Fuel Cell Flow Field Plate for Uniform Reactant Distribution
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Solution Overview
Problem
Existing fuel cell systems face challenges in achieving uniform distribution of reactants over the bipolar plate, particularly at high volume flows and velocities, leading to uneven distribution in the active area of the fuel cell stack.
Innovation Solution
The bipolar plate incorporates a channel elevation with a rise and descent upstream of the flow divider, changing the cross-sectional shape of the media flow from circular to elliptical, which gently impacts the flow divider, ensuring even distribution by maintaining a constant flow cross-section and using a rounded flow divider for redistribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If branching flow paths are used in the distribution area to distribute operating media evenly, then distribution capability is improved, but at high volume flows and velocities the distribution becomes uneven
Solution Approach 1:
The channel elevation is positioned upstream of the flow divider to pre-condition the flow before it reaches the division point. This preliminary action modifies the flow profile in advance, ensuring that when the flow divides, both branches receive evenly distributed media even at high volume flows and velocities.
Solution Approach 2:
The channel elevation changes the physical parameters of the flow by creating a raised section that modifies the flow profile. This parameter change transforms the flow from a concentrated stream into a more distributed pattern, improving distribution uniformity across branching paths while maintaining high volume flow capability.
2Ease of manufacture
If flow channels have constant cross-section to simplify manufacturing, then manufacturing complexity is reduced, but pressure losses increase and distribution uniformity deteriorates
Solution Approach 1:
Instead of changing the entire channel cross-section, only a localized elevation is introduced at specific positions upstream of flow dividers. This local modification optimizes flow distribution and reduces pressure losses without requiring complex fabrication throughout the entire channel system, maintaining ease of manufacture while improving performance.
3Loss of energy
If flow channels have varying cross-sections to compensate pressure losses, then pressure distribution is improved, but manufacturing complexity increases
Solution Approach 1:
The channel elevation performs pressure loss compensation in advance by modifying the flow profile upstream of critical division points. This preliminary pressure management eliminates the need for complex varying cross-sections throughout the channel, achieving pressure balance with a simpler localized geometric feature.
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 design enhances the even distribution of reactants over the bipolar plate and fuel cell stack, reducing turbulence and pressure losses, resulting in improved media distribution and operational efficiency.
Implementation Method 1
the central media flow, which is characterized by laminar flow, is forced to widen by reducing the height of the channel, so that the cross-sectional shape of the media flow transitions from a round to an elliptical shape
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
The invention relates to a flow field plate (3) which is formed so as to have, on each of the plate surfaces thereof that face away from one another, a reactant flow field which comprises a plurality of flow channels (9) for a reaction medium that are delimited by walls (11) of projections (10), wherein each reactant flow field is fluidically connected to a media port (4, 5) via a distributor field in a distributor region (14) which is located outside an active region (13), wherein at least one channel (15) of the distributor field is provided with a flow divider (12) for dividing a flowing reaction medium upstream of its introduction into the active region (13). The channel (15) having the flow divider (12) has a channel elevation (16) comprising a slope (17) which is present at a predetermined distance upstream of the flow divider (12). The invention further relates to a fuel cell stack (1) having a plurality of such flow field plates (3).