Multilayer Plastic Liner Structure for Hydrogen Blistering Control
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Solution Overview
Problem
Existing composite pressure vessels for hydrogen storage face issues with high hydrogen permeability in polymers, leading to blistering and mechanical degradation due to bubble formation, which compromises the integrity and weight of the liner.
Innovation Solution
A multilayer plastic liner structure is proposed, featuring a diffusion-delay layer with a lower hydrogen permeability inner layer made of PVDF and a higher permeability barrier layer of EVOH, along with a thermoplastic-based intermediate layer, which reduces hydrogen diffusion and prevents blistering, while maintaining mechanical characteristics and weight efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single-layer or conventional multilayer liner is used, then the liner provides basic hydrogen storage function, but hydrogen permeability is high leading to blistering and mechanical degradation
Solution Approach 1:
The liner is divided into multiple functional layers with distinct roles: an inner diffusion-delay layer (5-15 µm) to control hydrogen migration, intermediate adhesive layers for bonding, and outer barrier layers (EVOH) for hydrogen impermeability. This segmentation allows each layer to optimize its specific function, preventing blistering while maintaining storage capacity.
Solution Approach 2:
The invention uses a composite structure combining different materials: a fluorinated polymer diffusion-delay layer, EVOH barrier layer, and thermoplastic adhesive layers. This composite approach leverages the low permeability of fluorinated polymers and the barrier properties of EVOH to eliminate blistering while keeping the overall structure lightweight.
2Object-affected harmful factors
If barrier layers are added to reduce hydrogen permeability, then blistering is prevented, but the liner weight increases
Solution Approach 1:
Different layers are assigned specific thicknesses and material properties localized to their functions. The diffusion-delay layer is thin (5-15 µm) and fluorinated for low permeability, while the EVOH barrier layer provides the main hydrogen barrier. This localized optimization prevents blistering without requiring excessive material throughout the entire liner structure.
Solution Approach 2:
The invention changes the permeability parameter of the innermost layer by using fluorinated polymers with specifically controlled crystallinity (30-80%) and molecular weight (10,000-1,000,000 g/mol). This parameter optimization creates a diffusion-delay effect that prevents blistering while minimizing the layer thickness and associated weight.
3Reliability
If the inner layer has very low hydrogen permeability, then hydrogen diffusion is reduced, but the layer becomes too thin to provide adequate mechanical support
Solution Approach 1:
The fluorinated polymer diffusion-delay layer acts as an intermediary between the hydrogen storage environment and the EVOH barrier layer. It controls hydrogen migration through its low permeability while the intermediate adhesive layers and outer EVOH structure provide the necessary mechanical support, allowing the inner layer to be thin (5-15 µm) without compromising overall strength.
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 multilayer structure effectively mitigates blistering effects, ensuring the liner's integrity and reducing weight, thus enhancing the storage capacity and mechanical strength of hydrogen storage vessels.
Implementation Method 1
the inner layer (i.e. second barrier layer) acts as a diffusion-delay layer... slows down the migration (i.e. reduce the diffusion rate) of hydrogen inside the multilayer structure
Implementation Method 2
Hydrogen may concentrate in certain areas inside the polymer... These known liners suffer from the relatively high permeability of hydrogen in polymers
Data Source
Figure 1~2
Figure 3~4
AI summary
It is proposed a plastic liner for the storage of hydrogen, comprising: a first barrier layer (3), - a second barrier layer (7) configured to be an inner layer in contact with hydrogen, at least one intermediate layer arranged between the first and the second barrier layers, wherein the second barrier layer (7) has a lower hydrogen permeability than said at least intermediate layer such that the second barrier layer (7) slows down the migration of hydrogen inside said at least one intermediate layer.