Multilayer Hydrogen Tank Structure for Welded Stress Control
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Solution Overview
Problem
Current hydrogen storage tanks face issues with mechanical strength, recyclability, gas tightness, and manufacturing complexity, particularly due to residual stresses from thermal variations and the use of thermosetting resins like epoxy, which lead to microcracking and increased weight and cost.
Innovation Solution
A multilayer tank structure comprising a semi-crystalline thermoplastic polyamide sealing layer, an intermediate thermoplastic polyamide reinforcement layer, and an external polyphthalamide reinforcement layer, all welded together, to reduce residual stresses and enhance mechanical strength, recyclability, and gas tightness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If thermosetting resins like epoxy are used for composite reinforcement, then mechanical strength is improved, but microcracking occurs leading to reduced reliability and increased manufacturing complexity
Solution Approach 1:
The patent changes the material parameter from thermosetting resin to thermoplastic polyamide, fundamentally altering the bonding mechanism. This parameter change eliminates microcracking while maintaining mechanical strength, as the thermoplastic material provides ductility and stress redistribution capabilities that thermosetting resins lack.
2Strength
If thermosetting resins are used for composite reinforcement, then mechanical strength is improved, but recyclability deteriorates
Solution Approach 1:
The patent changes the material parameter from thermosetting resin to thermoplastic polyamide, fundamentally altering the bonding mechanism. This parameter change eliminates microcracking while maintaining mechanical strength, as the thermoplastic material provides ductility and stress redistribution capabilities that thermosetting resins lack.
3Ease of manufacture
If thermoplastic polyamide with low melting point is used for sealing layer, then ease of manufacture and welding are improved, but temperature resistance deteriorates
Solution Approach 1:
The patent applies local quality by differentiating material properties across layers: the sealing layer uses low-melting-point thermoplastic polyamide for ease of welding and sealing, while the reinforcement layer uses high-melting-point polyphthalamide for temperature resistance. This spatial differentiation of material properties resolves the contradiction between manufacturability and temperature resistance.
4Temperature
If polyphthalamide with high glass transition temperature is used for external reinforcement layer, then temperature resistance is improved, but weldability with sealing layer deteriorates
Solution Approach 1:
The patent applies local quality by differentiating material properties across layers: the sealing layer uses low-melting-point thermoplastic polyamide for ease of welding and sealing, while the reinforcement layer uses high-melting-point polyphthalamide for temperature resistance. This spatial differentiation of material properties resolves the contradiction between manufacturability and temperature resistance.
5Stability of the object's composition
If intermediate thermoplastic polyamide reinforcement layer is added, then residual stresses from thermal variations are reduced, but device complexity increases
Solution Approach 1:
The patent introduces an intermediate thermoplastic polyamide reinforcement layer that acts as a mediator between the sealing layer and external reinforcement layer. This intermediate layer has thermal expansion properties that match the sealing layer, reducing residual stresses at the interface. The principle of intermediary resolves the contradiction by adding a specific layer that facilitates stress management.
6Ease of manufacture
If Type IV tank structure with non-adhering layers is used, then manufacturing flexibility is improved, but sealing layer collapse occurs under pressure differential
Solution Approach 1:
The patent applies preliminary action by creating strong adhesion between the sealing layer and reinforcement layer through chemical bonding of the polyamide materials before the tank is pressurized. This preliminary bonding prevents sealing layer collapse when pressure differentials occur during operation, resolving the contradiction between manufacturing flexibility and operational reliability.
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 allows for easy manufacturing, rapid filling and emptying, high gas tightness, and reduced weight, while maintaining mechanical strength and reducing the carbon footprint.
Implementation Method 1
the outermost sealing layer being welded to the innermost intermediate composite reinforcement layer
Implementation Method 2
the outermost intermediate composite reinforcement layer being welded to the innermost external composite reinforcement layer
Data Source
AI summary
A tank comprising a multilayer structure for the storage of compressed gas, preferably under high pressure, in particular hydrogen, comprising at least the following three successive layers, from the inside out: - at least one sealing layer consisting of a composition comprising predominantly at least one semi-crystalline thermoplastic polyamide having a Tf, measured according to ISO 11357-3: 2013, less than or equal to 280°C, - at least one intermediate composite reinforcement layer consisting of a fibrous material in the form of continuous fibers impregnated by a composition comprising predominantly at least one semi-crystalline thermoplastic polyamide having a Tg measured according to ISO 11357-3: 2013, less than 100°C,- at least one outer layer of composite reinforcement consisting of a fibrous material in the form of continuous fibers impregnated by a composition comprising predominantly at least one polyphthalamide having a Tg, measured according to ISO 11357-3:2013, greater than 80°C, the outermost sealing layer being welded to the innermost intermediate composite reinforcement layer and the outermost intermediate composite reinforcement layer being welded to the innermost outer composite reinforcement layer.