Fuel Cell Separator Rib Recesses to Prevent GDL Sinking
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Solution Overview
Problem
In existing fuel cells, the gas diffusion layer (GDL) adjacent to the separator groove passages can deform and sink into the passages, creating resistance to reactant gas flow and increasing pressure loss.
Innovation Solution
The separator design includes ribs with recesses on the inner facing surface to restrict the GDL from sinking into the groove passages, using inclined inner side surfaces and varying rib widths to maintain a taut GDL state, and incorporates a base member with protrusions to stabilize the frame member.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the separator uses groove passages to supply reactant gas to the MEGA, then gas supply function is improved, but the GDL deforms and sinks into the groove passages causing increased pressure loss
Solution Approach 1:
The rib structure is segmented by introducing recesses that divide the rib into multiple sections. This segmentation allows the GDL to be supported at multiple points along the rib, preventing it from sinking into the groove passages while maintaining the groove passages' gas supply function.
Solution Approach 2:
The recesses act as intermediary structures between the ribs and the GDL. They provide a transition zone that supports the GDL and prevents direct contact between the GDL and the groove passages, thereby eliminating the sinking problem while preserving gas flow.
2Ease of manufacture
If the GDL is allowed to contact the separator ribs directly, then manufacturing simplicity is improved, but the GDL deforms and creates resistance to gas flow
Solution Approach 1:
The rib is divided into multiple sections by recesses, creating multiple contact points with the GDL. This segmentation prevents the GDL from deforming and sinking into the groove passages while maintaining a relatively simple manufacturing process.
Solution Approach 2:
The recesses create local variations in the rib structure, providing specific support zones where the GDL contacts the rib. This local quality change ensures proper GDL positioning and prevents harmful deformation without complicating the overall manufacturing process.
3Device complexity
If the separator structure is simplified without additional features, then device complexity is reduced, but the GDL sinking problem persists
Solution Approach 1:
The recesses segment the rib structure into multiple support sections, providing reliable GDL positioning. This segmentation approach maintains relatively low device complexity while significantly improving GDL positioning stability and preventing sinking.
Solution Approach 2:
The recesses are pre-formed in the separator structure to provide preliminary support to the GDL before assembly. This preliminary action ensures proper GDL positioning from the start, preventing sinking issues without requiring complex additional components.
Data Source
AI summary
A separator for a fuel cell includes a facing surface configured to face a power generating unit of the fuel cell. Groove passages and ribs that protrude toward the power generating unit are provided on the facing surface. At least one of the ribs includes at least one recess in a center of the rib in an arrangement direction of the groove passages. The recess includes a bottom surface, which faces the power generating unit, and two inner side surfaces, which rise from opposite ends in the arrangement direction of the bottom surface. The two inner side surfaces are inclined such that a given point on each inner side surface separates further away from the bottom surface in the arrangement direction as that point approaches the power generating unit in a direction in which the power generating unit and the separator face each other.