Hydrogen Circulation Pump Pressure Control for Fuel Cell Systems
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Solution Overview
Problem
In fuel cell systems, the pressure at the inlet of the hydrogen circulation pump becomes negative relative to the atmospheric pressure when the discharge valve is opened, leading to insufficient discharge of anode waste gas, as the output of the hydrogen circulation pump increases, causing backflow of atmospheric air and hydrogen.
Innovation Solution
The operation of the hydrogen circulation pump is controlled to maintain a higher pressure at its inlet than atmospheric pressure when the discharge valve is opened, preventing backflow and ensuring efficient discharge of anode waste gas by adjusting the rotational speed based on detected pressure differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the output of the hydrogen circulation pump is increased, then the discharge efficiency of anode waste gas is improved, but the pressure at the inlet of the pump becomes negative relative to atmospheric pressure, causing backflow of atmospheric air and hydrogen
Solution Approach 1:
The discharge valve is opened before increasing the pump output, and the pump output is gradually increased while maintaining positive pressure at the inlet. This preliminary action sequence prevents negative pressure formation and backflow while achieving efficient waste gas discharge.
Solution Approach 2:
The pump output is dynamically adjusted based on the discharge valve state and pressure conditions. The control unit continuously monitors and adjusts the pump output to maintain optimal pressure conditions, preventing negative pressure while maximizing discharge efficiency.
2Productivity
If the discharge valve is opened when the pump output is high, then anode waste gas can be discharged, but atmospheric air flows backward into the system due to negative pressure
Solution Approach 1:
The discharge valve is opened in advance before increasing pump output, and the pump output is gradually increased to maintain positive pressure. This preliminary action prevents atmospheric air backflow while enabling effective waste gas discharge.
Solution Approach 2:
The control unit monitors pressure conditions and adjusts the pump output accordingly. When the discharge valve is opened, the control unit increases pump output gradually while maintaining positive pressure at the inlet, preventing atmospheric air backflow through feedback control.
3Productivity
If the discharge valve is opened when the pump output is high, then waste gas discharge is achieved, but hydrogen flows backward through the stack unnecessarily
Solution Approach 1:
The discharge valve is opened before increasing pump output, and the pump output is gradually increased while maintaining positive pressure at the inlet. This prevents hydrogen backflow through the stack and unnecessary hydrogen loss while achieving waste gas discharge.
Solution Approach 2:
The control unit monitors pressure conditions and adjusts pump output to maintain positive pressure at the inlet when the discharge valve is opened. This feedback control prevents hydrogen from flowing backward through the stack, reducing hydrogen loss while maintaining discharge efficiency.
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 reliable and efficient discharge of anode waste gas, preventing atmospheric air and hydrogen backflow, and conserving hydrogen by ensuring it does not flow through the stack unnecessarily.
Implementation Method 1
the pressure at the inlet of the hydrogen circulation pump becomes negative relative to the atmospheric pressure when the discharge valve is opened
Implementation Method 2
a hydrogen circulation pump provided at the hydrogen circulation passage
Implementation Method 3
a fuel cell stack configured to electrochemically react hydrogen and oxygen so as to generate electricity
Implementation Method 4
a gas-liquid separator provided at the hydrogen circulation passage
Data Source
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AI summary
An object is to provide a fuel cell system that can make the pressure at the inlet of the hydrogen circulation pump higher than the atmospheric pressure in the process of opening a discharge valve and sufficiently discharge anode waste gas. In a hydrogen circulation type fuel cell system, the rotational speed of the hydrogen circulation pump is lowered in the process of opening a discharge valve, and the pressure difference between the inlet and the outlet of the hydrogen circulation pump is made lower than the hydrogen supply pressure to the stack. This can prevent the pressure on the inlet side of the hydrogen circulation pump in the hydrogen circulation passage from being a negative pressure with respect to the atmospheric pressure, and it is therefore possible to prevent backflow of atmospheric air in the process of opening the discharge valve and to sufficiently discharge anode waste gas.