Oblong Absorption Body for PCM Capsule Volume Expansion
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Solution Overview
Problem
Existing capsules containing phase change materials face deformation and weakening due to volume expansion during solidification, leading to potential failure, as they struggle to absorb the increased volume without inducing harmful internal stresses or compromising the capsule's integrity.
Innovation Solution
A capsule design featuring an oblong absorption body with a length equal to the internal diameter of a spherical envelope, which wedges into the capsule and compresses to absorb the volume expansion of the phase change material, preventing movement and maintaining symmetry, along with a filling orifice for easy placement and potential pressure sensing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the capsule is completely filled with phase change material, then the cooling energy storage capacity is maximized, but the capsule envelope undergoes deformation and weakening due to volume expansion during solidification
Solution Approach 1:
A compressible absorption body is introduced as an intermediary element between the phase change material and the capsule envelope. This absorption body serves as a mediator that absorbs the volume expansion during solidification through compression, preventing direct transmission of expansion forces to the envelope and thereby preventing deformation while allowing complete filling with PCM
Solution Approach 2:
The absorption body undergoes parameter change by being compressed during PCM solidification. Its compressibility allows it to change its volume parameter in response to the expanding PCM, absorbing the expansion volume and protecting the envelope from deformation while maintaining complete PCM filling
2Stability of the object's composition
If a spherical absorption body is used to absorb volume expansion, then the PCM solidifies uniformly from periphery to center without harmful stresses, but placing and maintaining the spherical absorption body in the center of the capsule is difficult
Solution Approach 1:
The invention transitions from a symmetric spherical absorption body to an asymmetric oblong absorption body with flattened ends. This asymmetric shape provides functional advantages: the oblong form with flattened ends facilitates stable placement against the capsule wall and prevents displacement during solidification, while still maintaining the ability to absorb volume expansion through compression along its longitudinal axis
3Use of energy by moving object
If the capsule wall is made thinner to improve heat transfer coefficient, then the heat exchange efficiency increases, but the capsule becomes more susceptible to deformation under internal pressure
Solution Approach 1:
The compressible absorption body acts as an intermediary that buffers internal pressure during PCM solidification. By absorbing the volume expansion through its own compression, it reduces the pressure transmitted to the thin capsule wall, thereby protecting the wall from deformation while allowing the wall to remain thin for optimal heat transfer efficiency
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
This design effectively absorbs the volume increase of phase change materials during solidification, preventing deformation and maintaining the capsule's integrity, while facilitating easy placement and monitoring of internal pressure, thus enhancing the durability and efficiency of the cooling process.
Implementation Method 1
During the so-called 'storage charge' phase, the heat transfer fluid, cooled by a refrigeration compressor, circulates in the tank at a temperature below the change of state temperature of the phase change material contained in the capsules, which has for the effect of solidifying the phase change material contained in the capsules and therefore of storing a certain quantity of cooling energy.
Implementation Method 2
The absorption body is compressible and therefore able to be compressed by the phase change material during its solidification so as to absorb the increase in volume of said material.
Data Source
Figure 1~3
Figure 4~5c
AI summary
The invention relates to an oblong absorption body (1) for a capsule (10) for a refrigeration apparatus intended to contain a phase-change material, characterised in that said body comprises a flexible casing (2) filled with gas at atmospheric pressure, having a main portion which is generally cylindrical, has a circular cross-section and ends in hemispherical end portions. The invention also relates to capsules provided with such an absorption body.