Rocket system and fuel tank system

Abstract

To provide a rocket system capable of effectively utilizing evaporation gas of fuel, and a fuel tank system.SOLUTION: A rocket system according to the present disclosure comprises a fuel tank that is filled with fuel, and cooling piping that is connected to the fuel tank and through which boil-off gas of the fuel is circulated. The boil-off gas circulated through the cooling piping cools the fuel tank.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates to rocket systems and fuel tank systems. [Background technology]

[0002] Liquid fuels such as liquid hydrogen and liquid methane are cooled to extremely low temperatures and then stored in fuel tanks, but there was a problem in that they were heated by the inflow of heat from outside into the fuel tank, reaching their boiling point and evaporating.

[0003] For example, Patent Document 1 listed below discloses a cryogenic propellant storage device for a liquid rocket, which is provided with a configuration for re-liquefying and storing evaporated gas of the cryogenic propellant. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6159641 Summary of the Invention [Problem to be solved by the invention]

[0005] However, although the prior art described in Patent Document 1 reduces the loss due to evaporation of the cryogenic propellant by re-liquefying the evaporated gas of the cryogenic propellant, there is a need to reduce the energy required for re-liquefaction, and there is also a need to effectively utilize the evaporated gas of the fuel in the fuel tank.

[0006] In view of the above-mentioned problems, the present disclosure aims to provide a rocket system and a fuel tank system that can effectively utilize fuel vapor. [Means for solving the problem]

[0007] In order to solve the above-mentioned problems and achieve the objectives, the rocket system according to the present disclosure comprises a fuel tank filled with fuel, and a cooling pipe connected to the fuel tank and through which boil-off gas of the fuel flows, and the boil-off gas flowing through the cooling pipe cools the fuel tank.

[0008] In order to solve the above-mentioned problems and achieve the objectives, the fuel tank system according to the present disclosure includes a fuel tank filled with fuel and a cooling pipe through which boil-off gas of the fuel in the fuel tank flows, and the boil-off gas flowing through the cooling pipe cools the fuel tank. [Effects of the Invention]

[0009] According to the present disclosure, it is possible to provide a rocket system and a fuel tank system that can effectively utilize fuel vapor. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a schematic diagram showing the structure of a rocket system according to the present disclosure. [Figure 2] FIG. 2 is a schematic diagram showing the structure of the rocket body according to the present disclosure. [Figure 3] FIG. 3 is a schematic diagram showing the configuration of a fuel tank system according to the present disclosure. [Figure 4] FIG. 4 is a schematic diagram showing the structure of the upper end portion of the fuel tank according to the present disclosure. [Figure 5] FIG. 5 is a schematic diagram showing a first example of the structure of the skirt portion of the fuel tank according to the present disclosure. [Figure 6] FIG. 6 is a schematic diagram showing a second example of the structure of the skirt portion of the fuel tank according to the present disclosure. [Figure 7] FIG. 7 is a schematic diagram showing the structure of a fuel tank according to the present disclosure. [Figure 8] FIG. 8 is a schematic diagram showing the structure of the second insulating material according to the present disclosure. [Figure 9]FIG. 9 is a schematic diagram showing the structure of a third insulating material according to the present disclosure. [Figure 10] FIG. 10 is a schematic diagram showing the configuration of an oxidizer tank system according to the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. However, the present disclosure is not limited to the embodiments described below.

[0012] (Rocket system configuration) First, the configuration of a rocket system 1 according to the present disclosure will be described with reference to Fig. 1. Fig. 1 is a schematic diagram showing the structure of a rocket system according to the present disclosure. The rocket system 1 according to the present disclosure comprises a fairing 11, a second stage rocket 12, a first stage rocket 13, and a solid rocket booster 14. As shown in Fig. 1, the fairing 11 is provided at the tip of the second stage rocket 12, and the solid rocket booster 14 is connected to the side of the first stage rocket 13.

[0013] Rocket system 1 carries payloads such as a satellite or a supply vehicle inside fairing 11 attached to the tip of second-stage rocket 12. After rocket system 1 is launched by the combustion of solid fuel in solid rocket boosters 14 connected to first-stage rocket 13, fairing 11 attached to the tip of second-stage rocket 12 separates, and then first-stage rocket 13 and second-stage rocket 12 separate, with second-stage rocket 12 traveling through space for a predetermined period of time. In the following description, first-stage rocket 13 or second-stage rocket 12 of rocket system 1 will be referred to as rocket body 2.

