Cryocooler Heat Transfer Coupling Using Thermal Shrink-Fit Contact
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Solution Overview
Problem
Existing cryocooler installations face challenges in achieving efficient mechanical and thermal connections, particularly in conduction-cooled superconducting magnets, where limited accessibility and differential thermal expansion of materials complicate the formation and maintenance of reliable heat transfer couplings.
Innovation Solution
The design incorporates a cryohead heat transfer coupling with an annulus and flexible thermally conductive links and blocks, where the materials' thermal expansion coefficients differ, allowing for a 'shrink-fitting' mechanism that ensures intimate physical and thermal contact, reducing the need for bolts or screws and accommodating differential component size changes during cooling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional mechanical connections (bolts, screws, fittings) are used to connect the cryohead to the cryostat and target components, then the connection is mechanically strong and reliable, but the installation process becomes complex and time-consuming, and the thermal contact efficiency is compromised due to limited accessibility and material differential thermal expansion
Solution Approach 1:
The patent utilizes differential thermal expansion between materials with different coefficients of thermal expansion (CTE). The annulus is made from a material with a higher CTE than the post material. During cooling from room temperature to cryogenic temperatures, the annulus contracts more than the post, creating a shrink-fit effect that generates compressive pressure and ensures intimate thermal contact between the coupling components and the cryohead flange and target component, eliminating the need for complex mechanical fasteners
Solution Approach 2:
The patent replaces traditional mechanical connection systems (bolts, screws, fittings, clamps) with a thermal contraction-based shrink-fit mechanism. The differential thermal expansion creates self-generating compressive forces that maintain reliable mechanical and thermal contact without requiring external fastening hardware, thereby simplifying the installation process and improving thermal contact efficiency
2Stability of the object's composition
If rigid mechanical connections are used to maintain thermal contact, then the structural stability is good, but the accommodation of differential component size changes during cooling is poor, leading to contact loss or stress concentration
Solution Approach 1:
The patent employs materials with different coefficients of thermal expansion (CTE) for the annulus and post. The annulus material has a higher CTE, causing it to contract more than the post during cooling. This differential contraction creates a shrink-fit effect that maintains structural stability while accommodating thermal size changes, generating compressive pressure that ensures continuous intimate contact between components throughout the temperature range
Solution Approach 2:
The patent changes the physical parameters of the materials selected for the annulus and post, specifically choosing materials with different CTE values. This parameter selection enables the system to adapt to thermal contraction during cooling while maintaining structural integrity and stable thermal contact, transforming the thermal contraction from a potential problem into a beneficial self-compressing mechanism
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 enables efficient heat transfer by maintaining compressive pressure and intimate contact between the cryohead and the article to be cooled, even under varying thermal conditions, facilitating easier assembly and maintenance while maintaining a vacuum seal.
Implementation Method 1
the socket parts, that are made from materials that as a whole contract more than the materials of the post, contract and compress over the post parts and produce mechanical-thermal connection desired for good conduction cooling
Implementation Method 2
heat removal by the cryohead is achieved inside a vacuum chamber, commonly called a cryostat, through conduction by means of physical contacts with the target components of the superconducting magnet
Data Source
AI summary
Embodiments for a cryohead heat transfer coupling as well as methods for extracting heat from an article using these couplings are provided. Couplings employ a component made from a material having a greater mean thermal coefficient of expansion than the mean thermal coefficient of expansion of other coupling components and of the article. As a result, differential contraction during cryocooling contributes a shrink fitting of a portion of the coupling resulting in enhanced thermal conduction when cooling and a releasing of the coupling when ambient temperature is restored.