Ceramic Heat Transfer Ducts for High Power Density Generator Cooling

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

High power density electrical machines generate excessive heat due to high current density, making it difficult to remove heat efficiently, which can lead to insulation breakdown and machine failure, as existing cooling methods like hollow strands, natural/forced convection, and indirect liquid cooling are insufficient.

Innovation Solution

A generator with a hollow heat transfer duct thermally coupled to the armature structure, made from materials with high thermal conductivity (at least 20 W/mK) and electrical breakdown strength (at least 60 V/mil), allowing efficient heat transfer while providing electrical insulation, potentially using ceramic materials like alumina and epoxy for enhanced thermal and mechanical performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If high power density is increased to reduce size and weight, then power density is improved, but heat generation increases making heat removal difficult

Engineering Contradiction:

Improvepower densityVSAvoidheat generation

Core Design Contradiction:

PowerVSTemperature

Solution Approach 1:

The patent introduces a ceramic tube as an intermediary heat transfer component between the conductor and coolant. The tube conducts heat away from the conductor while providing electrical insulation, solving the dual problem of heat removal and electrical isolation in high power density machines

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent uses ceramic materials that combine high thermal conductivity with high electrical insulation properties. This composite material approach allows the heat transfer duct to simultaneously conduct heat efficiently while blocking electrical current, resolving the contradiction between heat removal and electrical isolation

Inventive Principle:

Principle #40Composite materials

2Temperature

If indirect liquid cooling with metal tubes is used, then heat removal is improved, but insulation requirements increase tube wall thickness adding weight

Engineering Contradiction:

Improveheat removal efficiencyVSAvoidtube wall thickness

Core Design Contradiction:

TemperatureVSWeight of stationary object

Solution Approach 1:

The patent replaces metal tubes with ceramic tubes that inherently provide both thermal conduction and electrical insulation. This eliminates the need for thick insulating wall sections, reducing tube wall thickness while maintaining both heat removal efficiency and electrical isolation

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent changes the material parameter from metal to ceramic, which fundamentally alters the thermal and electrical properties. Ceramic materials have high thermal conductivity combined with high electrical resistivity, allowing thin-walled tubes to achieve both effective heat removal and sufficient electrical insulation

Inventive Principle:

Principle #35Parameter changes

3Loss of energy

If smaller conductor diameters are used to minimize AC losses, then AC losses are reduced, but heat removal from conductors becomes more difficult

Engineering Contradiction:

ImproveAC lossesVSAvoidheat removal difficulty

Core Design Contradiction:

Loss of energyVSTemperature

Solution Approach 1:

The ceramic heat transfer duct acts as an intermediary that directly contacts the small-diameter conductors and conducts heat away efficiently. The duct's high thermal conductivity compensates for the reduced conductor surface area, maintaining effective heat removal despite smaller conductor sizes

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent replaces traditional mechanical cooling approaches with a thermally conductive ceramic duct system. This substitution provides more efficient heat transfer pathways that are particularly effective for small-diameter conductors where conventional cooling methods become less effective

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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

The solution enables effective heat removal from high power density machines, reducing the risk of insulation breakdown and machine failure by utilizing materials with high thermal conductivity and electrical insulation properties, allowing for thinner, lighter designs that maintain efficient cooling.

Implementation Method 1

heat is conducted through various paths to reach the liquid coolant... The hollow heat transfer duct comprises a material having a thermal conductivity of at least 20 W/mK

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 2

electrical insulation between strands, between turns, and between coils are necessary... electrical breakdown strength of at least 60 V/mil

Methodology Applied

Scientific EffectElectrical insulation: Dielectric

Data Source

PatentUS7969049B2High power density cooling of electrical machines using ceramic tubes of high thermal conductivity

Publication Date: 2011.06.28 GENERAL ELECTRIC CO

AI summary

A high power density generator contains an armature structure having a plurality of conductors and at least one heat transfer tube thermally coupled to the conductors. The tube is hollow so as to allow a heat transfer fluid to pass through it. The tube is made of a material having a thermal conductivity λ of at least 20 W/mK, an electrical breakdown strength of at least 60 V/mil, and a mechanical strength adequate for handling, manufacturing and operation. In an embodiment of the invention, the tube is made of a ceramic material.