Geometrically compatible hydrogen tank manufacturing process

Abstract

The invention relates to a method for manufacturing a gaseous / liquid hydrogen storage tank for use in all air vehicles as well as passenger / load-carrying ground vehicles using hydrogen technology. In particular, hydrogen storage tanks having a shape conformable to aircraft wings or non-traditional aircraft form factors, i.e. not cylindrical or spherical, are effectively produced by the method subject to the invention.

Description

[0001] GEOMETRICALLY COMPATIBLE HYDROGEN TANK MANUFACTURING PROCESS

[0002] Technical Field of the Invention

[0003] The invention relates to a method for manufacturing a gaseous / liquid hydrogen storage tank for use in all air vehicles as well as passenger / load-carrying ground vehicles using hydrogen technology. In particular, hydrogen storage tanks having a shape conformable to aircraft wings or non-traditional aircraft form factors, i.e. not cylindrical or spherical, are effectively produced by the method subject to the invention.

[0004] State of the Art

[0005] Energy plays a crucial role in achieving sustainable development goals, and the use of fossil-based fuels in particular to meet societies' energy needs leads to significant economic, environmental, and social problems. From this point of view, hydrogen energy is an important alternative in solving these problems. As an energy carrier, hydrogen is expected to play a significant role in future energy scenarios. This is because hydrogen is primarily considered a clean energy source and is expected to play a significant role in achieving environmental sustainability goals [1], The need to reduce greenhouse gas emissions and combat climate change increases the importance of hydrogen [2,3], Furthermore, the high energy density of hydrogen allows more energy to be stored in a smaller volume, which reduces transportation and storage costs [4,5], However, there are also many challenges in the use of hydrogen. One of these is that the production costs of hydrogen are quite high [6,7], In addition, the storage and transportation challenges of hydrogen must also be taken into account [8], Hydrogen can be stored under high pressure or by liquefying. However, these methods entail additional costs for storage and transportation, as well as safety concerns. The low density of the gaseous form of hydrogen increases the need for large storage tanks. The expansion of the hydrogen economy requires a comprehensive infrastructure. This includes hydrogen production facilities, storage and distribution networks, and appropriate vehicles for use. Building and maintaining this infrastructure can be time consuming and costly [9], The hydrogen tanks used in the present art are particularly critical for the transportation and storage of hydrogen. Specialized tanks designed to safely store and transport hydrogen, especially in liquid or gaseous form, are used. These tanks enable hydrogen to be stored under high pressure or at low temperature, meeting requirements such as safety, efficiency, and durability. The term geometrically compatible hydrogen tank means that the geometric structure of the tank designs used for the safe, efficient, and effective storage of hydrogen must fully comply with the hydrogen storage requirements. This design is optimized to maximize the storage capacity, safety, and transport efficiency of hydrogen. Geometric compatibility is usually related to the shape and structure of the tank and its suitability for the storage conditions of hydrogen (pressure, temperature, volume). In this context, the most common form used in the design of hydrogen tanks is the cylinder, and cylindrical tanks are generally used for high-pressure gas storage. This design ensures a homogeneous distribution of pressure on the tank walls and increases the durability of the tank. In terms of geometric compatibility, the cylindrical shape minimizes the risk of cracking or deforming under pressure. However, these structures cause serious space problems for automobiles or aircraft such as airplanes. For this reason, recent developments in the present art have focused on the development of rectangular prisms or complexshaped tanks. Particularly complex shapes often require special molds and more precise production methods. This complicates the production process and means more labor, time, and material costs. Furthermore, special materials, high quality composites, or metal alloys used in complex shapes are more expensive than conventional materials, increasing the cost of production. In addition, the biggest issue in these tanks is the strength problem caused by the pressure on the lateral surfaces. For this reason, large surfaces need to be supported by mutual connections.

[0006] Due to reasons such as the limitations and shortcomings of the solutions in the present art, the space constraints caused by cylindrical hydrogen tanks in automobiles or aircraft such as airplanes, the high cost of hydrogen tank manufacturing, and the low strength properties of the tanks, it has become necessary to make a development in the manufacturing of gas / liquid hydrogen storage tank. Summary and Objects of the Invention

[0007] The invention describes a method for manufacturing a gaseous / liquid hydrogen storage tank for use in all air vehicles as well as passenger / load-carrying ground vehicles using hydrogen technology.

