Fuel Cell Humidifier Plate Stack for Membrane Support and Vapor Transfer
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Solution Overview
Problem
Existing fuel cell humidifiers face challenges in achieving high surface area exposure of membranes to exchange gases at controlled fluid flow rates, requiring tightly packed and thin plates with precise assembly to maintain performance and durability while minimizing cost and size.
Innovation Solution
A humidifier design featuring a stack of plates with alternating wet and dry gas flow passages, supported by porous materials and gas diffusion layers, allowing for efficient water vapor transfer between gas streams while maintaining structural integrity and minimizing compression loads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If plates are made thin to maintain tightly packed cell spacing, then membrane surface area exposure is improved, but structural integrity and assembly reliability deteriorate
Solution Approach 1:
The plate is divided into a rigid peripheral portion providing structural support and sealing surfaces, and a separate flexible central portion forming the flow field. This segmentation allows the peripheral portion to maintain structural integrity while the central portion can be optimized for membrane exposure and flexibility.
Solution Approach 2:
The plate combines materials with different properties: the peripheral portion uses rigid material for structural strength and sealing, while the central flow field portion uses flexible material that can conform to membranes and allow for manufacturing tolerances. This composite approach resolves the contradiction between thin plate requirements and structural integrity.
2Volume of moving object
If plates are made thin to reduce device size, then compactness is improved, but manufacturing precision requirements increase
Solution Approach 1:
By separating the plate into rigid peripheral portions and flexible central flow field portions, the design allows the flexible portions to accommodate manufacturing tolerances and assembly variations, reducing the overall precision requirements while maintaining compact dimensions.
Solution Approach 2:
The flexible central portion of the plate can change its shape and dimensions within certain ranges to compensate for manufacturing variations. This parameter flexibility allows for easier manufacturing and assembly while maintaining the compact size needed for the humidifier.
3Strength
If plate thickness is increased to improve structural integrity, then assembly reliability is improved, but device complexity and size increase
Solution Approach 1:
Rather than increasing the thickness of the entire plate, the design segments the plate into thin rigid peripheral portions for structural support and sealing, and separate flexible central portions for flow fields. This segmentation maintains structural integrity and simplifies the overall design while avoiding the need for thick plates throughout.
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 design enhances the transfer of water vapor between gas streams, optimizing membrane exposure and maintaining structural integrity, thus improving fuel cell performance and durability while reducing costs and size.
Implementation Method 1
water vapour is transferred from the wet gas stream, across the water-permeable membrane and through the gas diffusion layers, into the dry gas stream
Implementation Method 2
water vapour is transferred from the wet gas stream, across the water-permeable membrane and through the gas diffusion layers, into the dry gas stream
Data Source
AI summary
A humidifier for transferring water vapor from a first gas stream to a second gas stream in a fuel cell system has a stack of thin plates joined together at their edges by planar sealing surfaces, with water permeable membranes between the plates. Each plate defines a gas flow passage along its top and bottom surfaces, with an inlet and outlet defined along edges of the plate, and a flow field extending between the inlet and outlet openings. Inlet and outlet passages connect the inlet and outlet openings to the flow field, with the planar sealing surfaces including bridging portions extending across these passages. Support structures are provided throughout the flow field to support the membrane and diffusion medium layer(s). Each support structure comprises a porous material which is sufficiently porous to permit gas flow through the flow field.