Cryogenic Cable Termination Using Segmented Dual Cryogen Chambers
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Solution Overview
Problem
High voltage cable terminations face challenges in maintaining dielectric and thermal integrity, particularly in gaseous cryogen-cooled superconducting cables, due to low dielectric strength of gaseous media and heat influx issues.
Innovation Solution
The use of a dual cryogen system with a liquid cryogen in the upper cryostat chamber and gaseous cryogen in the lower chamber, along with capacitive grading and optimized conductor cross-sections, to maintain cryogenic temperatures and reduce heat influx, enhancing dielectric strength and thermal management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If gaseous cryogen is used for cooling, then heat conduction efficiency is improved, but dielectric strength deteriorates
Solution Approach 1:
The termination is divided into multiple chambers: a first chamber containing gaseous cryogen for cooling the conductor, and a second chamber containing liquid dielectric for insulation. This segmentation allows each chamber to be optimized for its specific function - gaseous cryogen provides efficient heat conduction while liquid dielectric provides high dielectric strength.
Solution Approach 2:
A cold shield is introduced as an intermediary component between the gaseous cryogen chamber and the liquid dielectric chamber. The cold shield is cooled by the gaseous cryogen and radiates coldness to the liquid dielectric, reducing heat influx to the conductor while maintaining the dielectric properties of the liquid medium.
2Reliability
If liquid dielectric is used to improve insulation, then dielectric strength is improved, but heat conduction efficiency deteriorates
Solution Approach 1:
The termination is divided into multiple chambers: a first chamber containing gaseous cryogen for cooling the conductor, and a second chamber containing liquid dielectric for insulation. This segmentation allows each chamber to be optimized for its specific function - gaseous cryogen provides efficient heat conduction while liquid dielectric provides high dielectric strength.
Solution Approach 2:
A cold shield is introduced as an intermediary component between the gaseous cryogen chamber and the liquid dielectric chamber. The cold shield is cooled by the gaseous cryogen and radiates coldness to the liquid dielectric, reducing heat influx to the conductor while maintaining the dielectric properties of the liquid medium.
3Volume of moving object
If conductor cross-section is reduced, then cable size is reduced, but current carrying capacity deteriorates
Solution Approach 1:
The system operates at reduced temperatures using cryogenic cooling, which fundamentally changes the electrical parameters of the conductor. At cryogenic temperatures, the conductor exhibits significantly higher current carrying capacity per unit cross-section, allowing reduced cable size while maintaining power transmission capability.
4Temperature
If thermal management is enhanced, then conductor temperature is reduced, but heat influx to conductor increases
Solution Approach 1:
The liquid dielectric, which would normally be a heat source due to its temperature, is converted into a beneficial component. By placing it in a separate chamber with a cold shield, its thermal mass helps stabilize temperatures while its high dielectric strength provides insulation. The system converts the potential harmful heat influx into a stabilizing thermal environment.
Solution Approach 2:
A cold shield is introduced as an intermediary component between the gaseous cryogen chamber and the liquid dielectric chamber. The cold shield is cooled by the gaseous cryogen and radiates coldness to the liquid dielectric, reducing heat influx to the conductor while maintaining the dielectric properties of the liquid medium.
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 approach effectively maintains dielectric and thermal integrity, reducing heat load and improving the efficiency of cable terminations by utilizing the higher dielectric strength and heat conduction properties of liquid cryogens while maintaining gaseous cryogen cooling efficiency.
Implementation Method 1
an upper cryostat chamber and a lower cryostat chamber. The upper cryostat chamber may have an interior cavity at least partially filled with a liquid cryogen. The lower cryostat chamber may have an interior cavity at least partially filled with a gaseous cryogen.
Implementation Method 2
The lower cryostat chamber may have an interior cavity at least partially filled with a gaseous cryogen. A power cable may extend into the interior cavity of the lower cryostat chamber and may be electrically coupled to the conductor.
Implementation Method 3
along with capacitive grading and optimized conductor cross-sections, to maintain cryogenic temperatures and reduce heat influx, enhancing dielectric strength and thermal management.
Data Source
AI summary
A cable termination comprising an upper cryostat chamber containing a liquid cryogen and a lower cryostat chamber containing a gaseous cryogen to maintain dielectric integrity and thermal management of an electric connection. A gaseous cryogen recirculation system may cause the gaseous cryogen to flow through the lower cryostat chamber and a power cable enclosure.