V(1-X)CrXO2 Electronic Phase Transition Heat Storage

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Solution Overview

Problem

Current heat storage materials face challenges such as low thermal conductivity, volume changes during phase transitions, and potential phase separation or decomposition, which affect their ability to maintain constant surface temperature and store heat efficiently.

Innovation Solution

A heat storage material utilizing V(1-X)CrXO2, which undergoes electronic phase transitions with multiple degrees of freedom, including spin and orbital degrees, is developed, offering high thermal conductivity, minimal volume change, and no phase separation or decomposition, with the ability to adjust phase transition temperature by varying the value of X.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If organic materials like paraffin are used for latent heat storage, then large enthalpy changes are achieved, but thermal conductivity is low causing large temperature difference between surface and interior

Engineering Contradiction:
Improveenthalpy changeVSAvoidtemperature uniformity
Core Design Contradiction:
Use of energy by moving objectVSTemperature

Solution Approach 1:

The invention changes the fundamental parameter of phase transition type from solid-liquid to electronic phase transition. This transforms the material's thermal properties, achieving high thermal conductivity (comparable to metals) while maintaining large enthalpy changes, thereby resolving the contradiction between energy storage capacity and temperature uniformity.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The invention creates a composite functional state by combining high thermal conductivity (typically metallic) with large enthalpy change (typically associated with phase transitions). The electronic phase transition material exhibits both properties simultaneously, effectively creating a composite-like performance from a single material system.

Inventive Principle:
Principle #40Composite materials

2Use of energy by moving object

If inorganic salt hydrates are used for latent heat storage, then large enthalpy changes are achieved, but volume changes during phase transitions cause liquid leakage

Engineering Contradiction:
Improveenthalpy changeVSAvoidvolume stability
Core Design Contradiction:
Use of energy by moving objectVSStability of the object's composition

Solution Approach 1:

The invention changes the phase transition mechanism from solid-liquid transition (which involves large volume changes and potential leakage) to electronic phase transition (which occurs within the solid state). This parameter change eliminates volume expansion/contraction issues and liquid leakage while preserving large enthalpy changes through electronic degree of freedom transitions.

Inventive Principle:
Principle #35Parameter changes

3Use of energy by moving object

If conventional heat storage materials are used, then heat storage effect is achieved, but phase separation or decomposition occurs during phase transitions

Engineering Contradiction:
Improveheat storage effectVSAvoidphase stability
Core Design Contradiction:
Use of energy by moving objectVSReliability

Solution Approach 1:

The invention changes the phase transition type to electronic phase transition, which involves transitions in electronic degrees of freedom (spin, orbital) rather than structural rearrangements. This eliminates the mechanisms that lead to phase separation and decomposition, ensuring material reliability and stability during repeated cycling while maintaining heat storage effectiveness.

Inventive Principle:
Principle #35Parameter changes

4Use of energy by moving object

If solid-liquid phase transition materials are used, then large enthalpy changes are achieved, but container must withstand large volume changes

Engineering Contradiction:
Improveenthalpy changeVSAvoidvolume stress
Core Design Contradiction:
Use of energy by moving objectVSStress or pressure

Solution Approach 1:

The invention changes the phase transition from solid-liquid (involving large volume changes) to electronic phase transition (occurring within solid state with minimal volume change). This eliminates the need for specialized containers designed to withstand large volume stresses, simplifying the overall system while preserving large enthalpy changes.

Inventive Principle:
Principle #35Parameter changes

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 material provides a novel heat storage solution with high thermal conductivity and stable phase transitions, enabling efficient heat storage and retrieval at desired temperatures, surpassing the limitations of existing materials like inorganic salt hydrates and organic materials.

Implementation Method 1

a substance that induces an electronic phase transition, wherein the electronic phase transition is a phase transition (associated) with multiple degrees of freedom including a spin degree of freedom and an orbital degree of freedom

Methodology Applied
Scientific EffectElectronic phase transition: Phase Change

Implementation Method 2

the substance exhibiting such phase transition has high thermal conductivity

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Data Source

PatentEP2987841B1Heat storage material
Publication Date: 2018.07.11 RIKEN CO LTD
  • EP2987841B1 patent drawingFigure 1
  • EP2987841B1 patent drawingFigure 2
  • EP2987841B1 patent drawingFigure 3(a)~3(b)

AI summary

The heat storage material of the present invention is a heat storage material comprising a substance that induces an electronic phase transition, wherein the electronic phase transition is a phase transition of multiple degrees (associated) with freedom including a spin degree of freedom and an orbital degree of freedom, which are internal degrees of freedom of electrons, and the substance is V(1-X)CrXO2 (0<X≤0.23).