- 1. SEMINARON MAGNETICREFRIGERATION PRESENTEDBY
GANESHPRALHADBHARAMBE UNDERTHEABLEGUIDANCEOF PROF.A. M. PATIL.
DEPARTMENTOFMECHANICALENGINEERING,
PADMABHUSHANVASANTRAODADAPATILINSTITUTEOFTECHNOLOGY,
BUDHAGAON,DIST.SANGLI.MAHARASHTRA.
2. ACKNOWLEDGEMENT
- THE AUTHOR OF THIS SEMINAR IS THANKFUL TO PROF. A.M. PATIL AND
PROF. DANGEFROM MECHANICAL DEPARTMENT FOR GIVING VALUABLE GUIDANCE
FOR PREPARING THIS SEMINAR. THEIRINSPIRATIONS HAVE SUCCEEDED IN
GIVING A FULL FORM AND SHAPE OF THIS SUBJECT IN DEPTH.
3. CONTENTS > Basicprinciplesofmagneticrefrigeration
>Thermodynamic cycle > Materials: Working
materials,Development in materials and Nano compositswhich can play
important role inupgradin the efficiency of
materials>Commercialaspects >Historicalbackground 4.
MAGETICREFRIGERATION
- To understand the principle and mechanism for generating
- cooling effect using the magnet.
- Practicalcases ofequipment building
5. Introduction:Principle
- Magetocalorificeffectis the basicprincipleon which the
coolingis achieved.
- All magnetsbears a property calledCurrieeffecti.e.If a
temperatureofmagnetisincreasedfrom lower to higher range
atcertaintemperature magnetlooses the magnetic field.
- Currietemperature.Depends on individualproperty of each
material.
- As Energyinput to the magnetis increased the orientation of the
magetic dipoles in a maget starts loosing orientation.And vice a
versaat currie temperature as maget looses energy to the media it
regains the property.
6. Thermo dynamiccycle 7. DETAILSOF THE THERMODYNAMICCYCLE
- PROCESSISSIMILARTOGASCOMPRESSIONAND EXPANSIONCYCLEASUSEDIN
REGULARREFRIGERATIONCYCLE.
- Stepsofthermodynamiccycle -
- Isomagneticenthalpictransfer
- Isomagneticentropictransfer
8. Adiabaticmagnetization
- Procedureto be followed :
- > Substance placed in insulated environment.
- > Magnetic field +Hincreased.
- > Magneticdipoles of atoms to align, thereby
- > TotalEntropy of the item is not reduced, and item heats
up
9. Isomagneticenthalpictransfer
- >Addedheatremovedbyfluid, gas gaseous or
- > Magneticfieldheldconstant to prevent the dipoles
- fromreabsorbing the heat.
- > Aftera sufficientcoolingmagnetocaloricmaterial
10. AdiabaticDemagnetization
- >Substancereturned to another adiabatic( insulated )
condition
- >Magneticfieldis decreased,
- >Thermal energy causes the magnetic moments to overcome the
field and sample cools ( adiabatic temperature change )
- >Energy transfers from thermal entropy to magnetic entropy (
disorder of the magnetic dipoles )
11. Isomagneticentropictransfer
- > Materialisplacedin thermal contact with the environment
being refrigerated.
- > Magneticfieldheldconstant to prevent from heating back
up
- > Because the working material is cooler than the
refrigerated environment, heat energy migrates into the working
material ( +Q )
- ***** Once the refrigerent and refrigerated environment are in
thermal equillibrium, the cycle begins a new
12. Advantages of Magnetic Refrigeration
- > Purchase cost may be high, but running costs are 20%less
than the conventional chillers
- > Thus life cycle cost is much less.
- > Ozone depleting refrigerants are avoided in this
system,hence it more eco-friendly.
- > Energy saving would lessen the strain on our household
appliances
- > Energy conservation and reducing the energy costs are
added advantages.
13. WorkingMaterials
- > Magneto caloric effect is an intrinsic porperty of
magnetic solid.
- > Ease of application and removal of magnetic effectis most
desired propery of material.It is individualcharacteristicsand
strongly depends on :
- Degree of freedom for magnetic dipoles during ordering and
randomization of particals.
- >ferrimagnets, antiferromagnets and spin glass sytems are
not suitable forthis application
- Alloysofgadolinium producing 3 to 4 K per tesla of change in
magnetic field are used for magnetic refrigeration or power
generation purposes.
