Fuel Cell Stack Metal Cap Sealing Thermal Expansion
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Solution Overview
Problem
The integration of a fuel cell stack with an external cathode gas guidance into a fuel cell system is complicated due to the different thermal expansion coefficients of the ceramic cap and the fuel cell stack, leading to potential gas leaks and inefficient gas separation.
Innovation Solution
A metal cap is attached to the base plate in a sealed manner, using an elastic metal foil to neutralize thermal expansions and ensure a tight encapsulation, with ceramic paper as a sealing material between the cap and fuel cells to facilitate gas guidance and prevent bypasses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a metal cap is added to encapsulate the fuel cell stack, then system integration and external sealing are improved, but device complexity increases
Solution Approach 1:
The metal cap is designed to perform multiple functions simultaneously: it provides external sealing for system integration, supports the ceramic cap structure, absorbs thermal expansion through its elastic foil, and maintains gastight connection to the base plate. This multi-functionality reduces the need for additional separate components.
Solution Approach 2:
The elastic metal foil in the metal cap acts as a flexible element that can deform to accommodate thermal expansion differences. This flexibility allows the rigid metal cap structure to adapt to dimensional changes without compromising the seal, simplifying the overall design compared to using rigid components with complex compensation mechanisms.
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 enhances the guidance of cathode gas through the fuel cell stack without performance loss, simplifies the integration of the fuel cell stack into a system, and maintains gas-tightness by compensating for thermal expansions and applying a defined bias.
Implementation Method 1
the different thermal expansion coefficients of the ceramic cap and the fuel cell stack, leading to potential gas leaks
Implementation Method 2
using an elastic metal foil to neutralize thermal expansions
Implementation Method 3
ceramic paper as a sealing material between the cap and fuel cells to facilitate gas guidance and prevent bypasses
Implementation Method 4
The functional principle of all fuel cells is based on that two different process gasses, for example a hydrogen-rich fuel gas and an oxygen-rich gas serving as an oxidant, are separately guided past an active layer, an electric voltage of approximately 0.7 V developing perpendicular to said layer due to the reaction taking place
Data Source
AI summary
The invention relates to a fuel cell stack comprising a base plate supporting fuel cells and a cap of an electrically insulating material, particularly of ceramics, for electrically insulating the fuel cells stacked on top of each other partially enveloping the fuel cells stacked on top of each other. According to the invention it is contemplated that a metal cap provided for guiding cathode gas envelops the cap including the fuel cells together with the base plate and that the metal cap is attached to the base plate in a sealed manner. The invention further relates to a method for producing a fuel cell stack.