Fuel Cell Stack Leak Isolation via Oxidant Inlet Blocking
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Solution Overview
Problem
Localized heating and potential failure of a fuel cell stack due to leaks between fuel and oxidant reactant flow fields, requiring costly and time-consuming disassembly of the entire cell stack to remove a single failed cell.
Innovation Solution
Blocking the oxidant inlets to the leaking fuel cell using a liquid sealant that cures in place, or alternative materials like hot glue or fluoroelastomers, to prevent overheating and combustion, allowing for localized repair without disassembling the stack.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a failed cell is removed from the fuel cell stack, then the leaking cell is eliminated, but the entire cell stack assembly must be disassembled which is time-consuming and expensive
Solution Approach 1:
The harmful element (oxidant gas flow) is extracted or removed from the failed cell by blocking the oxidant inlets, isolating the leak source without removing the cell itself from the stack assembly
Solution Approach 2:
The oxidant inlets are blocked as a preliminary protective action to prevent heat propagation to adjacent cells before the cell is fully removed or replaced, maintaining stack integrity during the repair process
2Reliability
If a failed cell is removed from the fuel cell stack, then the leaking cell is eliminated, but the manifolds must be removed and the entire cell stack assembly has to be disassembled
Solution Approach 1:
The harmful oxidant flow is extracted from the failed cell through inlet blocking, eliminating the need to disassemble manifolds and the entire stack assembly for access
Solution Approach 2:
The repair action is localized to the failed cell's oxidant inlets only, leaving the rest of the stack assembly intact with its original design features including manifolds and adhesive seals
3Ease of repair
If pressure is released on the various cells to remove a failed cell, then the cell can be accessed, but additional failure such as breakage of membranes can occur
Solution Approach 1:
The oxidant inlet blocking is performed as a preliminary protective measure to prevent pressure-induced membrane breakage and additional failures before pressure release and cell removal are attempted
Solution Approach 2:
The failed cell is protected from pressure release damage by blocking oxidant inlets beforehand, cushioning against the harmful effects of pressure differential that would otherwise cause membrane breakage
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
Prevents overheating and potential failure of adjacent cells by isolating the leak, enabling detection and isolation of the issue without disassembling the stack, thus reducing operational downtime and maintenance costs.
Implementation Method 1
the oxidant reactant gas flow field grooves are blocked by means of a liquid sealant that cures in place
Implementation Method 2
a liquid sealant that cures in place
Data Source
AI summary
The oxidant inlets of the reactant gas flow field grooves (41) of a fuel cell (11) which suffers a crossover between the fuel and oxidant flow fields, due to a leak in the seals, the maxtrix or the membrane of the fuel cell, are blocked with a liquid (50) which cures in place, hot glue, two-part epoxy, or fluoroelastomers. This prevents heating as a result of combusting fuel with oxygen near the site, which avoids excessive heating and damaging of successive fuel cells. As a result, a fuel cell power plant (8) can continue to operate with only a minor loss of voltage and power, thereby avoiding the need to tear down the stack by loosening the tie-bolts. Voltage and hydrogen levels may be used to detect the crossover. The particular cell (11) with the leak can be determined by voltage or hydrogen monitoring, or by immersing the stack in a liquid while applying gas to the fuel inlet of the stack.