Encapsulated Phase Change Material Capsules for Thermal Storage
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Solution Overview
Problem
Existing thermal energy storage systems using phase change materials suffer from heat exchanger deterioration due to solidification of phase change materials, which reduces their effectiveness.
Innovation Solution
An apparatus that encapsulates phase change material in capsules submerged in a heat transfer fluid within a tank, where thermal energy is transferred and retrieved without causing the phase change material to solidify on heat exchangers, using a control module to optimize thermocline conditions and employing methods such as coating phase change material particles with materials that vaporize or decompose to create voids for volume change accommodation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If phase change material is used in thermal energy storage systems with heat exchangers, then thermal energy storage capacity is improved, but heat exchanger effectiveness deteriorates due to solidification of phase change material on heat exchanger surfaces
Solution Approach 1:
The phase change material is divided into multiple small capsules instead of using a single large mass. This segmentation prevents solidification on heat exchanger surfaces by maintaining small particle sizes that remain liquid at operating temperatures, while still providing sufficient thermal energy storage capacity through the collective effect of multiple capsules.
Solution Approach 2:
A heat transfer fluid is introduced as an intermediary medium between the heat exchanger and the phase change material capsules. The fluid circulates through the heat exchanger and transfers thermal energy to and from the capsules, preventing direct contact between the phase change material and heat exchanger surfaces, thereby avoiding solidification issues.
2Use of energy by moving object
If phase change material solidifies to release thermal energy, then energy retrieval is achieved, but heat exchanger effectiveness is reduced
Solution Approach 1:
The heat transfer fluid serves as a mediator that absorbs thermal energy from the phase change material capsules during solidification without requiring the material to solidify on heat exchanger surfaces. The fluid carries the extracted energy away, maintaining heat exchanger effectiveness while achieving energy retrieval.
Solution Approach 2:
Instead of allowing phase change material to solidify on heat exchanger surfaces for energy release, the system inverts the approach by having liquid phase change material capsules suspend in a heat transfer fluid that circulates through external heat exchangers. Energy retrieval occurs through the fluid medium rather than direct material-solidification-on-surface.
3Reliability
If encapsulation methods are used to prevent solidification on heat exchangers, then heat exchanger effectiveness is maintained, but device complexity increases
Solution Approach 1:
Encapsulating phase change material in small capsules is relatively simple to implement and scales well. The capsules can be manufactured using straightforward processes and introduced into the system as a slurry or suspension, avoiding complex encapsulation structures while maintaining heat exchanger effectiveness.
Solution Approach 2:
The system changes the physical parameters of the phase change material by reducing it to small particle sizes and maintaining it in a liquid state through appropriate temperature control and encapsulation. This parameter change simplifies the overall system design compared to attempting to manage large-scale phase change material solidification on heat exchanger surfaces.
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 solution prevents heat exchanger deterioration by maintaining the phase change material in a liquid state during energy retrieval, optimizing thermal energy storage and retrieval efficiency through controlled thermocline management and encapsulation techniques.
Implementation Method 1
Thermal energy added to the heat transfer fluid by an external means is transferred to the phase change material within the capsules causing the phase change material to change from solid to liquid
Implementation Method 2
The phase change material releases thermal energy in the process of changing from liquid to solid. The released thermal energy is added to the heat transfer fluid and transported to an external means
Implementation Method 3
The heat transfer fluid functions as a medium for transferring thermal energy to and/or from the encapsulated phase change material
Data Source
AI summary
Methods of encapsulating a phase change material in a capsule including suspending a particle of the phase change material in an air stream, coating an entire surface of the suspended particle with at least one layer of a sacrificial compound, coating an entire surface of the layer of the sacrificial compound with at least one layer of a second material, and encapsulating the phase change material within a shell formed by the second material. The step of encapsulating comprising heating the particle coated with the sacrificial compound and the second material, thermally decomposing the sacrificial compound, and vaporizing the sacrificial, wherein the sacrificial compound has a decomposition temperature less than a phase change temperature of the phase change material and a phase change temperature of the second material.