[0008] The object of the invention is to provide reliable and high-strength hydrogen tanks. Low thermal expansion characteristic, which is a general technical characteristic of continuous fiber reinforced thermoplastic composite (CFRTPC) materials, not only increases the safety of hydrogen tanks of CFRTPC, but also improves the durability of the tanks. This increases the reliability of hydrogen tanks by ensuring that structural integrity is maintained even under different temperature and pressure conditions.

[0009] The main object of the invention is to provide a hydrogen tank that allows for optimized indoor use. In the method subject to the invention, the flexibility of the production process with additive manufacturing using CFRF (continuous fiber reinforced filament) enables the hydrogen tanks to be produced specifically to the desired geometry. Thus, the hydrogen tank is suitable for use in any vehicle of any volume.

[0010] Another object of the invention is to produce hydrogen tanks at low cost. The method subject to the invention does not require any additional process such as molding, adhering, surface forming, etc. in the production of tanks with complex geometries from continuous fiber reinforced thermoplastic material whose inner liner is produced by additive manufacturing, and therefore requires relatively low cost.

[0011] Description of the Drawings

[0012] Fig. 1. Example illustration of production of the sample inner liner by additive manufacturing along with fiber orientations and representative view of the sample composite liner cross-section and in the tank.

[0013] Fig. 2. Illustration of metal caps and metal cap-inner liner connection.

[0014] Fig. 3. Schematic representation of the outer shell creation process and example tank view.

[0015] Fig. 4. Examples of tank sections and shapes that can be produced in different geometries. Description of the References in the Drawings

[0016] 1. CFRTPC / CFR Filament

[0017] 2. 3D Printer / Additive Manufacturing

[0018] 3. Inner liner

[0019] 4. Metal Cap

[0020] 5. Outer shell

[0021] Detailed Description of the Invention

[0022] The invention relates to a method for manufacturing a gaseous / liquid hydrogen storage tank for use in all air vehicles as well as passenger / load-carrying ground vehicles using hydrogen technology. In particular, hydrogen storage tanks having a shape conformable to aircraft wings or non-traditional aircraft form factors, i.e. not cylindrical or spherical, are effectively produced by the method subject to the invention.

[0023] The method subject to the invention for manufacturing a gaseous / liquid hydrogen storage tank for use in all air vehicles as well as passenger / load-carrying ground vehicles using hydrogen technology comprises the process steps of: i. designing the inner liner (3) and the tank geometry, which will be suitable for the geometry inside the tank and will serve as support for the opposing surfaces, ii. producing the geometry of the specified inner liner (3) compatible with the tank geometry using CFRTPC / CFR (continuous fiber reinforced thermoplastic composite) (1) material by additive manufacturing method (2), iii. removing surface roughness caused by additive manufacturing on the outer surface of the tank geometry compatible with the desired geometric structure with computer-controlled machining methods (CNC) (milling, cutting, polishing) and / or increasing strength and reducing pores with processes such as heat treatment, hot pressing, hot pressing under pressure, etc., iv. adding at least one metal cap (4) to provide connections, v. forming the outer shell (5) that surrounds the tank, which is supported by the inner liner (3) and incorporates metal caps, from fiber-reinforced thermoplastic filaments or pre-preg composites by optimizing the fiber orientations using filament winding / automatic fiber placement method, vi. performing structural tests and safety tests of the produced tank.

[0024] The composite development of geometrically compatible tanks is realized by the production of a composite liner (3), an example of which is shown in Fig. 1. In this liner, large surfaces are reinforced by connecting them with mutual composite supports. These composite supports come in different structures and cellular geometries and can extend along the length of the liner or be produced in pieces. Due to its complex shape, this composite liner is manufactured using continuous fiber-reinforced filaments or tape (1). Using conventional composite production methods and conventional fiber lay-up (using fabric) is an impossible or difficult process due to intersections or junctions. For this reason, production will be realized with the use of thermoplastic resin in the process of manufacturing the liner. In the method subject to the invention, a method of producing the liner by additive manufacturing (2) using continuous fiber reinforced filaments (CFRF) (1) as shown in Fig. 1 is proposed. Thus, complex shaped liner geometries with very different internal configurations can be easily produced without the use of molds. As it is produced in two dimensions in a plane using additive manufacturing, it is easy to understand that the fiber direction is pressed parallel to the tube cross-section along the liner perimeter and along the supports, making the tank very strong circumferentially. At the same time, the fibers can carry significant loads in their own direction, and since the fiber direction is aligned with the support direction in the internal supports, the supports will have a significant load-bearing capacity due to lateral pressure.

