Light-weight cryogenic-compatible pressure vessel

Abstract

To provide a light-weight cryogenic-compatible pressure vessel which is used in a liquid hydrogen tank to attain preferable heat insulation performance as in a vacuum insulation structure and has an advantage of reduction of the weight.SOLUTION: A light-weight cryogenic-compatible pressure vessel enables a fluid, such as a cryogenic fluid or a compressed gas, to be stored at low temperature. Further, in the light-weight cryogenic-compatible pressure vessel, an inner pressure vessel 104 which surrounds a storage space 102 and is made of stainless steel or aluminum alloy, a ductile adhesive layer 112 which absorbs stress caused by heat expansion between the inner pressure vessel 104 and an outer layer of the inner pressure vessel 104 and has insulation properties, an insulative fiber reinforcement plastic layer 114 for ensuring to avoid galvanic corrosion caused between itself and the inner pressure vessel 104, a second fiber reinforcement plastic layer 116 which is light-weight and secures strength, a high heat insulation foaming agent layer 118 which inhibits heat transfer to the storage space 102, and a third fiber reinforcement plastic layer 120 which avoids an impact from the exterior of the foaming agent layer 118 are integrally wound.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a lightweight, low-temperature compatible pressure vessel suitable for use in liquid hydrogen tanks that achieve both weight reduction and heat insulation, for example, for use in vehicles. [Background technology]

[0002] In realizing a hydrogen-based society, high-energy-density liquid hydrogen is crucial, and research and development is shifting from gaseous hydrogen tanks to liquid hydrogen tanks, as proposed in, for example, Patent Documents 1 and 2. Patent Document 1 describes a lightweight composite material with a fiber-reinforced resin matrix as the internal pressure vessel, which presented the challenge of higher manufacturing costs compared to metal tanks. It also featured a vacuum insulation layer. Patent Document 2 describes a double-tank structure for the internal pressure vessel, consisting of a stainless steel inner tank and a GPI high-pressure pipe wrapped with reinforced fiber. The insulation performance is enhanced by providing a vacuum insulation layer between the stainless steel inner tank and the GPI high-pressure pipe. However, Patent Document 2 has the problem of high manufacturing costs because it requires four liquid hydrogen tanks to ensure the sealing performance of 70 MPa high-pressure hydrogen gas, which has high material permeability. Incidentally, Germany has been the first to develop liquid hydrogen tanks (made of stainless steel) for use in large commercial vehicles such as buses and trucks.

[0003] In aircraft applications (electrification of aircraft), challenges include tank weight and the use of materials in cryogenic environments. In personal automobile applications, challenges include tank weight, the use of materials in cryogenic environments, and the boil-off of liquid hydrogen. Furthermore, as shown in Patent Document 3, for example, a laminated plate structure of resin material and glass fiber reinforced resin composite material, with a metal piece at the bottom, has been proposed to reduce the weight of liquid hydrogen tanks. However, a problem with laminated plate structures is that they cannot obtain the same level of heat insulation as vacuum insulation structures.

[0004] Figure 4 is a cross-sectional view showing an example of a vacuum insulation structure used in a conventional gaseous hydrogen tank. Conventional gaseous hydrogen tanks include a storage chamber 402, an internal pressure vessel 404, a double-shell joint 405, an end opening 406, an end wall thickening section 407, an outer vessel 408, and a vacuum insulation layer 410 as the pressure vessel 400. The storage chamber 402 is a region for storing, for example, high-pressure gaseous hydrogen gas, and its temperature range is wide, from the liquid hydrogen temperature (20K) to the high temperature (up to 400K) that occurs when the storage chamber 402 is filled with compressed hydrogen. In applications such as storage for light vehicles using high-pressure gaseous hydrogen gas, the storage chamber 402 typically has an operating pressure of up to 70 MPa (700 bar) when 5 kg of H2 is stored in an external volume of 250 liters. The reason for setting the high-pressure gaseous hydrogen gas at 70 MPa (700 bar) is that the volume change between liquid hydrogen and gaseous hydrogen is approximately 800 times, and the energy density of a liquid hydrogen tank is 1.1 times that of a gaseous hydrogen tank at 70 MPa.