14. Development in WorkingMaterials
- >Recent research on materials exhibit a giant entropy change
showed.Alloys of gadolinium are promising materials as below as
compared to existing stocks.
- Gd 5 (Si xGe 1 x) 4,La(FexSi1 x)13Hx
- >These are some of the most promising substitutefor
Gadolinium.
- Such materials are called as magnetocaloric effect
materials
15. Development in WorkingMaterials
- Magneticrefrigerationworks in the vicinity of a materials Curie
temperature
- The range of operation is =+/- 20
- In 1950sMRCoperated near by 1 to 30 K, in 1976 this range had
expanded to 80 C around the Curie temperature.
- 1997 lead this activity to built commecial and industrial
use.
- Using the Ericcsons cycle system refrigerator was built and
used for 1500 hrs continuously.
- Gd alloys, most notablyGd alloy, most notably Gd5(Si2Ge2), due
to simultaneous magnetic and crystallographic first order
transition, the adiabatic temperature rise was 30%higher than that
of Just Gd and 200 600 % thanprevious refrigerent materials.
16. Development in WorkingMaterials
- MaterialDy0.5Er0.5)Al2 has paramagnetic to ferromagnetic
transition at 40 k where the large peak occur.
- Similar is Gd5(Si0.33Ge3.67) shows enormous peak
- It is possible to predict weight to mass ratio of components
which produce maximum constant magnetic entropy.This technique
allows one to find a suitable material composition which has a
constant slope on MCE vs temperature plot.It should have good
magnetocaloric effect and could withstand the process of
cooling.
- Gadolinium silicon germanium ternary system ( Gd-Si-Ge ),with
stoichiometry of Gd5(SixGe1-x)4
- Transition temperatures of the alloys formed by Gd, Tb, Dy, Ho,
Er, Tm and Lu shows transitions with transitions above 180 k.
17. Development in WorkingMaterials
- 10 Amorphous materialsshows high resistivity and improved
corrosion resistance which aids the process of magnetic
refrigeration.
- Amorphous alloys may be able to fill up the gaps between100 to
200k
- Gd0.54Er0.46)NiAlhas 11 top effects, is currently being
implemented in Erriccson cycle refrigerators.
18. NUCLEARDEMAGNETIZATION
- This type is one of the variant that continues to find
substantial research application.
- It follows the same principle,but in this case the cooling
powerarises from the magnetic dipoles of the nuclei of refrigent
atoms rather than their electronic configuration.
- Since these dipoles ar of much smaller magnitude, they are less
prone to self alignment and have lower intrinsic minimum
field.
- This allows NDR to cool the nuclear spin system to very low
temperatures, often 1 micro kelvin.
- Magnetic fieldsof 3 telsa or greator are often needed for the
intialmgneizationstep ofNDR
19. NANO MATERIALS FOR REFRIGERATION
- Newresearchshows that nanocomposites from metallic glasses
- could make promising magnetic refrigeration materials,
- >These materialsare as good as the best currenly available
magnetic refrigerantswith added adavantages.
- >Thisleads to environmental friendlyand more efficient than
the existing devices that rely on a vapour cycle.
- Energy effiiciency reaches upto 60 % .This saves 40%
energy.
- Working temperatures and operating range can be tailored by
tuning the composition and manipulating the microstructure.
- Properties are similar to crystallized and amorphous materials
due to unique microstructure
20. NUCLEARDEMAGNETIZATION
- This type is one of the variant that continues to find
substantial research application.
- It follows the same principle,but in this case the cooling
powerarises from the magnetic dipoles of the nuclei of refrigent
atoms rather than their electronic configuration.
- Since these dipoles ar of much smaller magnitude, they are less
prone to self alignment and have lower intrinsic minimum
field.
- This allows NDR to cool the nuclear spin system to very low
temperatures, often 1 micro kelvin.
- Magnetic fieldsof 3 telsa or greator are often needed for the
intialmgneizationstep ofNDR
21. NUCLEARDEMAGNETIZATION
- Nano composite made of gadolinium nanocrystallites embedded in
a gadolinium-aluminium-manganese (Gd60Al10Mn30) metallic glass
matrix.
- These materials exhibits unique properties of hysteric and hard
magnetic behaviour, which reduces the efficiency of cooling
process.
- Structural changes in these materials promote crack nucleation
and propogation that can cause severe damage to the refrigerant
material during cycling.Disadvantage of material.
22. PromotingenergyefficeincyThanking you