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MAGNETIC REFRIGERATION

MAGNETIC REFRIGERATION. INTRODUCTION. Magnetic refrigeration is a cooling technology based on the magneto caloric effect . Invented by Emil Warburg in 1880 Used to attain cryogenic temperatures well below 1 o K with the help of magnetic fields. PRINCIPLE OF MAGNETIC REFRIGERATION.

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MAGNETIC REFRIGERATION

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  1. MAGNETIC REFRIGERATION

  2. INTRODUCTION • Magnetic refrigeration is a cooling technology based on the magneto caloric effect. • Invented by Emil Warburg in 1880 • Used to attain cryogenic temperatures well below 1o K with the help of magnetic fields

  3. PRINCIPLE OF MAGNETIC REFRIGERATION • Magneto caloric effect is the basic principle on which the cooling is achieved. • Magneto caloric effect 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 called adiabatic demagnetisation .

  4. THERMODYNAMIC CYCLE

  5. STEPS OF THERMODYNAMIC CYCLE • Adiabatic magnetisation • Isomagneticenthalpic transfer • Adiabatic demagnetization • Isomagnetic entropic transfer

  6. REQUIREMENTS FOR PRACTICAL APPLICATIONS • Magnetic Materials • Regenerators • Super Conducting Magnets • Active Magnetic Regenerators(AMR’s)

  7. MAGNETIC MATERIALS • Magnetocaloric effect is an intrinsic property of a substance • Gadolinium and its alloys are the best materials available for magnetic refrigeration • They can reach ultra low temperatures

  8. REGENERATORS • Efficient heat transfer requires large surface areas offered by porous materials • When these porous materials are used in refrigerators they are referred to as regenerators

  9. SUPER CONDUCTING MAGNETS • The magnetic field is created by superconducting magnets • Most practical magnetic refrigerators are based on super conducting magnets operating at cryogenic temperatures • Commonly used is made of a Niobium-Titanium alloy

  10. ACTIVE MAGNETIC REGENERATORS • A regenerator that undergoes cyclic heat transfer operations and magneto caloric effect is called Active Magnetic Regenerator • It should be designed to possess: high heat transfer rate high magneto calorific effect affordable materials ease of manufacture

  11. APPLICATIONS • Liquefaction purposes in the case of hydrogen,nitrogen and helium • Also focuses on many future applications like magnetic household refrigeration,cooling in transportation,cooling electronic circuits etc.

  12. MERITS • High efficiency • Reduced operating cost • Reliability

  13. CONCLUSIONS • Magnetic refrigeration is a technology that has proven to be environmentally safe • 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

  14. THANK YOU

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