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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 Denmarkchrb@risoe.dtu.dk

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.