[0005] The internal pressure vessel 404 is a lightweight, rigid structure with high specific strength, and is configured to withstand the high pressure (due to compressed gas) from inside the fuel storage space 102, taking into consideration the critical importance of weight in pressure vessels in vehicle applications. The internal pressure vessel 404 is a tank housed inside a thin-walled high-pressure vessel made of materials such as SUS316 or chromium-nickel double-layer stainless steel, which have high hydrogen gas shielding performance and low-temperature brittleness. The outer vessel 408 operates to maintain the vacuum around the vessel necessary for the efficient operation of the multilayer insulation. The outer vessel 408 is insulated with a multilayer vacuum superinsulation layer. The multilayer vacuum superinsulation layer is insulated at a pressure of 0.01 Pa (7.5 × 10⁻⁶). -5 It exhibits excellent thermal properties under high vacuum conditions below mmHg. The internal pressure vessel 404 and the outer vessel 408 must be extremely robust in structure because they must safely withstand 70 MPa. While carbon fiber reinforced plastic (CFRP) could be used for the outer vessel 408, this still results in a heavy weight.

[0006] The end opening 406 is an opening for adding and removing liquid hydrogen to and from the storage chamber 402, and is provided at the end of the internal pressure vessel 404. The end wall thickness 407 is a wall thickness that forms the pipe wall surface of the end opening 406. The double-shell joint 405 is provided at the end wall thickness 407, and for example, the end of the internal pressure vessel 404 on the end opening 406 side and the end of the outer vessel 408 are joined, for example, by welding, creating a sealed structure that maintains the vacuum state of the vacuum insulation layer 410. The vacuum insulation layer 410 works to suppress heat transfer to the storage chamber 402. The insulation material used in the vacuum insulation layer 410 includes an external vacuum multilayer insulation material that reduces heat transfer to the storage space during low-temperature operation. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Patent No. 4815129 [Patent Document 2] Japanese Patent Publication No. 2018-66426 [Patent Document 3] Japanese Patent Publication No. 1-299400 [Overview of the project] [Problems that the invention aims to solve]

[0008] As mentioned above, in order to reduce the weight of liquid hydrogen tanks, a structure using a lightweight composite material with a fiber-reinforced resin matrix as an internal pressure vessel has been proposed in Patent Document 3. However, there was a problem in that a laminated plate structure alone could not provide the same level of heat insulation as a vacuum insulation structure. Patent Document 2 proposes a structure using thin sheets of stainless steel or aluminum alloy and carbon fiber reinforced polymer (CFRP), as well as a structure that combines vacuum insulation (the outermost layer being a thin sheet of stainless steel or aluminum alloy). However, this structure has the drawback of offering little advantage in terms of weight reduction (specific gravity). Furthermore, in the conventional structure shown in Figure 4, when storing low-temperature liquids or compressed gases at low temperatures, the vacuum insulation performance of the vacuum insulation structure deteriorates over time. In a vacuum insulation structure, in order to prevent the vacuum level from decreasing and the performance from deteriorating, it is necessary to operate a vacuum pump at all times to maintain the vacuum state, for example, as in electron microscopes (TEM, SEM, etc.) that maintain a vacuum state. The present invention aims to solve these problems and provide a lightweight, low-temperature-compatible pressure vessel suitable for use in liquid hydrogen tanks, which offers thermal insulation properties similar to a vacuum insulation structure, while also having the advantage of being lightweight. [Means for solving the problem]

