Multi-Injection Fuel Cell Stack Purging With Alternating Cell Groups
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Solution Overview
Problem
Fuel cell batteries face significant hydrogen losses during purging due to the need to evacuate reaction products, which is costly and inefficient, especially when complex recirculation systems are not used.
Innovation Solution
A fuel cell battery system is designed with multiple groups of cells, where reactants are selectively supplied and unconsumed reactants can flow between groups through evacuation manifolds, allowing for reduced purging frequency and maintaining reaction continuity by mixing reaction products, thereby minimizing hydrogen loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If frequent purging is performed to evacuate reaction products, then the electrochemical reaction can be maintained, but hydrogen loss increases significantly
Solution Approach 1:
The fuel cell battery is divided into multiple groups of cells (first group, second group, etc.) that can be operated independently. This segmentation allows selective supply of reactants to specific groups and enables different operational modes for different groups simultaneously, reducing the need for frequent system-wide purging.
Solution Approach 2:
The patent implements periodic supply of reactants to different cell groups in alternating phases. During Phase 1, the first group is supplied while the second group is not, and vice versa in Phase 2. This periodic action allows reaction products to accumulate temporarily and be evacuated less frequently, reducing hydrogen loss while maintaining reaction continuity.
2Duration of action of stationary object
If complex recirculation systems are used to maintain humidification, then membrane lifespan is extended, but device complexity increases
Solution Approach 1:
The system uses its own reaction products (water vapor in the exhaust stream) to humidify the incoming hydrogen fuel. The exhaust stream from the fuel cell, which contains water vapor, is recirculated back to the fuel inlet, creating a self-sustaining humidification system that extends membrane lifespan without requiring external humidification equipment.
Solution Approach 2:
The patent combines the exhaust stream with the incoming fuel stream in a single recirculation loop. By merging these two streams, the system achieves both humidification and reactant mixing in one integrated process, reducing the number of separate components needed while maintaining membrane health.
3Power
If reactants are supplied to all cell groups simultaneously, then power output is maximized, but hydrogen consumption increases due to frequent purging
Solution Approach 1:
The system dynamically adjusts the supply of reactants to different cell groups based on operational phase. During Phase 1, only the first group receives reactants; during Phase 2, only the second group receives reactants. This dynamic supply strategy allows the system to maintain power output while reducing overall hydrogen consumption by avoiding simultaneous supply to all groups.
Solution Approach 2:
The patent recovers unconsumed reactants from one cell group to supply another cell group. The exhaust stream containing unreacted hydrogen and water vapor from one group is recirculated to become the fuel source for another group, reducing overall hydrogen consumption while maintaining power output.
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 reduces hydrogen consumption by less frequent purging, sustains the electrochemical reaction, and extends the lifespan of electrolytic membranes by maintaining moisture levels.
Implementation Method 1
The anode and cathode are separated by an electrolyte, possibly a solid membrane, that is permeable to certain of the constituents of the reaction but not all. The solid electrolyte is a membrane that is permeable to hydrogen ions H+ but not to molecular dihydrogen H2 or electrons.
Implementation Method 2
A fuel cell battery is a stack of elementary cells in which an electrochemical reaction takes place between reactants that are gradually introduced as the reaction consumes them. Electrons flow from the anode to the cathode via the external circuit thus powered by the battery as the electrochemical reaction progresses.
Implementation Method 3
The reduction reaction at the anode is oxidation of hydrogen producing H+ ions, which pass through the membrane, and electrons, which are collected by the anode
Implementation Method 4
at the cathode these ions participate in the reduction of oxygen, requiring electrons and producing water
Data Source
AI summary
Fuel cell batteries are provided, and in particular hydrogen fuel cell batteries composed of at least one stack of cells. The battery is divided into at least two groups of cells able to be supplied with hydrogen separately. In a first phase, only the first group of cells and not the second is supplied; unconsumed hydrogen may however flow between the two groups via at least one evacuation manifold connected to the cells of the two groups. In a second phase, the supply to the two groups is reversed, unconsumed hydrogen still being able to flow between the two groups via the evacuation manifold. In a third phase, after a series of alternations of the two first phases, the two groups are first simultaneously supplied, then a purge valve of the evacuation manifold is opened then closed.