Magnetic Refrigeration
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#1
20-09-2008, 11:07 PM


It is not often that scientific discoveries hold the promise of saving consumer?s money while protecting the environment and reducing the use of fossil fuels. Define the perfect fuel and it would most lightly be one that burns cleanly, poses no harm to the environment and, above all, is renewable or in limitless supply.

The researchers in the U.S Department of Energy?s Ames Laboratory under a construct with the Astronautics Corporation of America have developed a refrigerator with out a standard gas-compression cooling system. Magnetic refrigeration is based on the ?Magnetocaloric effect?. This effect, discovered in 1881, is defined as the response of a solid to an applied magnetic field which is apparent as a change in its temperature. This effect is obeyed by all transition metals and lanthanide-series elements. When a magnetic field is applied, these metals, known as ferromagnets, tend to heat up. As heat is applied, the magnetic moments align. When the field is removed, the ferromagnet cools down as the magnetic moments become randomly oriented. .
Use Search at http://topicideas.net/search.php wisely To Get Information About Project Topic and Seminar ideas with report/source code along pdf and ppt presenaion
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shalini.50
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22-07-2010, 09:16 PM

please send me that ppt
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muthyala ravi
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#3
15-03-2011, 03:00 PM

good afternoon,
iam the student of mechanical branch .i need a ppt,and complete info about magnetic refrigeration for the technical seminor .please forward it to my emai (chinna.mechanical311@gmail.com).pleaseeeeeeee.
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seminar project explorer
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15-03-2011, 08:57 PM

Hi,
visit this thread for the full report of magnetic refrigeration:
topicideashow-to-magnetic-refrigeration-full-report?pid=40536#pid40536
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ashok.suram
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31-01-2012, 09:14 AM

total seminor on magnetic refregiration
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seminar paper
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06-04-2012, 03:21 PM

Magnetic Refrigeration



.ppt   seminar.ppt (Size: 1.06 MB / Downloads: 136)

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



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tsagar
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#7
10-04-2012, 01:54 PM

please send me the detailed seminar and presentation report on
magnetic refrigeration please
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10-07-2012, 02:49 PM

Magnetic Refrigeration


.pdf   Magnetic Refrigeration.pdf (Size: 1.1 MB / Downloads: 83)


Magnetocaloric effect


hemagnetocaloriceffect(MCE)resultsfromthecouplingofasystemofmagneticmoments(andthecrystallinelattice)withanexternalmagneticfield,andresultsinthecoolingorheatingofthesystem.

APPLICATIONS:

•Refrigeration1
•Air conditioning
•Thermal sensing
•Localized cooling (small scale)



Magnetic cooling prototypes


Small in size

Increase in a cooling capacity by a factor of 1.5

Decrease in a driving power by a factor of 1/3 than previous
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#9
11-07-2012, 10:20 AM

to get information about the topic "magnetic refrigeration" full report ppt and related topic refer the link bellow

topicideashow-to-magnetic-refrigeration-full-report

topicideashow-to-magnetic-refrigeration
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03-08-2012, 11:00 AM

to get information about the topic "magnetic refrigeration" full report ppt and related topic refer the link bellow

topicideashow-to-magnetic-refrigeration-full-report

topicideashow-to-magnetic-refrigeration
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sukriti singh
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#11
05-08-2012, 01:55 PM

Hello,
I am the student of third year mechanical, i want to give the seminar and presentation on magnetic refrigeration. So i request you to give me the complete information on this topic with some power point presentation.
thank you

Rupali Thete
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#12
04-07-2013, 03:57 PM

MAGNETIC REFRIGERATION


.doc   MAGNETIC REFRIGERATION.doc (Size: 89.5 KB / Downloads: 17)

ABSTRACT:

Refrigeration is a phenomenon in which the heat transfer from it to the external environment ,cooling the content to a temperature below the ambient temperature.
In recent times many inventions are made and one of the new generation refrigeration is magnetic refrigeration.

INTRODUCTION:

Magnetic refrigeration is a cooling technology based on the magnetocaloric 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. The fundamental principle was suggested by Debye (1926) and Giauque (1927) and the first working magnetic refrigerators were constructed by several groups beginning in 1933. Magnetic refrigeration was the first method developed for cooling below about 0.3 kelvins

The magnetocaloric effect:

The Magnetocaloric 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 also known as adiabatic demagnetization by low temperature physicists, due to the application of the process specifically to effect a temperature drop. In that part of the overall refrigeration process, a decrease in the strength of an externally applied magnetic field allows the magnetic domains of a chosen material to become disoriented from the magnetic field by the agitating action of the thermal energy present in the material. If the material is isolated so that no energy is allowed to migrate into the material during this time the temperature drops as the domains absorb the thermal energy to perform their reorientation. The randomization of the domains occurs in a similar fashion to the randomization at the curie temperature, except that magnetic dipoles overcome a decreasing external magnetic field while energy remains constant, instead of magnetic domains being disrupted from internal ferromagnetism as energy is added.

Example of magnetocaloric effect:

One of the most notable examples of the magnetocaloric effect is in the chemical element gadolinium and some of its alloys. Gadolinium's temperature is observed to increase when it enters certain magnetic fields. When it leaves the magnetic field, the temperature returns to normal. The effect is considerably stronger for the gadolinium alloy Gd5(Si2Ge2). Praseodymium alloyed with nickel (PrNi5) has such a strong magnetocaloric effect that it has allowed scientists to approach within one thousandth of a degree of absolute zero.

Thermodynamic cycle:

The cycle is performed as a refrigeration cycle, analogous to the Carnot cycle, and can be described at a starting point whereby the chosen working substance is introduced into a magnetic field(i.e. the magnetic flux density is increased). The working material is the refrigerant, and starts in thermal equilibrium with the refrigerated environment.

Applied technique:

1. The basic operating principle of an Adiabatic Demagnetization Refrigerator (ADR) is the use of a strong magnetic field to control the entropy of a sample of material, often called the "refrigerant".
2. Magnetic field constrains the orientation of magnetic dipoles in the refrigerant. The stronger the magnetic field, the more aligned the dipoles are, and this corresponds to lower entropy and heat capacity because the material has lost some of its internal degrees of freedom. If the refrigerant is kept at a constant temperature through thermal contact with a heat sink while the magnetic field is switched on, the refrigerant must lose some energy because it is equilibrated with the heat sink.
3. When the magnetic field is subsequently switched off, the heat capacity of the refrigerant rises again because the degrees of freedom associated with orientation of the dipoles are once again liberated, pulling their share of equipartitioned energy from the motion of the molecules, thereby lowering the overall temperature of a system with decreased energy.
4. Since the system is now insulated when the magnetic field is switched off, the process is adiabatic, i.e. the system can no longer exchange energy with its surroundings, and its temperature decreases below its initial value, that of the heat sink.

General procedure:

1. A strong magnetic field is applied to the refrigerant, forcing its various magnetic dipoles to align and putting these degrees of freedom of the refrigerant into a state of lowered entropy.
2. The heat sink then absorbs the heat released by the refrigerant due to its loss of entropy.
3. Thermal contact with the heat sink is then broken so that the system is insulated, and the magnetic field is switched off, increasing the heat capacity of the refrigerant, thus decreasing its temperature below the temperature of the He heat sink.
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