[0014] (Rocket body configuration) Next, the configuration of the rocket body 2 according to the present disclosure will be described with reference to Figure 2. Figure 2 is a schematic diagram showing the structure of the rocket body according to the present disclosure. The rocket body 2 includes a rocket engine 3, a frame 4, an oxidizer tank system 5, a fuel tank system 6, an air accumulator 7, a payload support structure (PSS) 8, a payload attachment fitting (PAF) 9, and a payload 10. Note that the payload support structure 8, the payload separation structure 9, and the payload 10 may not be necessary if the rocket body 2 is a first-stage rocket 13.

[0015] The rocket engine 3 generates thrust by burning fuel. Specifically, the rocket engine 3 generates thrust by mixing and burning fuel supplied from the fuel tank system 6 and oxidizer supplied from the oxidizer tank system 5. As shown in FIG. 2 , the rocket engine 3 is provided below the oxidizer tank system 5.

[0016] The frame 4 is connected to and supports the oxidizer tank system 5 and the fuel tank system 6. The frame 4 may be formed by a truss structure forming a plurality of triangles as shown in Fig. 2. The frame 4 has a first frame member provided on the side of the oxidizer tank system 5, a second frame member provided on the side of the fuel tank system 6, and a strength member provided between the first frame member and the second frame member.

[0017] The oxidizer tank system 5 includes, for example, an oxidizer tank that stores liquid oxygen as an oxidizer. The oxidizer tank system 5 is capable of supplying oxidizer to the rocket engine 3 by receiving a supply of working gas from the gas reservoir 7. The configuration of the oxidizer tank system 5 will be described in detail later.

[0018] The fuel tank system 6 includes a fuel tank that stores, for example, liquid hydrogen or liquid methane as fuel. The fuel tank system 6 is capable of supplying liquid hydrogen to the rocket engine 3 by receiving a working gas from an air accumulator 7. The configuration of the fuel tank system 6 will be described in detail later.

[0019] The gas accumulator 7 is capable of supplying the pressurized working gas (e.g., helium gas) to the oxidizer tank system 5 and the fuel tank system 6. In addition to the oxidizer tank system 5 and the fuel tank system 6, the gas accumulator 7 may also be capable of supplying the pressurized working gas to the rocket engine 3, the thrusters 20 for attitude control and orbit correction provided in the rocket body 2, etc. The working gas is not limited to helium gas, and any inert gas may be used, for example, nitrogen gas, argon gas, etc.

[0020] The payload support unit 8 is a support that supports the payload 10, and is connected to one of both ends of the fuel tank system 6. The payload support unit 8 may be formed, for example, in a cylindrical shape that tapers from the end connected to the fuel tank system 6 toward the payload 10. The payload support unit 8 may have, for example, a hollow space inside, and one of both ends is fixed to the fuel tank system 6, and the payload separation unit 9 is connected to the other end.

[0021] The load separation unit 9 has the function of separating the payload 10, and is provided at one of the ends of the load support unit 8. For example, the end of the load separation unit 9 that is connected to the load support unit 8 has the same size as the end of the load support unit 8. For example, the load separation unit 9 may be formed in a cylindrical shape that tapers from the load support unit 8 side toward the payload 10 side. For example, the load separation unit 9 may have a hollow space inside. One of the ends of the load separation unit 9 is fixed to the load support unit 8, and the payload 10 is detachably mounted on the other end.

[0022] (Fuel tank system configuration) Next, the configuration of a fuel tank system 6 according to the present disclosure will be described with reference to Fig. 3. Fig. 3 is a schematic diagram showing the configuration of a fuel tank system according to the present disclosure. As shown in Fig. 3, the fuel tank system 6 according to the present disclosure includes a fuel tank 61 having a skirt portion 62, cooling piping 63, a heat exchange unit 64, a refrigerator 65, refrigerant piping 66, and a solar panel 67. These components will be described in order below. The fuel tank system 6 further includes a first insulating material 100, a second insulating material 200, and a third insulating material, which will be described later.

