Bipolar Flow Field Plate With Coolant Sharing for Uniform Cooling
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Solution Overview
Problem
Existing bipolar flow field plates in fuel cells face issues with pressure drop and non-uniform coolant flow sharing, which affect the performance and lifetime of the membrane electrode assembly due to inadequate temperature management.
Innovation Solution
The design incorporates coolant flow channels that communicate with each other through flow sharing portions, utilizing projections and recesses on internal surfaces of the plates, with optional pillars to enhance flow sharing, maintaining consistent fuel and oxidant channel dimensions and reducing pressure drop.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If the size of coolant flow channels is increased to reduce pressure drop, then the pressure drop is reduced, but the thickness of the bipolar plate increases and the power density decreases
Solution Approach 1:
The bipolar plate is divided into two separate plates (anode-side plate and cathode-side plate) that are assembled together to form the coolant flow channels. This segmentation allows the coolant channels to be created through the assembly interface rather than requiring large channels within a single thick plate, thus reducing overall plate thickness while maintaining adequate coolant flow capacity to manage pressure drop.
Solution Approach 2:
The coolant flow channels are formed by nesting the anode-side plate and cathode-side plate together, where the coolant channels are created in the interface region between the two plates. This nested arrangement allows efficient use of space, enabling coolant flow path formation without increasing the overall plate thickness, thereby resolving the contradiction between pressure drop reduction and plate thickness control.
2Stress or pressure
If the distance between adjacent coolant channels and reactant channels is increased, then the pressure drop is reduced, but the channel pitch increases and power density decreases
Solution Approach 1:
The coolant flow channels are positioned in a different spatial dimension (at the interface between the two assembled plates) rather than being arranged in a single-plane configuration. This dimensional change allows coolant channels to be located optimally for heat removal without increasing the in-plane distance from reactant channels, thus reducing pressure drop while maintaining compact channel pitch and high power density.
3Temperature
If non-uniform coolant flow occurs in the coolant channels, then temperature management is inadequate, but the membrane electrode assembly lifetime is reduced
Solution Approach 1:
The design incorporates flow sharing portions with specific local geometries (including pillars and constricted regions) that create different flow resistance characteristics in different locations. This local quality variation ensures uniform coolant distribution across all coolant channels by compensating for positional differences, achieving adequate temperature management throughout the fuel cell and extending membrane electrode assembly lifetime through improved thermal uniformity.
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 achieves uniform coolant flow, reduces pressure drop, enhances heat transfer, and extends the lifetime of the membrane electrode assembly by improving temperature management without increasing the fuel cell stack's size or altering reactant channel dimensions.
Implementation Method 1
coolant flow channels which are additional flow channels provided within the body of the plate... at least two adjacent coolant flow channels in the active area of the bipolar flow field plate communicate to each other through a flow sharing portion, thereby sharing the coolant flow between them
Implementation Method 2
coolant needs to be provided between the adjacent membrane electrode assemblies in the stack of fuel cells to prevent the raise in temperature of the fuel cell stack due to the reactions taking place at the electrodes... enhancing heat transfer
Data Source
AI summary
A bipolar flow field plate for an electrochemical fuel cell comprises fuel supply channels formed on the first surface of the bipolar flow field plate, having a constant cross-section along the length of bipolar flow field plate, oxidant supply channels formed on another surface of the bipolar flow field plate, opposite to the first surface, and having a constant cross-section along the length of the bipolar flow field plate and coolant flow channels provided within the bipolar flow field plate, wherein at least two adjacent coolant flow channels in the active area of the bipolar flow field plate communicate to each other through a flow sharing portion. The size of the flow sharing portion can vary according to the coolant flow sharing needs. The projections of the bipolar flow field plate which form the coolant flow channels can be provided with pillars along the flow sharing portions of the plate.