Fuel Cell Separator Plate with Asymmetric Flow Obstacles
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Solution Overview
Problem
Fuel cells with coarse flow fields suffer from low reactant concentration over ribs, leading to performance degradation and condensate removal issues, particularly in regions closer to the exits, where reactant species starvation occurs, and existing solutions like interdigitated flow fields incur high pressure drops and inefficient condensate removal.
Innovation Solution
A separator plate unit with a serpentine flow field structure and strategically placed flow obstacles within the fluid guide channels, which divert part of the channel flow towards the gas diffusion layer, enhancing reactant concentration and condensate removal while reducing pumping power requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If an interdigitated flow field is used to increase reactant concentration over ribs, then reactant distribution is improved, but pressure drop increases significantly and pumping power demand rises
Solution Approach 1:
The flow field is segmented into serpentine channels with periodic obstacles that divide the channel into multiple flow paths. This segmentation allows reactants to be distributed more uniformly over the ribs while maintaining open channel continuity for low pressure drop
Solution Approach 2:
Flow obstacles act as intermediaries that redirect the main channel flow toward the gas diffusion layer and ribs without completely blocking the channel. These obstacles mediate between the need for high reactant concentration and low pressure drop by providing localized flow diversion while maintaining overall flow continuity
2Quantity of substance
If an interdigitated flow field is used to force mass flow toward GDL, then reactant concentration over ribs is improved, but condensate removal capability deteriorates
Solution Approach 1:
The flow field structure implements local quality variations through asymmetric obstacle placement and serpentine channel geometry. This creates regions of high velocity near obstacles for reactant distribution while maintaining overall channel flow continuity for condensate removal toward outlets
Solution Approach 2:
Instead of using dead-end channels that force flow toward GDL (interdigitated), the invention inverts the approach by using open serpentine channels with obstacles that redirect flow laterally. This inversion maintains condensate removal capability while achieving reactant concentration improvement
3Ease of manufacture
If coarse flow fields are used for manufacturing reasons, then manufacturing cost is reduced, but reactant concentration over ribs decreases causing performance degradation
Solution Approach 1:
The invention changes the geometric parameters of the flow field by introducing periodic obstacles with specific dimensions (0.5-2.0 mm length, 0.1-0.5 mm height) into coarse serpentine channels. This parameter modification enables reactant concentration improvement while maintaining manufacturability of coarse flow fields
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
The solution achieves a reactant concentration comparable to finer flow fields with reduced pressure drop, improving fuel cell performance and condensate removal efficiency, similar to conventional serpentine flow fields, while maintaining lower pumping power demands.
Implementation Method 1
a laminar flow of a dilute oxidant stream, for example air
Implementation Method 2
The laminar flow is changed to turbulent flow whereby enhancing the flow of oxygen to the membrane electrode assembly
Data Source
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AI summary
The present invention relates to a separator plate unit for a fuel cell, which comprises a flow field with fluid guide channels for the reaction fluids, which run parallel to each other and are bounded by ribs, wherein flow obstacles narrowing the flow cross section of the fluid guide channels are arranged within the fluid guide channels, with 2-8, preferably 3-6 flow obstacles per 100 mm channel length are provided, the arrangement of the flow obstacles being asymmetric with respect to flow guide channels being adjacent to each other, and wherein the flow obstacles have a cross section area of each at maximum 90 % of the cross section of the fluid guide channels. Further, the present invention also relates to a fuel cell comprising such a separator plate unit on the cathode side and/or anode side. The fuel cell of the invention shows enhanced performance.