[0023] The fuel tank 61 is a storage container that stores fuel. The fuel tank 61 may be made of a 2000 series aluminum alloy (Al-Cu alloy), a 7000 series aluminum alloy (Al-Zn-Mg alloy), or the like. The fuel tank 61 includes a cylindrical cylinder portion 611 and a semicircular dome portion 612. The cylinder portion 611 is manufactured by bending and welding a machined panel with integrated ribs, called an isogrid structure, whose inner surface is machined into a grid pattern. The dome portion 612 is manufactured by spinning, in which an aluminum plate is pressed into a dome shape while rotating. The fuel tank 61 can then be manufactured by welding the formed cylinder portion 611 and dome portion 612 together in the circumferential direction.

[0024] Note that tungsten inert gas (TIG) welding, friction stir welding (FSW), or the like may be used as a welding method for manufacturing the fuel tank 61. By using friction stir welding (FSW), pre-processing for the welding work is not required, which makes it possible to shorten the welding work time, and can achieve the effects of increasing the stability of the welding quality and improving reliability.

[0025] The skirt portion 62 is connected to one of both ends of the cylinder portion 611 of the fuel tank 61 and is formed in a cylindrical shape. The other end of the skirt portion 62, opposite the end connected to the cylinder portion 611 of the fuel tank 61, is connected to the payload support portion 8 and supports the payload support portion 8. As shown in FIG. 3 , a cooling pipe 63 passing through a heat exchange unit 64 is provided inside the skirt portion 62. The cooling pipe 63 passing through the skirt portion 62 is connected to the thruster 20. The skirt portion 62 will be described in detail later.

[0026] The cooling pipe 63 is a pipe through which boil-off gas of the fuel flows. The cooling pipe 63 may be made of a material with high thermal conductivity, such as an aluminum alloy, stainless steel, or Hastelloy (registered trademark). The cooling pipe 63 is connected to the top of the dome portion 612 of the fuel tank 61. Therefore, the boil-off gas of the fuel filled in the fuel tank 61 flows into the cooling pipe 63 due to an increase in pressure.

[0027] At least a portion of the cooling pipe 63 is provided at a position where the boil-off gas flowing inside the cooling pipe 63 can cool the fuel tank 61. At least a portion of the cooling pipe 63 may be provided at any position where the fuel tank 61 can be cooled, but may be provided at a position within a predetermined distance from the surface of the fuel tank 61, or more specifically, at a position in contact with the surface of the fuel tank 61. As will be described in detail later, in this embodiment, a portion of the cooling pipe 63 may be provided in contact with the inner surface of the skirt portion 62 of the fuel tank 61.

[0028] In addition, in this embodiment, the cooling pipe 63 is connected to the heat exchange unit 64. In this embodiment, the cooling pipe 63 is connected to the heat exchange unit 64 at a location upstream in the flow direction of the boil-off gas from the location where the fuel tank 61 is cooled (in this example, the location where the cooling pipe 63 contacts the inner surface of the skirt portion 62 of the fuel tank 61).

[0029] The heat exchange unit 64 exchanges heat between the refrigerant of the refrigerator 65 (described later) and the boil-off gas flowing through the cooling pipe 63. The heat exchange unit 64 may be configured to exchange heat by bringing the cooling pipe 63, through which the boil-off gas flows, into contact with the refrigerant of the refrigerator 65, thereby generating heat conduction or heat transfer between the two. For example, the heat exchange unit 64 may be a multi-tube heat exchanger, which has a thick cylindrical body and a large number of thinner circular pipes arranged inside it, and exchanges heat between the fluid inside the body and the fluid inside the circular pipes. That is, as shown in FIG. 3 , the heat exchange unit 64 may be connected to a refrigerant pipe 66 through which the refrigerant of the refrigerator 65 flows.

[0030] The refrigerator 65 includes a compressor that compresses a refrigerant and refrigerant piping 66 that circulates the refrigerant. The compressor may be a mechanical turbo compressor, such as a centrifugal type, that includes an impeller, bearings, etc. The refrigerant may be liquid helium, for example. This allows the refrigerator 65 to achieve cooling using a turbo Brayton cycle. Note that the refrigerator 65 may also be realized by active magnetic regenerative refrigeration (AMRR), which uses liquid helium as the refrigerant and utilizes the phenomenon in which a magnetic material releases heat when a magnetic field is applied to it and absorbs heat when the magnetic field is removed.

