Superconducting Cable with Intermediate Tube for Dielectric Pressure
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Solution Overview
Problem
The existing superconductive cable systems face limitations in length due to the degradation of electrical insulating properties of the dielectric as the coolant transitions from liquid to gas, leading to potential breakdowns between the conductor and shield.
Innovation Solution
A metallic intermediate tube is introduced with a constant-pressure fluid impregnating agent surrounding the cable, maintaining dielectric pressure and insulating properties by keeping coolant and impregnant pressures independent, allowing for extended cable length without recooling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the coolant penetrates the dielectric during operation, then very high power can be transmitted in the high-voltage range, but the refrigerant may reach its vaporization temperature causing transition from liquid to gaseous state which weakens the electrical insulating properties of the dielectric
Solution Approach 1:
The system divides the cooling function into two independent parts: the coolant circulates in the cryostat surrounding the cable, while the impregnating agent penetrates and fills the dielectric. This segmentation prevents the coolant from directly contacting and potentially vaporizing within the dielectric, maintaining electrical insulation reliability while still enabling high power transmission through effective cooling.
Solution Approach 2:
The impregnating agent serves as an intermediary substance that fills the dielectric and maintains constant pressure on it, preventing dielectric breakdown. It acts as a mediator between the cooling system and the electrical insulation, ensuring that the dielectric remains properly pressurized and insulated even as the coolant operates in the cryostat.
2Temperature
If the pressure of the refrigerant decreases with increasing distance from the feed point, then the refrigerant temperature increases, but this can lead to vaporization and breakdown of electrical insulation
Solution Approach 1:
The system separates the pressure control function for the dielectric from the coolant flow. The impregnating agent system maintains constant pressure independently of the coolant's pressure drop along the cable length, allowing the cable system to be extended much further without risking dielectric breakdown due to pressure loss.
Solution Approach 2:
The impregnating agent system is designed to automatically maintain constant pressure throughout the dielectric volume, compensating for any pressure drops in the coolant system. This self-regulating pressure maintenance ensures that the dielectric remains properly insulated regardless of the cable length or coolant pressure variations.
3Device complexity
If the coolant and impregnant pressures are coupled, then the system is simpler, but the limits for pressure and temperature of the coolant restrict the maximum cable length
Solution Approach 1:
The system divides the pressure control into two independent segments: the coolant pressure in the cryostat and the impregnating agent pressure surrounding the dielectric. This segmentation allows each system to be optimized independently - the coolant for thermal management and the impregnating agent for electrical insulation pressure maintenance - thereby enabling much longer cable lengths without compromising either cooling or insulation.
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 prevents breakdowns between the conductor and shield, enabling longer cable systems with consistent dielectric insulation, allowing for increased operational length and flexibility in coolant choice, and enabling multiple chiller connections without disrupting the cable.
Implementation Method 1
A superconductive cable has electrical conductors made of a special material that becomes superconductive at sufficiently low temperatures. As a result, the electrical resistance of a correspondingly constructed conductor approaches zero.
Implementation Method 2
A liquid coolant is pumped through the gap between the inner tube and the cryostat by means of a cooling unit or units indicated by a pump 12.
Implementation Method 3
The space enclosed by the intermediate tube 5 is filled with a liquid, preferably liquid, medium at room temperature as an impregnating agent
Implementation Method 4
The space enclosed by the intermediate tube 5 is filled with a liquid, preferably liquid, medium at room temperature as an impregnating agent, which is subjected to high-pressure gas.
Data Source
Figure 1
Figure 2
AI summary
A system is described comprising a superconducting cable with a superconducting conductor (2), a dielectric (3) surrounding the conductor, and a superconducting screen (4) arranged above the dielectric, which acts as a spacer. The cable is surrounded, with an air gap, by a cryostat (7) consisting of a metallic inner tube (8), a metallic outer tube (9), and superinsulation (10) arranged between them. Above the screen (4), leaving a gap (6) to the cryostat (7), a metallic intermediate tube (5) is arranged, which is completely enclosed along its entire length.A fluid medium at room temperature, pressurized to constant pressure, is introduced into the space between conductor (2) and intermediate tube (5) as an impregnating agent for the dielectric (3), and at least one coolant unit for supplying a liquid coolant is connected to the gap (6) between cryostat (7) and intermediate tube (5).