Fuel Cell Stack Separator Steps to Limit Cooling Side Flow
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Solution Overview
Problem
Existing fuel cell stacks suffer from reduced cooling efficiency due to side flows of the cooling medium, which are not effectively limited by varying depths of recess portions in the separators, leading to power generation efficiency loss.
Innovation Solution
The fuel cell stack design incorporates first and second protrusions on the separators that protrude towards adjacent cells, featuring step-like side wall portions to limit side flows by ensuring consistent contact and minimizing gaps, thereby controlling the flow of cooling medium.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If recess portions are made shallower to facilitate manufacturing, then ease of manufacture is improved, but gaps are likely to be created between bottom walls, causing cooling medium leakage and reducing cooling efficiency
Solution Approach 1:
A sealing member (O-ring) is introduced as an intermediary element between the recess portions of adjacent separators to seal gaps and prevent cooling medium leakage, thereby resolving the contradiction between ease of manufacture and cooling efficiency
Solution Approach 2:
The design allows for variable depths of recess portions within a controlled range, and the sealing member compensates for depth variations, enabling manufacturing flexibility while maintaining reliable sealing and cooling efficiency
2Reliability
If recess portions are made deeper to prevent gaps, then cooling efficiency is improved, but manufacturing complexity increases due to varying depths
Solution Approach 1:
The sealing member serves as a mediator that eliminates the need for complex deep recess structures, as it compensates for depth variations and ensures sealing, thereby maintaining cooling efficiency while reducing device complexity
Solution Approach 2:
The sealing function is segmented from the recess portion structure itself, allowing the recess portions to be simpler while the sealing member handles the gap prevention, thus reducing overall device complexity while maintaining reliability
3Reliability
If uniform depth of recess portions is maintained to prevent gaps, then cooling efficiency is improved, but manufacturing precision requirements increase
Solution Approach 1:
The sealing member acts as a tolerance compensator, absorbing variations in recess portion depths from manufacturing, thereby ensuring consistent sealing and cooling efficiency without requiring high manufacturing precision
Solution Approach 2:
The sealing member provides beforehand cushioning against potential gaps caused by manufacturing variations, ensuring that even if recess depths vary, the sealing function is maintained and cooling efficiency is preserved
Data Source
AI summary
A fuel cell stack includes single cells stacked in a first direction. Each single cell includes a power generating unit, a first separator, and a second separator. The first separator and the second separator hold the power generating unit between the first separator and the second separator. The first separator of each single cell includes first protrusions that protrude toward the second separator of another single cell that is adjacent in the first direction. The first protrusions are in contact with the second separator. Each of the first protrusions includes a top wall portion and two side wall portions. At least one of the two side wall portions includes a step portion having a shape of a step in the first direction.