Cryocooler Servicing in Sealed MRI Cryogenic Assemblies
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Solution Overview
Problem
Conventional MRI system servicing methods require shutting down the superconducting magnet, leading to significant cryogen loss, increased downtime, and high maintenance costs due to exposure to room temperature air and thermal conduction, which can cause quench events and ice formation, reducing efficiency and safety.
Innovation Solution
A method involving breaking the thermal connection between the cryocooler and thermal shield, maintaining the cryogenic region sealed, and heating the cryocooler while keeping the superconducting magnet energized, to reduce heating energy consumption and prevent ice formation, allowing for reduced downtime and cost-effective maintenance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of repair
If the cryocooler is serviced by removing it from the MRI system and exposing it to room temperature air, then the cryocooler can be accessed for maintenance, but ice formation occurs and system downtime increases
Solution Approach 1:
The patent divides the MRI system into separable components, allowing the cryocooler to be removed and serviced independently while the superconducting magnet remains in place. This segmentation enables maintenance of the cryocooler without requiring system shutdown or magnet ramp-down, thus reducing downtime while still providing access for repair.
2Reliability
If the superconducting magnet is ramped down to zero field for servicing, then safety is improved by preventing quench events, but cryogen loss increases and downtime increases
Solution Approach 1:
The patent extracts the cryocooler from the cryogenic environment and services it separately, while the superconducting magnet remains energized in its operational state. This allows servicing to be performed on the cryocooler without requiring the magnet to be ramped down, thereby preventing quench events and avoiding associated cryogen losses while maintaining magnet reliability.
3Ease of operation
If the cryocooler is exposed to room temperature air during servicing, then access for maintenance is improved, but ice formation occurs reducing efficiency
Solution Approach 1:
The patent performs preliminary heating of the cryocooler housing to above the freezing point of water before removing the cryocooler from the cryogenic region. This preliminary action prevents ice formation on the cryocooler components during subsequent exposure to room temperature air, ensuring that cooling efficiency is maintained after the cryocooler is reinstalled and cooled down.
4Stability of the object's composition
If thermal connection between cryocooler and thermal shield is maintained during heating, then structural stability is improved, but heating energy consumption increases
Solution Approach 1:
The patent dynamically adjusts the thermal connection between the cryocooler and thermal shield during the servicing process. The thermal connection is broken when the cryocooler needs to be heated, allowing energy-efficient heating without unnecessary thermal losses to the thermal shield. The connection can be reestablished when needed for structural support, optimizing both energy consumption and structural stability throughout the servicing sequence.
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 minimizes cryogen loss, reduces downtime, and maintains system efficiency by keeping the cryogenic region sealed during servicing, preventing quench events and ice formation, thus enhancing safety and cost-effectiveness.
Implementation Method 1
heating the housing to a temperature above the freezing point of water
Implementation Method 2
The bellows seal may be attached to the outer wall and allow relative movement between the housing and the outer wall
Implementation Method 3
The transitional wall can be thermally connected to the thermal shield using a thermally conductive element
Data Source
AI summary
A method can be used to perform an operation on a system that includes an assembly and a vessel that includes a wall and a thermal shield. The method can include breaking a thermal connection between the assembly and the thermal shield, separating the assembly and a surface within the vessel from each other, or any combination thereof. The method can also include changing a pressure with the vessel to be closer to atmospheric pressure, heating the assembly, or any combination thereof. In one embodiment, the method can be performed while keeping a cryogenic region substantially sealed, keeping a superconducting magnet energized, or a combination thereof. In a particular embodiment, the method can be used when servicing the assembly, such as a cryocooler.