[0009] [1] The lightweight low-temperature compatible pressure vessel of the present invention, as shown in Figure 1 for example, is a lightweight low-temperature compatible pressure vessel capable of storing fluids such as low-temperature fluids or compressed gases at low temperatures, comprising an internal pressure vessel 104 made of stainless steel or aluminum alloy surrounding a storage space 102, a ductile adhesive layer 112 surrounding the internal pressure vessel 104 that absorbs stress due to thermal expansion between the internal pressure vessel 104 and its outer layer and is insulating, an insulating fiber-reinforced plastic layer 114 surrounding the ductile adhesive layer 112 to reliably avoid galvanic corrosion with the internal pressure vessel 104, a second fiber-reinforced plastic layer 116 surrounding the insulating fiber-reinforced plastic layer 114 to ensure lightness and strength, a highly insulating foaming agent layer 118 surrounding the fiber-reinforced plastic layer 116 to suppress heat transfer to the storage space 102, and a third fiber-reinforced plastic layer 120 surrounding the foaming agent layer 118 to avoid external impact to the foaming agent layer 118, all integrally wound together. In the apparatus configured in this way, when storing low-temperature liquids or compressed gases at low temperatures, low-temperature insulation can be maintained without the vacuum insulation performance deteriorating over time, unlike in a vacuum insulation structure. Furthermore, the internal pressure vessel 104 is covered with an insulating adhesive layer 112 and a fiber-reinforced plastic layer 114, reliably preventing galvanic corrosion caused by the intervention of salt ions and other elements during operation.

[0010] [2] In the lightweight low-temperature compatible pressure vessel [1] of the present invention, preferably, as shown in Figure 1, for example, the internal pressure vessel 104 has a sandwich structure in which it is covered with second and third fiber-reinforced plastic layers (116, 120) and a foaming agent layer 118. [3] In the lightweight low-temperature compatible pressure vessel [1] or [2] of the present invention, preferably the ductile adhesive layer is configured to bend due to the expansion / contraction of the internal pressure vessel. [4] The lightweight low-temperature suitable pressure vessels [1] to [3] of the present invention may further include means of using a vacuum insulation structure in order to suppress heat transfer. In this case, the vacuum insulation structure may be configured to keep a vacuum pump running at all times so that the vacuum level can be restored even if the vacuum level decreases. [5] In the lightweight low-temperature compatible pressure vessels [1] to [4] of the present invention, preferably, the insulating fiber-reinforced plastic layer 114 may be any one of the following: a basalt fiber-reinforced plastic layer (BFRP), a glass fiber-reinforced plastic layer (GFRP), a polymer fiber-reinforced plastic layer (PFRP) containing aramid fibers (AFRP), or a composite material layer of the above fiber-reinforced plastics (BFRP / GFRP / AFRP / PFRP). [6] In the lightweight low-temperature compatible pressure vessels [1] to [5] of the present invention, preferably, the second fiber-reinforced plastic layer 116 may be any one of the following: a basalt fiber reinforced plastic layer (BFRP), a glass fiber reinforced plastic layer (GFRP), a polymer fiber reinforced plastic layer (PFRP) containing aramid fiber (AFRP), or a composite material layer of the above fiber-reinforced plastics (BFRP / GFRP / AFRP / PFRP), or a carbon fiber reinforced plastic layer (CFRP), or a composite material layer of the above fiber-reinforced plastics (BFRP / GFRP / AFRP / PFRP / CFRP). 〔7〕In the lightweight cryogenic-compatible pressure vessel [1] to [6] of the present invention, preferably, the third fiber-reinforced plastic layer 120 is a basalt fiber-reinforced plastic layer (BFRP), a glass fiber-reinforced plastic layer (GFRP), a polymer fiber-reinforced plastic layer (PFRP) containing aramid fiber (AFRP), or a composite material layer of the above fiber-reinforced plastics (BFRP / GFRP / AFRP / PFRP), or a carbon fiber-reinforced plastic layer (CFRP), or a composite material layer of the above fiber-reinforced plastics (BFRP / GFRP / AFRP / PFRP / CFRP). Any one of them may be used. 〔8〕In the lightweight cryogenic-compatible pressure vessel [1] to [7] of the present invention, preferably, the lightweight cryogenic-compatible pressure vessel is used as a liquid hydrogen tank, and the reference value of the pressure resistance is preferably set to a pressure lower than 70 MPa. 〔9〕In the lightweight cryogenic-compatible pressure vessel [8] of the present invention, preferably, the reference value of the pressure resistance is any one of 40 MPa, 25 MPa, or 10 MPa.

