AIP Fuel Cell Recirculation Layout for Nitrogen Crossover
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Solution Overview
Problem
In air-independent propulsion (AIP) fuel cell systems using a mixture of nitrogen and oxygen, nitrogen cross-over from the cathode to the anode leads to decreased nitrogen concentration at the cathode and increased concentration at the anode, reducing fuel cell performance.
Innovation Solution
A fuel cell system design that recirculates nitrogen from the anode to the cathode, maintaining nitrogen concentrations on both sides without the need for additional nitrogen supply, using a system with supply paths, circulation paths, and a hydrogen separator to manage nitrogen and hydrogen effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If nitrogen crosses over from cathode to anode, then hydrogen concentration at anode decreases leading to performance degradation, but purging nitrogen requires additional system complexity
Solution Approach 1:
The patent merges the nitrogen recirculation function with the existing exhaust gas handling system. The nitrogen separation unit processes the anode exhaust gas that would otherwise be discarded, extracting nitrogen and returning it to the cathode while the remaining gas is purged. This integration avoids adding completely separate purge systems.
Solution Approach 2:
The nitrogen separation unit acts as an intermediary device between the anode exhaust and the cathode inlet. It selectively separates nitrogen from the exhaust mixture and redirects it to where it is needed (cathode), while allowing other components to be purged, thus mediating the composition control without complex multi-component systems.
2Quantity of substance
If additional nitrogen supply system is added to maintain cathode nitrogen concentration, then nitrogen balance is improved, but overall system complexity increases
Solution Approach 1:
The system uses its own exhaust gas as the source of recirculated nitrogen, making the nitrogen supply self-sufficient. The nitrogen separated from anode exhaust is directly reused at the cathode, eliminating the need for external nitrogen storage tanks, compressors, or separate supply infrastructure.
Solution Approach 2:
Instead of discarding the anode exhaust gas containing nitrogen, the system recovers the nitrogen component and reallocates it to the cathode. This recovery approach transforms waste nitrogen from the anode side into a useful resource for maintaining cathode nitrogen concentration, avoiding the need for fresh nitrogen supply systems.
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 maintains stable nitrogen concentrations, preventing performance degradation and eliminating the need for additional nitrogen supply, thereby enhancing the operational efficiency and durability of AIP fuel cell systems.
Implementation Method 1
nitrogen crosses over the electrolyte membranes after a prolonged operation, it moves from the cathodes to the anodes
Implementation Method 2
Fuel cell systems are eco-friendly power generation systems that convert hydrogen into electrical energy through an electrochemical reaction with oxygen in the air
Data Source
AI summary
A fuel cell system includes a fuel cell including an anode, a cathode, and an electrolyte membrane, where the anode and the cathode face each other across the electrolyte membrane, and where the fuel cell is configured to generate power using a fuel and an oxidizing agent; a first supply path configured to supply the fuel to the anode; a first circulation path configured to supply unreacted fuel from the anode to the first supply path; a second supply path configured to supply the oxidizing agent to the cathode; a second circulation path configured to supply unreacted oxidizing agent from the cathode to the second supply path; and a third path connecting the second circulation path and the first circulation path, the third path configured to supply at least a portion of the unreacted fuel to the second circulation path.