Humidifier for fuel cell systems
Find Innovative SolutionsGenerate Solutions
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 while maintaining membrane durability and minimizing cost and size, particularly in achieving tightly packed and consistent cell spacing without damaging fragile membrane/diffusion layer media.
Innovation Solution
A humidifier design featuring a stack of plates with alternating gas flow passages, water-permeable membranes, and gas diffusion layers, where support structures like ribs and webs provide support for membranes and diffusion layers within flow fields, ensuring effective water vapor transfer between gas streams while maintaining structural integrity and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If tightly packed and very small and consistent repeat cell (plate to membrane) distances are necessary for high surface area exposure, then membrane surface area exposure is improved, but manufacturing precision and structural stability deteriorate due to the fragility of membrane/diffusion layer media
Solution Approach 1:
The patent uses gas diffusion layers as flexible support structures that conform to the membrane surface while providing mechanical strength. These thin film-like structures allow tight packing without requiring extremely precise manufacturing tolerances, as the flexible nature accommodates minor variations in assembly
Solution Approach 2:
The patent creates a composite structure by bonding gas diffusion layers to the membrane, forming a membrane-diffusion layer composite. This composite provides both the high surface area needed for vapor transfer and the structural integrity required for consistent cell spacing, resolving the contradiction between membrane exposure area and manufacturing precision
2Reliability
If compressive forces are minimized to avoid damaging fragile membrane/diffusion layer media, then membrane durability is improved, but the ability to maintain consistent cell spacing deteriorates
Solution Approach 1:
The gas diffusion layers act as flexible protective shells that distribute compressive forces uniformly across the membrane surface. This flexibility allows the structure to maintain consistent cell spacing under compression while preventing localized stress concentrations that would damage the fragile membrane
Solution Approach 2:
The patent incorporates gas diffusion layers as cushioning structures between the membrane and external compression forces. These layers absorb and distribute mechanical stresses before they reach the membrane, protecting it from damage while maintaining structural integrity for consistent spacing
3Manufacturing precision
If plate thickness is reduced to maintain tightly packed cell spacing, then cell spacing consistency is improved, but the ability to provide effective flow channels for gas communication deteriorates
Solution Approach 1:
The patent transitions from two-dimensional planar flow channels to three-dimensional serpentine or meandering flow paths within the plates. This dimensional change allows effective gas flow communication through thin plates by creating extended flow paths that compensate for the reduced plate thickness, maintaining flow effectiveness while achieving tight cell packing
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, maintains membrane durability, and achieves compact size and cost-effectiveness, addressing the challenges of achieving high surface area exposure and consistent cell spacing.
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
Implementation Method 3
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 vapour from a first gas stream to a second gas stream in a fuel cell system comprises a stack of thin plates having planar sealing surfaces at their edges, along which they are sealed together. A water permeable membranes is provided between each pair of plates in the stack. 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, and the planar sealing surfaces on both sides of the plate include bridging portions which extend across the inlet and outlet passages. Support structures such as ribs are provided throughout the flow field and the inlet and outlet passages to support the membrane and diffusion medium layer(s). The support structures may optionally be connected together by webs, and the webs are provided with holes to permit flow distribution between the top and bottom of each plate.