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Lecture 4: WHY MAGNETIC REFRIGERATION (MR)?, Name: SYAZA AMIRA BT…
Lecture 4:
WHY MAGNETIC REFRIGERATION (MR)?
Definition:
MR is an emerging technology based on the Magneto Caloric Effect (MCE).
WHY :!?:
TRADITIONAL : Vapor Compression Refrigeration (VCR)
:!: High Cost: Compressor and pressure operator.
:!: Refrigerant: Causing toxic and flammable.
MCE Principle
A heating and cooling of magneto caloric material when it is magnetized and demagnetized - Pressure has no influence.
Entropy:
1) Magnetic entropy 2)Thermal entropy
Theory of Magneto Caloric Effect
Using concept:
Refrigeration Cycle
1) Adiabatic Magnetization
2) Isomagnetic Cooling
3) Adiabatic Demagnetization
4) Isomagnetic Heating
Adiabatic Magnetization.
:pencil2: High Magnetic field (H)
:pencil2: Temperature (T) of materials increases.
Adiabatic
Demagnetization.
:pencil2: Low Magnetic field (H)
:pencil2: Temperature (T) of materials decreases.
Necessary part of MR
1) Magneto Caloric Material
2) Magnet
3) Cold Heat Exchange
4) Hot Heat Exchange
5) Heat Transfer Fluid
6) Motor
7) Pump
8) Valves
9) Power supply
Magneto Caloric Materials
Properties
:check: High MCE
:check: Low specific heat
:check: High thermal conductivity
:check: Non-toxic
:check: Resistance to corrosion
:check: High electrical resistance
:check: Low manufacturing cost
:check: Low environment impact
Example of material for Magnetic
Gadolinium and some alloys
Advantages
:<3: No compressor
:<3: No refrigerant
:<3: Low pressure operation
:<3: Low cost
:<3: Safety cooling
:<3: Achieving very low temperature
:<3: Highly reversible
Disadvantage
:warning: Initial cost of refrigerator is high due to Gadolinium
Limitations
:pen: Still in research
Applications
:star: Cryogenic engine :star: Air-condition
Name: SYAZA AMIRA BT ZULKEPLEE
Matric No.: A17SC0243
Magneto Caloric Effect MCE:
Due to varying magnetic entropy of magnetic material in varying magnetic field.
