Tubesheet Radial Openings for Aircraft Fuel Tank Gas Separation
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Solution Overview
Problem
Existing gas separation assemblies for aircraft fuel tanks face challenges with tubesheet durability due to pressure stress, leading to reduced service life and performance, especially at higher temperatures, where known designs lack effective reinforcement and are prone to epoxy matrix cracking.
Innovation Solution
A fluid separation assembly with a hollow fiber bundle encapsulated by first and second tubesheets, featuring radial through openings in the tubesheets to distribute pressure loads and minimize bending moments, allowing for efficient gas flow and extended service life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the tubesheet is used as a pressure boundary in known gas separation assemblies, then the assembly can maintain structural integrity, but the tubesheet experiences stress and pressure that reduce its service life
Solution Approach 1:
The invention divides the pressure boundary function into separate components: the housing serves as the primary pressure boundary while the tubesheet is relieved of pressure-bearing duties. This segmentation allows the tubesheet to focus solely on supporting the fiber bundle, eliminating stress-induced degradation and extending service life.
Solution Approach 2:
The invention introduces an intermediary structural arrangement where the housing acts as a mediator between the pressure environment and the tubesheet. By positioning the fiber bundle to rest on the tubesheet without pressure loading, the housing mediates the pressure forces, preventing them from transferring to the tubesheet and thereby preserving its longevity.
2Strength
If the operating temperature is lowered to increase tubesheet strength, then the tubesheet can withstand pressure better, but the inerting system's performance decreases and additional weight or pressure-boosting components are needed
Solution Approach 1:
The invention changes the operational parameters by decoupling temperature from pressure management. Since the tubesheet no longer bears pressure, the system can operate at higher temperatures that optimize nitrogen-oxygen separation efficiency without compromising tubesheet integrity. This eliminates the need for weight additions or pressure-boosting components.
3Productivity
If pressurized feed gas flows into the face of the tubesheet with exposed hollow fiber membranes embedded in epoxy matrix, then gas separation can occur, but the epoxy matrix may crack and separate from the fiber bundle, causing failure
Solution Approach 1:
The invention extracts the hollow fiber membranes from the epoxy matrix environment by providing a dedicated support structure. The fibers are positioned to rest directly on the tubesheet surface without being embedded in epoxy, eliminating the crack propagation pathway and separation failures while maintaining gas separation functionality.
Solution Approach 2:
The invention provides beforehand cushioning by introducing a compliant interface between the fiber bundle and tubesheet. This cushioning layer absorbs pressure fluctuations and mechanical stresses before they can reach the epoxy matrix, preventing crack initiation and propagation, thereby ensuring long-term reliability of the gas separation assembly.
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 radial through openings design enhances the tubesheet's strength, extends the service life of the gas separation assembly, and maintains performance at higher temperatures, reducing the need for additional weight or pressure components, while increasing the efficiency of nitrogen and oxygen separation.
Implementation Method 1
a hollow fiber bundle comprising a plurality of hollow fiber membranes
Data Source
Figure 1
Figure 2A~2B
Figure 3A~3D
AI summary
According to an embodiment, a fluid separation assembly has a hollow fiber bundle with a plurality of hollow fiber membranes, and a first tubesheet and a second tubesheet encapsulating respective ends of the hollow fiber bundle, wherein at least one tubesheet has a plurality of radial through openings formed in the at least one tubesheet. The radial through openings are in a repeating four opening pattern with four openings in a substantially square configuration. The assembly further has a housing surrounding the hollow fiber bundle and the first and second tubesheets, and the housing has a feed inlet port, a permeate outlet port, and a non-permeate outlet port. Feed gas, permeate gas, or non-permeate gas are introduced into or removed from the hollow fiber membranes via the plurality of radial through openings, such that the radial through openings intersect each or substantially each of the hollow fiber membranes.