Heat Exchanger With Segmented PCM Cells For Constant Outlet Temperature
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Solution Overview
Problem
Existing heat exchanger devices using phase-change materials (PCM) face limitations in maintaining constant thermal capacity and outlet temperature due to low heat conductivity and limited power capacity, especially in non-linear systems with unpredictable heat demand and availability.
Innovation Solution
The heat exchanger design concentrates phase-changing PCM in specific zones or cells, allowing sequential phase change along the exchanger, ensuring constant heat capacity and outlet temperature by moving the melting/solidification zone based on fluid flow and structural conditions, utilizing latent heat transfer only in a segment to maintain thermal stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If PCM is used in heat exchanger, then thermal capacity is improved, but thermal conductivity deteriorates
Solution Approach 1:
The heat exchanger is divided into multiple sequential zones (first zone, second zone, third zone) with PCM distributed throughout. This segmentation allows the phase change process to occur in distributed sections rather than all at once, maintaining higher thermal power capacity while utilizing the latent heat storage capability of PCM across the entire device length.
Solution Approach 2:
A heat transfer fluid acts as an intermediary between the PCM and the external system. The fluid flows through serpentine tubing that contacts PCM in all zones, facilitating heat transfer while the PCM provides thermal energy storage. This intermediary enables the system to maintain both high thermal capacity and adequate thermal conductivity through continuous fluid circulation.
2Device complexity
If heat is stored as sensible heat, then simplicity is improved, but temperature stability deteriorates
Solution Approach 1:
The system utilizes phase transition of PCM (melting and solidification) to store and release thermal energy at constant temperature. As the heat transfer fluid passes through zones with PCM, the phase change occurs at a relatively constant temperature, thereby stabilizing the outlet temperature of the fluid while storing significant thermal energy in the phase-change material.
3Use of energy by moving object
If PCM phase change occurs throughout the entire exchanger, then thermal capacity is improved, but power capacity deteriorates
Solution Approach 1:
The heat exchanger is divided into multiple sequential zones (first zone, second zone, third zone) with PCM distributed throughout. This segmentation allows the phase change process to occur in distributed sections rather than all at once, maintaining higher thermal power capacity while utilizing the latent heat storage capability of PCM across the entire device length.
Solution Approach 2:
The serpentine tubing configuration ensures continuous contact with PCM across all zones, maintaining continuous heat transfer. The phase change process occurs continuously as the fluid flows through each zone sequentially, ensuring uninterrupted thermal energy transfer while distributing the phase change load across multiple sections, thereby maintaining both high thermal capacity and power 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
This approach maintains a constant outlet temperature and heat capacity, optimizing heat transfer efficiency even in systems with varying energy demand and supply, enhancing energy efficiency in applications like domestic hot water systems and solar thermal systems by ensuring consistent heat delivery and storage.
Implementation Method 1
heat exchanger device comprising a phase-change material, PCM... storing this heat as sensible heat... In order to do that, the storage has to be made through latent heat
Implementation Method 2
the solidification and melting occurs in sequence, concentrating the phase changing of the material in a single part of the whole heat exchanger
Implementation Method 3
In the heat transfer process between two points using an operating fluid that recovered heat in one point (point A) and release this heat in a second point (point B)
Implementation Method 4
a plurality of heat-exchanging fins connected to said tubing arranged to define a plurality of cells receiving the phase-change material
Data Source
Figure 1
Figure 2~3c
Figure 4~5
AI summary
Heat exchanger device comprising a tubing for receiving and delivering a heat transfer fluid; a phase-change material, PCM, encompassing said tubing; a plurality of cells receiving the phase-change material, PCM, such that the flow of the heat transfer fluid in said tubing causes each cell PCM to change phase gradually in the direction of the inlet to the outlet. The cells may be closed cells or open cells, the tubing may comprise fins and the exchanger may comprise an external tank for containing the PCM. The heat exchanger may comprise a second tubing for receiving and delivering a second heat transfer fluid, wherein the second tubing is connected to the PCM cells and/or to the fins of the first tubing, such that heat is transferred between the first tubing and the second tubing as each cell PCM gradually changes phase.