Advantages of the Invention

[0011] According to the lightweight cryogenic-compatible pressure vessel of the present invention, it is possible to provide a lightweight cryogenic-compatible pressure vessel that has a heat insulation property like a vacuum heat insulation structure while having a multilayer laminate structure and has the advantage of weight reduction. Further, when the lightweight cryogenic-compatible pressure vessel of the present invention is used as a liquid hydrogen tank, the liquid hydrogen tank does not need to always ensure a high-pressure pressure resistance performance like a gas hydrogen tank. If heat insulation is ensured, it is possible to use a tank with a pressure resistance lower than 70 MPa. Therefore, the amount of CFRP used can be less than that of a gas hydrogen tank, and the tank can be manufactured in a lightweight and low-cost manner.

Brief Description of the Drawings

[0012] [Figure 1] It is a cross-sectional configuration diagram of a sandwich-structured liquid hydrogen tank showing an embodiment of the present invention. [Figure 2]This is a cross-sectional view of a liquid hydrogen tank with a laminated plate structure, illustrating a comparative example of the present invention. [Figure 3] This is an explanatory diagram of the model and equations (3 layers) used in thermal calculations. [Figure 4] This is a cross-sectional view showing an example of a vacuum insulation structure used in conventional gaseous hydrogen tanks. [Modes for carrying out the invention]

[0013] The best mode for carrying out the present invention will be described in detail below. Figure 1 is a cross-sectional view of a sandwich-structure liquid hydrogen tank showing one embodiment of the present invention. The liquid hydrogen tank shown in Figure 1 includes a pressure vessel 100 comprising a storage space 102, an internal pressure vessel 104, an end opening 106, an end wall thickness 107, an adhesive layer 112, an insulating fiber reinforced plastic (FRP) layer 114, a fiber reinforced plastic (FRP) layer 116, a foaming agent layer 118, and a fiber reinforced plastic (FRP) layer 120. The storage space 102 is, for example, a region for storing liquid hydrogen, and its temperature range is wide, from the liquid hydrogen temperature (20K) to the high temperature (up to 100K) that occurs when the storage space 102 is filled with compressed hydrogen. In applications such as storage for light vehicles using liquid hydrogen, the storage space 102 typically has an operating pressure of up to 70 MPa (700 bar) when 5 kg of H2 is stored in an external volume of 250 liters.

[0014] The internal pressure vessel 104 is a lightweight and rigid structure with high specific strength, and is configured to withstand the high pressure (due to compressed gas) from inside the fuel storage space 102, taking into consideration the critical importance of weight in pressure vessels in vehicle applications. The internal pressure vessel 104 is a tank housed inside a thin-walled high-pressure vessel made of materials such as SUS316 or a two-layer stainless steel-aluminum alloy mainly composed of chromium-nickel steel, which have high shielding performance for hydrogen gas and high low-temperature brittleness. The end opening 106 is an opening for bringing liquid hydrogen into and out of the storage chamber 102, and is provided at the end of the internal pressure vessel 104. The end wall thickness 107 is the wall thickness that forms the pipe wall surface of the end opening 106.

[0015] The adhesive layer 112 is, for example, a layer that joins the end of the internal pressure vessel 104 on the end opening 106 side to the ends of the fiber-reinforced plastic (FRP) layers 114 and 116 using, for example, an adhesive. As the adhesive, it is preferable to use a material that yields a ductile adhesive layer, such as urethane, silicone, or polyvinyl butyral resin. The thickness of the adhesive layer 112 is preferably 0.06 to 2 mm, more preferably 0.5 to 2 mm, and most preferably 1 to 2 mm. If it is thinner than 0.05 mm, it will not be able to absorb the stress caused by thermal expansion between the internal pressure vessel 104 and the outer layer, resulting in delamination, and the insulation necessary to prevent galvanic corrosion will not be ensured. If it is thicker than 2 mm, the amount of adhesive used will increase, soaring manufacturing costs and increasing the curing time.