[0031] The refrigerant piping 66 is a pipe through which the refrigerant of the refrigerator 65 flows. As shown in Fig. 3, the refrigerant piping 66 is piped from the refrigerator 65 toward the heat exchange unit 64 and connected to the heat exchange unit 64. The refrigerant piping 66 is piped so that the refrigerant returns to the refrigerator 65 after passing through the heat exchange unit 64. This allows the refrigerant to circulate between the heat exchange unit 64 and the refrigerator 65.

[0032] The solar cell panel 67 is a power generation unit that generates electricity using sunlight. The solar cell panel 67 includes solar cells that convert sunlight into electricity and back electrodes that serve as the substrates of the solar cells, and a third heat insulating material is provided on the side of the back electrode on which the solar cells are not provided. The solar cells may be, for example, thin-film solar cells. The thin-film solar cells may be realized by InGaP / GaAs dual-junction solar cells or InGaP / GaAs / Ge triple-junction solar cells.

[0033] InGaP / GaAs dual-junction solar cells and InGaP / GaAs / Ge triple-junction solar cells are solar cells that use semiconductors with two and three different bandgaps, respectively, that convert sunlight of different wavelength bands into electricity, and are electrically connected in series. As a result, the output voltage of the integrated solar cell is the sum of the output voltages of the individual solar cells, which is several times higher than that of a silicon solar cell. Therefore, the use of InGaP / GaAs dual-junction solar cells and InGaP / GaAs / Ge triple-junction solar cells can increase the power generation efficiency of solar power generation.

[0034] The solar cell may be a lattice-mismatched triple-junction solar cell. Lattice-mismatched triple-junction solar cells can be realized as a thin film of about 20 μm, and because they are flexible, they can be attached to a curved back electrode. Therefore, by using lattice-mismatched triple-junction solar cells, it becomes possible to install solar cells in places where installation was previously impossible, thereby increasing the amount of power generated by solar power generation.

[0035] Heat flows into the fuel tank system 6 described above from sunlight and various components such as the skirt portion 62 connected to the fuel tank 61. In contrast, according to the configuration of the fuel tank system 6 described above, the boil-off gas of the fuel filled in the fuel tank 61 passes through the cooling pipe 63 and flows to the heat exchange unit 64, where heat exchange takes place between the boil-off gas of the fuel and the refrigerant of the refrigerator 65. Therefore, the refrigerant of the refrigerator 65 can be appropriately cooled by the boil-off gas of the fuel.

[0036] Furthermore, since the cooling pipe 63 that has passed through the heat exchange unit 64 passes inside the skirt portion 62, the skirt portion 62 and, ultimately, the fuel tank 61 can be appropriately cooled by the boil-off gas flowing through the cooling pipe 63. Therefore, the fuel filled in the fuel tank 61 can also be appropriately cooled by the refrigerator 65 that further cools the cooled refrigerant, and further, the fuel tank 61 can also be appropriately cooled, thereby reducing the boil-off gas of the fuel. However, the configuration in which the cooling pipe 63 is connected to the heat exchange unit 64 and cools the refrigerant of the refrigerator 65 is not essential.

[0037] (Regarding the use of boil-off gas) Next, the use of the boil-off gas that has passed through the skirt portion 62 will be described. The boil-off gas that has flowed out of the cooling pipe 63 of the skirt portion 62 may be used as fuel for the thruster 20 or for vent retention. Alternatively, the boil-off gas may pass through the thruster 20 and be released directly from the thruster 20. That is, as shown in FIG. 3, the cooling pipe 63 may be connected to the thruster 20 after passing through the skirt portion 62. The thruster 20 and vent retention will be described below.

