Cold-Crystallizing PCM for Stable Long-Term Heat Storage

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Solution Overview

Problem

Current long-term heat storage solutions face challenges with metastability of supercooled phase change materials leading to spontaneous crystallization and inefficient heat release, particularly in large-scale applications, where heat storage is needed for extended periods with minimal energy loss.

Innovation Solution

A cold-crystallizing material composition comprising a phase change material and an additive, which stabilizes the supercooled state through increased viscosity and vitrification, allowing for repeatable heat storage and release via controlled heating, enabling efficient long-term heat storage without premature crystallization.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Duration of action of stationary object

If supercooled phase change materials are used for long-term heat storage, then heat energy can be stored for extended periods, but spontaneous crystallization occurs leading to premature heat release and loss of storage stability

Engineering Contradiction:
Improveheat storage durationVSAvoidstorage stability
Core Design Contradiction:
Duration of action of stationary objectVSReliability

Solution Approach 1:

The patent introduces an additive as an intermediary substance that modifies the phase change material system. This additive acts as a mediator to suppress spontaneous crystallization while maintaining the supercooled state, thereby preventing premature heat release and improving storage stability without compromising the long-term heat storage capability

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent changes the physical-chemical parameters of the phase change material by adding substances that increase viscosity and promote vitrification. This parameter change transforms the material properties to achieve a more stable supercooled state that resists spontaneous crystallization, enabling reliable long-term heat storage

Inventive Principle:
Principle #35Parameter changes

2Loss of energy

If phase change materials operate within narrow temperature ranges, then latent heat storage efficiency is improved, but the applicability is limited and requires precise temperature control

Engineering Contradiction:
Improvelatent heat storage efficiencyVSAvoidtemperature range applicability
Core Design Contradiction:
Loss of energyVSAdaptability or versatility

Solution Approach 1:

The patent employs parameter changes by modifying the phase change material composition to achieve a broader operational temperature window. The additive system allows the material to maintain its phase change properties across a wider temperature range, improving both energy storage efficiency and adaptability to different application conditions

Inventive Principle:
Principle #35Parameter changes

3Productivity

If common crystallization methods are used for heat release, then heat can be released from supercooled PCM, but the process lacks control and requires cooling or additional devices

Engineering Contradiction:
Improveheat release capabilityVSAvoidheat release system complexity
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The patent enables the phase change material system to serve itself by incorporating additives that allow controlled crystallization through simple heating. The material autonomously releases heat when heated above the cold-crystallization temperature without requiring external cooling systems, nucleation agents, or complex activation mechanisms, thereby simplifying the overall system design

Inventive Principle:
Principle #25Self-service

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 provides a stable and repeatable heat storage method with high latent heat capacity, allowing for efficient heat storage and release, suitable for both short-term and long-term applications, with improved stability and reduced energy loss over multiple cycles.

Implementation Method 1

Latent heat storages are based on utilization of latent heat of melting and crystallization of phase change materials (PCM)

Methodology Applied
Scientific EffectLatent heat of melting and crystallization: Latent Heat

Implementation Method 2

The present invention concerns a material composition that cold-crystallizes upon heating

Methodology Applied
Scientific EffectCold-crystallization: Crystallisation

Implementation Method 3

supercooling of a PCM in heat storing has also studied. By means of supercooling heat energy remains stored in a supercooled liquid for a longer term

Methodology Applied
Scientific EffectSupercooling: Supercooling

Implementation Method 4

stabilizes the supercooled state through increased viscosity and vitrification

Methodology Applied
Scientific EffectVitrification: Vitrification

Data Source

PatentEP3535342B1Cold-crystallizing material and method for utilizing cold-crystallization in heat storing
Publication Date: 2024.09.04 AALTO UNIV FOUND
  • EP3535342B1 patent drawingFigure 1

AI summary

The present invention relates to a cold-crystallizing material having high latent heat, and a method of using the present material for heat storing. The material of the invention comprises of a phase change material and an additive which is preferably a hydrophilic polymer matrix. Preferably, sugar alcohols, such as erythritol or D-mannitol, are used as the phase change material. The polymer of the invention is preferably cross-linked and ionic, i.e. a polyelectrolyte. PCM stores a high amount of heat energy while melting and releases the stored thermal energy by cold-crystallization. Compared to previously studied cold-crystallizing materials, the latent heat of the cold-crystallizing material of the invention is considerably higher, and cold-crystallization is more repeatable in successive melting-crystallization cycles. The material can be used for heat storing. Heat energy can be released from the material by a heat pulse on demand. The method is particularly suitable for long-term heat storing.