENTROPIC TRANSFER
•Material is placed in thermal contact with the Environment being refrigerated
•Magnetic field is placed in thermal contact with the environment being
refrigerated
•Magnetic field held constant to prevent material from heating back up
•Because the working material is cooler than the refrigerated environment,
heat energy migrates into the working material(+Q)
•Once the refrigerant and refrigerated environment are in thermal equilibrium,
the cycle continuous.

13. COMPARISON

14. CONSTRUCTION
•Components required for
construction:-
•Magnets
•Hot Heat exchanger
•Cold Heat Exchanger
•Drive
•Magneto caloric wheel

15. •Magnets: Magnets provide the magnetic field to the material so tha they can loose or gain
the heat to the surrounding and from the space be cooled respectively.
•Hot Heat Exchanger: The hot heat exchanger absorbs the heat from the material used
and gives off to the surrounding. It makes the transfer of heat much effective ferry magnets
•Cold Heat Exchanger: The cold heat exchanger absorbs the heat from the space to be
cooled and gives it to the magnetic material. It helps to make the absorption of heat effective.
•Drive: Drive provides the right rotation to the Magneto caloric wheel. Due to this heat flows
in the right desired direction.
•Magneto caloric Wheel: It forms the structure of the whole device. It joins both the two
magnets to work properly.

16. REQUIREMENT FOR PRACTICAL APPLICATIONS
•Magnetic Materials
•Regenerators
•Super Conducting Magnets
•Active Magnetic Regenerators

17. WORKING MATERIALS
•MCE is an intrinsic property of a magnetic
solid
•Ease of application and removal of
magnetic effect is most desired property of
material
•Alloys of gadolinium produce 3 to 4 K per
tesla of change in magnetic field are used
for magnetic refrigeration or power
generation purposes.
•ferrimagnets, antiferromagnets and spin
glass systems are not suitable for this
application.

18. REGENERATORS
•Magnetic refrigeration requires excellent heat transfer to and from the solid magnetic
material. Efficient heat transfer requires the large surface areas offered by porous
materials. When these porous solids are used in refrigerators, they are referred to
as "Regenerators"
•Typical regenerator geometries include:
•Tubes
•Perforated plates
•Wire screens
•Particle beds

19. SUPER CONDUCTING MAGNETS
•Most practical magnetic refrigerators
are based on superconducting
magnets operating at cryogenic
temperatures (i.e., at -269 C or 4 K)
•These devices are electromagnets
that conduct electricity with essentially
no resistive losses.
•The superconducting wire most
commonly used is made of a Niobium-
Titanium alloy

20. AMR
•A regenerator that undergoes cyclic heat transfer operations and the magneto caloric effect
is called an Active Magnetic Regenerator.
•An AMR should be designed to possess the following attributes:-
•High heat transfer rate
•High magneto caloric effect
•Sufficient structural integrity
•Low thermal conduction in the direction of fluid flow
•Affordable materials
•Ease of manufacture

21. BENEFITS
•TECHNICAL
•High Efficiency
•Reduced Operating Cost
•Compactness
•Reliability
•SOCIO-ECONOMIC
•Competition in Global Market
•Low Capital Cost
•Key Factor to new technologies

22. FUTURE APPLICATION
•At the present stage of the development of magnetic refrigerators with permanent magnets,
hardly any freezing applications are feasible
•Some of the future applications are:-
v Magnetic household refrigeration appliances
vMagnetic cooling and air conditioning in buildings and houses
vCentral cooling system
vRefrigeration in medicine.
vCooling in food industry and storage
vCooling in transportation
vCooling of electronic equipments

23. ADVANTAGES
•Purchase cost may be high, but running costs are 20% less than the conventional
chillers.
•Thus life cycle cost is much less.
•Ozone depleting refrigerants are avoided in this system, hence it more eco-friendly.
•Energy conservation and reducing the energy costs are added advantages.
•The efficiency of magnetic refrigeration is 60% to 70% as compared to Carnot cycle.
•Magnetic refrigeration is totally maintenance free & mechanically simple in
construction.

24. DISADVANTAGES
•As every coin has 2 sides, this technique also posses some drawbacks
to be worked on
•The initial investment is more as compared with conventional
refrigeration.
•The magneto caloric materials are rare earth materials hence their
availability also adds up an disadvantage in MAGNETIC
REFRIGERATION.

25. CONCLUSION
•It is a technology that has proven to be environmentally safe. Computer
models have shown 25% efficiency improvement over vapor compression
Systems.
•In order to make the magnetic refrigerator commercially Viable, scientists
need to know how to achieve larger temperature swings and also permanent
magnets which can produce strong magnetic fields of order 10 tesla.
•There are still some thermal and magnetic hysteresis problems to be Solved
for the materials that exhibit the MCE to become really useful Two
advantages to using magnetic refrigeration over vapor compressed systems
are no hazardous chemicals used and they can be up to 60% efficient.

26. 1.http://en.wikipedia.org/wiki/Magnetic_refrigeration
2.http://www.scribd.com/doc/19537314/Magnetic-Refrigeration
3.Lounasmaa, experimental principles and methods, academic press
4.Richardson and Smith, experimental techniques in condensed matter
physics at low temperature, Addison Wesley (2003)
5.A text book on cryogenic engineering by V.J.Johnson
6.“Refrigeration and Air conditioning” by Arora and Domkundwar
7.Magnetic Refrigeration, ASHRAE Journal (2007), by John Dieckmann,
8.Kurt Roth and James Brodrick

27. THANK YOU