Re-entrant Ends for Superconducting Machine Heat Leak Reduction

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Solution Overview

Problem

Superconducting electrical machines face significant challenges in maintaining low temperatures due to high heat transfer rates, requiring complex and expensive sealing and vacuum pumping systems, as well as cryocoolers that consume substantial power.

Innovation Solution

The design incorporates re-entrant ends with continuous segments in the rotor and stator, which provide thermal resistance to heat transfer, increasing the pathway for heat conduction and reducing the rate of heat transfer, thereby minimizing the energy required for cryocooling and reducing operational costs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If complex sealing and vacuum pumping systems are used to maintain low temperatures, then superconducting temperatures are maintained, but device complexity and cost increase

Engineering Contradiction:

Improvesuperconducting temperatureVSAvoidsealing and vacuum pumping systems

Core Design Contradiction:

TemperatureVSDevice complexity

Solution Approach 1:

The rotor and stator are divided into multiple segments (first rotor segment, second rotor segment, first stator segment, second stator segment) that are continuous with adjacent segments. This segmentation creates a re-entrant end structure that provides thermal resistance while maintaining structural integrity, reducing the need for complex sealing systems.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The re-entrant end structure acts as an intermediary element between the high-temperature environment and the superconducting components. It provides thermal resistance and extends the heat conduction pathway, serving as a thermal barrier that protects the superconducting windings without requiring complex active cooling systems.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Temperature

If cryocoolers are used to obtain superconducting coolant temperatures, then superconductivity is achieved, but power consumption increases significantly

Engineering Contradiction:

Improvecoolant temperatureVSAvoidpower consumption

Core Design Contradiction:

TemperatureVSUse of energy by moving object

Solution Approach 1:

The re-entrant end structure converts the harmful heat transfer into a beneficial extended heat conduction pathway. By increasing the path length and adding thermal resistance, it naturally reduces heat leak into the superconducting components, decreasing the cooling load on cryocoolers and their power consumption.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The invention changes the thermal parameters of the system by introducing a re-entrant end structure with specific geometric parameters (radial and axial dimensions). This structural parameter change increases thermal resistance and extends heat conduction path length, reducing the heat transfer rate and thereby reducing the energy required for cryocooling.

Inventive Principle:

Principle #35Parameter changes

3Loss of energy

If re-entrant ends with continuous segments are used to increase thermal resistance, then heat transfer rate is reduced, but structural flexibility requirements increase

Engineering Contradiction:

Improveheat transfer rateVSAvoidstructural flexibility

Core Design Contradiction:

Loss of energyVSAdaptability or versatility

Solution Approach 1:

The re-entrant end structure is designed to accommodate thermal expansion and contraction of the superconducting components during cooling and operation. The continuous segments allow for dynamic adjustment and flexibility, enabling the structure to adapt to dimensional changes while maintaining thermal resistance and structural integrity.

Inventive Principle:

Principle #15Dynamics

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 effectively maintains superconducting temperatures while reducing the energy needed for cryocooling, enhancing the efficiency and cost-effectiveness of superconducting electrical machines by increasing thermal resistance and accommodating structural flexibility.

Implementation Method 1

Heat distal from the rotor winding encounters thermal resistance provided by the at least one re-entrant end as the heat travels towards the rotor winding

Methodology Applied

Scientific EffectThermal resistance: Conduction (thermal)

Data Source

PatentUS10077955B2Superconducting electrical machine with double re-entrant ends for minimizing heat leak

Publication Date: 2018.09.18 KATO ENG CO

AI summary

A superconducting electrical machine includes at least one re-entrant end including at least two segments. The at least two segments are continuous. At least one re-entrant end may be included in a stator of the superconducting electrical machine, the stator being disposed substantially coannular with a longitudinal axis. At least one re-entrant end may also be included in a rotor of the superconducting electrical machine, the rotor being configured to rotate about a longitudinal axis. A first segment is substantially perpendicular to a plane parallel to the longitudinal axis, and a second segment is coannular with the longitudinal axis. Heat distal from rotor windings and/or stator windings encounters a thermal resistance provided by the at least two segments as the heat travels towards the rotor windings and/or stator windings.