Roof Structure Phase Change Layers for Heat Flux Control
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Solution Overview
Problem
Roof structures in buildings are inefficient in regulating thermal performance, leading to overheating in summer and excessive heating demands in winter, due to inadequate heat management through the roof.
Innovation Solution
Incorporating phase change materials, specifically non-combustible salt hydrates and crystalline alkyl hydrocarbons, into an elastomeric compound applied to carrier fabrics in strategic locations within roof structures to absorb and release latent heat, thereby controlling heat flux and providing thermal insulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If phase change material is applied in roof structures to improve thermal performance, then thermal comfort and energy efficiency are improved, but fire safety is compromised due to the flammability of organic phase change materials
Solution Approach 1:
The patent changes the chemical composition parameter of the phase change material from organic compounds to inorganic salt hydrates, fundamentally altering the material's fire resistance properties while maintaining its phase change thermal storage functionality. This parameter change resolves the contradiction by eliminating flammability without sacrificing thermal performance.
Solution Approach 2:
The patent employs salt hydrates that can be easily replaced or renewed in the roof structure. These inorganic materials provide the necessary thermal storage function temporarily during their operational lifecycle, and can be replaced if needed without complex disposal procedures, addressing both performance and safety requirements.
2Loss of energy
If phase change material is incorporated into concrete to improve thermal comfort, then energy efficiency is improved, but mechanical properties of the concrete are reduced
Solution Approach 1:
The patent extracts the phase change material from the concrete matrix itself and places it in separate encapsulated forms within the roof structure. This separation allows the concrete to maintain its full mechanical strength while the phase change material provides thermal storage functionality without compromising structural integrity.
Solution Approach 2:
The patent uses composite construction where encapsulated phase change material is integrated with roofing materials rather than mixing it into concrete. This composite approach allows each material to perform its optimal function - concrete for structural strength and encapsulated phase change material for thermal regulation - without mutual interference.
3Loss of energy
If phase change material is used to absorb latent heat during melting, then thermal storage capacity is improved, but material stability deteriorates due to incongruent melting behavior
Solution Approach 1:
The patent carefully selects specific salt hydrate compositions and controls their crystallization parameters to achieve congruent melting behavior. By adjusting the chemical composition parameters and controlling the phase change conditions, the material maintains stable reversible cycling between solid and liquid states, ensuring long-term reliability of the thermal storage system.
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
Significantly enhances thermal comfort and reduces energy demands by absorbing solar heat during summer and releasing it during winter, leading to improved energy efficiency and reduced heating and cooling needs.
Implementation Method 1
Phase change material is a highly-productive thermal storage medium which possesses the ability to change its physical state within a certain temperature range. When the melting temperature is obtained during a heating process, the phase change from the solid to the liquid state occurs. During this melting process, the phase change material absorbs and stores a large amount of latent heat.
Implementation Method 2
the phase change from the solid to the liquid state occurs. During this melting process, the phase change material absorbs and stores a large amount of latent heat. The temperature of the phase change material remains nearly constant during the entire process.
Implementation Method 3
Incorporating non-combustible salt hydrates or crystalline alkyl hydrocarbons into an elastomeric compound applied to specific locations within roof structures to absorb and release latent heat, controlling heat flux through the roof, thereby enhancing thermal insulation
Data Source
AI summary
The technique comprises the utilization of phase change materials to control the heat flux into and out of a building through the roof components. In order to effectively control the heat flux through the roof components, phase change materials are arranged in two locations inside the roof structure. A first phase change material is used in the upper part of the roof above the insulation. A second phase change material is used in the lower part of the roof below the insulation. The melting point of the first phase change material is higher than the crystallization point of the second phase change material. The phase change materials are incorporated into an elastomeric compound which is applied to one or both sides of a carrier fabric. The phase change materials are preferable non-combustible salt hydrates in order to meet fire-resistant requirements of building materials.