Fuel Cell Coolant Passageway Bubble Control
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Solution Overview
Problem
In fuel cells, low flow rates in coolant passageways lead to gas bubble blockage, causing localized heating, dehydration, and performance degradation, especially in systems without coolant pumps or external plumbing.
Innovation Solution
The design of gas tolerant coolant passageways with specific configurations, such as diverging channels and hydrophilic/hydrophobic layers, that allow gas bubbles to migrate towards vents, ensuring continuous coolant flow and preventing blockages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of stationary object
If coolant passageways are made smaller to reduce coolant volume, then coolant volume is reduced, but gas bubbles aggregate and block coolant flow
Solution Approach 1:
The passageway cross-section is varied along its length, with the inlet having a larger cross-sectional area than the outlet. This local variation in geometry creates conditions that prevent bubble aggregation while maintaining low overall coolant volume, resolving the contradiction between reduced coolant volume and maintained flow reliability
Solution Approach 2:
The patent changes the geometric parameters of the passageway, specifically the cross-sectional area, as a function of position along the passageway. This parameter change creates a gradient that influences bubble behavior, preventing blockage while keeping the system compact
2Productivity
If coolant flow rate is reduced to minimize cooling, then cooling demand is reduced, but gas bubbles block coolant flow more easily
Solution Approach 1:
The passageway is designed with non-uniform cross-section along its length, creating local variations in flow characteristics. This local quality variation ensures that even at low overall flow rates, the coolant maintains sufficient velocity in critical sections to prevent bubble aggregation and maintain flow continuity
Solution Approach 2:
The patent creates dynamic flow conditions within the passageway through its geometric design, where the varying cross-section produces changes in flow velocity and pressure distribution. This dynamic behavior prevents static bubble formation and maintains reliable flow at low rates
3Reliability
If gas venting is improved to remove bubbles, then coolant flow blockage is reduced, but system complexity increases
Solution Approach 1:
The passageway geometry itself performs the function of preventing bubble aggregation and facilitating gas removal. The varying cross-section creates natural flow patterns that self-regulate bubble behavior, eliminating the need for additional venting mechanisms or complex control systems
Solution Approach 2:
The patent extracts the gas removal function from the passageway walls through carefully designed geometric features that create preferential flow paths. Gas bubbles are naturally directed toward specific regions of the passageway where they can be efficiently removed, separating the gas and liquid phases without additional 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 solution ensures unimpeded coolant flow, improves hydration and cooling in fuel cells, and prevents gas bubble aggregation, maintaining performance even at low flow rates.
Implementation Method 1
the passageways may have at least one liquiphobic wall, and the gas may have a proclivity to flow along the liquiphobic wall
Implementation Method 2
The flow of coolant is the purpose, rather than the flow of gas; however, the control of gas flow is accomplished by affecting the characteristics of the coolant channels with respect to gas
Data Source
AI summary
To mitigate bubble blockage in water passageways (78, 85), in or near reactant gas flow field plates (74, 81) of fuel cells (38), passageways are configured with (a) cross sections having intersecting polygons or other shapes, obtuse angles including triangles and trapezoids, or (b) hydrophobic surfaces (111), or (c) differing adjacent channels (127, 128), or (d) water permeable layers (93, 115, 116, 119) adjacent to water channels or hydrophobic/hydrophilic layers (114, 120), or (e) diverging channels (152).