Two-Stage Cryocooler Method to Accelerate Cool Down Time
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Solution Overview
Problem
Cryogenic systems, such as MRI systems, require extended periods to cool to operational temperatures using conventional cryocoolers, leading to inefficiencies and increased costs due to prolonged downtime before they can be used or tested.
Innovation Solution
A method involving a two-stage cooling process where a single-stage cryocooler initially cools a target member to a higher temperature with greater cooling power than the cryocooler, followed by a cryocooler taking over to reach the operational temperature, significantly reducing the overall cooling time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If a single-stage cryocooler is used to cool the target member, then the cooling time is reduced initially, but the target member cannot reach the required operational temperature
Solution Approach 1:
The cooling process is divided into two distinct stages: a first cooling stage using a single-stage cryocooler to rapidly reduce temperature from ambient to an intermediate temperature range (e.g., 50K-150K), and a second cooling stage using a two-stage cryocooler to further cool from the intermediate temperature to the final operational temperature (e.g., 4K). This segmentation allows each cryocooler type to operate in its optimal temperature range, achieving both speed and depth of cooling.
2Temperature
If a two-stage cryocooler is used to cool the target member, then the required operational temperature is achieved, but the total cooling time increases to two or more weeks
Solution Approach 1:
The single-stage cryocooler performs preliminary cooling action first, rapidly reducing the target member's temperature from ambient conditions to an intermediate temperature range where the two-stage cryocooler becomes effective. This preliminary action removes the bulk of the thermal load before the more complex two-stage system engages, significantly reducing the total time required to reach operational temperature.
3Temperature
If cryogens are used to cool the cryogenic system, then the target temperature is achieved, but the system complexity and operational constraints increase
Solution Approach 1:
The invention replaces the traditional cryogen-based cooling system (which requires liquid nitrogen or liquid helium baths, transfer mechanisms, and associated safety infrastructure) with a mechanical cryocooler system. The cryocoolers use solid-state or gas-based refrigeration cycles to achieve the same cooling effect without requiring large quantities of cryogenic fluids, thereby reducing system complexity and operational constraints.
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 method halves the time required to cool a cryogenic system, allowing it to become operational faster and reducing equipment needs by simultaneous cooling of the target member and radiation shields.
Implementation Method 1
cooling a target region of a cryogenic system with a first cooling apparatus, the first cooling apparatus being adapted to cool the target region to a first temperature by thermal conduction between the first apparatus and the target member
Implementation Method 2
cooling the target member of the cryogenic system from the first temperature to an operating temperature using a cryocooler
Data Source
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AI summary
The present invention provides a method of accelerating cool down of a target member of a cryogenic system to a cryogenic operating temperature. The method comprises the steps of cooling a target region of a cryogenic system with a first cooling apparatus, the first cooling apparatus being adapted to cool the target region to a first temperature by thermal conduction between the first apparatus and the target member, and having a first cooling power at the first temperature; and cooling the target member of the cryogenic system from the first temperature to an operating temperature using a cryocooler, where the first cooling power of the first cooling apparatus at the first temperature is greater than the cooling power of the cryocooler at the first temperature. This allows a target member of a cryogenic system to be cooled more rapidly than when conventional methods are used.