Fuel Cell Anode Gas Supply Control for Impurity Removal
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Solution Overview
Problem
In anode gas non-recirculation type fuel cell systems, residual impurity gases like nitrogen accumulate during long-term deactivation, leading to insufficient hydrogen partial pressure and potential fuel cell degradation when the system is reactivated, especially under pulsating anode gas supply pressure conditions.
Innovation Solution
Incorporating an impurity gas concentration detector and an anode gas supply unit that adjusts pulsative pressure and cycle based on detected impurity gas concentrations in the buffer tank to prevent reverse flow of impurities back into the fuel cell stack, ensuring adequate hydrogen concentration and removing impurities during reactivation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If supply pressure of anode gas is pulsated during system activation, then impurity gas (nitrogen) is removed from the fuel cell stack, but high-concentration residual impurity gas may flow reversely from the buffer tank to the fuel cell stack, causing insufficient hydrogen partial pressure and reduced electrical voltage
Solution Approach 1:
The patent employs a feedback control mechanism where the supply pressure of anode gas is adjusted based on the electrical voltage of the fuel cell. When voltage drops below a predetermined threshold during pulsation, the supply pressure is increased to prevent reverse flow of impurity gas from the buffer tank, thereby maintaining hydrogen partial pressure and preventing fuel cell degradation
Solution Approach 2:
The system dynamically adjusts the supply pressure of anode gas during the pulsation process. Rather than maintaining a fixed pressure, the control unit modifies the pressure in real-time based on fuel cell performance indicators, allowing the system to adapt to changing conditions and prevent harmful reverse flow while effectively removing impurities
2Reliability
If a large amount of impurity gas accumulates in the buffer tank during long-term deactivation, then impurity gas can be exhausted from the fuel cell stack, but the high-concentration impurity gas in the buffer tank creates risk of reverse flow when supply pressure is pulsated
Solution Approach 1:
The control system continuously monitors the electrical voltage of the fuel cell and uses this feedback to adjust the supply pressure of anode gas. When voltage indicates insufficient hydrogen partial pressure, the system responds by increasing supply pressure to counteract reverse flow from the buffer tank, effectively managing the high-concentration impurity gas situation
Solution Approach 2:
The system takes preliminary action by monitoring voltage trends and adjusting supply pressure before severe reverse flow occurs. The control unit detects early signs of hydrogen partial pressure insufficiency and preemptively increases supply pressure to prevent the harmful effect of impurity gas reverse flow
Data Source
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AI summary
An anode gas non-recirculation type fuel cell system includes a fuel cell stack constituted by stacking a plurality of fuel cells, a buffer tank for discharging, to an outside, impurity gas included in anode off-gas exhausted from the fuel cell stack, an impurity gas concentration detector for detecting concentration of impurity gas in the buffer tank, and an anode gas supply unit for supplying anode gas to the fuel cell stack. When pressure-supplying impurity gas in the fuel cell stack to the buffer tank while pulsating a supply pressure by the anode gas supply unit, an activation control is executed by changing, by the anode gas supply unit, at least one of a pulsative pressure and a pulsative cycle of anode gas supply according to concentration of impurity gas in the buffer detected by the impurity gas concentration detector. According to the fuel cell system, it is possible to get adequate concentration of hydrogen gas in a fuel cell stack and to remove impurity at its activation.