Fuel Cell Stack End Member Cooling Flow Path Design
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Solution Overview
Problem
In fuel cell stacks, the end unit cells experience excessive cooling water flow issues, leading to temperature decreases that can result in dew condensation and degraded power generation performance, as existing solutions like end plates with circulation flow paths do not effectively introduce sufficient cooling water to prevent temperature drops.
Innovation Solution
A fuel cell stack design featuring an end member with a first discharge hole, a second discharge hole, a circulation flow path, a constriction portion to enhance cooling water flow near the inlet, and a cover portion to control flow near the outlet, ensuring a consistent flow rate and preventing excessive temperature drops.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If cooling water circulation is increased to cool end unit cells, then temperature decrease is suppressed, but excessive cooling and dew condensation occur
Solution Approach 1:
The patent applies local quality by providing different cooling water flow paths for different regions: the circulation flow path portion provides enhanced cooling to the end unit cell through the circulation hole, while the through-flow path allows normal cooling water flow through other unit cells. This localized cooling approach prevents excessive cooling and dew condensation in non-end regions while effectively cooling the end unit cell.
Solution Approach 2:
The cooling water flow path is segmented into two distinct paths: a circulation flow path portion with a circulation hole that recirculates cooling water specifically for the end unit cell, and a through-flow path that allows cooling water to flow through all unit cells. This segmentation enables independent control of cooling water flow to different regions, preventing the need for excessive overall cooling.
2Temperature
If conventional end plate with circulation flow path is used, then temperature decrease of end unit cell is suppressed, but sufficient cooling water flow is not introduced
Solution Approach 1:
The patent applies preliminary action by forming protrusions on the inner wall surface of the circulation hole that guide and direct cooling water into the circulation flow path portion before it reaches the end unit cell. This preliminary guidance ensures that cooling water is effectively introduced into the circulation path, increasing the amount of cooling water that reaches the end unit cell compared to conventional designs.
Solution Approach 2:
The circulation hole acts as an intermediary element that receives cooling water from the cooling water supply and distributes it specifically to the end unit cell. The protrusions on the circulation hole's inner wall surface further mediate the flow, directing cooling water into the circulation path and ensuring sufficient quantity reaches the target region.
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 design effectively suppresses temperature decreases in end unit cells by ensuring a higher flow rate of cooling water through the circulation flow path, thereby maintaining optimal power generation performance.
Implementation Method 1
circulation flow path portion (181) that circulates a part of the cooling water (22) discharged from the unit cells (112)
Implementation Method 2
constriction portion (184) that reduces a cross-sectional area of the second discharge hole (119a)
Implementation Method 3
cooling water (22) that cools the unit cells (112) and whose temperature is increased by receiving heat from the unit cells (112)
Data Source
AI summary
A fuel cell stack includes a stacked body including unit cells that are stacked and an end member arranged at an end side of the stacked body in a stacking direction of the stacked body.