[0038] The thruster 20 is a device that controls the attitude of the rocket body 2 using thrust. The thruster 20 may be a chemical propulsion thruster that generates thrust by generating high-temperature, high-pressure gas through catalytic decomposition or combustion of fuel. A chemical propulsion thruster includes a fuel valve that controls the supply of fuel, an injector that injects and mixes the fuel, and a combustor that accelerates the combustion of the injected fuel and the generated combustion gas. Hydrogen or hydrazine-based fuel may be used as the fuel. Dinitrogen tetroxide may be used as the oxidizer. By using boil-off gas that has passed through the skirt portion 62 as fuel for the thruster 20, the boil-off gas is appropriately heated in the skirt portion 62, allowing for appropriate thrust generation. Even when the boil-off gas is directly released from the thruster 20, a certain degree of thrust can be obtained depending on the mass of the hydrogen and the release speed from the thruster 20 due to its pressure. In other words, even if the oxidizer in the thruster 20 is lost, the boil-off gas can still be released directly from the thruster 20 to generate thrust.

[0039] The thruster 20 may be a DC (Direct Current) arcjet. The DC arcjet includes a DC cathode, a DC anode, a nozzle, and an insulator. The fuel gas in the DC arcjet, which may be hydrogen, is partially ionized by a high-voltage pulse discharge between the DC cathode and the DC anode. The fuel gas is then heated by Joule heating due to the DC arc discharge, and the ionization progresses further, resulting in a high-enthalpy gas. The generated high-enthalpy gas expands through the nozzle, and thrust is generated by this accelerated gas. Even when the thruster 20 is a DC arcjet, if the boil-off gas is released as is, a certain degree of thrust can be obtained depending on the mass of the hydrogen and the release speed from the thruster 20 due to its pressure.

[0040] Vent retention is a method of retaining fuel at the bottom of the fuel tank 61 by controlling the attitude of the rocket body 2 using the thrust of the retention thrusters 20. Depending on the attitude of the rocket body 2, gravity may prevent the fuel from being retained at the bottom of the fuel tank 61, so it is necessary to use the thrust of the retention thrusters 20 to stabilize the fuel at the bottom of the fuel tank 61. In other words, by ejecting the retention thrusters 20 rearward of the axis of the rocket body 2, the liquid fuel in the fuel tank 61 is stabilized at the bottom of the tank.

[0041] According to the fuel tank system 6 described above, the boil-off gas after heat exchange can be caused to flow through the cooling pipe 63 wound around the inner surface of the skirt portion 62, thereby cooling the fuel tank 61. Furthermore, the boil-off gas that has passed through the skirt portion 62 can be used as vent retention or fuel for the thruster 20. Note that the boil-off gas flowing through the cooling pipe 63 in the skirt portion 62 is heated to an appropriate temperature by heat exchange between the skirt portion 62 and the fuel tank 61 connected to the skirt portion 62, and therefore can be appropriately used as fuel for the thruster 20.

[0042] (Regarding the structure of the top of the fuel tank) Next, the structure of the upper end of the fuel tank 61 according to the present disclosure will be described with reference to FIG. 4. FIG. 4 is a schematic diagram showing the structure of the upper end of the fuel tank according to the present disclosure. As shown in FIG. 4, a payload support section 8 is connected to one of the ends of the fuel tank 61, and a payload separation section 9 is provided on the payload support section 8. A solar cell panel 67 is provided on the outer circumferential surface of the payload support section 8. A skirt section 62 is also connected to one end of the fuel tank 61. This allows the solar cell panel 67 to be appropriately exposed to sunlight while the rocket body 2 is traveling in space. Therefore, the solar cell panel 67 can appropriately generate electricity, and the electricity can be used to appropriately drive the refrigerator 65.

[0043] Next, the structure of the skirt portion 62 of the fuel tank 61 will be described. The skirt portion 62 is formed in a cylindrical shape and has a cooling pipe 63 on its inner surface. The shape of the cooling pipe 63 provided in the skirt portion 62 may be any shape as long as it can realize heat exchange between the boil-off gas flowing through the cooling pipe 63 and the skirt portion 62, and ultimately heat exchange with the fuel tank 61 via the skirt portion 62, and may be, for example, a shape described below.

