ADIABATIC DEMAGNETISATION REFRIGERATOR
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12-01-2011, 02:26 PM
ADIABATIC DEMAGNETISATION REFRIGERATOR.pptx (Size: 355.81 KB / Downloads: 129)
Magnetic refrigeration is a physical process that exploits the magnetic properties of certain solid materials to produce refrigeration.
Magnetic refrigeration is a cooling technology based on the magneto caloric effect. This technique can be used to attain extremely low temperatures (well below 1 Kelvin), as well as the ranges used in common refrigerators, depending on the design of the system.
Principle of Magnetic refrigeration :
Magneto calorific effect is the basic principle on which the cooling is achieved.
All magnets bears a property called Currie effect i.e. If a temperature of magnet is increased from lower to higher range at certain temperature magnet looses the magnetic field.
The Adiabatic Demagnetization Refrigerator:Temperature and Entropy Cycle
Operating Cycle 1: Brief Description
Temperature Entropy Graph
entropy of FAA at low magnetic field
entropy of FAA at high magnetic field
path of an ADR salt pill over this diagram as the ADR runs through its cycle
Ideal ADR Cycle
Steps of thermodynamic cycle -
Isomagnetic enthalpic transfer
Isomagnetic entropic transfer
Work is now underway at the Cryogenics Branch to choose the proper materials and designs for the advanced ADR.
Proper materials for the salt pills of the simple ADR's that combine to make up the advanced ADR.
Most suitable type of magnetic shielding.
Workable magnet design for use at the 6 to 8 Kelvin cold end temperature of a suitable mechanical cooler.
Advantages of Magnetic Refrigeration
MG do not use hazardous or environmentally damaging chemicals
Purchase cost may be high, but running costs are 20% less than the conventional chillers
Ozone depleting refrigerants are avoided in this system, hence it more eco-friendly