[0016] The fiber-reinforced plastic (FRP) layers 114 and 116 are wrapped around the outer surface of the internal pressure vessel 104 via the adhesive layer 112, thereby reinforcing the circumferential strength of the internal pressure vessel 104. In addition, the fiber-reinforced plastic (FRP) layer 114 surrounds the ductile adhesive layer 112 and provides insulation to reliably prevent galvanic corrosion with the internal pressure vessel 104. The fiber-reinforced plastic layer (FRP) 114 may be any one of the following: a basalt fiber-reinforced plastic layer (BFRP), a glass fiber-reinforced plastic layer (GFRP), a polymer fiber-reinforced plastic layer (PFRP) containing aramid fiber (AFRP), or a composite material layer of the above fiber-reinforced plastics (BFRP / GFRP / AFRP / PFRP). To ensure insulation, conductive carbon fiber-reinforced plastic layers (CFRP) or composite material layers of carbon fiber-reinforced plastics (BFRP / GFRP / AFRP / PFRP / CFRP) are not used. The thickness of the fiber-reinforced plastic layer (FRP) 114 should be determined based on design guidelines such as the size and strength of the tank.

[0017] The fiber-reinforced plastic (FRP) layer 116 surrounds the insulating fiber-reinforced plastic layer 114, ensuring lightness and strength. The fiber-reinforced plastic (FRP) layer 116 may be one of the following: a basalt fiber-reinforced plastic layer (BFRP), a glass fiber-reinforced plastic layer (GFRP), a polymer fiber-reinforced plastic layer (PFRP) containing aramid fiber (AFRP), or a composite material layer of the above fiber-reinforced plastics (BFRP / GFRP / AFRP / PFRP), or a carbon fiber-reinforced plastic layer (CFRP), or a composite material layer of the above fiber-reinforced plastics (BFRP / GFRP / AFRP / PFRP / CFRP). The thickness of the fiber-reinforced plastic layer (FRP) 114 should be determined based on design guidelines such as the size and strength of the tank.

[0018] The foaming agent layer (insulating layer) 118 works to suppress heat transfer to the storage space 102. The insulating material used in the foaming agent layer (insulating layer) 118 includes a porous insulating material that reduces heat transfer to the storage space during low-temperature operation, and the foaming agent layer fills the gaps in the fiber-reinforced plastic layers (FRP) 116 and 120. Suitable foaming agents include, for example, urethane, propylene, phenol, styrene, isocyanate, and all-resin materials. A foaming ratio of 15 to 60 times is preferred. The foaming agent layer contains a honeycomb core as a uniform concept, and may be made of, for example, aluminum alloy, aramid fiber-reinforced plastic, paper honeycomb core, or corrugated core. The thickness of the foaming agent layer (insulating layer) 118 is preferably 15 to 25 mm, more preferably 15 to 20 mm, and most preferably 15 to 18 mm. If it is thinner than 14 mm, high insulation performance that suppresses heat transfer to the internal pressure vessel 104 cannot be ensured. If it is thicker than 25 mm, the external dimensions of the liquid hydrogen tank become large, making it unsuitable for vehicle-mounted applications where storage space is limited.

[0019] The fiber-reinforced plastic (FRP) layer 120 is provided to protect the porous insulation material from external impacts. The fiber-reinforced plastic (FRP) layer 120 is insulated by the porous insulation layer and exhibits excellent thermal properties. The fiber-reinforced plastic layer (FRP) 120 may be one of the following: a basalt fiber-reinforced plastic layer (BFRP), a glass fiber-reinforced plastic layer (GFRP), a polymer fiber-reinforced plastic layer (PFRP) containing aramid fiber (AFRP), or a composite material layer of the above fiber-reinforced plastics (BFRP / GFRP / AFRP / PFRP), or a carbon fiber-reinforced plastic layer (CFRP), or a composite material layer of the above fiber-reinforced plastics (BFRP / GFRP / AFRP / PFRP / CFRP). The thickness of the fiber-reinforced plastic layer (FRP) 120 should be determined based on design guidelines such as the size and strength of the tank.

