Magnetic refrigeration is a technology that has proven to be environmentally safe. Computer models have shown 25% efficiency improvement over vapor compression systems.

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BY
P. Phani Krishna
16R21A03E1

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Principle of Magnetic Refrigeration
 Magneto calorific effect is the basic principle on which the
cooling(Magnetic refrigeration) is achieved.
 The Magneto caloric effect (MCE, from magnet and calorie) is a
magneto-thermodynamic phenomenon in which a reversible
change in temperature of a suitable material is caused by exposing
the material to a changing magnetic field
 This is also known as adiabatic demagnetization by low
temperature physicists, due to the application of the process
specifically to affect a temperature drop.

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Comparison between Magnetic Refrigeration and Vapor
Compression Refrigeration

4. Thermo dynamic cycle
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Working Process

5. Working Process in Magnetic Refrigeration
1. Adiabatic Magnetization
 The substance is placed in an insulated environment and magnetic field is a
pplied. The increasing external magnetic field (+H) causes the magnetic dip
oles of the atoms to
align.
 As a result material’s magnetic entropy and heat capacity decreases. The ne
t result is that the item heats up
(T + ΔTad).
2. Isomagnetic Enthalpic Transfer
 This added heat can then be removed by a fluid like water or helium
 The magnetic field is held constant to prevent the dipoles from reabsorbing
the heat
 Once sufficiently cooled, the magneto caloric material and the coolant are
separated (H=0).
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6. 3. Adiabatic Demagnetization
 The substance is returned to another adiabatic(insulated) condition so that tot
al entropy remains constant.
 The applied magnetic field is decreased, the thermal energy causes the do
mains to overcome the field, and thus the sample cools.
 Energy (and entropy) transfers from thermal entropy to magnetic entropy (dis
order of the magnetic dipoles).
4. Isomagnetic Entropic Transfer
 The magnetic field is held constant to prevent the material from heating up b
ack
 The material is placed in thermal contact with the environment being refriger
ated
 Because the working material is cooler than the
refrigerated environment heat energy migrates into the working material (+Q)
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Future Applications
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
Magnetic household refrigeration appliances
Magnetic cooling and air conditioning in buildings and houses
Central cooling system
Refrigeration in medicine
Cooling in food industry and storage
Cooling in transportation
Cooling of electronic equipment's

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CONCLUSION
 Magnetic refrigeration 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

9. Thank you
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