Concentric Annular Heat Exchanger for SOFC Thermal Stress
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Solution Overview
Problem
High-temperature heat exchangers for SOFC fuel cells face mechanical stress issues due to thermal expansion, which can lead to irreversible deformations, and existing solutions either use expensive materials or complex designs with inefficient heat exchange optimization.
Innovation Solution
A high-temperature heat exchanger design featuring concentric annular conduits with mechanically decoupled walls, allowing independent expansion and minimizing mechanical forces, combined with thermal insulation to optimize heat exchange and prevent parasitic heat losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If high temperature gases around 900°C are used in the heat exchanger, then heat exchange efficiency is improved, but thermal expansion generates significant mechanical stresses leading to irreversible deformations
Solution Approach 1:
The heat exchanger is divided into multiple independent concentric annular circuits that can expand independently. Each circuit is structurally separated from others, allowing differential thermal expansion without generating harmful mechanical stresses, thus maintaining structural integrity at high temperatures
Solution Approach 2:
The design accommodates thermal expansion by allowing dimensional changes in each independent circuit. The concentric annular structure with independent circuits enables each component to undergo thermal expansion parameter changes without compromising the overall structural integrity of the heat exchanger
2Stability of the object's composition
If materials with low coefficients of thermal expansion (e.g., ceramic materials) are used, then thermal expansion problems are reduced, but manufacturing cost increases
Solution Approach 1:
By segmenting the heat exchanger into independent concentric annular circuits, the design allows the use of standard metallic materials instead of expensive ceramics. Each segment can expand independently, achieving thermal stability through structural design rather than material selection
Solution Approach 2:
The invention replaces expensive ceramic materials with cheaper standard metallic materials. The structural design compensates for the higher thermal expansion of metals through independent circuit segmentation, making the system cost-effective while maintaining functionality
3Strength
If specific designs of exchanger are proposed to overcome thermal expansion, then thermal expansion problems are solved, but device complexity increases
Solution Approach 1:
The heat exchanger employs multiple independent concentric annular circuits that are structurally simple yet effective. Each circuit operates independently, allowing thermal expansion without complex compensation mechanisms, thus solving thermal stress problems while maintaining design simplicity
Solution Approach 2:
The concentric annular circuits are nested within each other in a compact arrangement. This nested structure achieves thermal expansion management through simple geometric configuration rather than complex mechanical designs, reducing overall device complexity
4Loss of energy
If heat loss zones are present in the exchanger, then parasitic heat exchanges occur, but heat exchange optimization is prevented
Solution Approach 1:
Adjacent annular ducts from different circuits are merged into a single integrated structure. This merging eliminates heat loss zones between separate components, preventing parasitic heat exchanges and optimizing the overall heat exchange efficiency of the system
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 extends the service life of the heat exchanger by preventing deformation and allows for cost-effective production using standard materials, while optimizing heat exchange efficiency and reducing mechanical stresses.
Implementation Method 1
certain constituent elements of these exchangers expand greatly under the effect of high temperatures. These thermal expansions, which in addition are not uniform due to the presence of temperature gradients between the inlet and the outlet of the heat exchange circuits, generate significant mechanical stresses
Implementation Method 2
a heat exchanger is used with the actual fuel cell which makes it possible to preheat the air before it is introduced into the cell core
Implementation Method 3
the first and second circulation circuits comprising common exchange surfaces heat
Implementation Method 4
at least one side of each wall common to two adjacent conduits belonging to the first or to the second circulation circuit comprises a layer of thermal insulation. By isolating all or part of the baffles formed by two adjacent ducts, any parasitic heat exchanges in the same fluid are avoided
Data Source
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AI summary
The invention relates to a heat exchanger (110) for a hot fuel cell (101). The exchanger comprises a first circulation circuit (111) for receiving a flow of fresh air (113) and a second circulation circuit (112) for receiving a hot fluid (114) from the fuel cell, the first and second circulation circuits having common heat exchange surfaces. According to the present invention, the first and second circulation circuits (111, 112) each comprise a plurality of interconnected concentric annular conduits (1110-1115; 1120-1123). The two walls of each conduit are mechanically decoupled from each other, allowing them to expand independently and preventing mechanical stresses within the exchanger.