Magnetic Refrigeration down
to 1.6K for FCC_ee
Jakub Tkaczuk
Supported by:
DRF Energy Program – DESA41K
CERN FCC Collaboration
Contents
• Magnetic refrigeration
• State of the Art
• Active Magnetic Regenerative Refrigerator
• Static Magnetic Refrigerator
o Heat exchange conditions
o Heat losses
o Possible improvements
• Perspectives
Contents
• Magnetic refrigeration
• State of the Art
• Active Magnetic Regenerative Refrigerator
• Static Magnetic Refrigerator
o Heat exchange conditions
o Heat losses
o Possible improvements
• Perspectives
Magnetic refrigeration
Magnetic refrigeration is based on the Magneto-Caloric Effect (MCE) (reversible
variation of internal energy when applied magnetic field in a suitable material)
𝜕𝑇
𝑀𝐶𝐸 =
𝜕𝐵
Remove magnetic field
spins randomize
temperature decreases
𝑆
Apply magnetic field
spins align
temperature increases
Magnetic refrigeration
Ideal Carnot cycle
2 adiabatic transformations
2 isothermal transformations
Contents
• Magnetic refrigeration
• State of the Art
• Active Magnetic Regenerative Refrigerator
• Static Magnetic Refrigerator
o Heat exchange conditions
o Heat losses
o Possible improvements
• Perspectives
State of the Art
Hitachi rotating
design
CEA
design
CERN
design
Hitachi
static design
MIT
design
State of the Art
Cold source
Temperature
1.8K
1.8K
1.8K
1.8K
1.8K
Warm source
temperature
4.2K
4.2K
4.2K
4.5K
4.2K
Useful power
1.35 W
1.8 W
0.5 W
10 W
12 mW
1 W/kg
0.1 W/kg
?
0.12
Q / m_GGG
η
10.6 W/kg 1.7 W/kg 0.7 W/kg
0.53
0.34
0.13
See presentation: FCC Week 2015
Contents
• Magnetic refrigeration
• State of the Art
• Active Magnetic Regenerative Refrigerator
• Static Magnetic Refrigerator
o Heat exchange conditions
o Heat losses
o Possible improvements
• Perspectives
Active Magnetic Regenerative Refrigerator
ADR
Adiabatic Demagnetization Refrigerator
AMRR
Active Magnetic Regenerative Refrigerator
Large DT possible
But :
• More material
• More exchanged
power
Every part of magneto-caloric
material goes through its own cycle
Active Magnetic Regenerative Refrigerator
Outputs for AMRR:
Inputs for one GGG core:
Active Magnetic Regenerative Refrigerator
Contents
• Magnetic refrigeration
• State of the Art
• Active Magnetic Regenerative Refrigerator
• Static Magnetic Refrigerator
o Heat exchange conditions
o Heat losses
o Possible improvements
• Perspectives
Static Magnetic Refrigerator
Contents
• Magnetic refrigeration
• State of the Art
• Active Magnetic Regenerative Refrigerator
• Static Magnetic Refrigerator
o Heat exchange conditions
o Heat losses
o Possible improvements
• Perspectives
Static Magnetic Refrigerator – Heat exchange conditions
Warm source
Kutateladze correlation:
Nucleate boiling – far from
film boiling transition
Static Magnetic Refrigerator – Heat exchange conditions
Cold source
Condensation is limited by Kapitza resistance
For small temperature differences:
For larger temperature differences:
Static Magnetic Refrigerator – Heat exchange conditions
No heat losses taken into account yet
L
5 cm
D
5 cm
Contents
• Magnetic refrigeration
• State of the Art
• Active Magnetic Regenerative Refrigerator
• Static Magnetic Refrigerator
o Heat exchange conditions
o Heat losses
o Possible improvements
• Perspectives
Static Magnetic Refrigerator – Heat losses
Energy balance with Kapitza resistance
Largest heat losses: GGG – warm source
So large heat loss is not possible
Conclusion:
GGG temperature is not homogeneous,
it is significantly influenced by the heat
exchange with the warm source.
Static Magnetic Refrigerator – Heat losses
Diffusion inside GGG:
Largest heat losses: GGG – warm source
Static Magnetic Refrigerator – Heat losses
Other heat losses
negligible
Scaling the SMR:
670 kg of GGG is needed to obtain 1kW.
GGG dimensions: D = 50 cm, L = 50 cm
Contents
• Magnetic refrigeration
• State of the Art
• Active Magnetic Regenerative Refrigerator
• Static Magnetic Refrigerator
o Heat exchange conditions
o Heat losses
o Possible improvements
• Perspectives
Static Magnetic Refrigerator – Possible improvements
Gas heat switch
50 µm
“off ” conduction is satisfying
“on” conduction is not satisfying –
2-5 µm heat switch required –
technically impossible
Contents
• Magnetic refrigeration
• State of the Art
• Active Magnetic Regenerative Refrigerator
• Static Magnetic Refrigerator
o Heat exchange conditions
o Heat losses
o Possible improvements
• Perspectives
Perspectives
Short term
Study of heat switch solution on the warm source interface
Experimental, cryogenic validation of selected heat switch
Mid-term
design of a 0.3 W magnetic refrigerator for laboratory demonstration
Long term
design of kW range refrigerator for FCC
Thank you