Persistent Current Switch Heat Dissipation Arrangement
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Solution Overview
Problem
Superconducting magnets in cryogenic environments face inefficiencies due to energy dissipation in persistent current switches, which requires large, expensive switches or excessive cryogen consumption for heat removal, as existing refrigeration systems are inefficient at low temperatures.
Innovation Solution
A persistent current switch assembly with a heat dissipation arrangement that includes a convective heat dissipation loop and thermally conductive links, allowing for efficient heat transfer to a first heat exchange element at a higher temperature during energization and to a second heat exchange element at superconducting temperature during operation, reducing energy loss and cryogen consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a persistent current switch is used in a cryogenic environment to energize superconducting magnets, then the magnet can be charged and operated in persistent mode, but energy is dissipated as heat in the switch requiring large, expensive switches or excessive cryogen consumption
Solution Approach 1:
The heat dissipation path is segmented into two distinct paths: a first heat exchange element that dissipates heat during the charging phase when the switch is resistive, and a second heat exchange element that maintains thermal contact during persistent mode operation. This segmentation allows optimized heat management for each operational phase, reducing overall energy loss and cryogen consumption.
Solution Approach 2:
The thermal connection between the persistent current switch and heat exchange elements is made dynamic rather than static. The switch is thermally coupled to the first heat exchange element during charging and to the second heat exchange element during persistent mode operation. This dynamic thermal coupling adapts to operational requirements, minimizing heat dissipation into the cryogenic environment when not needed.
2Temperature
If refrigeration systems are used to remove heat from the cryogenic environment, then heat can be removed from the persistent current switch, but the systems are inefficient at very low temperatures requiring large, expensive switches
Solution Approach 1:
Heat exchange elements serve as thermal intermediaries between the persistent current switch and the cryogenic environment. These intermediaries facilitate efficient heat transfer during charging operations without requiring the persistent current switch itself to be oversized or complex. The heat exchange elements absorb and dissipate heat, protecting the switch from thermal stress while maintaining compact dimensions.
3Ease of operation
If the persistent current switch is heated to resistive mode temperature to allow charging, then current can flow to energize the magnet, but heat is transferred into the cryogenic environment requiring cooling
Solution Approach 1:
The heat dissipation function is segmented between two distinct heat exchange elements operating at different times. The first heat exchange element is specifically dedicated to handling heat loads during charging operations when the switch is in resistive mode. This temporal segmentation allows the switch to be heated for charging without imposing continuous heat load on the cryogenic environment, as the second heat exchange element takes over during persistent mode when no heating is required.
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 solution minimizes energy dissipation in the cryogenic environment, reducing the need for large switches and costly cryogens by efficiently managing heat through multiple heat exchange paths, thereby enhancing operational efficiency and cost-effectiveness.
Implementation Method 1
a convective heat dissipation loop thermally coupling the persistent current switch to a first heat exchange element
Implementation Method 2
a thermally conductive link thermally coupling the persistent current switch to a second heat exchange element
Implementation Method 3
a superconducting convection cooling loop disposed within the enclosure and connected to the second heat exchange element, the superconducting convection cooling loop having a cryogenic fluid disposed therein and being configured to cool the electrically conductive coil to the superconducting temperature
Data Source
Figure 1~2
Figure 3
Figure 4
AI summary
An apparatus including a persistent current switch of a superconducting material which is electrically superconducting at a superconducting temperature and electrically resistive at a resistive mode temperature which is greater than the superconducting temperature. The apparatus further includes a first heat exchange element; a convective heat dissipation loop thermally coupling the persistent current switch to the first heat exchange element; a second heat exchange element spaced apart from the first heat exchange element; and a thermally conductive link thermally coupling the persistent current switch to the second heat exchange element. The first heat exchange element is disposed above the persistent current switch. The thermally conductive link may have a greater thermal conductivity at the superconducting temperature than at a second temperature which is greater than the superconducting temperature.