Cryogenic Collapsible Container with Folded Polymer Bladder
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Solution Overview
Problem
Current propellant management devices (PMDs) face challenges in handling cryogenic liquids in microgravity environments, particularly due to surface tension-based mechanisms that struggle with low flow rates and are prone to issues like bulk permeation and tearing, leading to inefficiencies and potential engine failure.
Innovation Solution
A collapsible container system with foldable panels and impermeable materials, such as polyimide or fluropolymer films, that uses a pressurant to collapse and expel cryogenic fluids, eliminating reliance on surface tension and providing high flow rates and thermal insulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If surface tension-based PMD mechanisms are used to expel cryogenic liquids in microgravity, then the system can operate without gravity-dependent components, but the flow rates are low and the system is prone to bulk permeation and tearing issues
Solution Approach 1:
The patent employs a flexible bladder made of elastomeric material that can expand and contract to expel propellant. The bladder replaces rigid surface tension-based structures with a compliant membrane that mechanically pushes the liquid, achieving higher flow rates while maintaining reliability through the material's elasticity and resistance to permeation and tearing.
Solution Approach 2:
The system uses a pressurant gas introduced into the bladder to provide pneumatic pressure for propellant expulsion. This pneumatic mechanism drives the flexible bladder to expand and contract, creating controlled high-flow expulsion without relying on surface tension or gravity-dependent components.
2Temperature
If traditional rigid container structures are used for cryogenic storage, then structural strength is maintained, but thermal insulation is poor and the system cannot collapse for efficient fluid expulsion
Solution Approach 1:
The flexible bladder made of elastomeric material provides both thermal insulation and fluid expulsion capability. The material's flexibility allows the bladder to expand and contract for efficient propellant delivery, while its inherent thermal properties provide insulation for cryogenic storage without requiring additional rigid insulating structures.
Solution Approach 2:
The system changes the physical state and properties of the container material to achieve both thermal insulation and mechanical compliance. The elastomeric material is selected for its specific thermal properties and mechanical flexibility, allowing it to maintain insulation while enabling dynamic expansion and contraction for fluid expulsion.
3Measurement precision
If surface tension mechanisms are used to determine fuel levels in microgravity, then gravity-independent operation is achieved, but the position determination is imprecise and can lead to gas inclusion in the fuel delivery
Solution Approach 1:
The patent replaces surface tension-based level determination with a mechanical pressurant-driven system. The pressurant gas pressure directly controls the bladder expansion and contraction, providing precise control over fuel delivery and ensuring gas-free operation by mechanically pushing the liquid rather than relying on imprecise surface tension indicators.
Solution Approach 2:
The flexible bladder system is self-regulating through the pressurant gas pressure. As propellant is expelled, the bladder automatically contracts and draws in more propellant, maintaining continuous gas-free delivery without requiring external level measurement or intervention. The system self-adjusts to deliver precise amounts of liquid fuel.
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 collapsible container system enhances cryogenic fluid expulsion with higher flow rates, reduced operational complexity, and improved thermal insulation, addressing the limitations of traditional PMDs by mechanically pumping liquids and preventing mass transfer between phases.
Implementation Method 1
An inlet allows for a pressurant to be added to the space between the wall of the housing and the collapsible container. In doing so, the pressure of the space between the housing and the container increases causing the container to assume a collapsed state.
Data Source
AI summary
Collapsible containers are an attractive alternative to surface-tension propellant management devices (PMDs) for handling cryogenic liquids, as the collapsible container comparatively may 1) allow higher expulsion flow rates than vanes and sponges, 2) significantly reduce operational complexity, and 3) thermally insulate the propellant from environmental heat leaks. Furthermore, while historical cryogenic collapsible containers suffered from the low ductility of polymer films at cryogenic temperatures, the technology disclosed herein shows that the incorporation of folded patterns into the collapsible container substantially increases the reusability of the cryogenic PMD.