[0044] A first example of the shape of the cooling pipes 63 provided in the skirt portion 62 will be described with reference to FIG. 5. FIG. 5 is a schematic diagram showing a first example of the structure of the skirt portion of a fuel tank according to the present disclosure. As shown in FIG. 5, the skirt portion 62 of the fuel tank 61 has cooling pipes 63 with a cylindrical cross section wound around its inner surface. As shown in FIG. 5, three cooling pipes 63 with a cylindrical cross section may be wound around the skirt portion 62 of the fuel tank 61, or more cooling pipes 63 may be wound around the skirt portion 62 of the fuel tank 61. Furthermore, the skirt portion 62 and the cooling pipes 63 may be connected by brazing using, for example, an Ag-Pd brazing filler metal.

[0045] A second example of the shape of the cooling pipe 63 provided in the skirt portion 62 will be described with reference to FIG. 6. FIG. 6 is a schematic diagram showing a second example of the structure of the skirt portion of the fuel tank according to the present disclosure. As shown in FIG. 6, the cooling pipe 63 may be a pipe having a rectangular cross section with a hollow interior. As shown in FIG. 6, the cooling pipe 63 may be arranged so that the side of the major axis of the rectangle abuts against the inner surface of the skirt portion 62 and is wrapped around the inner surface of the skirt portion 62. This increases the contact area between the cooling pipe 63 and the inner surface of the skirt portion 62, thereby facilitating heat exchange between the boil-off gas and the inner surface of the skirt portion 62.

[0046] The structure of the fuel tank 61 is not limited to the example described above, and may be, for example, a structure in which the cooling piping 63 is wrapped around the entire outer peripheral surface of the cylinder portion 611 of the fuel tank 61. Alternatively, a structure in which the cooling piping 63 is wrapped around the outer peripheral surface of the dome portion 612 on the side where the fuel is stored of the fuel tank 61 may be used. This allows the fuel tank 61, and ultimately the fuel filled in the fuel tank 61, to be appropriately cooled by boil-off gas.

[0047] Furthermore, without being limited to the embodiment in which the cooling pipe 63 is provided on the skirt portion 62 of the fuel tank 61, if the fuel tank 61 is an inner tank, an outer tank may be provided that directly covers the outer surface of the inner tank, and boil-off gas may be circulated inside the outer tank to form a jacket tank type heat exchanger that performs heat exchange between the inner tank and the fuel tank 61.

[0048] According to the structure of the fuel tank 61 described above, the fuel tank 61 can be appropriately cooled by boil-off gas generated when the fuel inside the fuel tank 61 evaporates. Therefore, heat input from the outside to the fuel tank 61 can be appropriately prevented, and the amount of evaporation of the fuel filled in the fuel tank 61 can be reduced.

[0049] (About insulation) Next, the position of the heat insulating material provided in the fuel tank 61 will be described with reference to FIG. 7. FIG. 7 is a diagram showing the structure of the fuel tank according to the present disclosure. As shown in FIG. 7, the fuel tank 61 includes a cylinder portion 611 and a dome portion 612. A first heat insulating material 100 is provided on the outer peripheral surface of the cylinder portion 611, and a second heat insulating material 200 is provided on the first heat insulating material 100. Furthermore, the first heat insulating material 100 is provided on the outer peripheral surface of the dome portion 612, and a third heat insulating material is provided on the first heat insulating material 100.

[0050] The following describes the heat insulating materials (first heat insulating material 100, second heat insulating material 200, third heat insulating material) applied to the fuel tank 61. The configuration of these materials will be explained below in order.

[0051] The first insulating material 100 is an insulating material provided on the outer peripheral surfaces of the cylinder portion 611 and the dome portion 612 of the fuel tank 61. The first insulating material 100 may be, for example, polyisocyanurate foam (PIF). Polyisocyanurate foam is a type of foamed plastic that is made heat-resistant by modifying rigid urethane foam. The thermal conductivity of polyisocyanurate foam is 0.020 W / mK, which is extremely low, and therefore it is possible to appropriately prevent heat input to the fuel tank 61 from the outside.

[0052] The first insulating material 100 may also be an ultrafine particle aerogel insulating material. An ultrafine particle aerogel insulating material is made of ultrafine silica particles in a floating structure that prevents them from contacting each other, and the minute spaces formed by the ultrafine silica particles prevent contact between molecules, thereby preventing heat transfer. Because the ultrafine particle aerogel insulating material also has a thermal conductivity similar to that of polyisocyanurate foam, it can appropriately prevent heat input from the outside to the fuel tank 61.

