Perforated Bipolar Plate Flow Field for Fuel Cell Flooding
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Solution Overview
Problem
Fuel cell performance is hindered by flooding due to liquid droplets obstructing flow channels, leading to non-uniform reactant distribution, reduced current generation, and increased electrical load, which affects durability and operation.
Innovation Solution
Incorporating perforated wall portions between adjacent channels in the flow-field plates to create a pressure difference that draws liquid droplets into passageways, preventing channel obstruction and promoting uniform flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If liquid droplets are removed from channels to prevent flooding, then uniform reactant distribution is improved, but additional structures (perforated walls) are required which increase device complexity
Solution Approach 1:
The wall portions between adjacent channels are made perforated with multiple openings, creating a porous structure that allows liquid droplets to pass through while maintaining the separator function. This resolves the contradiction by adding liquid removal capability without requiring completely separate drainage systems.
Solution Approach 2:
The wall portions are divided into multiple discrete perforations rather than being completely open, segmenting the flow control function into distributed openings that collectively manage liquid removal while maintaining structural integrity.
2Object-affected harmful factors
If channel width is increased to prevent droplet obstruction, then flooding is reduced, but reactant distribution uniformity deteriorates due to larger dead zones
Solution Approach 1:
Instead of increasing channel width (one-dimensional solution), the invention adds a vertical dimension by creating passageways through the wall portions, allowing liquid droplets to be removed in the thickness direction while maintaining channel width for uniform reactant distribution.
Solution Approach 2:
The perforated wall portions act as intermediary structures between adjacent channels, providing a medium through which liquid droplets can pass from one channel to another, thereby preventing flooding without altering channel dimensions.
3Productivity
If perforated walls are added to create pressure difference, then liquid droplet removal is enhanced, but manufacturing complexity increases
Solution Approach 1:
The liquid removal function is merged with the existing wall portions between channels, combining two functions (separation and liquid removal) into a single integrated structure, thereby enhancing droplet removal without adding separate manufacturing steps.
Solution Approach 2:
The perforated wall portions serve multiple functions: separating adjacent channels, managing liquid droplets, and creating pressure differences. This multi-functionality reduces the need for additional dedicated components, simplifying overall manufacturing.
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 solution effectively reduces flooding, maintains uniform reactant distribution, enhances current generation, and improves fuel cell performance by ensuring continuous flow and preventing stagnant zones.
Implementation Method 1
The passageway is sized so as to create a pressure difference between the channel portions. The pressure difference draws at least a portion of a liquid droplet obstructing one of the channel portions toward and into the passageway.
Implementation Method 2
The passageway is at least one of shaped, textured and coated so as to create a surface tension gradient between the surface at least partially defining the passageway and a surface of one the channel portions obstructed by a liquid droplet. The surface tension gradient draws at least a portion of the liquid droplet into the passageway.
Data Source
AI summary
A fuel cell system includes a bipolar plate having a flow field formed therein. The flow field is partially defined by at least two adjacent channel portions separated by a wall portion. The wall portion includes a surface at least partially defining a passageway between the channel portions. The passageway may be sized so as to create a pressure difference between the channel portions. The pressure difference may draw at least a portion of a liquid droplet obstructing one of the channel portions toward and into the passageway.