06-04-2012, 03:21 PM
Magnetic Refrigeration
seminar.ppt (Size: 1.06 MB / Downloads: 160)
History
The effect was discovered in pure iron in 1881 by german physicist Emil. Warburg.
Major advances first appeared in the late 1920s when cooling via adiabatic demagnetization was independently proposed by two scientists: Debye (1926) and Giauque (1927).
The process was demonstrated a few years later when Giauque and MacDougall in 1933 used it to reach a temperature of 0.25 K.
Between 1933 and 1997, a number of advances in utilization of the MCE for cooling occurred.
Magnetic Refrigeration Cycle
The steps of a magnetic refrigeration process are analogous vapour compression refrigeration cycle.
one can see from the figure shown that instead of compression of a gas, a magnetocaloric material is moved into a magnetic field and that instead of expansion it is moved out of the field.
The main difference in both cycles is that the heat injection and rejection in a gaseous refrigerant is a rather fast process, because turbulent motion transports heat very fast. But this is not the case in the solid magnetocaloric materials.
Adiabatic Magnetization
The substance is placed in an insulated
environment. The increasing external magnetic
field causes the magnetic dipoles of the atoms to
align, thereby decreasing the material's magnetic
entropy and heat capacity. Due to this
temperature of magnetocaloric material increases
is increased
Magnets
Magnets are the main functioning element
Of the magnetic refrigeration. Magnets
provide the magnetic field to the material so
that they can loose or gain the heat to the
surrounding and from the space to be
cooled respectively.
Hot Heat Exchanger
The hot heat exchanger absorbs the heat
from the material used and gives off to the
surrounding. It makes the transfer of heat
much effective.
Conclusion
Magnetic refrigeration is undoubtedly a
promising technology that should be
encouraged because of its numerous
advantages, in particular energy saving and
environmental benefits
seminar.ppt (Size: 1.06 MB / Downloads: 160)
History
The effect was discovered in pure iron in 1881 by german physicist Emil. Warburg.
Major advances first appeared in the late 1920s when cooling via adiabatic demagnetization was independently proposed by two scientists: Debye (1926) and Giauque (1927).
The process was demonstrated a few years later when Giauque and MacDougall in 1933 used it to reach a temperature of 0.25 K.
Between 1933 and 1997, a number of advances in utilization of the MCE for cooling occurred.
Magnetic Refrigeration Cycle
The steps of a magnetic refrigeration process are analogous vapour compression refrigeration cycle.
one can see from the figure shown that instead of compression of a gas, a magnetocaloric material is moved into a magnetic field and that instead of expansion it is moved out of the field.
The main difference in both cycles is that the heat injection and rejection in a gaseous refrigerant is a rather fast process, because turbulent motion transports heat very fast. But this is not the case in the solid magnetocaloric materials.
Adiabatic Magnetization
The substance is placed in an insulated
environment. The increasing external magnetic
field causes the magnetic dipoles of the atoms to
align, thereby decreasing the material's magnetic
entropy and heat capacity. Due to this
temperature of magnetocaloric material increases
is increased
Magnets
Magnets are the main functioning element
Of the magnetic refrigeration. Magnets
provide the magnetic field to the material so
that they can loose or gain the heat to the
surrounding and from the space to be
cooled respectively.
Hot Heat Exchanger
The hot heat exchanger absorbs the heat
from the material used and gives off to the
surrounding. It makes the transfer of heat
much effective.
Conclusion
Magnetic refrigeration is undoubtedly a
promising technology that should be
encouraged because of its numerous
advantages, in particular energy saving and
environmental benefits