Vacuum Insulation Envelope Rupture Zone for Overpressure Control
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Solution Overview
Problem
Vacuum insulating panels used in cryogenic fluid storage vessels can experience overpressure due to gas diffusion through the envelope, leading to deformation and potential bursting, especially when defects or wear occur, posing safety risks during maintenance.
Innovation Solution
Incorporating a degradation element with a rupture zone that has lower mechanical resistance than the rest of the envelope, allowing controlled release of internal pressure through stress concentration zones, additional spot welds, and tearing elements to manage overpressure and prevent deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the envelope is made hermetic and gas-impermeable to maintain vacuum, then insulation performance is improved, but gas diffusion and pressure rise still occur over time due to defects and wear
Solution Approach 1:
The patent incorporates a degradation element (rupture zone, stress concentration zone, tearing element) into the envelope structure before the panel is put into service. This preliminary action prepares a controlled weak point that will activate only when needed - specifically when gas diffusion causes overpressure. The degradation element is positioned and designed in advance to rupture at a predetermined pressure threshold, preventing uncontrolled bursting while maintaining vacuum during normal operation.
Solution Approach 2:
The degradation element acts as an intermediary mechanism between the hermetic envelope and the external environment. Instead of the envelope directly bursting under overpressure, the degradation element serves as a controlled interface that ruptures at a predetermined pressure point. This intermediary structure manages the transition from vacuum state to atmospheric state, preventing direct uncontrolled failure while allowing safe pressure equalization.
2Reliability
If the envelope thickness is increased to prevent gas diffusion, then vacuum maintenance is improved, but weight and device complexity increase
Solution Approach 1:
The patent applies local quality by creating a specific localized region (degradation element) with different mechanical properties than the rest of the envelope. The rupture zone has reduced thickness or includes stress concentration features (notches, holes, weakened seams) that create a predetermined weak point. This localized modification allows the overall envelope to maintain sufficient thickness for gas barrier performance while having a specific controlled area that will fail at a predetermined pressure, avoiding the need to increase the entire envelope's thickness.
3Strength
If the envelope is designed to be highly resistant to overpressure, then structural integrity is improved, but controlled pressure release becomes difficult and deformation risk increases
Solution Approach 1:
The patent applies preliminary anti-action by pre-positioning degradation elements (rupture zones, stress concentration zones, tearing elements) that will counteract the overpressure condition before it causes harmful effects. These elements are designed to activate at a predetermined pressure threshold, creating a controlled release mechanism that prevents uncontrolled bursting and panel deformation. The preliminary placement of these weak points ensures that when overpressure occurs, the release happens in a controlled manner rather than allowing the envelope to deform or burst unpredictably.
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 solution effectively manages overpressure by allowing controlled release of gas, preventing deformation and bursting, ensuring safety during maintenance and reducing the risk of gas leakage.
Implementation Method 1
a core 2 made of a porous material whose porosity has a volume fraction greater than 90% and the average size of the cavities is ideally less than 100 μm
Implementation Method 2
The presence of a depression in the envelope makes it possible to obtain a panel having excellent insulation characteristics. It is therefore important not only to choose for the envelope a material which is hermetic and very poorly permeable to gases
Data Source
Figure 1A~2C
Figure 3A~3D
Figure 4A~4C
AI summary
An isolation unit comprising: a core (2) produced from a porous insulating material; an outer casing (3) produced from a deformable impervious material forming a sealed inner space (9) in which the core of the isolation unit is positioned, said inner space having, in an operational state of the isolation unit, a vacuum relative to an environment (16) outside the isolation unit; - an element (24, 24A, 24B, 42, 43) for degrading the casing, suitable for degrading the casing in response to an overpressure in the inner space of the casing relative to the environment outside the isolation unit causing a deformation of the casing, the degrading of the casing by the degrading element bringing the inner space of the casing into communication with the environment outside the isolation unit.