Fuel Cell Stack Assembly With Tensioned Skirt Compression
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Solution Overview
Problem
Solid oxide fuel cell stacks face challenges in maintaining compressive load and structural integrity due to thermal cycling, which can lead to reduced efficiency and risk of short circuits, especially with the use of tie-bars that require careful design and materials selection for different stack designs.
Innovation Solution
A metal supported solid oxide fuel cell stack assembly with a skirt attached between the base plate and end plate, under tension to maintain compressive force, and an expansion plate with a higher coefficient of thermal expansion than the skirt and fuel cell stack, eliminating the need for tie-bars and enhancing thermal management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If tie-bars are used to maintain compression on the fuel cell stack, then structural integrity is improved, but the risk of short circuits increases due to thermal expansion at high temperatures
Solution Approach 1:
The patent removes tie-bars from the fuel cell stack assembly entirely, replacing them with a compression plate that applies compressive force through the fuel cell layers. This extraction eliminates the short circuit risk associated with tie-bars while maintaining structural integrity through the compression plate and gasket system.
Solution Approach 2:
The patent introduces a compression plate as an intermediary component between the end plate and fuel cell stack. This compression plate, combined with gaskets, mediates the application of compressive force without requiring direct contact between metal tie-bars and the fuel cell components, thereby preventing short circuits while maintaining structural integrity.
2Reliability
If multiple tie-bars are used to maintain compression load, then gas sealing is improved, but device complexity increases due to alignment and assembly requirements
Solution Approach 1:
The patent merges the functions of multiple tie-bars into a single compression plate that applies compressive force across the entire fuel cell stack. This consolidation maintains gas sealing through the compression gasket while eliminating the complexity of aligning and assembling multiple individual tie-bars.
Solution Approach 2:
The patent extracts the compression function from multiple discrete tie-bars and implements it through a unified compression plate system. This simplifies the assembly process by eliminating the need for precise alignment of multiple components while maintaining the necessary compressive force for gas sealing.
3Manufacturing precision
If assembly bars with larger diameter are used for alignment, then manufacturing precision is improved, but the need for replacement with smaller tie-bars increases device complexity
Solution Approach 1:
The patent removes the two-step process of using assembly bars for alignment and then replacing them with tie-bars. Instead, the compression plate is directly installed and used to apply compressive force, eliminating the need for temporary alignment components and simplifying the manufacturing process while maintaining alignment precision.
4Strength
If tie-bars are used to maintain compression, then structural support is improved, but thermal mass increases which slows temperature reach
Solution Approach 1:
The patent extracts tie-bars from the assembly, removing their thermal mass contribution. The replacement compression plate system provides necessary structural support with minimal thermal mass, enabling faster heating to operating temperature while maintaining structural integrity through the compression gasket and plate design.
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 solution reduces thermal mass, increases performance by faster temperature reach, simplifies manufacturing, and reduces the risk of short circuits, while maintaining gas sealing and electrical conductivity, thus improving the overall efficiency and lifespan of the fuel cell stack.
Implementation Method 1
the at least one expansion plate has a coefficient of thermal expansion greater than a coefficient of thermal expansion of the skirt, and the coefficient of thermal expansion of the skirt is greater than a coefficient of thermal expansion of the at least one fuel cell stack
Data Source
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AI summary
The present invention is concerned with an improved fuel cell stack assembly (10) comprising a metal base plate (20) on which is mounted at least one fuel cell stack (30) and a metal end plate (40), each stack comprising at least one fuel cell stack layer (50) that comprises at least one fuel cell (101, 102) and at least one electrically insulating compression gasket (110), wherein a skirt (130) is attached to the base and end plates enclosing the stack and is under tension therebetween so as to maintain a compressive force through the stack, thereby obviating the need for tie-bars.