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 SEMINAR ON

 MAGNETIC REFRIGRATIONATTRACTIVE ALTERNATIVE COOLING TECHNOLOGY 

BY :

RAMAKANTH P JOSHI

1JS06ME034

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OUTLINE 

Magnetocaloric effect

Principle

Prototype : Ames lab & astronaut corp

America

Advantages of magnetic refrigeration

Technology comparison

Future scope

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MAGNETS

Ferromagnetic materials ² alloy of Al, Ni,Fe,Co

Paramagnetic materials ² Cr,Mn, Pt, Pd, K, Cu.

Diamagnetic materials ² Zn, Bismuth, antimony. 

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W AYS TO COOL

Expansion and compression of  gas <30% Fridge, Bicycle pump

Evaporation of  liquids very robust plants, animals, weather

Peltier effects  not very efficient Radiators

Magnetic refrigeration ~60% Proof  of principle apparatus ( Cooling with the help of  external magnetic field)

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INTRODUCTION

PRINCIPLE : Magnetocaloric effect due

to variable field

Currie temperature

(768°C for Fe)

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DEMONSTRATION OF MCE

In a small physics experiment the magneto calorific effect in a gadolinium 

sample is demonstrated. Magnetization heats the sample up and

demagnetization cools it down 

B

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  THERMO DYNAMIC CYCLE   THERMO DYNAMIC CYCLE 

Steps of thermodynamic cycle

Adiabatic magnetization

Isomagnetic enthalpic transfer 

Adiabatic demagnetization

Isomagnetic entropic transfer 

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GRAPHICAL REPRESENTATION

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REGENERATORS

(a) Tubes ± Cu or Ag

( b) Perforated plates ± stainless steel

(c) Wire screens - Cu

(d) Particle beds ± ceramic or metal sphere

AIM : To achieve good thermal conductivity

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DESIRED PROPERTIES OF WORKING

MATERIALS

Large magneto calorific effect

Significant MCE at reasonable fields  Curie temperature

Environment friendly materials

Affordable, abundant and easily synthesizable materials

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WORKING MATERIALS

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COMPARISONCOMPARISON

Analogy between magnetic refrigeration and vapor cycle refrigeration 

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 TECHNOLOGY COMPARISON

COMPRESSION MAGNETIC

Environmental 

impact

Liquid based

(CFC)

Environmentally

safe

Cooling 

efficiency

<40% 60%

durability ~20 years ~50 years

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 ADV ANTAGES OF MAGNETIC

REFRIGERATION

Green technology

Noise-less technology

Very high thermodynamic efficiency Low energy consumption

Simple design and building 

Long  life Low pressure

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IDEAL APPLICATIONS

1) House hold refrigerators appliances

2) Central cooling  systems

3) Room air conditioners

4) Supermarket refrigeration ( display cabinets)

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FUTURE SCOPE 

Less mass of  magnet by 3-d field concentration

Higher volume fractions of porous structures

Higher frequencies of  rotation

Application of  hybrid materials

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CONCLUSION

MCE : dH implies dS

Magnetic refrigeration can be cycled

Magnetic refrigeration demonstrated to be 

1. most efficient

2. very compact

3. eco friendly

4. Trouble free

Prominent MCE materials for room temperature : Rare earth metals.

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BIBLIOGRAPHY 

BASIC AND APPLIED THERMOD YNAMICS by Dr. P K Nag  2/e TMH publication

www.wikipedia.com

www.freepatentsonline.com

www.globlespec.com

Research paper: magnetic refrigeration by JEFF JOHNSON

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