Solid-State Martensitic Phase Change Materials for Thermal Storage

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Solution Overview

Problem

Current thermal energy storage systems using solid-to-liquid phase change materials face challenges with low thermal conductivity, requiring encapsulation and additives that reduce the mass and volume of active PCM material, limiting their efficiency in compact thermal energy storage applications.

Innovation Solution

The use of solid-solid Martensitic transformation phase change materials that undergo a reversible or irreversible crystalline structure change with temperature, eliminating the need for encapsulation and enhancing thermal conductivity, allowing for high volumetric latent heat storage without voids or phase segregation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If solid-to-liquid phase change materials are used for thermal energy storage, then high thermal capacitance is achieved, but low thermal conductivity limits heat transfer efficiency

Engineering Contradiction:

Improvethermal capacitanceVSAvoidheat transfer efficiency

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The patent uses composite materials combining phase change material with graphite particles or expanded graphite to enhance thermal conductivity. The graphite additive creates conductive networks within the PCM matrix, allowing efficient heat transfer while maintaining the high thermal capacitance of the phase change material.

Inventive Principle:

Principle #40Composite materials

2Reliability

If encapsulation and thermal conductivity additives are added to solid-to-liquid PCMs, then heat transfer is enhanced, but the mass and volume of active PCM material are reduced

Engineering Contradiction:

Improveheat transfer efficiencyVSAvoidactive PCM material

Core Design Contradiction:

ReliabilityVSQuantity of substance

Solution Approach 1:

The patent merges the phase change material with graphite particles or expanded graphite to form a composite where the additive serves dual purposes: enhancing thermal conductivity and providing structural support. This eliminates the need for separate encapsulation materials, maximizing the volume of active PCM material.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent utilizes expanded graphite's porous structure to create a three-dimensional conductive network within the PCM. This porous structure provides extensive surface area for heat transfer while maintaining high PCM content, as the graphite framework supports the PCM without requiring additional encapsulation materials.

Inventive Principle:

Principle #31Porous materials

3Power

If metallic fin structures or high thermal conductivity additives are used, then power is increased, but module capacity is reduced

Engineering Contradiction:

Improveheat transfer powerVSAvoidPCM material

Core Design Contradiction:

PowerVSQuantity of substance

Solution Approach 1:

The patent creates a composite material where graphite particles or expanded graphite are distributed within the PCM matrix. This composite structure provides thermal conductivity enhancement throughout the entire volume of PCM, rather than requiring separate metallic fin structures that would displace PCM material. The result is high heat transfer power with maximum PCM content.

Inventive Principle:

Principle #40Composite 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 approach provides efficient thermal energy storage and transient thermal management by eliminating the need for encapsulation and additives, offering higher thermal conductivity and volumetric latent heat compared to traditional solid-liquid PCMs, enabling more compact and efficient thermal energy storage systems.

Implementation Method 1

solid state Martensitic transformation phase change material which is configured to readily undergo a solid-solid martensitic transformation from one crystalline structure to another different crystalline structure during a change in temperature

Methodology Applied

Scientific EffectMartensitic transformation: Phase Change

Implementation Method 2

enhancing thermal conductivity

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Data Source

PatentUS12071583B2Solid state martensitic transformation phase change material components for thermal energy storage and transient heat transfer systems

Publication Date: 2024.08.27 UNITED STATES OF AMERICA THE AS REPRESENTED BY THE SEC OF THE ARMY

AI summary

A heat exchange component includes a part configured for exchanging thermal energy, the part is formed of at least one solid state Martensitic transformation phase change material which is configured to readily undergo a solid-solid martensitic transformation from one crystalline structure to another different crystalline structure during a change in temperature in the normal and/or anticipated operating temperatures of the heat exchange component. In some embodiments, the system further includes a temporally-evolving external temperature/heat source which changes the temperature and resultant phase of the solid-state phase change material. The temporally-evolving external temperature/heat source may involve a solid conducting material or electronic/photonic component, a fluid, a plasma, and/or a radiation source. The heat exchange component may be configured as a flat plate, tube, finned structure, porous structure, graded structure, cold plate, heat exchanger, condenser, evaporator, or any component generally regarded as a thermal energy storage or heat transfer structure in various embodiments.