Fuel Cell Subgasket Baffles Mitigate Reactant Bypass
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Solution Overview
Problem
In fuel cell stacks, reactant bypass flow occurs due to the spacing between diffusion media and seals, leading to wasteful usage of reactants, reduced durability, reliability, and performance, especially at low stoichiometric ratios.
Innovation Solution
A subgasket with an elongate primary seal and inwardly extending baffles is used to minimize reactant bypass flow by creating a barrier that directs a higher percentage of reactants to the active regions of the fuel cell stack, optimizing the seal between the diffusion media and fuel cell plates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the diffusion media and seal are spaced apart to accommodate manufacturing tolerances, then the seal reliability is improved, but reactant bypass flow increases causing waste and performance degradation
Solution Approach 1:
The seal structure is segmented into multiple functional zones: an outer seal portion for sealing and an inner baffle portion for flow management. This segmentation allows the seal to simultaneously provide reliable sealing while preventing reactant bypass flow through the baffle's flow redirection capability.
Solution Approach 2:
The baffle acts as an intermediary element between the seal and the diffusion media. It intercepts bypassing reactants and redirects them toward the active region, mediating between the sealing function and the reactant delivery function to eliminate waste while maintaining seal integrity.
2Ease of manufacture
If the diffusion media and seal are spaced apart to avoid overlapping, then manufacturing ease is improved, but reactant bypass flow occurs reducing productivity
Solution Approach 1:
The seal is divided into distinct functional segments: the outer seal portion maintains the spaced-apart configuration for easy manufacturing, while the inner baffle portion actively manages reactant flow to prevent bypass, thereby maintaining fuel cell efficiency without complicating manufacturing.
Solution Approach 2:
The seal structure performs multiple functions simultaneously: sealing (outer portion) and flow management (inner baffle portion). This multi-functionality allows a single component to address both manufacturing ease and fuel cell productivity without requiring additional separate parts.
3Loss of substance
If the seal is positioned closer to the diffusion media to eliminate bypass flow, then reactant efficiency is improved, but manufacturing precision requirements increase
Solution Approach 1:
The seal is segmented into an outer seal portion that maintains adequate spacing for manufacturing tolerances and an inner baffle portion that extends toward the diffusion media to eliminate bypass flow. This segmentation allows the structure to achieve high reactant efficiency without imposing stringent positioning precision requirements on the entire seal.
Solution Approach 2:
Different portions of the seal have different spatial relationships with the diffusion media: the outer seal portion is spaced apart for manufacturing ease, while the inner baffle portion is positioned closer to the diffusion media to prevent bypass flow. This local differentiation of spatial quality allows the system to achieve high reactant efficiency without requiring uniform high precision across the entire seal assembly.
Data Source
AI summary
A subgasket for a fuel cell is provided. The subgasket includes a barrier layer having an elongate primary seal formed thereon. The seal has at least one inwardly extending baffle adapted to militate against a reactant bypass flow in the fuel cell. A fuel cell and fuel cell stack having the subgasket are also provided.