Fuel Cell Rib Segmentation for Water Retention
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Solution Overview
Problem
Conventional fuel cells face challenges in retaining water under low- or non-humidification conditions, leading to reduced power density and MEA deterioration due to water being discharged through oxidizing gas channels, which decreases the durability and efficiency of the fuel cell.
Innovation Solution
The fuel cell design incorporates alternating water retention regions and oxidizing gas supply regions between oxidizing gas channels, allowing for sufficient water retention and efficient oxygen supply to the MEA, even with less humidified or non-humidified gases, by optimizing the rib width and channel configuration to maintain high water content and oxygen concentration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If rib width is reduced to supply more oxidizing gas to the MEA, then oxidizing gas supply is improved, but water retention capability deteriorates
Solution Approach 1:
The rib structure is segmented into multiple regions with different widths: a first rib portion with a first width and a second rib portion with a second width greater than the first width. This segmentation allows different sections of the rib to perform different functions - the narrower first portion supplies oxidizing gas efficiently while the wider second portion retains water, thus resolving the contradiction between gas supply and water retention.
2Productivity
If oxidizing gas channels are configured to maximize gas supply, then power generation efficiency is improved, but water discharge increases leading to MEA deterioration
Solution Approach 1:
Different regions of the rib are given different local qualities through varying widths. The first rib portion has a narrower width optimized for oxidizing gas supply to maintain high power generation efficiency, while the second rib portion has a wider width that creates capillary pressure to retain water and prevent its discharge, thereby eliminating the harmful effect of water discharge on MEA.
3Quantity of substance
If a humidifier is installed to ensure sufficient water content, then water content is improved, but system size and cost increase
Solution Approach 1:
The fuel cell system achieves water retention through its own structural design - the rib with varying widths creates capillary pressure differences that automatically retain water within the MEA. This self-service mechanism eliminates the need for external humidifiers, thereby reducing system size and complexity while maintaining sufficient water content for polymer electrolyte membrane functionality.
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
This design ensures MEA durability and high power density by retaining water within the fuel cell and effectively supplying oxygen, even under non-humidified conditions, thereby enhancing the fuel cell's operational efficiency and extending its lifespan.
Implementation Method 1
The polymer electrolyte membrane is composed of an electrolyte which contains a polymer ion-exchange membrane
Implementation Method 2
The catalyst electrode is composed of a catalyst layer that promotes a redox reaction therein
Implementation Method 3
The gas diffusion layer is composed of a carbon coat layer for improving adhesion to the catalyst layer and of a gas diffusion base layer through which a gas supplied from an external source is allowed to diffuse to the catalyst layer
Implementation Method 4
a second rib portion extending from one end of the first rib portion in the second direction, the second rib portion having a second width in the first direction, the second width being greater than the first width
Data Source
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AI summary
A fuel cell comprising: a membrane electrolyte assembly having a polymer electrolyte membrane and a pair of catalyst electrodes, namely an air electrode and a fuel electrode sandwiching the polymer electrolyte membrane; a pair of separators, namely an air electrode separator and a fuel electrode separator sandwiching the membrane electrolyte assembly; two or more oxidizing gas channels running in a certain direction for the purpose of supplying an oxidizing gas to the air electrode; and two or more linear fuel gas channels arranged parallel to the certain direction for the purpose of supplying a fuel gas to the fuel electrode. Large gaps and small gaps are provided alternately between adjacent two oxidizing gas channels along the certain direction, and the fuel gas channels do not overlap portions of the oxidizing gas channels, that are parallel to the fuel gas channels.