Annular Cryocooler Layout for Shorter Rotor Cooling Paths
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Solution Overview
Problem
Integrating cryocoolers into a spinning rotor of superconducting motors is challenging due to alignment issues, weight, and complexity, particularly for larger rotors, which limits practical use and increases cooling path length.
Innovation Solution
The cryocooler is designed in an annular form with a central hollow bore, allowing for multiple cryocoolers in a concentric arrangement, providing improved diameter-to-length ratio without proportional weight gain, and facilitating passage for power conduits and direct wire connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If cryocoolers are integrated into the rotor, then cooling capability is improved, but weight and complexity increase
Solution Approach 1:
The cryocooler is nested within the hollow bore of the rotor shaft, utilizing the existing hollow space. This allows the cryocooler to be integrated without adding external bulk or proportional weight increase to the rotor assembly
Solution Approach 2:
The cryocooler is oriented with its cooling axis aligned with the rotor spin axis, transitioning from a conventional transverse mounting to an axial configuration. This dimensional change optimizes space utilization and reduces the cryocooler's susceptibility to bending torques during rotation
2Temperature
If cryocoolers are mounted on the shaft, then cooling capability is improved, but device complexity increases
Solution Approach 1:
The hollow bore of the rotor shaft serves multiple functions: it provides structural support for the rotor, accommodates the cryocooler integration, and allows passage for power conductors. This multi-functionality reduces the need for separate components and simplifies the overall system architecture
Solution Approach 2:
The cooling system is segmented into modular components (cryocooler, heat exchangers, insulation layers) that can be independently designed, installed, and maintained within the hollow bore, reducing overall system complexity
3Temperature
If conventional cryocooler mounting is used, then cooling capability is provided, but heat transfer path length increases
Solution Approach 1:
The cryocooler is pre-positioned with its cold end extending into the rotor hub where the superconducting coils are located. This preliminary positioning minimizes the thermal conduction path length from the cryocooler to the coils, reducing heat transfer resistance and improving cooling efficiency
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 design enhances efficiency and reduces weight by allowing for multiple cryocoolers and direct wire connections, minimizing heat transfer, and simplifying cooling paths in superconducting machines.
Implementation Method 1
superconducting coils to provide improved efficiency and lighter weight
Implementation Method 2
The substantial demands of standard cryogenic cooling sufficient to cool such motors
Implementation Method 3
confining the cooling to a thermally isolated rotor (which may be isolated in a rotor-specific vacuum envelope)
Data Source
AI summary
A cryocooler useful for superconducting electrical machines provides an annular construction offering greater stiffness and a shorter conduction path length to superconducting coils as well the ability to provide serial and parallel assemblies of cryocoolers and passageways for ancillary power conductors.