DC-HTS Cables for Power Distribution in Hybrid-Electric ......3 ITEP-SUPRA Conventional: Propulsion...

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INSTITUTE OF TECHNICAL PHYSICS (ITEP) - SUPERCONDUCTING MATERIALS AND ENERGY APPLICATIONS (SUPRA)

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DC-HTS Cables for Power Distribution in Hybrid-Electric Aircraft Sonja I. Schlachter, Wilfried Goldacker, Bernhard Holzapfel, Andrej Kudymow, Hong Wu

ITEP-SUPRA 2

Why do we need electric or hybrid-electric aircraft? Goals of „FLIGHTPATH 2050“:

Protecting environment and energy supply Reduction of carbon footprint of aviation sector.

  75%* reduction in CO2 emissions per passenger kilometre   90%* reduction in NOx emissions   Aircraft movements are emissions-free when taxiing

  Reduction of noise emission of flying aircraft is by 65%.

Ø  Electrical and hybrid-electrical engines have entered the aviation market.

* These are relative to the capabilities of typical new aircraft in 2000.

Sonja Schlachter – “DC-HTS Cables for Power Distribution in Hybrid-Electric Aircraft” Coated Conductors for Applications 2016, September 11-14, 2016, Aspen, Colorado, USA

Sept. 12, 2016

Source: Flightpath 2050 - Europe’s Vision for Aviation http://ec.europa.eu/transport/modes/air/doc/flightpath2050.pdf - doi: 10.2777/50266

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Conventional:

Propulsion of Aircraft


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100% 42%

Thrust generation by engine (turbojet) or linked to engine (turboprop, turbofan)

  Low efficiency, high emissions

100% 98% 93%

  Trust generation decentralized Battery: weight problem for larger aircraft! http://www.faz.net/-gpc-8jirb

Solar Impulse 2

All Electric with Battery and e-Motor (small aircraft)

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Solution for larger Aircraft:


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http://img.welt.de/img/wirtschaft/crop127296741/4926936553-ci3x2l-w900/E-Thrust-2-.jpg

Hybrid-electric propulsion systems:

Thrust generation decentralized à design space for aircraft Already applied in ships, trains, mining trucks but: different boundary conditions for aviation !

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https://de.wikipedia.org/wiki/Luftdruck

Boundary Conditions for Aviation

  Low air pressure at high flight altitudes Ø  Low breakdown voltage,

danger of arcing (Paschen‘s Law)

  Enhanced radiation at high flight altitudes Ø  Electronic noise and signal spikes in microelectronic circuits Ø  Low voltages preferred

  Weight and size matter…   Limited resources (propellant, cooling water, electric power, …)   Safety !!!


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https://en.wikipedia.org/wiki/Paschen%27s_law

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  TELOS - Thermo-Electrically Optimised Aircraft Propulsion Systems

  Goals:   Exploration of technical aspects of hybrid-electric propulsion system   Development and test of demonstrators

Funding: Federal Ministry of Economic Affairs and Energy

  Duration: 01/2016 – 03/2019

  Partners:   Airbus Group Innovations, München   Airbus Operations GmbH, Hamburg   Siemens AG, Erlangen   Karlsruhe Institute of Technology   New Materials Bayreuth GmbH   Technical University of Munich

TELOS - Project


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à HTS Generator à DC HTS Cables

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Cryogenic system / Operating Temperature

Boundary conditions for superconducting DC cables in hybrid-eletric aircraft


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Required power level for aircraft: 1 - 10 MW range

Aircraft and duty cycle

Req

uire

men

ts o

f oth

er c

ompo

nent

s of

hyb

rid-e

lect

ric p

ropu

lsio

n sy

stem

Voltage level 1 - 10 kV

Current 0.1 – 10 kA

Installation and operation

Cable Length / joints

Safety and redundancy

SC Material MgB2, REBCO, BSCCO

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Cooling System with Cryocoolers? Efficiency and Availability


Example: Aerospace-Cooler Northrop Grumman

www.northropgrumman.com/aerospacesystems

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à  No lightweight cryocoolers in the required cooling power range available à  Reservoir with cryogenic liquid (e.g. LN2, LH2) or à  Combination of cryocooler and liquid cryogen (reduce Th, e.g. with LNG)?

F. Berg et al., ASC 5LOr1C-01

Operation temperature, assumption Th = 303 K 77 50 40 30 20

COPideal, (Winput @ 303K per Wlifted @ Tc) 2.94 5.06 6.58 9.1 14.15

COPreal for >100 W heat loads (Winput @ 303 K per Wlifted@Tc)

~12-20 ~25-35 ~35-50 ~50-75 ~100-200

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0 5 10 15 20 25 30 35 400

500

1000

1500

2000

2500

HTS-Cable 1 kA 5 kA 10 kA

Sys

tem

wei

ght (

kg)

Cable length (m)0 5 10 15 20 25 30 35 40

0

500

1000

1500

2000

2500


Aluminium 1 kA 5 kA 10 kA

Sys

tem

wei

ght (

kg)

Cable length (m)

Normal conducting, 2 poles (Aluminium, I / A = 1 A/mm2)   M = L ⋅ (mAl + mInsulation+ mCooling) + …

Weight: Normal- vs. Superconducting System


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DC-HTS Cable + Cryosystem, I = 1 kA, 5 kA, 10 kA, Cooling: subcooled LN2

Weight (M: total mass, m: mass / length)

Calculations include green parameters (Cooling time 3h):

Superconducting, 2 poles:   M = L ⋅ (mCryostat + mSC + mDielektric + mFormer + …) + MCL + MTerminals + MCryogenic System + …

