Cenosphere Microencapsulation for PCM Leakage and Strength
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Solution Overview
Problem
Existing methods for incorporating phase change materials (PCMs) and admixtures into construction materials, such as concrete, face challenges like reduced mechanical strength, chemical instability, flammability, and leakage, due to interactions with cement hydration and poor delivery systems.
Innovation Solution
Encapsulating PCMs and admixtures within cenospheres, which are hollow inorganic particles with high stiffness and strength, to create compositions like CenoPCMs that provide improved thermal conductivity, stability, and mechanical strength, while preventing leakage and enhancing energy efficiency in building materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If PCMs are microencapsulated using polymeric shells, then thermal storage capacity and heat transfer area are improved, but mechanical strength and chemical stability are reduced
Solution Approach 1:
The patent changes the material parameter of the encapsulation shell from polymeric to inorganic (cenosphere) material, which fundamentally alters the mechanical and chemical properties while maintaining the thermal storage function. This parameter change resolves the contradiction by providing both high thermal storage capacity and high mechanical strength simultaneously.
Solution Approach 2:
The patent creates a composite structure where PCMs are encapsulated within inorganic cenosphere shells. This composite approach combines the thermal energy storage capability of PCMs with the mechanical strength and chemical stability of inorganic materials, resolving the contradiction between thermal performance and mechanical properties.
2Ease of operation
If polymeric shells are used to encapsulate PCMs, then handling and reactivity control are improved, but thermal conductivity and chemical stability are reduced
Solution Approach 1:
The patent changes the chemical composition parameter of the shell from organic polymer to inorganic cenosphere material, which improves chemical stability against UV light, oxidation, and aggressive chemicals while maintaining ease of handling. This parameter change directly resolves the contradiction between ease of operation and chemical stability.
3Ease of manufacture
If porous materials are used to absorb PCMs, then manufacturing simplicity is improved, but leakage control and thermal storage stability are reduced
Solution Approach 1:
The patent uses cenosphere shells that act as flexible containment structures with controlled permeability. The shells provide a balance between allowing PCM absorption/manufacturing simplicity and preventing leakage through their controlled shell structure, resolving the contradiction between ease of manufacture and leakage control.
4Productivity
If admixtures are directly added into concrete mix, then productivity is improved, but compatibility and mechanical strength are reduced
Solution Approach 1:
The patent segments the admixture into separate encapsulated units (cenospheres containing admixtures) that can be uniformly distributed throughout the concrete mix. This segmentation allows direct addition into the mix (maintaining productivity) while preventing negative interactions with cement hydration (preserving strength).
Solution Approach 2:
The cenosphere shell acts as an intermediary between the admixture and the concrete matrix, allowing the admixture to be delivered efficiently while preventing direct harmful interactions with cement hydration. This intermediary role resolves the contradiction between productivity and strength.
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
CenoPCMs offer enhanced thermal storage capacity, chemical stability, and mechanical strength, overcoming previous limitations in PCM integration, and can be effectively used in various building materials to improve energy efficiency and reduce environmental impact.
Implementation Method 1
PCMs are first absorbed into porous materials such as light weight aggregates and diatomite particles to form stable composites
Implementation Method 2
PCMs change their phase from solid to liquid and vice versa at their phase change temperatures with large amount of energy absorbed or released
Implementation Method 3
PCMs change their phase from solid to liquid and vice versa at their phase change temperatures with large amount of energy absorbed or released
Implementation Method 4
The thermal conductivity of the polymer shells is often very low, making thermal exchange between the PCMs inside the shell and the outside environment much more difficult
Data Source
AI summary
Disclosed are methods for incorporating core materials such as phase change materials or admixtures into building materials like concrete. The methods use cenospheres, which are then etched and loaded with the core material. The composition can also be coated with a thin film. Compositions containing cenospheres loaded with the various core materials are disclosed, as are building materials containing such compositions.