Modular Fuel Cell Assembly with Compressible Interface
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Solution Overview
Problem
Traditional polymer electrolyte membrane (PEM) fuel cell stacks suffer from incomplete electrical contact between bipolar separator plates and membrane electrode assemblies, leading to poor electrical conduction and gas/liquid leakage due to their 'filter-press' structure, which is inefficient in sealing and maintaining contact.
Innovation Solution
The PEM modular unit fuel cell assembly incorporates a reticulated structure for even stress distribution, a corrugated or finned spring cooling and transport structure for heat removal and compliance, and a thin sheet metal bipolar plate for improved electrical contact and sealing, allowing for better reactant transport and cooling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional filter-press structure with thick end plates and tie-rods is used, then sealing and structural integrity are attempted, but electrical contact between bipolar separator plates and membrane electrode assemblies is incomplete, leading to poor electrical conduction
Solution Approach 1:
The fuel cell stack is divided into modular repeating units, each containing a membrane electrode assembly and bipolar separator plate combination. This segmentation allows each module to be independently optimized for electrical contact while simplifying the overall assembly process and reducing the complexity of traditional filter-press structures with thick end plates and tie-rods.
Solution Approach 2:
The patent introduces a compressible layer between the bipolar separator plate and membrane electrode assembly, adding a dimensional element that enables conformal contact. This compressible interface layer allows the rigid bipolar plates to achieve intimate electrical contact with the flexible membrane electrode assemblies through compression, resolving the electrical conduction issue without requiring complex fastening mechanisms.
2Reliability
If a traditional filter-press structure is used to seal hydrogen and oxidant, then sealing is attempted, but gas and liquid leakage occurs due to incomplete sealing
Solution Approach 1:
The patent employs flexible gasket seals between the bipolar separator plates and membrane electrode assemblies. These thin film gaskets conform to the mating surfaces and maintain sealing under compression, providing reliable gas and liquid seals without requiring the thick end plates and complex fastening systems of traditional filter-press structures.
Solution Approach 2:
The compressible layer serves dual functions: maintaining intimate electrical contact and providing sealing. By adding this dimensional element, the system achieves both electrical conduction and gas/liquid sealing through a single structural feature, eliminating the need for separate complex sealing mechanisms.
3Reliability
If machined graphite bipolar separator plates are used, then electrical conduction is attempted, but production costs are high due to machining requirements
Solution Approach 1:
The patent changes the manufacturing parameters of bipolar separator plates from precision machining to stamping or forming processes. By accepting slightly different surface finish parameters and using compression to achieve contact, the system maintains electrical conduction reliability while dramatically reducing production costs and manufacturing complexity.
Solution Approach 2:
The introduction of the compressible layer decouples the requirement for precise surface flatness from the requirement for intimate electrical contact. This allows bipolar plates to be manufactured using simpler, lower-cost processes while the compressible layer provides the necessary conformal contact for electrical conduction.
4Temperature
If cooling is required to remove heat from fuel cell stacks, then liquid cooling is used, but heat removal efficiency is reduced due to poor thermal contact
Solution Approach 1:
The compressible layer serves as a thermal interface material that improves heat transfer between the bipolar separator plates and membrane electrode assemblies. By adding this dimensional element, the system achieves intimate thermal contact that enhances heat removal efficiency without requiring separate cooling mechanisms.
Solution Approach 2:
The flexible gasket seals and compressible layers create intimate thermal contact surfaces that facilitate efficient heat transfer from the electrochemical reactions to the cooling channels, improving overall heat removal efficiency while maintaining the liquid cooling approach.
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 design enhances electrical conduction, reduces gas and liquid leakage, and improves the overall performance and efficiency of the fuel cell stack by ensuring intimate electrical contact and effective sealing, while also reducing production costs through the use of cost-effective materials and manufacturing techniques.
Implementation Method 1
a reticulated structure configured to distribute compressive stresses evenly when the modular unit fuel cell is compressed in a fuel cell stack
Implementation Method 2
a corrugated or finned spring cooling and transport structure for heat removal and compliance
Implementation Method 3
a thin sheet metal bipolar plate for improved electrical contact and sealing
Implementation Method 4
a fuel and an oxidizer are electrochemically converted at the cell electrodes to produce electrical power
Data Source
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AI summary
A modular unit fuel cell is disclosed, which comprises a membrane electrode assembly (MEA), an anode current collector/porous transport layer (PTL), a bipolar separator plate (BSP), a corrugated or finned spring cooling and transport structure, a cathode current collector/PTL and an anode frame. In this embodiment, air is passed through the finned spring cooling and transport structure and the air acts as both the cathode reactant and as a coolant.