Cryogenic Cable Termination Unit With Annular Cooling

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Solution Overview

Problem

Superconducting cable systems require reliable and cost-effective termination units that can maintain cryogenic temperatures while connecting high-voltage phase conductors and neutral conductors to external equipment, posing challenges due to complex designs and increased complexity in fabrication and utilization.

Innovation Solution

A termination unit with a thermally insulating envelope that injects cooling fluid through a controlling valve, featuring longitudinal holes for heat exchange and spacers for flow control, allowing for stable and efficient cooling of branch current leads, and adaptive inserts for modular assembly and radial distance regulation, enabling reliable connections for superconducting and hyper-conducting cables.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a termination unit for superconducting cable systems is designed to maintain cryogenic temperatures, then the reliability of the connection is improved, but the device complexity increases

Engineering Contradiction:
Improveconnection reliabilityVSAvoidtermination unit complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The termination unit is divided into distinct functional modules: a cryogenic section for maintaining low temperatures, a transition section for thermal and electrical transition, and an ambient section for external connections. This segmentation allows each module to be optimized independently while simplifying the overall design and assembly process.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

A transition section acts as an intermediary between the cryogenic and ambient sections, providing both thermal isolation and electrical connection. This intermediary component enables reliable connections across temperature boundaries without requiring the entire termination unit to operate at cryogenic temperatures, thereby reducing complexity.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Use of energy by moving object

If cooling fluid is injected through a controlling valve with forced annular flow, then the cooling efficiency is improved, but the device complexity increases

Engineering Contradiction:
Improvecooling efficiencyVSAvoidcooling system complexity
Core Design Contradiction:
Use of energy by moving objectVSDevice complexity

Solution Approach 1:

The cooling system utilizes forced annular flow of cooling fluid through the termination unit, leveraging fluid dynamics principles to achieve efficient heat removal. The controlling valve regulates fluid flow rate and pressure, optimizing cooling performance without requiring complex active control systems.

Inventive Principle:
Principle #29Pneumatics and hydraulics

Solution Approach 2:

The cooling fluid flows in an annular path around the central conductor, utilizing the radial dimension for heat exchange. This annular flow configuration maximizes the cooling surface area and improves heat removal efficiency compared to linear flow paths, while maintaining a relatively simple valve control mechanism.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

3Use of energy by moving object

If longitudinal holes are provided for heat exchange with cooling fluid, then the heat exchange efficiency is improved, but the manufacturing precision requirements increase

Engineering Contradiction:
Improveheat exchange efficiencyVSAvoidhole alignment precision
Core Design Contradiction:
Use of energy by moving objectVSManufacturing precision

Solution Approach 1:

The termination unit incorporates longitudinal holes or porous structures that allow cooling fluid to penetrate and exchange heat with the conductor. These holes can be formed using standard drilling or machining processes with reasonable tolerances, and their primary function is to provide flow paths rather than require precise dimensional control.

Inventive Principle:
Principle #31Porous materials

Solution Approach 2:

Multiple longitudinal holes are provided throughout the termination unit to ensure adequate heat exchange. Rather than requiring a single precisely positioned hole, the design uses multiple holes with relaxed tolerance requirements, where the collective effect of all holes provides the necessary cooling performance.

Inventive Principle:
Principle #16Partial or excessive action

4Ease of operation

If longitudinal spacers are used for flow control and fixed distance maintenance, then the flow control capability is improved, but the device complexity increases

Engineering Contradiction:
Improveflow control capabilityVSAvoidinternal structure complexity
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The longitudinal spacers are designed to automatically maintain fixed distances between components and regulate cooling fluid flow without requiring external control mechanisms. The spacers' geometric features inherently provide flow restriction and positioning functions, eliminating the need for additional active control devices.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The longitudinal spacers serve multiple functions simultaneously: they maintain fixed distances between the conductor and termination housing, control cooling fluid flow rate, provide mechanical support, and ensure proper alignment of internal components. This multi-functionality reduces the overall number of parts needed while improving flow control capability.

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

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

The solution provides stable and efficient cooling, allowing for high current ratings and reliable connections, reducing fabrication costs and increasing the reliability of superconducting cable systems by maintaining cryogenic temperatures effectively.

Implementation Method 1

the termination unit is configured to inject through a controlling valve cooling fluid in a forced annular flow through the termination unit

Methodology Applied
Scientific EffectForced Convection: Forced Convection

Implementation Method 2

A termination unit with a thermally insulating envelope that injects cooling fluid

Methodology Applied
Scientific EffectThermal Insulation: Thermal Insulation

Data Source

PatentEP2127051B1A cryogenic cable termination unit
Publication Date: 2017.09.13 NKT CABLES ULTERA
  • EP2127051B1 patent drawingFigure 1~2
  • EP2127051B1 patent drawingFigure 3~4
  • EP2127051B1 patent drawingFigure 5

AI summary

This invention relates to a termination unit comprising an end-section of a cable. The end section of the cable defines a central longitudinal axis and comprising end-parts of N electrical phases,an end-part of a neutral conductor and a surrounding thermally insulation envelope adapted to comprising a cooling fluid. The end-parts of the N electrical phases and the end-part of the neutral conductor each comprising at least one electrical conductor and being arranged in the cable concentrically around a core former with a phase 1 located relatively innermost, and phase N relatively outermost in the cable, phase N being surrounded by the neutral conductor, electrical insulation being arranged between neighbouring electrical phases and between phase N and the neutral conductor, and wherein the end-parts of the neutral conductor and the electrical phases each comprise a contacting surface electrically connected to at least one branch current lead to provide an electrical connection: The contacting surfaces each having a longitudinal extension, and being located sequentially along the longitudinal extension of the end-section of the cable. The branch current leads being individually insulated from said thermally insulation envelope by individual electrical insulators.