Carbon Dioxide Separator Membrane for Fuel Cell Water Balance
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Solution Overview
Problem
High temperature fuel cell systems face inefficiencies due to carbon dioxide and water management issues, with existing carbon dioxide separators being sensitive to oxygen and water loss, which affects the overall performance and efficiency of the fuel cell operation.
Innovation Solution
A carbon dioxide separator system is introduced, featuring a carbon dioxide separation membrane with higher permeability to carbon dioxide and water than to hydrogen gas and nitrogen, and a blocking layer to prevent oxygen and water permeation, allowing for efficient recycling of the fuel exhaust stream and improved water balance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a carbon dioxide separation membrane is used to remove CO2 from the fuel exhaust stream, then the efficiency of the fuel cell system is improved, but the membrane becomes sensitive to oxygen and water loss which affects performance
Solution Approach 1:
The membrane is divided into multiple functional layers: a carbon dioxide separation membrane layer for CO2 removal, an oxygen-blocking layer to prevent oxygen permeation, and a hydrophobic water-blocking layer to control water loss. This segmentation allows each layer to perform its specific function independently, resolving the contradiction between CO2 removal efficiency and membrane reliability.
Solution Approach 2:
The invention uses a composite membrane structure combining different materials with complementary properties: the carbon dioxide separation membrane (with high CO2 permeability), the oxygen-blocking material (with low oxygen permeability), and the hydrophobic water-blocking material (with selective water vapor transmission). This composite structure achieves both efficient CO2 removal and protection against oxygen and water loss.
2Productivity
If water is removed from the system to maintain water balance, then system performance is improved, but excessive water removal affects membrane function and system reliability
Solution Approach 1:
The hydrophobic water-blocking layer is applied specifically on the carbon dioxide separation membrane to provide localized water management. This layer allows controlled water vapor transmission while blocking liquid water and excessive water loss, maintaining the water balance locally at the membrane level without affecting overall system performance.
3Stability of the object's composition
If oxygen permeation is allowed through the membrane, then the membrane structure remains stable, but oxygen loss reduces fuel cell efficiency and increases harmful emissions
Solution Approach 1:
The oxygen-blocking layer is introduced as a separate functional component that extracts and blocks oxygen from permeating through the carbon dioxide separation membrane. This layer specifically targets oxygen molecules while allowing CO2 separation and water management functions to continue, thereby eliminating harmful oxygen loss without compromising membrane structure stability.
4Productivity
If the carbon dioxide separation membrane has high permeability to CO2 and water, then CO2 removal efficiency is improved, but water loss through the membrane increases affecting water balance
Solution Approach 1:
The hydrophobic water-blocking layer acts as an intermediary between the carbon dioxide separation membrane and the external environment. It mediates water vapor transmission by allowing controlled passage of water vapor while blocking excessive water loss, thus maintaining the water balance while preserving the high CO2 permeability of the underlying separation membrane.
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 system effectively removes carbon dioxide from the fuel exhaust stream, increasing the efficiency of the fuel cell stack by recycling a purified fuel stream, while controlling water permeation to maintain optimal water balance, thus enhancing the performance and longevity of the fuel cell system.
Implementation Method 1
a carbon dioxide separation membrane disposed between the sweep channel and the feed channel, the carbon dioxide separation membrane having a higher permeability to carbon dioxide and water than to hydrogen gas, carbon monoxide, and nitrogen gas
Implementation Method 2
a first oxygen blocking layer disposed between the carbon dioxide separation membrane and the sweep channel, the oxygen blocking layer having a higher permeability to water and carbon dioxide than to oxygen gas and nitrogen gas
Implementation Method 3
a first hydrophobic water blocking layer
Data Source
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AI summary
A system and method in which a high temperature fuel cell stack exhaust stream is recycled back into the fuel inlet stream of the high temperature fuel cell stack. The recycled stream may be sent to a carbon dioxide separator that separates carbon dioxide from the fuel exhaust stream. The carbon dioxide separator may include a carbon dioxide separation membrane, an oxygen blocking membrane, and a water blocking membrane.