[0053] As a result, when the fuel is liquid hydrogen, since the boiling point of hydrogen is -253°C, by covering the outer surface of the fuel tank 61 with the first insulating material 100 and preventing the inflow of heat from the surroundings, the amount of evaporation of liquid hydrogen can be reduced.

[0054] The second insulating material 200 is an insulating material provided on the first insulating material 100 provided on the outer peripheral surface of the cylinder portion 611 of the fuel tank 61. The second insulating material 200 may be a load-bearing multi-layer insulating material (LB (Load-Bearing) NICS (Non-Inter-Layer Contact Spacer) MLI (Multi-Layer Insulation)).

[0055] The load-bearing multilayer insulation material (LB NICS MLI) is a multilayer insulation material (MLI) that is made up of a film 210 that prevents radiant heat transfer by depositing aluminum on polyimide, a highly heat-resistant engineering plastic, and a spacer 220 that is made of a highly heat-resistant material such as engineering plastic.The multilayer insulation material (MLI) is covered with a vacuum film and evacuated using a vacuum pump 300, allowing it to maintain high insulation performance even in an atmospheric environment.

[0056] Here, the structure of the load-bearing multilayer insulation will be explained using Figure 8. Figure 8 is a schematic diagram showing the structure of the second insulation according to the present disclosure. As shown in Figure 8, the load-bearing multilayer insulation has a structure in which a multilayer insulation (MLI) is covered with a flat plate formed using fiber reinforced plastic 230 (CFRP (Carbon Fiber Reinforced Plastics)). The inside of the load-bearing multilayer insulation is then evacuated using a vacuum pump 300. Therefore, high insulation performance can be maintained even in areas exposed to the atmosphere. By providing the second insulation 200 described above on the first insulation 100, heat input into the fuel tank 61 due to solar radiation can be appropriately prevented.

[0057] The third insulating material is an insulating material provided on top of the first insulating material 100 provided on the outer peripheral surface of the dome portion 612 of the fuel tank 61. The third insulating material may be, for example, an interlayer non-contact type multilayer insulating material (NICS MLI). The interlayer non-contact type multilayer insulating material includes a film 210 that prevents radiant heat transfer by vapor-depositing aluminum on polyimide, a highly heat-resistant engineering plastic, and a spacer 220 formed of a highly heat-resistant material such as an engineering plastic. The interlayer non-contact type multilayer insulating material is formed by alternately stacking approximately 10 to 20 films 210 and spacers 220.

[0058] Here, the structure of the non-contact interlayer multilayer insulation (NICS MLI) will be described with reference to Figure 9. Figure 9 is a schematic diagram showing the structure of a third insulation material according to the present disclosure. As shown in Figure 9, the non-contact interlayer multilayer insulation material comprises films 210 and spacers 220. As shown in Figure 9, the non-contact interlayer multilayer insulation material has a structure in which spacers 220 are arranged between films 210, and the spacers 220 are alternately stacked between the films 210. This eliminates indeterminate interlayer contact of the films 210, and can significantly improve the insulation performance compared to conventional MLI in which the films 210 contact each other between the layers.

[0059] As a result, by providing a load-bearing multilayer insulation material with a vacuum drawn between films 210 in cylinder portion 611 exposed to the atmosphere and providing an interlayer non-contact multilayer insulation material in dome portion 612 which is not exposed to the atmosphere, cylinder portion 611 exposed to the atmosphere can be properly insulated from fuel tank 61 even in space, and dome portion 612 which is not exposed to the atmosphere can be properly insulated by the interlayer non-contact multilayer insulation material. Therefore, the inflow of heat into fuel tank 61 can be prevented by the insulation material, and the boil-off gas of fuel in fuel tank 61 can be properly reduced.

[0060] (Oxidizer Tank System) Next, the configuration of the oxidant tank system 5 will be described with reference to Fig. 10. Fig. 10 is a schematic diagram showing the configuration of the oxidant tank system according to the present disclosure. As shown in Fig. 10, the oxidant tank system 5 according to the present disclosure includes, as main components, an oxidant tank 51 and a solar panel 52. The oxidant tank system 5 further includes a first insulating material 100, a second insulating material 200, and a third insulating material.