[0025] Different fibers (carbon, basalt, glass, etc.) can be used for the inner liner (3), as well as both thermoplastic and thermoset resins. 3D manufacturing methods are used during the manufacturing process. After the liner is manufactured, at least one metal cap (4) (Metal boss: for gas connection) is mounted on the ends in a concave shape and in accordance with the liner geometry (Fig. 2). Although the circumferential strength is very high in the liner due to the fiber direction, the strength in the axial direction is very weak due to the nature of additive manufacturing (interlayer strength is very weak in continuous fiber reinforced composites). For this reason, in order to strengthen this aspect, both the liner and the caps are subjected to composite wrapping together and an outer shell (5) is formed to both carry the axial load and hold the metal covers together with the body. Filament winding is used for shell formation or automated fiber placement (Automated Fiber Placement; AFP, Fiber (or Filament) Winding; etc.), which is more suitable for complex shapes (Fig. 3). In this method, it is necessary to use the same thermoplastic resin as the thermoplastic resin from which the inner liner is manufactured in order to achieve a superior degree of adhesion between the inner liner (3) and the outer shell (5). Before proceeding to these processes, the liner surfaces are first smoothed by CNC machining (Computer-aided numerical control) to adjust the geometric tolerances and remove the roughness of the surfaces, and if necessary, the liner strength is increased and possible pores are reduced by heat treatment or hot pressing after additive manufacturing (post processing).

[0026] The flexibility of the production process using additive manufacturing with CFRF enables the custom production of hydrogen tanks in the desired geometry. This enables more optimized interior space utilization and a more efficient use of space in vehicle designs. This is where the greatest advantage of the invention emerges. By making it possible to produce the most suitable tank for the structure being designed, it enables the production of vehicles and structures with minimum volume and weight without making changes to the existing design. Whether it's a long, slender wing body, rectangular volumes defined in automobiles, or custom designs, production can be carried out in various configurations. In addition, fiber directions can be optimized according to stress values and thickness and internal structure can be designed in values suitable for the desired pressures. In this way, the geometry and strength of the material can be adjusted to the desired values.

[0027] The low thermal expansion not only increases the safety of CFRTPC hydrogen tanks, but also improves the durability of the tanks. This increases the reliability of hydrogen tanks by ensuring that structural integrity is maintained even under different temperature and pressure conditions. As a result, the use of CFRTPC provides lighter, more compact and more reliable hydrogen storage solutions, improving the performance of aerial platforms while reducing costs. Fig. 4 shows some examples. In addition, the outside of the tanks produced by the method subject to the invention can also be used as cryogenic tanks by isolating them with another tank. Furthermore, its thermoplastic nature provides a significant advantage over thermoset resin composite pressure tanks in terms of recyclability. Industrial Applicability of the Invention

[0028] The invention relates to a method for manufacturing a gaseous / liquid hydrogen storage tank for use in all air vehicles as well passenger / load-carrying ground vehicles using hydrogen technology, and is industrially applicable.

[0029] The invention is not limited to the above descriptions and the person skilled in the art can readily present other different embodiments of the invention. These should be considered within the protection scope of the invention claimed by the claims.

[0030] REFERENCES

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Claims

CLAIMS1. A method for manufacturing gaseous / liquid hydrogen storage tanks, characterized in that it comprises the process steps of: i. designing the inner liner (2) and the tank geometry, which will be suitable for the geometry inside the tank and will serve as support for the opposing surfaces, ii. producing the specified inner liner (2) and tank geometry using CFRTPC (continuous fiber reinforced thermoplastic composite) material by additive manufacturing method, iii. removing surface roughness caused by additive manufacturing on the outer surface of the tank geometry compatible with the geometric structure desired for production with computer-controlled machining methods (CNC) (milling, cutting, polishing) and / or performing the process of increasing strength and reducing pores with processes such as heat treatment, hot pressing, hot pressing under pressure, etc., iv. adding at least one metal cap (1) to provide connections, v. forming the outer shell (3) that surrounds the tank, which is supported by the inner liner (2) and incorporates metal caps, using filament winding / automatic fiber placement method, vi. performing safety tests of the produced tank.

2. A hydrogen storage tank produced by the method according to claim 1.

3. A hydrogen storage tank according to claim 2 for use in passenger / load carrying land vehicles and all aircraft using hydrogen technology.

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