Silica-Encapsulated Nano PCM for Thermal Stability
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Solution Overview
Problem
Phase change materials face challenges with low thermal conductivity and poor stability, particularly in nano-scale forms which are unstable in solutions and prone to agglomeration, affecting their temperature sensitivity and practical application.
Innovation Solution
A silica-encapsulated nano-phase change material is developed, where a silica shell is used to enhance thermal conductivity and stability, preventing agglomeration and liquid leakage, through a method involving emulsification of n-octadecane and hydrolytic polycondensation of ethyl orthosilicate, followed by centrifugal drying.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If nano-scale phase change materials are used to improve thermal conductivity, then thermal conductivity is improved, but stability deteriorates due to agglomeration in solution and thin films
Solution Approach 1:
A silica shell is introduced as an intermediary layer between the phase change material core and the external environment. This shell prevents direct contact and interaction between nanomaterial particles, thereby preventing agglomeration while maintaining thermal conductivity through the shell structure.
Solution Approach 2:
The invention creates a composite microcapsule structure consisting of a phase change material core surrounded by a silica shell. This composite structure combines the high thermal conductivity of the phase change material with the stability and anti-agglomeration properties of the silica shell, resolving the contradiction between thermal conductivity and stability.
2Duration of action of stationary object
If micro-encapsulation technology is used to improve durability and specific surface area, then durability is improved, but thermal conductivity deteriorates due to encapsulation layer
Solution Approach 1:
The silica shell is designed as a thin film structure that provides mechanical protection and durability while minimizing thermal resistance. The shell thickness is optimized to be sufficient for protection but thin enough to allow efficient heat transfer, thus balancing durability and thermal conductivity.
3Quantity of substance
If nano-phase change materials are used to increase energy storage density, then energy storage density is improved, but stability deteriorates due to liquid leakage during phase change
Solution Approach 1:
The silica shell acts as a containment intermediary that holds the liquid phase change material during melting and solidification cycles. This shell prevents liquid leakage while allowing the high energy storage density of the nano-phase change material to be fully utilized.
Solution Approach 2:
The silica shell provides a flexible yet protective barrier that can accommodate volume changes during phase transition without breaking, preventing liquid leakage while maintaining the integrity of the encapsulated high-energy-density material.
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 silica-encapsulated nano-phase change material exhibits improved thermal conductivity and stability, with a large phase change temperature range and energy storage density, suitable for temperature regulation and practical production.
Implementation Method 1
a silica shell is adopted to the surface of the phase change material by utilizing a micro-encapsulation technologies, which can prevent liquid leakage brought about by the melting of the phase change and improve the thermal stability of the phase change material
Implementation Method 2
Latent heat energy storage is one of the important application directions of solar energy, which utilizes the property of energy absorbing during the phase change of the material
Implementation Method 3
In the step S1, the emulsification of n-octadecane is conducted
Implementation Method 4
In the step of S2, hydrolytic polycondensation of ethyl orthosilicate is conducted
Implementation Method 5
In the step of S2, hydrolytic polycondensation of ethyl orthosilicate is conducted
Implementation Method 6
In the step S3, a centrifugal drying is performed
Data Source
AI summary
A silica-encapsulated nano-phase change material and its preparation method are provided. An n-octadecane SiO2 nanoscale phase change material is prepared by sol-gel and microemulsion coupling under alkaline conditions using silica as the shell material and n-octadecane as the core material in a microcapsule and using ethyl n-silicate as the silica source, cetyltrimethylammonium bromide as the emulsifier, and water and ethanol as the solvents. The materials prepared have a particle size of about 500 nm, a phase transition temperature of 27.7° C., a latent heat of phase transition of 159.74 J/g, and an elevated thermal decomposition temperature of 50° C. increase compared with that of the existing n-octadecane.