Three-Layer Hollow Fiber Membrane for Strength and Moisture Diffusion
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Hollow fiber membranes for humidification in fuel cell systems face challenges in achieving high tensile strength and moisture diffusion characteristics while maintaining gas barrier properties, with existing methods either compromising on mechanical strength or separation characteristics.
Innovation Solution
A three-layer hollow fiber membrane structure is developed, comprising a high-density sponge inner layer, a finger-shaped intermediate layer, and a low-density sponge outer layer, produced using a combination of thermally induced phase separation and non-solvent induced phase separation methods, with specific polymer resin and solvent compositions to enhance mechanical strength and moisture diffusion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a hollow fiber membrane is produced using a non-solvent induced phase separation method, then the membrane has a three-dimensional network structure with macrovoids, but the tensile strength is insufficient
Solution Approach 1:
The invention divides the membrane structure into multiple distinct layers (first layer with finger-like pores, second layer with sponge structure, third layer with macrovoids) rather than using a single uniform structure. Each layer is produced by a different phase separation method, allowing optimization of each layer's properties independently while maintaining overall structural control and high tensile strength.
Solution Approach 2:
Different regions of the membrane are given different structures and properties: the first layer has finger-like pores for high water vapor permeability, the second layer has sponge structure for mechanical strength, and the third layer has macrovoids for rapid water vapor transport. This local differentiation resolves the contradiction by providing strength where needed while maintaining permeability elsewhere.
2Strength
If a hollow fiber membrane is produced using a thermally induced phase separation method, then the membrane has a bead structure with high mechanical strength, but it is difficult to control the pore size and separation characteristics are low
Solution Approach 1:
The invention segments the membrane into three layers with distinct pore structures. The first layer uses TIPS method to create finger-like pores with controllable size, while the second and third layers use NIPS method to create sponge structure and macrovoids. This segmentation allows precise pore size control in the first layer while maintaining high mechanical strength through the other layers.
Solution Approach 2:
The first layer is specifically designed with finger-like pores of controlled size for separation functionality, while the second and third layers provide mechanical support with different structures. This local quality differentiation enables both precise pore control and high mechanical strength simultaneously.
3Quantity of substance
If the pore diameter is reduced to achieve high water vapor permeability, then water vapor permeation increases, but gas barrier properties deteriorate due to air leakage
Solution Approach 1:
The invention creates different pore structures in different layers: the first layer has finger-like pores for water vapor permeability, while the second layer has a denser sponge structure that provides gas barrier properties. This local differentiation allows water vapor to pass through while blocking air leakage, resolving the contradiction between permeability and gas barrier function.
Solution Approach 2:
The membrane combines multiple materials and structures in a composite configuration. The first layer uses polyimide or polysulfone for finger-like pore formation, while the second and third layers use different polymer compositions to create sponge structure and macrovoids. This composite structure achieves both high water vapor permeability and effective gas barrier properties.
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 membrane exhibits excellent tensile strength, high moisture diffusion characteristics, and controlled gas transmission rates, effectively addressing the limitations of previous membrane technologies.
Implementation Method 1
a hollow fiber membrane for humidification is required to have high water vapor permeability
Implementation Method 2
A hollow fiber membrane for humidification is required to have gas barrier properties for preventing leakage of air from hollow fibers
Implementation Method 3
a membrane is produced by discharging a spinning solution in which a polymer resin is dissolved in a good solvent through a spinneret, bringing the discharged spinning solution into contact with a liquid including a non-solvent, and thereby inducing solidification of the spinning solution
Data Source
AI summary
The present invention relates to a hollow fiber membrane including, sequentially from the center: a first layer having a high-density sponge structure including pores with a size of 1 nm or less; a second layer including a finger-shaped structure; and a third layer having a low-density sponge structure including pores with a size of 10 to 1,000 μm, and to a method for producing the hollow fiber membrane.