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

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/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.

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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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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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