Fuel Cell Bleed Manifold Valve Ice Blockage Detection
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Solution Overview
Problem
Fuel cell systems face challenges in determining whether bleed valves in the bleed manifold unit (BMU) are blocked with ice, which can prevent anode exhaust gas bleeding and lead to system instability and inefficiency, especially during start-up in cold conditions.
Innovation Solution
A system and method using a controller to diagnose valve blockages by sequentially opening and closing bleed valves and measuring pressure signals across a flow restriction to determine if ice is blocking the flow, allowing for switching to alternative bleeding methods like center bleed if blockages are detected.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If bleed valves are used to remove nitrogen from the anode side, then nitrogen concentration control is improved, but valve blockage with ice can cause system failure
Solution Approach 1:
The system performs preliminary actions by monitoring pressure differentials across bleed valves during normal operation to detect ice blockage before it causes system failure. The controller continuously compares measured pressure with expected pressure values to identify blockage conditions early, allowing preventive measures to be taken before nitrogen concentration control is compromised.
Solution Approach 2:
The system uses feedback by continuously measuring pressure differentials across bleed valves and comparing them with expected values. When the pressure differential exceeds a threshold indicating potential ice blockage, the controller receives feedback and can switch to alternative bleeding methods or adjust operations to prevent system instability.
2Reliability
If alternative bleeding methods like center bleed are used when BMU valves are blocked, then system operation is maintained, but hydrogen loss increases
Solution Approach 1:
The system performs preliminary detection of ice blockage conditions using pressure differential measurements before switching to alternative bleeding methods. By detecting blockage early through pressure monitoring, the system can prepare for alternative methods only when necessary, minimizing unnecessary hydrogen loss that would occur with continuous use of less efficient bleeding methods.
Solution Approach 2:
The system changes operational parameters by switching between different bleeding methods based on detected conditions. When ice blockage is detected through pressure differential analysis, the controller changes from using the blocked BMU valves to using alternative methods like center bleed, optimizing the balance between maintaining system operation and minimizing hydrogen loss.
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
Enables effective anode exhaust gas bleeding by identifying and addressing ice blockages in BMU valves, ensuring system operation and efficiency by switching to less efficient but necessary center bleeding when necessary, thus preventing hydrogen loss and maintaining stack stability.
Implementation Method 1
measuring a pressure differential across the flow restriction with the pressure sensor to determine if there is flow through the flow restriction
Data Source
AI summary
A system and method for determining whether valves in a fuel cell system bleed manifold unit (BMU) are blocked with ice or have otherwise failed. The system opens a first bleed valve, closes a second bleed valve and opens an exhaust valve, and then reads a pressure signal to determine whether there is flow through a flow restriction to determine whether the first bleed valve or the exhaust valve is blocked. The system then closes the exhaust valve, leaves the first bleed valve open, and again reads the pressure signal to determine the pressure drop across the flow restriction, which will indicate whether the flow restriction the pressure sensor lines are blocked. The system then closes the first bleed valve and opens the second bleed valve to determine whether the pressure signal indicates a flow through the second bleed valve.