Alternating Channel PCM Cooling System for Aircraft Weight Reduction

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Solution Overview

Problem

Conventional shell-and-tube heat-exchangers are heavy and inefficient for cooling systems in aircraft, particularly when using phase change materials with low thermal conductivity, making them unsuitable for airborne applications where weight reduction is critical.

Innovation Solution

A cooling system comprising an array of plates with alternating channels, a conduit system, and a phase change material, where the coolant is circulated through one type of channel and the phase change material is located in another, using seals to prevent mixing, and employing materials like paraffin wax, eutectics, or hydrogen peroxide and water for effective heat transfer.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Weight of moving object

If a conventional shell-and-tube heat-exchanger is used, then cooling capability is provided, but weight increases to an unacceptable level

Engineering Contradiction:

Improveweight of cooling systemVSAvoidcooling capability

Core Design Contradiction:

Weight of moving objectVSReliability

Solution Approach 1:

The cooling system is segmented into alternating channels: first-type channels for coolant flow and second-type channels for phase change material, separated by plates. This segmentation allows independent optimization of each channel's function while reducing overall system weight compared to conventional shell-and-tube designs.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent utilizes phase change material (PCM) that transitions between solid and liquid phases to absorb and release heat. The PCM in second-type channels undergoes phase transitions to provide cooling, replacing heavy conventional heat exchanger components with a lighter phase-change-based system that maintains cooling capability.

Inventive Principle:

Principle #36Phase transitions

2Device complexity

If phase change material with low thermal conductivity is used, then system complexity is reduced, but thermal transfer efficiency deteriorates

Engineering Contradiction:

Improvesystem complexityVSAvoidthermal transfer efficiency

Core Design Contradiction:

Device complexityVSLoss of energy

Solution Approach 1:

Metal foam is introduced as an intermediary material within the phase change material channels. The metal foam serves as a thermal conductor that bridges the low thermal conductivity limitation of PCM, enhancing heat transfer between the coolant channels and phase change material without requiring complex active control systems.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The system uses composite construction by combining phase change material with metal foam matrix. This composite structure leverages the high latent heat storage capability of PCM while the metal foam provides thermal conductivity pathways, achieving both simplified system design and improved thermal transfer efficiency.

Inventive Principle:

Principle #40Composite materials

3Loss of energy

If foam metal is incorporated to improve thermal transfer, then thermal conductivity increases, but system weight increases

Engineering Contradiction:

Improvethermal transfer efficiencyVSAvoidsystem weight

Core Design Contradiction:

Loss of energyVSWeight of moving object

Solution Approach 1:

The patent employs porous metal foam material with controlled porosity (typically 70-90% void space) filled with phase change material. The porous structure provides sufficient thermal conductivity through the metal skeleton while the majority volume is occupied by low-density PCM, achieving improved heat transfer without proportionally increasing system weight.

Inventive Principle:

Principle #31Porous materials

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 configuration enables efficient cooling with reduced weight and size, allowing for lighter cooling systems that can handle non-constant heat sources, such as directed energy weapons, while maintaining effective thermal transfer and minimizing component count.

Implementation Method 1

the phase change material may be located within the number of the second type of channels

Methodology Applied

Scientific EffectPhase change: Phase Change

Implementation Method 2

A number of conventional heat-exchangers exist that may be used as phase change heat exchangers

Methodology Applied

Scientific EffectLatent heat: Latent Heat

Implementation Method 3

The conduit system may be capable of circulating coolant through the number of the first type of channels

Methodology Applied

Scientific EffectConvection: Convection

Implementation Method 4

A shell-and-tube heat exchanger may not provide effective thermal transfer to and from a phase change material

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Data Source

PatentUS7859845B2Phase change material cooling system

Publication Date: 2010.12.28 THE BOEING CO

AI summary

A cooling system may comprise an array of plates, an array of channels, a conduit system, and a phase change material. The array of channels may have a number of a first type of channels alternating with a number of a second type of channels. The conduit system may be capable of circulating coolant through the number of the first type of channels. The phase change material may be located within the number of the second type of channels.