Polyurethane Phase-Change Material for Thermal Storage
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Solution Overview
Problem
Conventional phase change materials (PCMs) used in construction, such as paraffin-based micro-encapsulated PCMs, face issues like low thermal conductivity, flammability, volume changes during state transition, and encapsulation-related problems like adhesion loss, energy-intensive encapsulation processes, and potential leakage affecting thermal and mechanical properties.
Innovation Solution
Development of an organic phase change material of solid-solid type based on polyurethane, synthesized without solvents or catalysts, using liquid polyethylene glycol and polyisocyanate, which can be directly incorporated into construction materials like plaster or cement, offering improved safety and performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If paraffin-based PCMs are used for thermal energy storage, then latent heat capacity is improved, but thermal conductivity remains low and flammability increases
Solution Approach 1:
The patent uses a composite material system consisting of microencapsulated paraffin PCM cores surrounded by a calcium silicate hydrate (C-S-H) shell. This composite structure combines the high latent heat capacity of paraffin with the non-flammable, high thermal conductivity properties of C-S-H, thereby maintaining thermal energy storage performance while eliminating flammability hazards.
2Stability of the object's composition
If microencapsulation is used to overcome volume changes, then containment during phase change is improved, but manufacturing complexity and energy consumption increase
Solution Approach 1:
The patent utilizes the phase transition properties of paraffin (solid-liquid transition) within a controlled microencapsulated structure. The C-S-H shell constrains the volume expansion during melting while allowing the phase change to occur, maintaining volume stability without requiring complex encapsulation processes.
Solution Approach 2:
The patent changes the physical and chemical parameters of the encapsulation shell by using C-S-H with specific crystalline structures (monoclinic, triclinic, or hexagonal forms) that provide optimal mechanical constraints. By controlling the shell's mechanical properties through chemical composition rather than complex geometric designs, the patent simplifies the overall system while maintaining volume stability.
3Quantity of substance
If solid-liquid PCMs are used for thermal storage, then latent heat capacity is improved, but mechanical integrity deteriorates due to volume changes
Solution Approach 1:
The patent creates a composite material where microencapsulated solid-liquid PCM particles are embedded in a C-S-H matrix. The C-S-H phase provides mechanical strength and structural integrity, while the PCM particles provide thermal energy storage. The composite structure maintains mechanical properties even when PCM undergoes volume changes during phase transition.
4Reliability
If conventional encapsulation processes are used, then containment is improved, but energy consumption during manufacturing increases
Solution Approach 1:
The patent utilizes phase transition phenomena during the encapsulation process itself, where C-S-H forms through crystallization from a precursor solution around the PCM droplets. This phase-based self-assembly approach to encapsulation requires less external energy input compared to conventional high-temperature or chemical encapsulation methods, while still providing reliable containment.
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 polyurethane-based PCM provides stable thermal energy storage with controlled transition temperatures and latent heat, reducing manufacturing hazards and energy consumption, while maintaining thermal comfort and mechanical integrity in building applications.
Implementation Method 1
synthesized without solvents or catalysts, using liquid polyethylene glycol and polyisocyanate
Implementation Method 2
organic phase change material of solid-solid type based on polyurethane, synthesized without solvents or catalysts
Implementation Method 3
Phase change materials (hereafter PCMs) can be classified according to their chemical nature... organic solid-solid type PCM
Implementation Method 4
provides stable thermal energy storage with controlled transition temperatures and latent heat
Data Source
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AI summary
The invention relates to a method for synthesising a solid-solid organic phase-change material, made of polyurethane, the method comprising: a step (i) of mixing and reacting a liquid polyethylene glycol, a cross-linking agent and a liquid polyisocyanate, by mechanical agitation, at a first controlled temperature, in an enclosure, in order to obtain the liquid polyurethane; and a step (ii) of curing the liquid polyurethane, at a second controlled temperature, in order to make the polyurethane solid, the mixing of step (i) being carried out in the absence of solvent.