Dual Cooling Paths for Superconducting Switches
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Solution Overview
Problem
Conventional superconducting magnet systems face challenges with high cooling times, excessive helium boil-off, and increased costs due to large helium inventories and inefficient heat dissipation in persistent current switches, which affect the reliability and efficiency of magnetic devices like MRI systems and generators.
Innovation Solution
A persistent current switch system utilizing dual cooling paths, comprising a solid thermal component and a cooling tube, to rapidly cool the winding unit by circulating a coolant like liquid helium, hydrogen, or neon, which recirculates evaporated coolant back to the reservoir, reducing the need for continuous helium supply and minimizing heat load.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a large helium vessel with thousands of liters of liquid He is used to cool the persistent current switch, then the cooling capacity is sufficient, but the system becomes expensive, heavy, and difficult to transport and install
Solution Approach 1:
The patent divides the cooling system into two separate cooling paths: a first cooling path using a solid thermal component (heat conduction) and a second cooling path using a cooling tube with liquid helium circulation. This segmentation allows each path to contribute differently to the overall cooling capacity, enabling the system to achieve sufficient cooling with a much smaller helium inventory than conventional single-path systems.
2Loss of time
If the conductance of the heat conduction path is increased to reduce cooling time, then the cooling time from switch-OFF to switch-ON state is reduced, but excessive heat is conducted to the cryogenic tank when the switch is in the switch-OFF state, consuming all stored liquid cryogen before completing superconducting coil ramp-up
Solution Approach 1:
The patent employs dynamic control of the cooling system by selectively activating different cooling paths based on the operational state of the persistent current switch. The controller activates the first cooling path (solid thermal component) when the switch needs rapid cooling during transition to superconducting state, and activates the second cooling path (liquid helium circulation) when the switch is in switch-OFF state to prevent excessive heat conduction from consuming the liquid cryogen reservoir.
Solution Approach 2:
The system changes the thermal conduction parameters dynamically by switching between two different cooling mechanisms. The solid thermal component provides high conductance when needed for rapid cooling, while the liquid helium circulation path provides controllable heat removal to prevent excessive heat transfer to the cryogenic tank. This parameter switching allows the system to achieve fast cooling times without permanently high heat conduction that would deplete the cryogen reservoir.
3Device complexity
If conventional single cooling path systems are used, then the system structure is simple, but the cooling time is excessively long (300 minutes)
Solution Approach 1:
The patent segments the cooling function into two distinct cooling paths with different thermal characteristics. The first cooling path uses a solid thermal component for rapid heat conduction, while the second cooling path uses liquid helium circulation for sustained heat removal. This segmentation enables the system to achieve fast cooling times (reduced from 300 minutes) by utilizing both paths in coordination, while maintaining a relatively simple overall structure through integrated controller management.
4Ease of operation
If the persistent current switch is operated in normal state with high temperature, then the switch can be easily controlled, but the cooling time to transition to superconducting state becomes unacceptably long
Solution Approach 1:
The patent implements dynamic cooling control that activates the high-conductance first cooling path (solid thermal component) specifically during the transition phase when the persistent current switch needs to cool from normal state to superconducting state. This dynamic activation provides the necessary rapid cooling to reduce transition time from 300 minutes to approximately 20 minutes, while the controller manages the switching between operational states to maintain ease of operation.
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 significantly reduces cooling times from 300 minutes to approximately 20 minutes, decreases the size and weight of magnetic devices, and eliminates the need for frequent helium refilling, enhancing system reliability and reducing operational costs.
Implementation Method 1
a solid thermal component directly connected to the winding unit and to a cooling tube, the cooling tube circulating a coolant to remove heat from the winding unit absorbed by the solid thermal component
Implementation Method 2
a cooling tube directly connected to the winding unit and to a reservoir, the cooling tube circulating a coolant to remove heat from the winding unit
Implementation Method 3
the outlets of the first and second cooling tubes are configured to convey the evaporated coolant to a recondenser, wherein the evaporated coolant is recondensed and returned to the reservoir
Data Source
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AI summary
A persistent current switch system is presented. One embodiment of the persistent current switch system includes a vacuum chamber having a winding unit and dual cooling paths. The dual cooling paths are configured to circulate a coolant flow. The dual cooling paths are defined by a first cooling path and a second cooling path. The first cooling path includes a solid thermal component disposed in direct contact with the winding unit and the second cooling path includes a cooling tube disposed in direct contact with the winding unit and configured to circulate a coolant therein. The dual cooling paths cool the temperature of the winding unit below the threshold temperature to transition the persistent current switch system from the first mode to the second mode. A method of for cooling a winding unit in a persistent current switch system and a switching system including dual cooling paths are also disclosed.