Composite Thermochemical Material for Seasonal Solar Heat Storage
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Solution Overview
Problem
Thermochemical materials used for thermal energy storage, such as salt hydrates, face issues with insufficient physical, mechanical, and chemical stability, leading to problems like corrosion, structural changes, and limited cyclability, which restrict their use in applications requiring lower dehydration temperatures.
Innovation Solution
Encapsulating thermochemical materials in a water vapor permeable polymeric material to enhance stability and cyclability, allowing for lower dehydration temperatures and improved heat storage efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If salt hydrates are used for thermochemical storage, then heat storage density is improved, but physical and chemical stability deteriorates
Solution Approach 1:
The patent applies composite materials by combining salt hydrate particles with a porous ceramic matrix material. The ceramic matrix provides structural stability and mechanical strength while the salt hydrate particles maintain their high heat storage density. The composite structure prevents dissolution and aggregation of the salt hydrate, solving the contradiction between high storage density and material stability.
Solution Approach 2:
The patent uses porous ceramic matrix material with controlled porosity to host the salt hydrate particles. The porous structure allows vapor transport necessary for the thermochemical reaction while the ceramic framework provides mechanical stability and prevents material degradation. This resolves the contradiction by providing both the porosity needed for function and the structural integrity for stability.
2Quantity of substance
If hygroscopic deliquescent salts are used, then water uptake capacity is improved, but cyclability deteriorates
Solution Approach 1:
The porous ceramic matrix provides a structured framework that maintains bed porosity during repeated water uptake and release cycles. The rigid ceramic structure prevents the material from collapsing or aggregating, thereby maintaining vapor transport pathways and enabling long-term cyclability while preserving the high water uptake capacity of deliquescent salts.
Solution Approach 2:
The composite structure separates the functional role of water uptake (performed by the hygroscopic salt hydrate particles) from the structural role (performed by the ceramic matrix). This division allows the salt to exhibit its full hygroscopic potential without suffering from dissolution and aggregation problems, thereby improving cyclability.
3Quantity of substance
If TCM grains are pulverized, then packing density is improved, but vapour transport deteriorates
Solution Approach 1:
The porous ceramic matrix provides a structured framework that maintains interconnected vapor transport pathways even when salt hydrate particles are finely divided. The matrix structure prevents complete densification and aggregation, ensuring that vapor can reach the pulverized particles efficiently. This resolves the contradiction by allowing high packing density while maintaining vapor transport speed through the porous ceramic network.
4Quantity of substance
If full dehydration is achieved at high temperatures, then storage capacity is improved, but application versatility deteriorates
Solution Approach 1:
The patent modifies the dehydration temperature parameter by using salt hydrate-ceramic composite materials that can achieve effective dehydration at lower temperatures than pure salt hydrates. The ceramic matrix facilitates heat and mass transfer, enabling complete dehydration at temperatures suitable for conventional building applications. This expands application versatility while maintaining full storage capacity.
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 encapsulated thermochemical materials exhibit improved stability, cyclability, and reduced dehydration temperatures, enabling their effective use in building and construction applications for solar heat storage at lower temperatures, with enhanced heat transport and storage density.
Implementation Method 1
a water vapour permeable polymeric material
Implementation Method 2
a chemical reaction between two compounds A and B with heat release (exothermic reaction)
Implementation Method 3
When this C compound is subjected to decomposition by heat during summer, two compounds A and B are formed
Data Source
AI summary
The invention describes a composite material for heat storage comprising a thermochemical material (TCM) encapsulated in a water vapour permeable polymeric material. The thermochemical material preferably comprises at least one salt, at least one salt hydrate or a mixture of these, wherein the salt is preferably capable of binding water in an exothermic reaction, such as calcium chloride. Encapsulation in a water vapour permeable polymeric material results in an improved stability, cyclability of the thermochemical material, a reduced regeneration temperature and reduced corrosion of the environment. The composite according to the invention is particularly suitable for energy storage, preferably in the field of building and construction, and more preferably in the seasonal storage of solar energy.