Segmented Tubesheet Design for Thermal Stress in Gas Separation Modules
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Solution Overview
Problem
Air separation modules in aircraft fuel tank flammability reduction systems have limited service life due to reduced separation efficiency and component failure, leading to increased maintenance and downtime, primarily caused by thermal expansion and physical aging which results in cracking and gas leaks.
Innovation Solution
The implementation of a segmented tubesheet design with compliance materials in gas separation modules, allowing for expansion and contraction without cracking, and the use of a matrix with nano-silica particles and thermoplastic veils to enhance toughness and reduce thermal stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a continuous tubesheet is used to secure hollow fiber membranes, then structural integrity is maintained, but thermal expansion and contraction cause cracking and gas leaks over time
Solution Approach 1:
The tubesheet is divided into multiple segments that can expand and contract independently during thermal cycles. This segmentation prevents the development of cracking stresses that would occur in a continuous tubesheet, thereby eliminating gas leaks and extending service life while maintaining structural integrity through the coordinated movement of segments.
2Strength
If compliance material is added to segment joints to accommodate thermal expansion, then crack resistance is improved, but device complexity increases
Solution Approach 1:
A compliance layer is incorporated into the segment joints of the tubesheet, providing flexibility to accommodate thermal expansion and contraction. This flexible layer allows the segments to move relative to each other without creating cracking stresses, thereby protecting the hollow fiber membranes while adding minimal structural complexity.
3Strength
If nano-silica particles are added to the matrix material, then toughness is enhanced and thermal stress is reduced, but manufacturing complexity increases
Solution Approach 1:
The matrix material is formulated as a composite incorporating nano-silica particles, which enhance the toughness and thermal stress resistance of the tubesheet. This composite material provides improved mechanical properties and thermal stability while maintaining manufacturability through established composite fabrication techniques.
4Productivity
If the operational temperature range is extended, then separation efficiency is improved, but thermal stress and cracking risk increase
Solution Approach 1:
The segmented tubesheet design explicitly accommodates thermal expansion and contraction of the hollow fiber membranes during temperature cycling. By allowing the segments to move independently, the design reduces thermal stress concentrations that would otherwise lead to cracking, thereby enabling extended operational temperature ranges without compromising structural integrity or separation efficiency.
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
This design extends the operational temperature range, increases separation efficiency, reduces module size and weight, and decreases maintenance frequency, thereby enhancing the reliability and longevity of air separation modules.
Implementation Method 1
thermal expansion and physical aging which results in cracking and gas leaks
Implementation Method 2
The ASM removes some oxygen from air to generate nitrogen-enriched air
Data Source
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AI summary
A gas separation module includes at least one inlet port, a plurality of outlet ports, and a plurality of hollow fiber membranes. Individual fibers have a feed end and a product end with a retentate interior side and a permeate exterior side. The module includes a feed tubesheet within the shell segregating the at least one inlet port and the permeate side of the fibers. The feed tubesheet includes a matrix and at least one segment joint. The segment joint separates segments of the feed tubesheet from one another. A formation method includes positioning a hollow fiber membrane material in association with at least one tubesheet segment joint and applying a matrix. The method includes forming a feed tubesheet from cured matrix and the segment joint and forming a plurality of hollow fiber membranes from the fiber material. The segment joint separates segments of the feed tubesheet from one another.