Fuel Cell Flat Flow Field Water Discharge
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Solution Overview
Problem
In fuel cells with a horizontal stacking configuration, water tends to be retained as stagnant water at lower positions due to gravity, leading to metal ion dissolution from separators and degradation of the electrolyte membrane and electrode performance.
Innovation Solution
The implementation of a fuel cell design with a reactant gas flow field featuring corrugated grooves and a flat flow field at the lowermost position, where the flat flow field's bottom extends straight in the horizontal direction, allowing water to flow smoothly and be discharged effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If corrugated flow fields are used in horizontal stacking configuration, then the fuel cell can be placed in limited height space, but water is retained as stagnant water in recesses at lower positions
Solution Approach 1:
The flow field is segmented into corrugated flow grooves and a flat flow field region. The corrugated portions provide flow paths while the flat flow field at the lowermost position collects and discharges water, dividing the flow field functionality to resolve water retention issues.
Solution Approach 2:
The invention introduces a horizontal dimension to water discharge by creating a flat flow field that extends horizontally at the lowermost position. This allows water to be discharged in the horizontal direction rather than being trapped in vertical recesses, solving the water retention problem while maintaining compact height.
2Ease of operation
If corrugated flow fields extend in stacking direction, then flow paths are provided, but metal ions are dissolved from separators and electrodes due to water retention
Solution Approach 1:
The harmful stagnant water is extracted from the flow field system by providing a dedicated flat flow field region that collects and removes water horizontally. This prevents water from remaining in contact with separators and electrodes, eliminating the source of metal ion dissolution.
Solution Approach 2:
The invention converts the harmful effect of water retention into a beneficial discharge mechanism. The flat flow field at the lowermost position uses gravity to naturally collect and discharge water horizontally, transforming the problem of water accumulation into an effective water removal system that protects against ion dissolution.
3Reliability
If flat flow field is provided at lowermost position with straight bottom, then water flows smoothly and is discharged effectively, but flow field structure becomes more complex
Solution Approach 1:
The flat flow field is merged with the corrugated flow grooves to form an integrated flow field structure. The flat portion and corrugated portions work together as a unified system, combining the flow distribution function of corrugated grooves with the water collection function of the flat field without requiring separate components.
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 enables reliable discharge of water produced in power generation reactions, preventing water retention and subsequent ion absorption in the electrolyte membrane, thus suppressing membrane and electrode degradation.
Implementation Method 1
water tends to be retained as stagnant water in the recesses at lower positions in the direction of the gravity
Data Source
AI summary
A fuel cell includes a membrane electrode assembly, a first separator, and a second separator. The second separator has a fuel gas flow field connected to a fuel gas supply passage and a fuel gas discharge passage. The fuel gas flow field includes a plurality of corrugated flow grooves and a flat flow field. The corrugated flow grooves extend in the horizontal direction, respectively, and are arranged in the direction of the gravity. The flat flow field is provided within a power generation area, at the lowermost position in the direction of the gravity, and extends in the horizontal direction.