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Commercial Design and Performance Test of Large-sized HTS
Magnets with Conduction Cooling System for MW-class HTS DC
Induction Furnace
supercoil
supercoil
2016. 09.13 (Tue.), 14:45 ~ 15:00, in CCA 2016
Presenter : Jongho Choi
Super coil in Korea
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/26 2 Contents
I. Introduction of the HTS DC induction furnace
II. Design specification of the HTS magnets and the 300 kW HTS DC IF
III. Fabrication process of the HTS magnets with the conduction cooling system
IV. Current flowing test results of the HTS magnets
V. Conclusions
Super coil
/26 Conventional Furnaces in industries
Aluminum extrusion plant
located in Gyeongnam
Forging company located in
Gyeongnam
These are available for the preheating process of the metal billets, in order to producing parts for
the airplanes, automobiles, and electric power machineries.
Gas furnace for busbar
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Comparison with several induction heating methods
Atmosphere furnace AC induction furnace HTS DC induction furnace
Loss Conductive, convective, radiative loss Joule’s heat at copper wire No loss!! (HTS resistance is zero)
Machine Efficiency 20~30% 50~60% (High copper loss) Over 90%
Additional device Special chamber to minimize heat
loss
Inductor and capacitor bank and
water-cooling system for copper coil Cryo-cooling system needed
Product quality Bad! (Required enough heating time) Bad! (System frequency: 50~60 Hz) Good! (Operated with low speed)
Why we need to develop the HTS DC induction furnace
Normal conductor
Superconductor
Tc 0 K
Resi
stance
Temperature
HTS wire has 100 times of the
current density than a copper wire.
Superconductor’s characteristic
curve depended on a temperature
The system efficiency is possible to reach over 90%.
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Experimental view
Thermal graphical image
Real-time monitoring system
Trial performance
You tube link: Operation of a 10 kW HTS DC induction heating machine
We are convinced about the commercialization possibility through this results.
Results of the 10 kW-class HTS DC induction heater developed 5
Super coil
/26 Design process for 300 kW HTS DC IF
Target : 300kW class HTS DC induction
furnace • Metal billet type : Aluminum Billet
• Average temperature : 540 (°C)
• Temperature deviation : below ±5 (°C))
• Magnetic flux density at the center of the billet : 1 (T)
Determination of the size • Decide radius (mm), length (mm), weight (kg)
Determine the specification of the magnet to
generate the uniform magnetic field • Maximum magnetic field
• Type of HTS wire
• Shape of HTS magnet
• Considering the perpendicular magnetic flux density
Determine the resistive heating and operating
range for heating with FEM tool • Rotating speed (rpm)
• Mechanical torque (N·m)
Design completion of an 300 kW-class HTS DC
induction furnace
No. 1 No. 2 D180mm billet D380mm billet
Candidate 2
1.1 T, 3.4 km, 1 ea
Several candidates
Considering metal billet sizes
We finally adapted the candidate 2, because of the highest magnetic field we could get.
6
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/26 Development of the electromagnetic FEM analysis model
Design of the magnet
system
Cryostat
GM-cryocooler
with 2nd stages
Iron core
FEM results of a 300 kW HTS DC IF We developed the electromagnetic FEM model
of 300kW-class HTS DC IF.
We designed the HTS magnet with the
magnetic flux density of 1.1 T at the center of
the billet.
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Heat invasion loads
813 K
Conduction
Convection
Radiation
Conduction
①Metal current
leads
②Supporters
(300K1st stage)
③Supporters
(1st stage2nd
stage)
④HTS current leads
Convection
①From metal billet
Radiation
①Metal billet
Outer cryostat
②Outer cryostat
Inner radiation
shield
③Inner radiation
shield HTS
magnets
Heat invasion loads analysis
We need to analyze heat loads of the conduction cooling system for HTS magnet operation. There
are three conditions, such as conduction, convection and radiation.
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Self-weight of a DPC
of HTS magnet : about
150 kg
Iop (A) Fx (ton) Fy (ton) Fz(ton)
100 -0.20 0.0030 0.00075
200 -0.82 0.012 0.0030
300 -1.76 0.027 0.0068
440 -2.40 0.057 0.015
500 -2.28 0.073 0.019
600 -1.73 0.106 0.027
The volume integral of
Lorentz force by each
component according
to the operating
current
Target current
Fx is caused by the attracting force between
iron core and HTS magnet
Lorentz forces and their directions
ǀFxǀ
ǀFxǀ
We calculated Lorentz forces of the HTS magnets for mechanical structure design.
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Expected heat loads of the 2nd stage cryo-cooler
Highest temp. in the
radiation shield : 91.3 K
1st stage temp. :
55.9 K
2nd stage temp. :
6.99 K
Highest temp. in
the HTS magnet:
9.65 K
Maximum stress:
29.5 MPa
Mechanical analysis model
45 W (1st)
7 W (2nd)
Results of the heat transfer and mechanical analysis
Total heat load was expected to 45 W at the 1st stage.
