Multilayer Hydrogen Tank Liner Using Polyamide Composites
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Solution Overview
Problem
Current hydrogen tanks face challenges such as low thermal resistance, high permeability to hydrogen, and limited mechanical strength at high temperatures, which hinder efficient hydrogen storage and distribution, particularly in the context of increasing filling speeds and maintaining optimal operating temperatures for hydrogen fuel cells.
Innovation Solution
A multilayer structure comprising a semi-crystalline polyamide thermoplastic polymer for the sealing layer and a semi-crystalline polyamide polymer for the composite reinforcement layer, with a limited proportion of impact modifier and plasticizer, where the number of carbon atoms per amide function in the polymers differs by no more than 20%, enhancing mechanical strength and thermal resistance while reducing hydrogen permeability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If HDPE is used as the liner material, then the manufacturing process is simple and cost-effective, but the thermal resistance is insufficient and hydrogen permeability is too high
Solution Approach 1:
The patent employs a composite liner structure consisting of multiple layers with different polymer materials. The inner layer uses PA6 or PA612 for thermal resistance, while outer layers use other polymers to balance mechanical properties and hydrogen barrier performance. This composite approach allows the system to achieve high thermal resistance without sacrificing manufacturability, as each layer contributes specific properties that compensate for the limitations of individual materials.
2Temperature
If PA6 is used as the liner material, then the thermal resistance is improved, but the resistance to cold is insufficient
Solution Approach 1:
The patent applies local quality by using different polymer materials in different layers of the liner structure. The inner layer in contact with hydrogen uses PA6 or PA612 for thermal resistance, while outer layers use polymers with better low-temperature flexibility. This spatial differentiation of material properties allows the liner to simultaneously achieve high thermal resistance and good cold resistance without compromising either performance aspect.
3Productivity
If the filling speed is increased to match fuel tank standards, then the productivity is improved, but the thermal heating of the tank increases significantly
Solution Approach 1:
The patent converts the harmful thermal heating effect into a beneficial outcome by selecting polymer materials with specific thermal properties. The liner is designed to withstand and manage the thermal load generated during high-speed filling, transforming the previously problematic heat generation into an acceptable operating condition. The multilayer structure dissipates and manages thermal energy, allowing high filling speeds to be maintained without excessive temperature rise that would compromise safety or performance.
4Productivity
If the operating temperature is increased to 120°C, then the filling speed can be increased, but the mechanical strength of conventional liners deteriorates
Solution Approach 1:
The patent uses a multilayer composite liner structure where each layer is made of polymers with complementary properties. The combination of different polymers (PA6, PA612, and other thermoplastics) creates a synergistic effect where the composite structure maintains mechanical strength at elevated temperatures of up to 120°C. This allows the liner to withstand the thermal and mechanical stresses of high-speed filling operations while preserving structural integrity and preventing deformation or failure.
Data Source
AI summary
A multilayer structure for storing hydrogen, including, from the inside, at least one sealing layer and at least one composite reinforcement layer, an innermost composite reinforcement layer being welded to an outermost adjacent sealing layer, the sealing layers being a composition predominantly of: at least one semi-crystalline polyamide thermoplastic polymer P1i, i=1 to n, n being the number of sealing layers, excluding an amide polyether block (PEBA), up to 50% by weight of impact modifier relative to the total weight of the composition, up to 1.5% by weight of plasticizer relative to the total weight of the composition, and at least one of the composite reinforcement layers of a fibrous material in the form of continuous fibers, which is impregnated with a composition predominantly of at least one semi-crystalline polyamide polymer P2j, j=1 to m, m being the number of reinforcement layers.