Superconducting Cable Dual Coolant Passage Design
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Solution Overview
Problem
Superconducting feeder cables for electric railways require a large number of power leads, complicating the coolant circulation system and preventing effective use of low temperatures, as they typically operate with direct current and cannot utilize the same principles as AC superconducting cables, which use one line for both outgoing and returning coolant flows.
Innovation Solution
A superconducting cable design featuring two coolant passages - an outgoing and a returning passage - within a heat-insulating pipe structure, where the superconductor is cooled by the returning coolant passage, allowing for efficient coolant circulation without a separate returning line, and optionally using a second superconductor for power redistribution between substations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a separate returning line for coolant is provided for superconducting feeder cables, then the coolant can be circulated effectively, but the device complexity increases and costs rise
Solution Approach 1:
The patent merges the outgoing and returning coolant passages into a single cable structure. The outgoing passage is formed inside the inner tube, while the returning passage is formed in the space between the inner and outer tubes. This integration allows both coolant flows to coexist within one cable without requiring separate returning lines, thus reducing device complexity while maintaining effective coolant circulation.
Solution Approach 2:
The patent implements a nested structure where the outgoing coolant passage is embedded within the inner tube, and the returning coolant passage is positioned in the annular space between the inner and outer tubes. The heat insulating material is nested between the two passages. This nested arrangement enables compact integration of multiple coolant flow paths within a single cable structure.
2Loss of energy
If multiple superconducting cables are provided to enable separate outgoing and returning coolant lines, then coolant circulation is improved, but the device complexity and cost increase
Solution Approach 1:
The patent combines both outgoing and returning coolant functions into a single superconducting cable by creating dual passages within one cable structure. This eliminates the need to deploy multiple separate cables for coolant circulation, reducing the quantity of superconducting cables required while maintaining effective thermal management.
3Device complexity
If AC superconducting cable principles are applied to DC superconducting feeder cables, then coolant circulation is simplified, but the adaptability to DC-specific requirements is reduced
Solution Approach 1:
The patent adapts the cooling system to DC feeder cable specific requirements by providing multiple power leads for local power distribution to trolley lines. The coolant passage configuration is specifically designed to accommodate the DC feeder cable's functional requirements, with the returning passage positioned to allow superconductor placement on the outer circumferential side where power leads connect.
Solution Approach 2:
Unlike AC cables where one line serves both outgoing and returning functions, this DC feeder cable implementation uses a single cable with internally differentiated passages - the inner tube for outgoing coolant and the annular space for returning coolant. This inverted approach to the conventional single-purpose line design enables DC-specific power distribution while maintaining simplified single-cable architecture.
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 enables effective cyclic use of low coolant temperatures, improving power transmission efficiency and reducing the need for additional cables, thus lowering costs and simplifying the configuration, while maintaining the superconducting state and preventing voltage drops.
Implementation Method 1
a heat insulating material is disposed between the outgoing coolant passage and the returning coolant passage
Implementation Method 2
Superconductivity is a phenomenon of electric resistance rapidly becoming zero in a substance such as a certain metal, alloy, and compound when cooled to the ultra-low temperature
Implementation Method 3
the superconductor is cooled by the coolant that flows through the returning coolant passage
Data Source
AI summary
A superconducting cable comprises a superconductor 60, two or more coolant passages including an outgoing coolant passage 12 and a returning coolant passage 14 that transfer a coolant that cools the superconductor, and a heat insulating pipe 10 inside which the superconductor 60 and the coolant passages are formed. For the coolant passages, by a double structured tube of an inner tube 6 and an outer tube 8, the outgoing coolant passage 12 is formed in the internal space of the inner tube 6 and the returning coolant passage 14 is formed in the space between the inner tube 6 and the outer tube 8, the inner tube 6 is formed between the outgoing coolant passage 12 and the returning coolant passage 14 of a heat insulating material, the superconductor 60 is disposed on the outer circumferential side of the inner tube 6, and the superconductor is cooled by the coolant that flows through the returning coolant passage.