MRI Cryogenic Cooling with Switched Dual Cryocoolers
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Solution Overview
Problem
Conventional magnetic resonance devices with cryocoolers require excessive time for cooling superconducting magnet coils from room temperature to operating temperature, and existing pre-cooling methods are impractical for customer installations.
Innovation Solution
A cryogenic system with a switching device that controls a second cryocooler to operate only when high cooling capacity is needed, using a heat switch to thermally connect and disconnect components based on temperature thresholds, enhancing cooling efficiency and reducing operational costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single cryocooler is used to cool superconducting magnet coils, then the system structure is simple, but the cooling time from room temperature to operating temperature is excessively long (up to 120 days for 7.0 T device)
Solution Approach 1:
The cooling system is segmented into two independent cryocoolers with different functions: a first cryocooler for pre-cooling from room temperature to intermediate temperature, and a second cryocooler for final cooling to operating temperature. This segmentation allows each cryocooler to operate in its optimal temperature range, dramatically reducing total cooling time while maintaining manageable system complexity.
Solution Approach 2:
The first cryocooler performs preliminary cooling action to reduce the temperature of the magnet coils from room temperature to an intermediate temperature range before the second cryocooler takes over. This preliminary action removes the majority of the thermal load, allowing the second cryocooler to reach operating temperature much faster than if it started from room temperature.
2Productivity
If a second cryocooler is added to reduce cooling time, then the cooling capacity is increased, but the operational costs increase due to continuous operation of multiple cryocoolers
Solution Approach 1:
The second cryocooler operates periodically rather than continuously - it is activated only during high-demand periods such as initial cooling, quench recovery, or when additional cooling capacity is required. During normal operation, only the first cryocooler runs, significantly reducing operational energy costs while maintaining the ability to provide high cooling capacity when needed.
Solution Approach 2:
The system dynamically adjusts the number of active cryocoolers based on real-time cooling demands. The control system monitors temperature and cooling requirements, activating the second cryocooler only when necessary, thereby optimizing the balance between cooling capacity and operational energy consumption.
3Loss of time
If pre-cooling loops with liquid nitrogen are used at production sites, then the cooling time is reduced, but the method is not practical for customer site installations
Solution Approach 1:
The cryogenic system is self-sufficient with integrated cryocoolers that do not require external liquid cryogen infrastructure. The system performs its own pre-cooling and final cooling operations using the first and second cryocoolers, eliminating the need for customer sites to have liquid nitrogen storage and handling capabilities, thereby greatly simplifying installation and 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
The system significantly reduces cooling time for superconducting magnets, potentially by a factor of 2.5 to 3, while minimizing operational costs by selectively activating the second cryocooler during high-demand periods.
Implementation Method 1
a first cryocooler thermally connected to the at least one superconducting magnet
Implementation Method 2
using a heat switch to thermally connect and disconnect components based on temperature thresholds
Implementation Method 3
a second cryocooler configured to cool a component of the magnet arrangement in dependence of the switching device
Implementation Method 4
superconducting magnet coils comprising low temperature superconducting materials typically exhibit superconducting temperatures below 5 K
Data Source
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AI summary
The invention relates to a cryogenic system (30) for a magnetic resonance device (10), comprising a magnet arrangement (11) including at least one superconducting magnet (12), a first cryocooler (31a) thermally connected to the at least one superconducting magnet (12), a switching device (38), and a second cryocooler (31b) configured to cool a component of the magnet arrangement (11) in dependence of the switching device (38), wherein the switching device (38) is configured to enable cooling of the component of the magnet arrangement (11) via the second cryocooler (31b) when a temperature of the component of the magnet arrangement (11) exceeds a predefined temperature level, and to disable cooling of the component of the magnet arrangement (11) via the second cryocooler (31b) when the temperature of the component of the magnet arrangement (11) is below the predefined temperature level. The invention further relates to a magnetic resonance device (10), comprising an inventive cryogenic system (30).