Transcript Document 7443868

Presented By,
Ananthu Sivan
Feby Philip Abraham
S4, Dept. of Mechanical Engineering,
Mohandas College of Engineering & Technology, Anad, Trivandrum
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 INTRODUCTION
 WHAT IS MAGNETIC REFRIGERATION??
 MAGNETOCALORIC EFFECT
 HOW DOES AN ADR WORK??
 MAGNETIC REFRIGERATION CYCLE
 CONSTRUCTIONAL COMPONENTS
 WORKING MATERIALS
 GMCE MATERIALS
 ALTERNATIVE TECHNIQUES
 COMMERCIAL DEVELOPMENT
 CONCLUSION
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 Refrigeration is the process of removing heat from an
enclosed space or from a substance and moving it to a
place where it is unobjectionable
 The primary objective of refrigeration is lowering the
temperature of the enclosed space or substance and
then maintaining that lower temperature.
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 Magnetic refrigeration is a cooling technology based
on the magneto caloric effect.
 It is used to attain temperature well below 1 Kelvin.
 Magnetic refrigeration currently finds application in
cryogenics.
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 Some magnetic materials heat up when they are
placed in a magnetic field and cool down when they
are removed from a magnetic field. This is known as
the magnetocaloric effect.
 The effect was discovered in pure iron in 1880 by
German physicist Emil Warburg
 In 1997, the first near room temperature proof of
concept magnetic refrigerator was demonstrated by
Prof. Karl A. Gschneidner
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Illustration of the
Magnetocaloric
effect
Gadolinium alloy
heats up inside the
magnetic field and
loses thermal energy
by irradiation, so
that it exits the field
cooler than when it
entered.
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Magnetic Refrigeration Cycle
1.
Adiabatic magnetization
2.
Isomagnetic enthalpic transfer
3.
Adiabatic demagnetization
4.
Isomagnetic entropic transfer
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1.
Working material is placed in an insulated environment
2.
Increasing magnetic field is applied
3.
Magnetic dipoles of the atoms of the material align
4.
Decreases material’s magnetic entropy and heat capacity
5.
Total entropy of the material remains conserved (Laws of
Thermodynamics)
6.
Results in heating up of the material (T+ΔTad)
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1.
Heat generated in the previous process is removed by
a fluid (He or H2O)
2.
Magnetic field is held constant
3.
After being sufficiently cooled, the magnetocaloric
material and coolant are separated
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1.
The substance is brought to another insulated
environment
2.
Magnetic field is decreased
3.
Magnetic entropy increases, thermal entropy
decreases
4.
Material cools down
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1.
Magnetic field is held constant
2.
Environment to be cooled is brought in contact with
the magnetocaloric material
3.
Heat transfers from space to be cooled to the
magnetocaloric material
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 Magnets
 Hot Heat Exchanger
 Cold Heat Exchanger
 Drive
 Magnetocaloric Wheel
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Magnets provide the magnetic field to the material so
that they can lose or gain the heat to the surrounding
and from the space to be cooled respectively
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The hot heat exchanger absorbs the heat from the
material used and gives off to the surrounding. It
increases the efficiency of heat transfer
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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
efficient.
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Drive provides the right rotation to the Magneto
caloric wheel. Due to this, heat flow in the desired
direction is achieved.
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It forms the base structure of the whole device. It is the
fundamental element in the whole system. It joins the
two magnets and ensures proper operability.
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An artist’s rendition of a Rotary Magnetic Refrigerator
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Proposed
representation of a
commercial system
This is the picture of
a proposed
commercial
magnetic
refrigeration system
which is being
developed by
Camfridge and
Whirlpool. It is
planned to be
launched in the UK
in the year 2012.
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 Magneto caloric effect is characteristic of the material
 The ability of a material to produce a change in its
temperature per Tesla of change in magnetic field, is
the deciding factor.
 Alloys of gadolinium can be used for magnetic
refrigeration.
 Paramagnetic Salts like Cerium Magnesium Nitrate
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 Giant Magnetocaloric Effect Materials
 Exhibits GIANT change in entropy
 Most promising material with respect to magnetic
refrigeration, at room temperature
 Examples -
Gd5(SixGe1−x)4
La(FexSi1−x)13Hx
MnFeP1−xAsx
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 Nuclear Demagnetization Refrigeration
 Working Principle remains the same
 Cooling power arises from the magnetic dipoles of the nuclei of the
refrigerant atoms, rather than their electron configurations.
 They have much smaller magnetic dipoles
 Less prone to self alignment
 Lower intrinsic minimum fields
 Temperatures of up to 1 µK or less, achievable
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 Pros :
1. Viable in various industries and research facilities
2. Environmentally friendly, as it doesn’t require any polluting gases
3. Comparatively lower power consumption, research shows them to be
50% more efficient than conventional cooling systems
4. In commercial refrigeration a key cost is maintenance caused by
leakage of refrigerant. By eliminating gases this maintenance cost
will be removed.
5. In domestic refrigeration low noise is valuable; elimination of gas
compression reduces noise.
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 Cons:
1. Various technical difficulties remain at large
2. Availability of good working material is a concern
3. Superconducting magnets are required to produce
sufficient field
4.Magnetic hysteresis losses are considerable for
certain materials
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Gschneidner stated in 1999 that:
“Large-scale applications using magnetic refrigeration,
such as commercial air conditioning and supermarket
refrigeration systems, could be available within 5–10
years. Within 10–15 years, the technology could be
available in home refrigerators and air conditioners.”
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 http://en.wikipedia.org/wiki/Magnetic_refrigeration
 http://cryo.gsfc.nasa.gov/ADR/ADR_primer/ADR_primer.html
 http://imagine.gsfc.nasa.gov/docs/teachers/lessons/xray_spectra/background-
adr.html
 http://www.physlink.com/Education/AskExperts/ae488.cfm
 http://www.ameslab.gov/content/magnetocaloric-effect-magnetic-
refrigeration-and-ductile-intermetallic-compounds
 http:/newenergyandfuel/com/2009/05/25/progress-update-on-magnetic-
refrigeration/magnetic-refrigeration-process-graph/
 http://www.camfridge.com/Pages/story.html
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