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Magnetic Refrigeration – an Energy Efficient Technology for the Future
Bahl, Christian Robert Haffenden; Smith, Anders; Pryds, Nini; Linderoth, Søren
Published in:Energy solutions for CO2 emission peak and subsequent decline
Publication date:2009
Link back to DTU Orbit
Citation (APA):Bahl, C. R. H., Smith, A., Pryds, N., & Linderoth, S. (2009). Magnetic Refrigeration – an Energy EfficientTechnology for the Future. In Energy solutions for CO2 emission peak and subsequent decline: Proceedings(pp. 107-115). Danmarks Tekniske Universitet, Risø Nationallaboratoriet for Bæredygtig Energi. Denmark.Forskningscenter Risoe. Risoe-R No. 1712(EN)
E Effi i t T h l f th F t an Energy Efficient Technology for the Future
Ch i i B hlChristian Bahl
Fuel Cells and Solid State Chemistry Division Fuel Cells and Solid State Chemistry Division Risø National Laboratory for Sustainable Energy
Technical University of [email protected]
Refrigeration g
Why magnetic refrigeration ?y g gCompressor refrigerationRefrigeration
%High energy consumptionGreenhouse gasses
15 %
Ozone layer depleting
R f i t Gl b l W i O D l ti Refrigerant Global Warming Potential, CO2 = 1
Ozone Depletion Potential
R‐11 (Freon) 4800 1Electricity
consumptionR22 1800 0,05
R134a 1400 0
R
consumption
R410a 1700 0
Source: IPCC, www.epa.gov
The magnetocaloric effectgDiscovered in 1881 by Emil Warburg Emil Warburg.
Ann. Phys. (Leipzig) 13, 141 (1881)
N S
T = T0
N S
T = T0
N ST = T0+ΔT T T0T T0 0
The magnetocaloric effectg
atio
nStrongest at the Curie temperature T
NS
NS
agne
tisa
TCtemperature TC.
G i h h h f
Temperature
MaGrows with the strength of
the magnetic field.p
calo
ric
ect
ocal
oric
ec
t
Mag
neto
effe
TCMag
neto
effe
Temperature
M
Magnetic field
M
Refrigeration cycleg yssor
tion
mpres
frigerat
Compression ExpansionCo
Ref
Rejectheat
Absorbheat
Refrigeration cycleg yssor
tion
mpres
frigerat
Compression ExpansionCo
Ref
M i i D i iic
ion
Rejectheat
Absorbheat
Magnetisation Demagnetisation
Mag
neti
rigerati
Mrefr
Active Magnetic Regenerationg g
erat
ure
Tem
p
The material is magnetisedgN
S
erat
ure
Tem
p
The pistons are movedpN
S
erat
ure
Tem
p
Heat rejectionjN
S
erat
ure
Tem
p
Magnetic field removedg
erat
ure
Tem
p
Pistons moved back
erat
ure
Tem
p
Heat absorbtion
erat
ure
Tem
p
Back to start
erat
ure
Tem
p
Magnetocaloric materialsgGadolinium is the benchmark material with TC = 20 °C.
LCSM is a magnetic ceramic La0.67Ca0.33‐xSrxMnO3
where TC can be controlled.It is easy to process.
c ef
fect
It does not corrode.It is cheap ! et
ocal
oric
Mag
ne
Temperature
Optimising the Curie temp.p g p
erat
ure
Tem
pe
Temperature
Processing the LCSMgTape casting into thin sheetsL l d iLarge scale productionGraded tapes possible
Extrusion of ceramicsMonolithic block – no assembly required.
0.8mm
0.4mm
MagnetsgElectromagnets use large amounts of poweramounts of power.
Th The strongest permanent magnet known is Nd2Fe14B.
Nd is expensive so the magnet b ll blmust be as small as possible –
but give as strong a field as iblpossible.
Magnet designg g
Halbach cylinder
Magnetic Refrigeration Deviceg gNow we are ready to build a machine ...
World status ofWorld status ofmagnetic refrigeration devicesg g
World status ofWorld status ofmagnetic refrigeration devicesJapanese deviceg g
ng p
ower 500 W
Temperature spanC
oolin
7.5 °CTemperature span
World status ofCanadian deviceWorld status ofmagnetic refrigeration devicesw
erg g
oolin
g po
w
50 W
Temperature span
Co 29 °C
Test device at Risø DTUøVersatile and simple to use.E k hEasy to make changes.
Numerical model
Heat and mass transfer is l l t d i h llcalculated in each cell.
Energy and mass i i dconservation is ensured.
ChallengesgPromising technology…
Hi h ffi iHigh efficiency.No CFC or HCFC gasses.C d iCompact and quiet.
But …Expensive materials – optimise design.Sensitive to design – versatile test machine and model.Competitive market.
er
Future ing
pow
e
100 W
Commercially relevant prototype i b d d
Temperature span
Coo
l
40 °C
remains to be demonstrated.Risø DTU is planning a prototype for the end of 2010.
p p
15 people working on a three‐way approach:Magnetocaloric materialsNumerical modellingTest machine
Magnetic Heat Pumps are also an attractive possibility.
AcknowledgmentsContributions from all the colleagues in the Magnetic Refrigeration group at Risø DTURefrigeration group at Risø DTU.
Part of this work is supported by the Programme Commission on Energy and Environment (EnMi) Commission on Energy and Environment (EnMi) (Contract No. 2104‐06‐0032) which is part of the Danish Council for Strategic Research.g
Our industrial collaborators, Danfoss A/S, Sintex A/S and Vacuumschmeltze GmbHand Vacuumschmeltze GmbH.