Fuel Cell Water Content Control via Closed-Loop Gas Circulation
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Solution Overview
Problem
Conventional fuel cell systems face complexity and inefficiency in maintaining desired power generation performance due to the need for separate humidified gas supply systems and high energy consumption in adjusting relative humidity, leading to impurity ion retention and degraded performance.
Innovation Solution
A method involving a fuel cell system with a water content adjusting device and an oxygen-containing gas supply apparatus that circulates oxygen in a closed channel to maintain a lean oxygen state, allowing for controlled water content adjustment and impurity ion removal, thereby maintaining power generation performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a separate highly humidified gas supply pipe is provided to supply highly humidified gas to the fuel cell, then impurity ions can be removed and power generation performance can be maintained, but the system becomes complicated
Solution Approach 1:
The patent combines the humidified gas supply function with the existing air supply system by introducing a humidifier into the existing air supply pipe that supplies air to the cathode. This merging approach eliminates the need for a separate highly humidified gas supply pipe while still achieving the desired humidification effect for removing impurity ions and maintaining power generation performance.
Solution Approach 2:
The air supply system is given multiple functions: it not only supplies oxygen to the cathode for power generation but also, after passing through the humidifier, supplies highly humidified gas for washing the electrode catalyst layer and removing impurity ions. This multi-functionality approach reduces system complexity by eliminating dedicated separate systems.
2Reliability
If the flow rate of oxygen-containing gas is increased to adjust relative humidity and remove impurity ions, then power generation performance can be maintained, but energy consumption becomes large
Solution Approach 1:
The patent introduces a humidifier as an intermediary device in the air supply line. The humidifier adds moisture to the air stream without requiring a significant increase in gas flow rate. This intermediary approach enables effective humidification and impurity ion removal while avoiding the high energy consumption associated with pumping large quantities of oxygen-containing gas.
Solution Approach 2:
Instead of changing the flow rate parameter of the oxygen-containing gas to achieve humidification, the patent changes the humidity parameter by introducing a humidifier. This parameter change approach allows for effective impurity ion removal while maintaining energy-efficient operation without requiring large increases in gas flow rate.
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 simplifies the system, reduces energy consumption, and effectively removes impurity ions like sulfate ions, ensuring reliable power generation performance by maintaining the fuel cell's water content and voltage within optimal ranges.
Implementation Method 1
The fuel cell generates electrical energy by electrochemical reaction of a fuel gas supplied to the anode and an oxygen-containing gas supplied to the cathode
Implementation Method 2
sulfuric acid ions may be eluted from the polymer ion exchange membrane through water in the fuel cell
Data Source
AI summary
An operation method of a fuel cell system includes the step of determining whether or not performance recovery control of a fuel cell stack should be started. This operation method includes the step of, if it is determined that the performance recovery control should be started, supplying water content to a membrane electrode assembly by a water content adjusting device, while maintaining power generation voltage of the fuel cell stack at 0.3 V or lower in a state where an oxygen-containing gas is circulated through a closed circulation channel.