MAGNETIC REFRIGERATION - PowerPoint Presentation

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MAGNETIC REFRIGERATION

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Presented By,

Ananthu

Sivan

Feby

Philip Abraham

S4, Dept. of Mechanical Engineering,

Mohandas College of Engineering & Technology,

Anad

, TrivandrumSlide2

INTRODUCTIONWHAT IS MAGNETIC REFRIGERATION??

MAGNETOCALORIC EFFECTHOW DOES AN ADR WORK??MAGNETIC REFRIGERATION CYCLECONSTRUCTIONAL COMPONENTS

WORKING MATERIALS

GMCE MATERIALSALTERNATIVE TECHNIQUESCOMMERCIAL DEVELOPMENTCONCLUSION

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CONTENTSSlide3

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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INTRODUCTIONSlide4

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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What is Magnetic Refrigeration??Slide5

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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Magneto-caloric EffectSlide6

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

Adiabatic magnetization

Isomagnetic

enthalpic transfer

Adiabatic demagnetization

Isomagnetic

entropic transfer

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How Does an ADR Work?? Slide8

Working material is placed in an insulated environment

Increasing magnetic field is applied

Magnetic dipoles of the atoms of the material align

Decreases material’s magnetic entropy and heat capacity

Total entropy of the material remains conserved (Laws of Thermodynamics)

Results in heating up of the material (

T+ΔT

ad

)

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Adiabatic MagnetizationSlide9

Heat generated in the previous process is removed by a fluid (He or H

2O)

Magnetic field is held constant

After being sufficiently cooled, the magnetocaloric

material and coolant are separated

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Isomagnetic

Enthalpic

TransferSlide10

The substance is brought to another insulated environment

Magnetic field is decreased

Magnetic entropy increases, thermal entropy decreases

Material cools down

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Adiabatic DemagnetizationSlide11

Magnetic field is held constant

Environment to be cooled is brought in contact with the

magnetocaloric

materialHeat transfers from space to be cooled to the magnetocaloric

material

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Isomagnetic

Entropic TransferSlide12

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Magnetic Refrigeration CycleSlide13

Magnets

Hot Heat ExchangerCold Heat ExchangerDrive

Magnetocaloric

Wheel

13Constructional ComponentsSlide14

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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MagnetsSlide15

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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Hot Heat ExchangerSlide16

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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Cold Heat ExchangerSlide17

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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DriveSlide18

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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Magnetocaloric

WheelSlide19

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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Working MaterialsSlide22

Giant Magnetocaloric

Effect MaterialsExhibits GIANT change in entropyMost promising material with respect to magnetic refrigeration, at room temperature

Examples - Gd

5(SixGe1−x)4

La(FexSi1−x

)

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H

x

MnFeP

1−x

As

x

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GMCE MaterialsSlide23

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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Alternative TechniquesSlide24

Pros :

Viable in various industries and research facilities

Environmentally friendly, as it doesn’t require any polluting gases

Comparatively lower power consumption, research shows them to be 50% more efficient than conventional cooling systems

In commercial refrigeration a key cost is maintenance caused by leakage of refrigerant. By eliminating gases this maintenance cost will be removed.

In domestic refrigeration low noise is valuable; elimination of gas compression reduces noise.

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Commercial DevelopmentSlide25

Cons:

Various technical difficulties remain at large

Availability of good working material is a concern

Superconducting magnets are required to produce sufficient field

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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ConclusionSlide27

http://en.wikipedia.org/wiki/Magnetic_refrigeration

http://cryo.gsfc.nasa.gov/ADR/ADR_primer/ADR_primer.htmlhttp://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-compoundshttp:/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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ReferencesSlide28

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Thank You