Fuel Cell Start-Up Control for Membrane Protection
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Solution Overview
Problem
During the start-up of a fuel cell system, simultaneous performance of the cathode recovery and purge processes leads to overflow in the diluting system due to excessive anode gas supply, which prevents sufficient dilution and can cause deterioration of the solid polymer electrolyte membrane.
Innovation Solution
A fuel cell system with a control unit that sequentially releases the sealing of the cathode and anode passages, allowing anode gas in the cathode passage to be processed first, followed by the anode passage, and includes an anode gas-quantity acquiring unit to calculate the purge allowing time based on the anode gas quantity, preventing overflow and ensuring efficient gas processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the cathode recovery process and purge process are simultaneously performed at start-up, then the start-up speed is improved, but the diluting system overflows due to excessive anode gas supply
Solution Approach 1:
The patent divides the gas discharge process into two separate sequences: first discharging anode gas from the cathode passage, then discharging anode gas from the anode passage. This segmentation prevents the simultaneous discharge of large quantities of anode gas that would cause diluting system overflow, while still achieving relatively quick start-up by systematically managing the discharge timing of each gas source.
2Reliability
If the sealing of cathode passage is maintained during stoppage, then the solid polymer electrolyte membrane is protected from unexpected reactions, but the cathode passage cannot be quickly recovered at start-up
Solution Approach 1:
The patent performs preliminary discharge of anode gas from the cathode passage before full operation begins. By pre-discharging the accumulated anode gas during the start-up sequence before cathode gas is fully supplied, the system prepares the cathode passage in advance, preventing potential membrane damage while enabling rapid transition to full operation without prolonged recovery time.
3Productivity
If the purge process is performed immediately at start-up, then the anode passage is quickly replenished with high-concentration anode gas, but the diluting system overflows due to combined anode gas from both passages
Solution Approach 1:
The patent implements a periodic, two-stage discharge sequence: first discharging anode gas from the cathode passage, then subsequently discharging anode gas from the anode passage. This periodic action distributes the gas discharge over time rather than simultaneously, preventing diluting system overflow while ensuring both passages are thoroughly purged and replenished with high-concentration anode gas for efficient operation.
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 prevents overflow in the diluting system, allows for gradual processing of anode gas, and enables quick start-up of the fuel cell system while protecting the solid polymer electrolyte membrane by controlling the electric power generation before the purge process is completed.
Implementation Method 1
a solid polymer electrolyte membrane being interposed between the cathode passage and the anode passage
Implementation Method 2
the anode gas sealed off in the anode passage permeates the solid polymer electrolyte membrane and thus leaks to the cathode passage
Data Source
AI summary
A fuel cell system includes a fuel cell, a cathode supply passage, a cathode discharging passage, an anode supply passage, an anode discharging passage, a pair of cathode shutoff units, an anode shutoff unit, an anode discharging unit, a discharged gas processing unit, and a control unit. The control unit releases the sealing of the cathode passage by the pair of cathode shutoff units, at the time of start-up of the fuel cell system, and releases the sealing of the anode passage by the anode discharging unit, thereby performing a purge process to allow discharge of the anode gas.