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0 10 20 30 400

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24Aluminium

1 kA 5 kA 10 kA


Loss

es o

f Al @

300

K (

kW)

Loss

es o

f HTS

-Sys

tem

@ 7

7 K

(kW

)

Cable Length (m)0 10 20 30 40

0

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Loss

es o

f HTS

-Sys

tem

@ 7

7 K

(kW

)

Cable Length (m)

Losses: Normal- vs. Superconducting System


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Normal conducting, 2 poles (Aluminium, I / A = 1 A/mm2) PAl, 300 K = ρAl ⋅ L/A ⋅ I 2 + PInfra

Superconducting, 2 poles (Aluminium, I / A = 1 A/mm2)   PHTS, Top = L ⋅ (pcryostat + pDC + pAC) + PCL + PTerminals + PCryogenic System + …

P: total losses, p: losses / length

Calculations include green parameters (Cooling time 3h):

DC-HTS Cable + Cryosystem, I = 1 kA, 5 kA, 10 kA, Cooling: subcooled LN2

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TELOS: Lightweight demo-cable with cryogenic system

DC HTS-Cable:   Number of poles: 2   Rated voltage: 1 kV ≤ U ≤ 10 kV   Rated current: 3 kA, scaleable to 10 kA   Joint with sc short circuit

Weight and loss optimization!

Cryogenic system:   Subcooled LN2 (LH2)


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Fields and Forces in CC-Cables (2x 3 kA, 4 kV)

Stack Cable Type A (+ -)

Distance between 2 poles Stack Cable Type B (+ - + -…..+ -) Distance between tapes Coaxial Cable

(CORC-type )

1 mm 2 mm 3 mm 4 mm 5 mm 0.1 mm 0.2 mm 0.4 mm 0.8 mm 1 mm Inner pole Outer

pole Bmax

[10-3 Tesla] 281.4 266.4 253.1 241.5 231.7 28.4 27.4 26 24.9 24.4 139.3 73 B∥max

[10-3 Tesla] 281.4 266.4 253.1 241.5 231.7 28.4 27.4 26 24.9 24.4 139.2 73 B⊥max

[10-3 Tesla] 119.4 138.4 151.4 161.1 167.4 16 18.9 21.2 23.7 23.5 46.7 28 Emax

[106 V/m] 5.35 3.56 2.98 2.19 2.13 41.0 25.3 19.2 11.3 9.69 2.29 Eavg

[106 V/m] 4.00 2.00 1.33 1.00 8.00 40.0 20.0 10.0 5.00 4.00 0.89 Fmax ** [N/m] 341.7 303.5 272.5 245.6 224.2 *** *** 2.95 2.57 2.45 30.1 11


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Bending and Joints

Stack Cable Type A (+ -) Stack Cable Type B (+ - + -…..+ -)

Coaxial Cable (CORC-type )

Bending J (⊥ tape plane), L (|| tape plane)

J (⊥ tape plane), L (|| tape plane) J

Joints Cable end –Cable end J L K

T-Joint J L L


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Which bending radii do we need?   Movement of wings: R large

Bending in fuselage:   limited by flexibility of cryostat, e.g.

Rbend ≥ 0.6 m for NEXANS Cryoflex® (several bends, depending on cryostat-Ø)   „Stiff“ conduit bends

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Conclusion

  Complex parameter space for optimization of power distribution in aircraft with hybrid-electric propulsion systems:

  e.g.: Voltage level, weight, losses, air pressure, reliability, maintainability, aircraft environment

  DC HTS cables allow weight and loss reduction at lengths of a few meters compared to Al busbars.

  LN2 cooling makes sense for “stand-alone” power distribution system (Carnot)

Ø  However, optimization of the whole propulsion system necessary: Ø  Optimum voltage levels for all components Ø  Combined cryogenic system of all superconducting components

(e.g. LH2 cooling + fuel cells)

Ø  Weight optimization for all components Ø  Cost, maintainability and reliability


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Acknowledgement

  This work is supported by the Federal Ministry for Economic Affairs and Energy in Germany under support code 20Y1516C.


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Fields and Forces in CC-Cables (2x 3 kA, 4 kV)

Stack Cable Type A (+ -)

Distance between 2 poles Stack Cable Type B (+ - + -…..+ -) Distance between tapes Coaxial Cable

(CORC-type )

1 mm 2 mm 3 mm 4 mm 5 mm 0.1 mm 0.2 mm 0.4 mm 0.8 mm 1 mm Inner pole Outer

pole Bmax

[10-3 Tesla] 281.4 266.4 253.1 241.5 231.7 28.4 27.4 26 24.9 24.4 139.3 73 B∥max

[10-3 Tesla] 281.4 266.4 253.1 241.5 231.7 28.4 27.4 26 24.9 24.4 139.2 73 B⊥max

[10-3 Tesla] 119.4 138.4 151.4 161.1 167.4 16 18.9 21.2 23.7 23.5 46.7 28 Emax

[106 V/m] 5.35 3.56 2.98 2.19 2.13 41.0 25.3 19.2 11.3 9.69 2.29 Eavg

[106 V/m] 4.00 2.00 1.33 1.00 8.00 40.0 20.0 10.0 5.00 4.00 0.89 Fmax ** [N/m] 341.7 303.5 272.5 245.6 224.2 *** *** 2.95 2.57 2.45 30.1 11


Sept. 12, 2016

DC-HTS Cables for Power Distribution in Hybrid-Electric ......3 ITEP-SUPRA Conventional: Propulsion...

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