Thermal Storage Heat Exchanger With Compliant PCM Chambers
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Solution Overview
Problem
Existing thermal storage heat exchangers using paraffin as phase change materials face limitations due to low thermal conductivity and high volume requirements, which are unsuitable for high heat rate applications, while ice/water PCM heat exchangers face challenges with volumetric expansion, leading to structural issues and reduced energy density.
Innovation Solution
A thermal storage heat exchanger design that employs ice/water as a phase change material, featuring compliant layers that deform to accommodate expansion, enhancing energy density and reducing the size and weight of thermal management systems by maintaining effective heat transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If ice/water PCM is used in heat exchanger, then thermal storage capacity and thermal conductivity are improved, but volumetric expansion occurs causing structural damage
Solution Approach 1:
The patent employs a flexible membrane as the chamber wall that can deform elastically to accommodate the volumetric expansion of ice/water PCM during freezing. This flexible shell allows the chamber to expand and contract with the phase change material without structural damage, resolving the contradiction between high thermal storage capacity and structural integrity.
2Stability of the object's composition
If paraffin PCM is used in heat exchanger, then structural stability is maintained, but thermal conductivity is low and volume requirements are high
Solution Approach 1:
The patent changes the physical parameters of the PCM from paraffin to ice/water, which has superior thermal conductivity and higher thermal storage density. The flexible membrane chamber enables this parameter change by accommodating the expansion characteristics of ice/water that paraffin does not exhibit, thereby improving thermal storage density while maintaining structural stability through the flexible design.
3Strength
If rigid chamber walls are used to contain PCM, then structural integrity is maintained, but expansion of ice/water PCM causes damage
Solution Approach 1:
The patent transitions from static rigid chamber walls to dynamic flexible membranes that can adapt their volume in response to PCM phase changes. The flexible membrane chamber dynamically expands during freezing and contracts during melting, maintaining structural integrity while accommodating volume changes, thus resolving the contradiction between strength and adaptability.
4Quantity of substance
If high thermal storage density is achieved using ice/water, then energy density improves, but compliant structure is required increasing device complexity
Solution Approach 1:
The patent uses flexible membranes to create compliant chambers that accommodate ice/water expansion. While this adds some structural complexity, it enables high energy density thermal storage using ice/water PCM. The flexible shell design is relatively simple compared to complex expansion compensation mechanisms, achieving a balance between energy density improvement and acceptable device complexity.
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 design significantly improves specific and volumetric energy density, enabling efficient thermal energy storage and transfer in high heat rate applications, addressing the limitations of paraffin-based systems and structural issues with ice/water expansion.
Implementation Method 1
a phase change material (PCM), such as paraffin, is used as the thermal storage material in the heat exchanger
Implementation Method 2
thermal energy storage (TES) heat exchangers are widely used to temporarily store excess thermal energy
Implementation Method 3
One wall of each chamber is formed of a compliant layer configured to deform to increase a volume of the chamber as the PCM expands upon freezing
Implementation Method 4
The at least one conduit and the one or more chambers are thermally coupled for transfer of thermal energy between the working fluid and the PCM in each chamber
Implementation Method 5
at least one conduit configured to carry a working fluid
Data Source
AI summary
A heat exchanger includes at least one conduit configured to carry a working fluid. The heat exchanger also includes a plurality of chambers in proximity to the at least one conduit, each chamber configured to contain a phase change material (PCM) that expands upon freezing. The at least one conduit and the plurality of chambers are thermally coupled for transfer of thermal energy between the working fluid and the PCM in each chamber. One wall of each chamber is formed of a compliant layer configured to deform to increase a volume of the chamber as the PCM expands upon freezing.