7 W was expected for the 2nd stage and HTS magnet.
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/26 Real drawing of the 300 kW HTS DC IF
The 300kW induction motor was selected with 12 poles at 60 Hz. Machine size: Length 7.4m X Height 2.9m X Width 4.7m
Loading/unloading machine of Aluminum billet
HTS magnets and their conduction cooling system
Aluminum billet (Length: 700mm, Diameter: 240mm)
Supporting system for Heavy weight parts
Gripping system
3 Phase 380V, 12 poles, 300 kW induction motor (Weight : 6 tons, Torque: 484 kg・m, Rated speed: 592 rpm, current 682 A)
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/26 Winding composition of HTS magnet
We fabricated the large-sized two HTS magnets for induction furnace in the world.
The HTS magnet size: length 1.25m X height 0.62 m
HTS magnet bobbin
HTS tape (1.7km)
SUS tape (1km)
Co-winding method
HTS magnet wound
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Critical current estimation process – Only B//c considered
140 A@77K
540 A@30K
Max. 5.6E-3 (T)
Min. 0 (T)
5.0E-3 (T)
4.0E-3 (T)
3.0E-3 (T)
2.0E-3 (T)
1.0E-3 (T)
Max. 4.01E-3 (T)
Min. -4.02E-3 (T)
2.0E-3 (T)
0E-3 (T)
2.0E-3 (T)
(a) (b)
We estimated the critical current of the magnet in 77 K. It was 140 A with the perpendicular magnetic flux density of 4 mT/A.
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/26 Experiment preparation of the magnet under the LN2
We installed the magnetic sensor at the center of the magnet. We performed the critical current test and measured magnetic flux density.
Cooling HTS magnet in
liquid nitrogen, 77.4 K
Installation of the magnetic sensor at the center of the magnet C
ritical curren
t and
mag
netic
field cu
rves u
nder th
e LN
2
Quench occurrence point
145 A
Installed magnetic sensor
(+) Current terminal (-) Current
terminal
Magnetic flux density
measurement
Ramping rate: 0.5 A/s
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Critical current comparison – DPC No.1 and No.2
Ic1: 145 A
Ic2: 165 A
Total length of HTS wire
for an HTS magnet:
1.7 km 170mV
This picture shows the critical current curves of the two HTS magnets.
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/26 Assembly for the magnet experiment
We completed the experimental set-up.
HTS magnet with the conduction cooling system MLI shielding against radiation
Me CEO
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/26 System composition of the cooling down test
Cryostat B
Cryostat A
GM 2nd stage Cryocooler
Compressor Chiller
We composed the system components for cooling down test of the HTS magnets with the conduction cooling.
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/26 Cooling down test results of Cryostat B
The total cooling time took 3 days and 2 hours. The temperature at the 1st stage of cryo-cooler was saturated at 74K. Temperatures of the 2nd stage was cooled down and saturated at 5.3 K.
Saturated temperature of the HTS magnet and conduction cooling system
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/26 Current flowing test results of the HTS magnets
We composed the measurement program for HTS magnet
Magnetic field measurement field
Temperature monitoring field
Current measurement field
Detecting two terminal voltages fields
HTS current lead voltage measurement fields
Current control field
Terminal voltages according to the current
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/26 Current flowing test results of two magnets connected in series
When discharging with (-) 0.5 A/s, the voltage variation occurs. It means that the magnet is unstable condition at that time. The current bypasses into the other turns.
When the current with 0.5 A/s ramping rate was supplied into the magnets, the terminal voltages increase with inductive voltage and the temperatures of HTS magnet increased at 6 K owing to AC losses.
Temperature
Temperature
Voltage Current
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/26 Current flowing test results of two magnets connected in series
Maximum magnetic flux densities were measured to 0.33 T of the cryostat A and 0.325 T of the cryostat B when the current of 360 A flew into the magnets in series connection. This results are almost same as the FEM simulation results.
0.33 (T) (Cryostat A)
0.325(T) (Cryostat B)
360 A
Electromagnetic FEM analysis results
Max. 1.24E-3 (T)
Min. 1.13E-5 (T)
1.0E-3 (T)
0.8E-3 (T)
0.6E-3 (T)
0.4E-3 (T)
0.2E-3 (T)
0.328 (T) @360 A
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/26 Test video of the excitation of the magnets
The operational characteristics of HTS magnet with the conduction cooling system were demonstrated by the experimental test.
SuNAM HTS
wire (12mmx
0.15mm), 3.4 km
Metal
insulation(MI)
type
528 mH without
iron core
(Cryostat B)
Rc: 23.6 mΩ
(Cryostat B)
Tc: 22.4 s
(Cryostat B)
Je: 200A/mm2
(Cryostat B)
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/26 Excitation ceremony on the 9th of August, 2016
The excitation ceremony of the magnets was successfully held on the 9th of August.
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/26 Conclusion and discussion
We developed the HTS magnet with the conduction
cooling system for HTS DC induction furnace.
The successful excitation ceremony was held on the
9th of August, 2016.
Now, we are going on developing the rotating system
for HTS DC induction furnace.
Super coil for the commercialization of the HTS DC
IF was established on the 1st of September.
Super coil aims for the design and engineering works
of the HTS magnets and their application system.
View of the experimental site
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/26 25
Thank you for your attention.
Technologies are not developed by people.
Technologies are not developed by supplier.
Technology has to focus on only NEEDS.
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