Flow-Field Plate With Integrated Water Separation for Anode Recirculation
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Solution Overview
Problem
Existing fuel cell systems face inefficiencies and operational stability issues due to external components used for anode recirculation, leading to heat losses, pressure losses, and increased installation space, which hinder effective separation of liquid water and gas.
Innovation Solution
A flow-field plate with a gas inlet and a water/gas separator, where the flow cross-section between the gas inlet and the separator is widened to decelerate the gas/exhaust gas mixture, preventing liquid water entry into the fuel cell stack and incorporating angled walls and baffle plates to enhance separation and flow guidance, while maintaining a compact design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If external components (jet pump, recirculation blower) are used for anode recirculation, then fuel can be reintroduced into the fuel cell stack, but additional surfaces for heat losses, pressure losses occur, and additional installation space is required
Solution Approach 1:
The patent integrates the water/gas separator directly into the flow-field plate structure, merging previously separate external components (jet pump, recirculation blower, water/gas separator) into a single integrated unit. This eliminates additional installation space, reduces heat loss surfaces, and minimizes pressure losses by removing intermediate connection points and external component interfaces.
2Productivity
If external components are used for anode recirculation, then fuel can be reintroduced into the fuel cell stack, but additional installation space must be provided
Solution Approach 1:
The water/gas separator is integrated directly into the flow-field plate, combining multiple functions (flow distribution, water separation, gas recirculation) into a single compact structure. This eliminates the need for separate external components and their associated installation space, achieving space-efficient design while maintaining anode recirculation functionality.
3Reliability
If the flow cross-section at the gas inlet is made smaller than at the water/gas separator, then the gas/exhaust gas mixture is decelerated for more effective separation, but the flow field channel dimensions are constrained
Solution Approach 1:
The flow-field plate features a localized expansion region between the gas inlet and the water/gas separator, where the flow cross-section increases specifically in the recirculation channel. This local geometric modification allows deceleration of the gas/exhaust gas mixture for effective water separation without altering the overall flow field channel dimensions, maintaining both separation effectiveness and flow field integrity.
4Reliability
If the flow cross-section is widened between the gas inlet and the water/gas separator, then liquid water entry into the anode chambers is prevented, but the flow path length increases
Solution Approach 1:
A localized expansion region is created between the gas inlet and the water/gas separator, providing a deceleration zone that prevents liquid water from entering the anode chambers. This local geometric feature achieves the protective function without significantly extending the overall flow path length, as the expansion is confined to a specific region rather than extending the entire flow path.
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 solution enables effective separation of liquid water and gas, preventing damage to the fuel cell and improving anode recirculation efficiency by decelerating the gas mixture and guiding it back into the flow field, thus enhancing the operational stability and reducing heat and pressure losses.
Implementation Method 1
there is between the gas inlet and the flow field a pressure gradient which causes an exhaust gas flowing into the channels to be drawn toward the gas inlet
Implementation Method 2
a water/gas separator fluidically connected to the gas inlet for removing liquid water and/or water vapor from a gas
Implementation Method 3
By widening the flow cross-section between the gas inlet and the water/gas separator, the gas/exhaust gas mixture flowing therein is decelerated so that a more effective separation of liquid water in the water/gas separator is made possible
Data Source
AI summary
A flow-field plate is provided for distributing a reactant to an electrode or a gas diffusion layer of a fuel cell, the flow-field plate having a gas inlet, and having a plurality of channels defining a flow field. A pressure gradient is present between the gas inlet and the flow field given a state of throughflow, which leads to an intake of exhaust gas flowing in the channels in the direction of the gas inlet. Furthermore, there is a water/gas separator which is fluidically connected to the gas inlet for separating liquid water and/or water vapor from a gas which is connected to the flow field in order to supply the gas separated in the water/gas separator to the flow field. A flow cross-section at the gas inlet or at the gas inlet region is smaller than the flow cross-section at or in the region of the water/gas separator.