Superconductive Multi-Phase Cable Eccentric Thermal Contraction

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Solution Overview

Problem

The manufacturing process for fluid-cooled cable systems is complex, time-consuming, and inefficient, with challenges in achieving uniform cooling and managing thermal contraction, leading to increased material usage and reduced reliability.

Innovation Solution

A superconductive multi-phase, fluid-cooled cable system is designed with an eccentric arrangement of conductors relative to the thermal insulation, allowing for better space utilization, reduced flow resistance, and enhanced thermal contraction management through a meandering path within the cryostat, which simplifies manufacturing and installation while reducing material usage and improving reliability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If concentric cable assembly is manufactured with cryostat, then uniform cooling is achieved, but manufacturing complexity and time increase significantly

Engineering Contradiction:
Improveuniform coolingVSAvoidmanufacturing complexity
Core Design Contradiction:
TemperatureVSDevice complexity

Solution Approach 1:

The cable conductor assembly is pre-cooled to cryogenic temperature before being inserted into the cryostat. This preliminary cooling action eliminates the need for complex internal cooling channels and centring mechanisms during assembly, while still achieving uniform cooling through the flexible cryogenic envelope that conforms to the cable's shape.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

A flexible cryogenic envelope replaces the rigid concentric cryostat structure. This flexible film can adapt to the cable's shape and position, providing uniform thermal contact without requiring precise centring mechanisms or complex rigid structural assemblies.

Inventive Principle:
Principle #30Flexible shells and thin films

2Temperature

If concentric arrangement is used, then thermal insulation is improved, but thermal contraction management becomes difficult

Engineering Contradiction:
Improvethermal insulationVSAvoidthermal contraction management
Core Design Contradiction:
TemperatureVSDevice complexity

Solution Approach 1:

The cable conductor assembly is allowed to move dynamically from a concentric position at room temperature to an eccentric position at cryogenic temperature. This dynamic repositioning accommodates thermal contraction without requiring complex expansion joints or adjustment mechanisms, as the flexible envelope adapts to the position change.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The system transitions from a symmetric concentric arrangement to an asymmetric eccentric arrangement during cooling. This asymmetric final position naturally accommodates the thermal contraction of the cable, eliminating the need for symmetric contraction management mechanisms.

Inventive Principle:
Principle #4Asymmetry

3Loss of energy

If precise centring is achieved during cryostat manufacturing, then eddy current losses are reduced, but manufacturing time and complexity increase

Engineering Contradiction:
Improveeddy current lossesVSAvoidmanufacturing speed
Core Design Contradiction:
Loss of energyVSProductivity

Solution Approach 1:

The cable is pre-cooled before insertion, which eliminates the need for precise centring during assembly. The flexible envelope naturally positions the cable in an optimal eccentric configuration that minimizes eddy current losses without requiring time-consuming precision alignment procedures.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The flexible cryogenic envelope self-adjusts to the cable's position and shape through thermal contact, automatically achieving an optimal configuration that minimizes eddy current losses without requiring external centring mechanisms or manual adjustment.

Inventive Principle:
Principle #25Self-service

4Reliability

If thicker silver sheath is used to stabilize BSCCO conductors, then reliability improves, but material cost increases

Engineering Contradiction:
Improveconductor stabilityVSAvoidsilver material usage
Core Design Contradiction:
ReliabilityVSQuantity of substance

Solution Approach 1:

The operating temperature parameter is changed to cryogenic levels, which fundamentally alters the electrical properties of the conductor. At these low temperatures, the superconducting material exhibits enhanced stability and current-carrying capacity, eliminating the need for thick stabilizing silver sheaths and reducing material usage.

Inventive Principle:
Principle #35Parameter changes

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This design results in a more efficient, cost-effective, and reliable cable system with reduced material consumption, improved thermal management, and increased flexibility for AC and DC operations, accommodating thermal expansion and contraction effectively.

Implementation Method 1

fluid-cooled cable system

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 2

cooling fluid in the form of liquid nitrogen can flow in the central and ring-shaped concentric cooling channels

Methodology Applied
Scientific EffectConvection: Convection

Implementation Method 3

superconductive multi-phase, fluid-cooled cable system

Methodology Applied
Scientific EffectSuperconductivity: Superconductivity

Implementation Method 4

accommodating thermal shrinkage and/or expansion of the cable

Methodology Applied
Scientific EffectThermal contraction: Thermal Contraction

Data Source

PatentEP2950312B1A superconductive multi-phase cable system and its use
Publication Date: 2020.06.17 NKT CABLES ULTERA
  • EP2950312B1 patent drawingFigure 1
  • EP2950312B1 patent drawingFigure 2
  • EP2950312B1 patent drawingFigure 3

AI summary

The invention relates to a superconductive multi-phase, fluid-cooled cable system comprising a) a cable comprising at least three electrical conductors constituting at least two electrical phases and a zero- or neutral conductor, at least one of said electrical conductors comprising superconductive material, said electrical conductors being mutually electrically insulated from each other, at least two of said electrical conductors being concentrically arranged around each other separated by an electrical insulation, said zero- or neutral conductor forming a common electrical return conductor, and b) a thermal insulation defining a central longitudinal axis and surrounding the cable. At least a part of said superconductive material is present in the form of superconductive tapes, each electrical phase conductor comprising two or more layers of said superconductive tapes, where in each of the electrical phase conductors these layers are organized into one or more groups, each of said groups comprising one or more layers of superconductive tapes arranged with the same pitch direction designated "S" or "Z", where Z refers to a "right-hand" winding and S to a "left-hand" winding of the superconductive tapes, and wherein the superconductive tapes in a first group in each of the electrical phase conductors are stranded with the same pitch direction, e.g. "S". This reduces the eddy-current losses of the cable.