Fuel Cell Anode Passivation Using Exhaust Air Recirculation
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Solution Overview
Problem
Fuel cell anode surfaces are susceptible to corrosion due to the absence of oxygen during shutdown, leading to degradation of the passivation layer and reduced service life.
Innovation Solution
A method is proposed where exhaust air with low oxygen concentration from the exhaust air path of a fuel cell stack is periodically branched off and introduced into the anode circuit to build up or maintain a passivation layer, thereby reducing corrosion risk.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If no oxygen is supplied to the anode during shutdown to prevent degradation, then fuel cell degradation is reduced, but the passivation layer on the anode surface deteriorates leading to increased corrosion susceptibility
Solution Approach 1:
The patent introduces exhaust air containing oxygen into the anode circuit during shutdown to create a protective atmosphere that maintains the passivation layer on the anode surface, preventing corrosion while the fuel cell is not in operation
Solution Approach 2:
The patent applies passivation by introducing oxygen-containing exhaust air into the anode circuit before corrosion can occur during shutdown, thereby preemptively protecting the anode surface and maintaining the passivation layer
2Object-affected harmful factors
If exhaust air is introduced into the anode circuit to maintain passivation layer, then corrosion risk is reduced, but system complexity increases due to additional control requirements
Solution Approach 1:
The patent utilizes the existing exhaust air path and oxygen already present in the system, making the exhaust air serve a dual function: discharge during operation and passivation during shutdown, thereby avoiding the need for separate oxygen supply systems
Solution Approach 2:
The system uses its own exhaust air, which contains oxygen, to perform the passivation function during shutdown, making the system self-sufficient and eliminating the need for external oxygen sources or additional complex control 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
The method effectively reduces the risk of corrosion on anode surfaces, thereby increasing the service life of the fuel cell stack by maintaining a stable passivation layer.
Implementation Method 1
exhaust air from the exhaust air path or an exhaust air path of another fuel cell stack is branched off periodically and introduced into the anode circuit of the anode to build up a passivation layer of the anode and/or to repassivate a passivation layer of the anode
Data Source
AI summary
The invention relates to a method for operating a fuel cell system (1) comprising at least one fuel cell stack (100) having a cathode (110) and an anode (120), wherein, during normal operation of the fuel cell system (1), the cathode (110) is supplied with air via a supply air path (111), and exhaust air exiting the fuel cell stack (100) is discharged via an exhaust air path (112), and wherein the anode (120) is supplied with hydrogen via an anode circuit (121). According to the invention, in order to create a passivation layer of the anode (120) and/or for the repassivation of a passivation layer of the anode (120), periodically, exhaust air is branched off from the exhaust air path (112) or an exhaust air path (212) of another fuel cell stack (200) and introduced into the anode circuit (121) of the anode (120).The invention also relates to a fuel cell system (1) for carrying out a method according to the invention.