[0020] Figure 2 is a cross-sectional view of a liquid hydrogen tank with a laminated plate structure, illustrating a comparative example of the present invention. The liquid hydrogen tank shown in Figure 2 includes a storage space 202, an internal pressure vessel 204, an end opening 206, an end wall thickening section 207, an adhesive layer 212, and a fiber-reinforced plastic (FRP) layer 214 as the pressure vessel 200. Note that the storage space 202, internal pressure vessel 204, end opening 206, end wall thickness 207, adhesive layer 212, and fiber reinforced plastic layer (FRP) 214 are the same as the storage space 102, internal pressure vessel 104, end opening 106, end wall thickness 107, adhesive layer 112, and fiber reinforced plastic layers (FRP) 114, 116, and 120, respectively, so their explanation is omitted.

[0021] The heat conduction state in the apparatus configured in this way will be explained. Figure 3 is an explanatory diagram of the model and equation (3 layers) used for thermal calculations. This study focuses on vacuum insulation structures (comparative example shown in Figure 4) where stainless steel or aluminum alloy is used as the metal material for the internal pressure vessel. Here, we assume that the internal temperature of the stainless steel and aluminum alloy vacuum insulation structures is -253°C and the external temperature is 10°C. Furthermore, we assume that the vacuum insulation structures have a thermal conductivity of approximately 0.02 [W / m·K] due to the effects of thermal radiation and heat conduction at the edges. The overall thickness of the storage chamber wall is fixed to the same thickness as the vacuum insulation structure (comparative example shown in Figure 4) for both the sandwich structure (example shown in Figure 1) and the laminated plate structure (comparative example shown in Figure 2), which is 25 mm. The heat quantity Q is also the same as that of the vacuum insulation structure.

[0022] Under the above conditions, the effective thermal conductivity, apparent specific gravity, and external temperature (internal temperature -253°C) were determined for each structure. The heat transfer area A was assumed to be 1.

number

number

[0023] Example 1 (When the metal material of the internal pressure vessel is stainless steel) Vacuum insulation structure (comparative example shown in Figure 4) Stainless steel (thermal conductivity k is 80 [W / m·K], specific gravity 8 g / cm³) 3 ) In Figure 3, layer lA is a stainless steel layer with a thickness of 10 mm, layer lB is a vacuum insulation layer with a thickness of 10 mm, and layer lC is a stainless steel layer with a thickness of 5 mm. The effective thermal conductivity (k) is 0.05 [W / m·K], and the apparent specific gravity is 4.8 g / cm³. 3 This is the result.

[0024] Laminated board structure (comparative example shown in Figure 2) Adhesive (thermal conductivity k0.3 [W / m·K], specific gravity 1.2 g / cm³) 3 ), FRP (thermal conductivity k0.6 [W / m·K], specific gravity 1.5 g / cm³) 3 ) Layer 1A is a stainless steel layer with a thickness of 2 mm, layer 1B is an adhesive layer with a thickness of 1 mm, and layer 1C is an FRP layer with a thickness of 22 mm. The effective thermal conductivity (k) is 0.62 [W / m·K], and the apparent specific gravity is 2.0 g / cm³. 3 The external temperature will be -232°C.

[0025] Sandwich structure (an example shown in Figure 1) Foaming agent (core material) (thermal conductivity k0.03 [W / m·K], specific gravity 0.05 g / cm³) 3 ) Layer 1A is a stainless steel layer with a thickness of 2 mm, layer 1B is an adhesive layer with a thickness of 1 mm, layer 1C is an FRP layer with a thickness of 5 mm, layer 1D is a foaming agent layer with a thickness of 15 mm, and layer 1E is an FRP layer with a thickness of 2 mm. The effective thermal conductivity (k) is 0.05 [W / m·K], and the apparent specific gravity is 1.1 g / cm³. 3 The external temperature will be 18°C.

