Superconducting DC Cable Segmented Cryostat Cooling

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Solution Overview

Problem

Existing superconductive DC cable systems face challenges in efficient cooling due to thermal insulation provided by the dielectric, which hampers the effective transfer of cryogenic liquids to the superconducting phase conductors, making it difficult to adapt to varying current intensities and requiring complex structural arrangements.

Innovation Solution

A compact and modular design where each phase conductor is surrounded by a shell of insulating material, allowing direct cooling by a coolant moving through the cryostat, with a variable number of DC transmission elements that can be adjusted based on current requirements, and thermally insulated by the cryostat to maintain the superconducting state.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a dielectric is used to insulate phase conductors in a superconductive cable, then electrical insulation is provided, but thermal insulation is also created which hampers effective cooling of the superconducting phase conductors

Engineering Contradiction:
Improveelectrical insulationVSAvoidcooling efficiency
Core Design Contradiction:
ReliabilityVSTemperature

Solution Approach 1:

The cable structure is segmented into multiple independent transmission elements, each with its own cooling path. The dielectric is positioned only where electrically necessary, not as a continuous barrier around each conductor, allowing coolant access while maintaining electrical insulation where required.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The dielectric is extracted from positions where it would block cooling paths. Instead of surrounding each phase conductor completely with dielectric insulation, the dielectric is placed only in locations where electrical insulation is critical, removing the thermal barrier effect from the cooling pathway.

Inventive Principle:
Principle #2Taking out (Extraction)

2Ease of manufacture

If a fixed structural arrangement of superconductive cables is used, then manufacturing is simplified, but adaptability to different current intensities is reduced

Engineering Contradiction:
Improvestructural simplicityVSAvoidcurrent intensity adaptability
Core Design Contradiction:
Ease of manufactureVSAdaptability or versatility

Solution Approach 1:

The cable system employs a dynamic configuration where the number of active transmission elements can be adjusted based on current requirements. Elements can be selectively activated or deactivated, allowing the system to adapt its capacity dynamically while maintaining a simple, repeatable modular structure for manufacturing.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

Each transmission element is designed as a universal module that can function independently or in combination with other identical modules. This multi-functionality allows the same structural design to serve different current intensity requirements by simply varying the number of active elements, eliminating the need for multiple specialized designs.

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Reliability

If multiple superconductive conductors are arranged in a cryostat with traditional insulation, then electrical isolation is maintained, but the structure becomes complex and cooling efficiency decreases

Engineering Contradiction:
Improveelectrical isolationVSAvoidstructural complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

Multiple transmission elements are merged into a single integrated cryostat assembly with a unified cooling system. The elements share common support structures and cooling pathways, eliminating redundant insulation and structural components while maintaining electrical isolation through strategic dielectric placement only where needed.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The cryostat structure implements local quality by providing dielectric insulation only in specific locations where electrical isolation is required, rather than using continuous insulation layers. This allows coolant to flow freely around conductors in most areas, reducing thermal resistance while maintaining electrical safety where critical.

Inventive Principle:
Principle #3Local quality

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 simplifies the cooling process, allows for easy adaptation to different current intensities, and provides efficient thermal insulation, ensuring reliable operation of the superconductive DC cable system by directly exposing the superconductive elements to the coolant, thereby maintaining the superconducting state within the specified temperature range.

Implementation Method 1

each phase conductor consists of a large number of superconductive elements which are only surrounded by a shell made of insulating material, so that the same or the respective phase conductor are cooled directly by a coolant moving through the cryostat

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 2

The cable is placed in a cryostat consisting of two concentric tubes with vacuum insulation between them

Methodology Applied
Scientific EffectVacuum insulation: Thermal Insulation

Implementation Method 3

superconductive cables have electrical conductors made of a composite material which contains ceramic material which changes to the superconductive state at sufficiently low temperatures. The electrical direct current resistance of a correspondingly constructed conductor is zero with sufficient cooling

Methodology Applied
Scientific EffectSuperconductivity: Superconductivity

Data Source

PatentEP2551859B1Assembly with a superconducting electric direct current cable system
Publication Date: 2014.10.01 NEXANS SA
  • EP2551859B1 patent drawingFigure 1~4

AI summary

An arrangement is described comprising a superconducting direct current (DC) cable system, which includes at least one DC transmission element (4) consisting of two mutually insulated phase conductors, and a cryostat suitable for conveying a coolant, in which the DC cable system is arranged. The cryostat consists of at least one metallic tube surrounded by a completely closed layer with thermally insulating properties. Each of the two phase conductors (5, 6) consists of several superconducting elements (9) combined into a unit. A separating layer (7) of insulating material is provided between the two phase conductors (5, 6), and the two phase conductors (5, 6), including the separating layer (7), are surrounded by a sheath (8) of insulating material to form a DC transmission element (4).