Compressible Fabric Fuel Cell Stack for Length and Pressure Stability
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Solution Overview
Problem
In fuel cell stacks, the length of stacked cells is not constant during operation, making it difficult to implement and position connections for cell voltage monitoring, and leading to inefficiencies in power generation due to thermal expansion and pressure changes.
Innovation Solution
Incorporating a compressible fabric structure with a spring function in the fuel cell stack to compensate for length changes, ensuring a constant stack length and contact pressure across all operating states, which is achieved by assigning different spring constants to various regions of the fabric structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If fixing elements are used to hold fuel cells at a defined distance, then the fuel cell stack structure is stabilized, but the stack length cannot remain constant during operation due to thermal expansion and pressure changes
Solution Approach 1:
The fabric structure's physical parameters (length, density, porosity) are allowed to change dynamically in response to operating conditions. The fabric's spring constant and compressibility enable it to adapt its dimensions while maintaining structural integrity, resolving the contradiction between structural stability and length constancy.
Solution Approach 2:
The fabric is constructed from composite materials with specific mechanical properties, combining elasticity and compressibility to achieve both structural stability and adaptive length compensation. The composite nature allows simultaneous fulfillment of structural support and dimensional compensation functions.
2Length of moving object
If the fabric structure is compressed to compensate for length changes, then stack length constancy is achieved, but the complexity of the device increases
Solution Approach 1:
The fabric structure performs multiple functions simultaneously: it distributes reactants, provides structural support, compensates for length changes, and maintains contact pressure. This multi-functionality eliminates the need for separate components for each function, thereby reducing overall device complexity despite the sophisticated behavior required.
Solution Approach 2:
The fabric structure autonomously compensates for length changes and maintains contact pressure through its inherent elastic and compressible properties, without requiring external control systems or additional actuators. This self-regulating behavior achieves length constancy while minimizing added complexity.
3Length of moving object
If the fabric structure is made highly compressible to compensate for thermal expansion, then length compensation is improved, but the contact pressure becomes insufficient
Solution Approach 1:
The fabric's physical parameters (porosity, density, spring constant) are optimized to achieve the right balance between compressibility for length compensation and stiffness for maintaining contact pressure. The parameter optimization ensures that the fabric compresses sufficiently to compensate for thermal expansion while still providing adequate contact pressure.
Solution Approach 2:
The composite material composition of the fabric provides a balance between softness (for compression) and structural integrity (for contact pressure). The material selection and structure enable simultaneous achievement of length compensation and sufficient contact force.
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 maintains a constant fuel cell stack length and contact pressure, facilitating easier cell voltage monitoring and reducing the risk of component damage from excessive pressures, while allowing for individual adjustment of contact force across different areas.
Implementation Method 1
at least one of the fuel cells has at least one compressible fabric structure to which a spring function with a spring constant is assigned, and in that by means of the spring function a change in length of the fuel cell along the stack direction can be compensated by an opposite negative change in length of the compressible fabric structure
Implementation Method 2
A fabric is associated with the bipolar plate and thus with the fuel cell. The fabric is formed from several fibers made of different materials. The fabric is intended to provide structures for distributing the reaction gases, with the fabric exhibiting elastic properties, so that the fabric reacts to pressure changes with a change in length.
Data Source
Figure 1~2
Figure 3~4
AI summary
The invention relates to a fuel cell stack (1) having a plurality of fuel cells (2) stacked one over the other in a stacking direction. At least one of the fuel cells (2) has at least one compressible fabric structure (3) which is assigned a spring function with a spring constant. The spring function allows a change in length of the fuel cell (2) in the stacking direction to be compensated by an opposite negative change in length of said compressible fabric structure (3).