[0026] While laminated board structures offer a 58% weight reduction, their thermal insulation effect is very small. The sandwich structure offers a 76% weight reduction and maintains a higher temperature than vacuum insulation for the same amount of heat. It has excellent thermal insulation properties.

[0027] Example 2 (When the metal material of the internal pressure vessel is an aluminum alloy) Vacuum insulation structure (comparative example shown in Figure 4) Aluminum alloy (thermal conductivity k 240 [W / m·K], specific gravity 2.8 g / cm 3 ) Layer lA is an aluminum alloy layer with a thickness of 10 mm, layer lB is a vacuum insulation layer with a thickness of 10 mm, and layer lC is an aluminum alloy layer with a thickness of 5 mm. k (effective thermal conductivity) is 0.05 [W / m·K], and the apparent specific gravity is 1.7 g / cm 3 becomes.

[0028] Laminated plate structure (comparative example shown in Figure 2) Adhesive (thermal conductivity k 0.3 [W / m·K], specific gravity 1.2 g / cm 3 ), CFRP (thermal conductivity k 0.6 [W / m·K], specific gravity 1.5 g / cm 3 ) Layer lA is an aluminum alloy layer with a thickness of 2 mm, layer lB is an adhesive layer with a thickness of 1 mm, and layer lC is a FRP layer with a thickness of 22 mm k (effective thermal conductivity) is 0.62 [W / m·K], and the apparent specific gravity is 1.6 g / cm 3 , and the external temperature is -232°C.

[0029] Sandwich structure (example shown in Figure 1) Foaming agent (core material) (thermal conductivity k 0.03 [W / m·K], specific gravity 0.05 g / cm 3 ) Layer lA is an aluminum alloy layer with a thickness of 2 mm, layer lB is an adhesive layer with a thickness of 1 mm, layer lC is a FRP layer with a thickness of 5 mm, lD (foaming agent layer): 15 mm, lE (FRP layer): 2 mm k (effective thermal conductivity) is 0.05 [W / m·K], and the apparent specific gravity is 0.7 g / cm 3 , and the external temperature is 18°C.

[0030] In the laminated plate structure, the weight reduction effect is 5%, and the heat insulation effect is very small. In the sandwich structure, the weight reduction effect is 57%, and at the same heat quantity, a higher temperature can be maintained than in vacuum insulation. It has excellent heat insulation properties.

[0031] When the lightweight, low-temperature compatible pressure vessel of the present invention is used as a liquid hydrogen tank, it is not necessary to constantly ensure high-pressure resistance like a gaseous hydrogen tank. As long as thermal insulation is ensured, it is possible to have a tank with a pressure resistance of less than 70 MPa. Because the pressure resistance is less than 70 MPa, it does not require the use of as much CFRP as the gaseous hydrogen tank shown in Figure 4, resulting in a tank that can be manufactured at a lighter weight and lower cost. Even at low pressure, a structure that can withstand a certain amount of pressure is necessary, and when applying the lightweight, low-temperature compatible pressure vessel of the present invention to a liquid hydrogen tank, the standard value of the pressure resistance depends on the design, including cost. The standard pressure resistance value should preferably be 40 MPa, 25 MPa, or 10 MPa, but it is not limited to these values; any other appropriate value may be used as long as the pressure is lower than 70 MPa.

[0032] While several embodiments of the present invention have been described, these embodiments are presented as examples only and are not intended to limit the scope of the invention. These novel embodiments can be carried out in a variety of other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their variations are included in the scope and spirit of the invention, as well as in the claims and their equivalents. [Industrial applicability]

[0033] The lightweight, low-temperature compatible pressure vessel of the present invention is suitable for use in liquid hydrogen tanks and can be applied to commercial vehicles such as aircraft (hydrogen-burning aircraft and electric aircraft), trucks, and buses, as well as personal vehicles, but is not limited to these. Furthermore, it is suitable for use in ships and liquid hydrogen storage base tanks. [Explanation of Symbols]

