Solid Oxide Fuel Cell Cathode Voltage Control via Combustor
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Solution Overview
Problem
In solid oxide fuel cell systems, the open circuit voltage takes a long time to converge to a target voltage during stop control, leading to potential cathode electrode deterioration due to oxygen partial pressure fluctuations, necessitating repeated discharge operations to maintain safe voltage levels.
Innovation Solution
A solid oxide fuel cell system with a combustor in the cathode gas supply line, a fuel supply unit, and a cathode gas supply unit, where the cathode gas supply amount and fuel supply are controlled to generate combustion gas, which is then used to lower the open circuit voltage efficiently, avoiding cathode electrode deterioration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the discharge circuit is used to lower the open circuit voltage to the target voltage, then the voltage safety is improved, but the oxygen partial pressure around the cathode electrode decreases causing electrode deterioration
Solution Approach 1:
The patent introduces a combustor as an intermediary device in the cathode gas supply line. The combustor burns fuel to generate heat that raises the oxygen partial pressure around the cathode electrode, counteracting the oxygen depletion caused by discharge operations. This intermediary heating mechanism allows voltage discharge to proceed while preventing electrode deterioration.
2Measurement precision
If repeated discharge operations are performed to maintain target voltage, then the voltage convergence is improved, but the time required for voltage stabilization increases
Solution Approach 1:
The patent applies preliminary action by heating the cathode gas supply line and combustor before discharge operations begin. This pre-heating ensures that the oxygen partial pressure is maintained at appropriate levels from the start, preventing the need for repeated discharge operations and reducing the overall voltage stabilization time.
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 approach allows for rapid convergence of the open circuit voltage to a target value without degrading the cathode electrode, reducing the time required for voltage stabilization and preventing electrode deterioration.
Implementation Method 1
a combustor disposed in a cathode gas supply line of the fuel cell, a fuel supply unit configured to supply a fuel to the combustor
Implementation Method 2
the oxygen inside the passage diffuses around the cathode electrode, so that the open circuit voltage increases again
Data Source
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AI summary
A solid oxide fuel cell system includes a solid oxide fuel cell, a combustor disposed in a cathode gas supply line of the fuel cell, a fuel supply unit configured to supply a fuel to the combustor, and a cathode gas supply unit configured to supply a cathode gas to the cathode gas supply line. The system further includes a stop control unit configured to perform a stop control of the fuel cell, which includes a control that sets a cathode gas supply amount from the cathode gas supply unit to a predetermined amount and a control that supplies the fuel from the fuel supply unit in a supply amount corresponding to the cathode gas supply amount.