Fuel Cell Air Humidifier Membrane Stack With Exhaust Path Spacers
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing membrane stacks in air humidifiers for fuel cells face issues with increased flow resistance in exhaust air paths due to membranes being pressed outward by higher pressure in supply air paths, leading to reduced functional reliability.
Innovation Solution
Incorporation of spacers made of dimensionally stable material between adjacent membranes in exhaust air paths to maintain a predetermined flow cross-section, with features like tapered design, permeable channels, and ribs to enhance airflow and humidity transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If thin membranes are arranged close together in the stacking direction to ensure compact design, then the device volume is reduced, but the flow resistance in exhaust air paths increases when supply air pressure exceeds exhaust air pressure
Solution Approach 1:
A spacer element is introduced as an intermediary component between adjacent membranes in the exhaust air path. This spacer maintains a predetermined spacing distance, preventing membrane contact while preserving the compact stacked design. The spacer acts as a mediator that resolves the conflict between compactness and flow resistance by providing structural separation without significantly increasing device volume.
Solution Approach 2:
The problem of membrane contact in the stacking direction is resolved by introducing spacing in the same dimension (stacking direction) but at a different location (in the exhaust air path rather than eliminating membranes). The spacer creates a dimensional separation that maintains the compact stacked structure while preventing harmful membrane interaction.
2Reliability
If membranes are pressed outward by higher supply air pressure, then humidity transfer efficiency is maintained, but the cross-sectional area for exhaust air flow is reduced
Solution Approach 1:
The spacer element serves as a mediator that decouples the pressure-driven membrane deformation from the exhaust air flow path. By maintaining a fixed spacing distance, the spacer allows membranes to respond to pressure differences for humidity transfer while preventing them from encroaching on the exhaust air flow cross-section.
Solution Approach 2:
The spacer provides localized structural support specifically in the exhaust air path regions where membranes are adjacent. This localized intervention maintains membrane flexibility for humidity transfer in supply air paths while preventing membrane contact in exhaust air paths, creating different functional qualities in different locations.
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 spacer design maintains airflow efficiency and humidity transfer while reducing flow resistance and ensuring structural stability, enhancing the functional reliability of the membrane stack.
Implementation Method 1
The spacers are made of a different material than the membranes. For example, they can be made from a relatively stable plastic and therefore have relatively high dimensional stability. In any case, the spacers are significantly more dimensionally stable than the thin membranes.
Implementation Method 2
The membrane stack has several membranes which are permeable to humidity, i.e., to water and/or water vapor, and impermeable to air
Implementation Method 3
For example, when the air humidifier is in operation, the pressure in the supply air flow may be higher than in the exhaust air flow. This presses the membranes in the supply air paths outwards against the exhaust air paths
Data Source
AI summary
A membrane stack for an air humidifier of a fuel cell for humidifying a dry supply air flow of the fuel cell via a humid exhaust air flow of the fuel cell may include a plurality of membranes and a plurality of spacers. The membranes may be permeable to humidity and impermeable to air. The membranes may be arranged one above another in a stacking direction such that at least a subset of the membranes each separate a respective supply air path of a plurality of supply air paths, which each connect a supply air inlet to a supply air outlet, from a respective exhaust air path of a plurality of exhaust air paths, which each connect an exhaust air inlet to an exhaust air outlet. The spacers may each be arranged in the stacking direction between two directly adjacent membranes and in one of the exhaust air paths.