[0034] 100, 200, 400 pressure vessels 102, 202, 402 storage spaces 104, 204, 404 Internal pressure vessels 106, 206, 406 end opening 107, 207, 407 Thick end part 112, 212 (ductile) adhesive layer 114, 214 Fiber-reinforced plastic layer (FRP) 116. Second Fiber Reinforced Plastic (FRP) Layer 118 Foaming agent layer 120 Third Fiber Reinforced Plastic Layer (FRP) 405 Double shell junction 408 Outer container 410 Vacuum insulation layer

Claims

1. 1. A lightweight cryogenic compatible pressure vessel capable of storing a fluid, such as a cryogenic fluid or compressed gas, at cryogenic temperatures, comprising: an inner pressure vessel made of stainless steel or aluminum alloy enclosing the storage space; a ductile adhesive layer surrounding the inner pressure vessel, absorbing stress due to thermal expansion between the inner pressure vessel and an outer layer thereof, and having insulating properties; an insulating fiber-reinforced plastic layer surrounding the ductile adhesive layer to ensure that galvanic corrosion with the inner pressure vessel is avoided; A second fiber-reinforced plastic layer that surrounds the insulating fiber-reinforced plastic layer and ensures light weight and strength; a foam layer surrounding the second fiber-reinforced plastic layer to inhibit heat transfer to the storage space; A lightweight low-temperature compatible pressure vessel, characterized in that a third fiber-reinforced plastic layer is integrally wound around the foaming agent layer to surround the foaming agent layer and protect the foaming agent layer from external impact.

2. 10. The lightweight cryogenic compatible pressure vessel of claim 1, wherein the inner pressure vessel has a sandwich construction covered by the second and third fiber reinforced plastic layers and a foam layer.

3. 3. The lightweight cryogenic compatible pressure vessel of claim 1 or 2, wherein the ductile adhesive layer is configured to flex due to expansion / contraction of the inner pressure vessel.

4. 10. The lightweight cryogenic compatible pressure vessel of claim 1 further comprising means for inhibiting heat transfer in conjunction with vacuum insulation.

5. 2. The lightweight cryogenic compatible pressure vessel of claim 1, wherein the insulating fiber reinforced plastic layer is any one of a basalt fiber reinforced plastic layer (BFRP), a glass fiber reinforced plastic layer (GFRP), a polymer fiber reinforced plastic layer (PFRP) containing aramid fiber (AFRP), or a composite layer of the above fiber reinforced plastics (BFRP / GFRP / AFRP / PFRP).

6. 2. The lightweight, cryogenically compatible pressure vessel of claim 1, wherein the second fiber reinforced plastic layer is any one of a basalt fiber reinforced plastic layer (BFRP), a glass fiber reinforced plastic layer (GFRP), a polymer fiber reinforced plastic layer (PFRP) containing aramid fiber (AFRP), or a composite layer of the above fiber reinforced plastics (BFRP / GFRP / AFRP / PFRP), or a carbon fiber reinforced plastic layer (CFRP), or a composite layer of the above fiber reinforced plastics (BFRP / GFRP / AFRP / PFRP / CFRP).

7. 2. The lightweight, cryogenically compatible pressure vessel of claim 1, wherein the third fiber reinforced plastic layer is any one of a basalt fiber reinforced plastic layer (BFRP), a glass fiber reinforced plastic layer (GFRP), a polymer fiber reinforced plastic layer (PFRP) containing aramid fiber (AFRP), or a composite material layer of the above fiber reinforced plastics (BFRP / GFRP / AFRP / PFRP), or a carbon fiber reinforced plastic layer (CFRP), or a composite material layer of the above fiber reinforced plastics (BFRP / GFRP / AFRP / PFRP / CFRP).

8. 2. The lightweight, cryogenic pressure vessel according to claim 1, which is used as a liquid hydrogen tank and has a standard pressure resistance set to a pressure lower than 70 MPa.

9. 9. The lightweight, low-temperature compatible pressure vessel according to claim 8, wherein the reference pressure resistance is any one of 40 MPa, 25 MPa, and 10 MPa.

Images