Fuel Cell Oxygen Consumption Pumping Control
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Solution Overview
Problem
In fuel cell systems, the oxygen consuming process leads to a pumping phenomenon where the concentration of oxidant gas decreases excessively at the oxidant electrode, causing fuel gas to leak to the exhaust side during restart, resulting in inefficiency and inconvenience.
Innovation Solution
A fuel cell system with a voltmeter, ammeter, restricting valve, and load control unit that controls the output current to reduce as the output voltage increases during the oxygen consuming process, thereby restraining the pumping phenomenon and minimizing fuel gas leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the restricting valve is closed during the oxygen consuming process, then oxygen consumption is effective and cell deterioration is curbed, but the concentration of oxidant gas excessively decreases causing fuel gas to leak to the exhaust side
Solution Approach 1:
The patent applies dynamics by making the restricting valve switchable between open and closed states based on operational phase. During normal operation, the valve remains open to maintain proper gas concentrations. During the oxygen consuming process, the valve is closed to prevent fuel gas leakage while still allowing controlled oxygen consumption through the load control mechanism.
Solution Approach 2:
The patent changes the operational parameters by controlling the load to progressively increase current extraction during the oxygen consuming process. This parameter change (increasing current) drives oxygen consumption without requiring the restricting valve to remain closed throughout, thereby preventing excessive oxidant gas depletion and fuel gas leakage while still achieving cell protection.
2Duration of action of moving object
If current is continuously taken out during the system stop period, then oxygen consuming process is maintained, but the concentration gradient causes pumping phenomenon and fuel gas generation at oxidant electrode
Solution Approach 1:
The patent implements periodic action through the progressive current increase strategy during the oxygen consuming process. Rather than maintaining constant current extraction, the system periodically increases the current in stages, allowing the chemical reactions to proceed while managing the consumption rate of oxidant gas. This periodic modulation prevents excessive concentration depletion.
Solution Approach 2:
The patent employs feedback control where the load control unit monitors the system state and adjusts the current extraction accordingly. During the oxygen consuming process, the feedback mechanism ensures that current is increased in a controlled manner based on voltage measurements and system response, preventing runaway oxidant gas consumption and the associated pumping phenomenon.
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 system effectively reduces fuel gas leakage to the exhaust side during the oxygen consuming process, maintaining optimal gas concentrations and enhancing the efficiency of the fuel cell system's restart process.
Implementation Method 1
a fuel cell configured to be supplied with fuel gas and oxidant gas and generate electric power by causing the fuel gas and the oxidant gas to react with each other
Implementation Method 2
a voltmeter configured to measure an output voltage of the fuel cell
Implementation Method 3
an ammeter configured to measure an output current of the fuel cell
Data Source
AI summary
A fuel cell system includes a fuel cell including a fuel electrode being supplied with fuel gas and an oxidant electrode being supplied with oxidant gas and generating electric power by causing the fuel gas and the oxidant gas to react with each other, a voltmeter measuring an output voltage of the fuel cell, an ammeter measuring an output current of the fuel cell, a restricting valve provided upstream and downstream of an oxidant electrode side of the fuel cell and being opened in a power generation state and being closed in a stopped state or under the oxygen consuming control, and a load control unit controlling a current value of an output current to be output by the fuel cell and, under the oxygen consuming control, controlling the output voltage of the fuel cell such that the output current reduces as the output voltage of the fuel cell increases.