[0061] The oxidizer tank 51 is a storage container that stores an oxidizer. The oxidizer tank 51 may be made of an aluminum alloy. The oxidizer tank 51 can be manufactured in the same manner as the fuel tank 61 described above. As shown in FIG. 9 , the oxidizer tank 51 also includes a cylindrical cylinder portion 511 and a semicircular dome portion 512. That is, the oxidizer tank 51 can be manufactured by welding the cylinder portion 511 and the dome portion 512 together in the circumferential direction.

[0062] The oxidizer tank 51 includes a first insulating material 100 applied to the outer peripheral surface of the cylinder portion 511 of the oxidizer tank 51, and a third insulating material provided on the outer peripheral surface of the first insulating material 100. Note that the first insulating material 100 and the third insulating material may be the same as those described in the description of the fuel tank system 6 above, and therefore detailed description thereof will be omitted.

[0063] The oxidizer tank 51 also includes a first insulating material 100 on the outer peripheral surface of the dome portion 512 of the oxidizer tank 51, and a third insulating material provided on the outer peripheral surface of the first insulating material 100. The first insulating material 100 and the third insulating material may be the same as those described in the description of the fuel tank system 6 above, and therefore detailed description thereof will be omitted.

[0064] The solar cell panel 52 is a solar cell that generates electricity using sunlight. As shown in FIG. 10, the solar cell panel 52 is arranged between the fuel tank 61 and the oxidizer tank 51. The solar cell panel 52 may be the same as the solar cell panel 67 provided in the fuel tank system 6. The solar cell panel 52 includes solar cells that convert sunlight into electricity and a back electrode that serves as a substrate for the solar cell, and a third heat insulating material is provided on the side of the back electrode on which the solar cell is not provided. This allows the rocket body 2 to generate electricity using sunlight while traveling in space. In addition, heat generated by the power generation of the solar cell panel 52 can be prevented from being transmitted to the oxidizer tank 50.

[0065] The oxidizer tank system 5 may include a skirt portion, a cooling pipe, a heat exchange unit, and a refrigerator, similar to the fuel tank system 6. This allows the oxidizer tank 51 to be cooled by boil-off gas of the oxidizer evaporated from the oxidizer tank.

[0066] According to the oxidant tank system 5 described above, it is possible to appropriately insulate the oxidant filled in the oxidant tank 51 by preventing heat input from the outside to the oxidant. Therefore, it is possible to appropriately reduce evaporation of the oxidant from the oxidant tank.

[0067] (Composition and Effects) The rocket system 1 according to the first aspect of the present disclosure comprises a fuel tank 61 filled with fuel, and a cooling pipe 63 connected to the fuel tank 61 and through which boil-off gas of the fuel flows, and the boil-off gas flowing through the cooling pipe 63 cools the fuel tank 61.

[0068] According to this configuration, the boil-off gas generated when the fuel in the fuel tank 61 evaporates can be used to cool the fuel tank 61. This reduces the boil-off gas generated by the rise in fuel temperature, thereby providing a rocket system 1 that can effectively utilize the evaporated gas from the fuel.

[0069] The rocket system 1 according to the second aspect of the present disclosure is the rocket system 1 according to the first aspect, in which the fuel tank 61 comprises a cylindrical cylinder portion 611 and a hemispherical dome portion 612 connected to both ends of the cylinder portion 611, and the cooling piping 63 is wrapped around the inner surface of a cylindrical skirt portion 62 connected to one end of the cylinder portion 611 of the fuel tank 61.

[0070] According to this configuration, the fuel tank 61 can be appropriately cooled by circulating boil-off gas through the cooling piping 63 wrapped around the skirt portion 62 of the fuel tank 61. Therefore, it is possible to provide a rocket system 1 that can effectively utilize the evaporated gas of the fuel.

[0071] A rocket system 1 according to a third aspect of the present disclosure is a rocket system 1 according to the first or second aspect, and includes a thruster 20 that controls the attitude of the rocket body by thrust, a cooling pipe 63 connected to the thruster 20, and boil-off gas is guided to the thruster 20 via the cooling pipe 63.

[0072] According to this configuration, the boil-off gas after cooling the fuel tank 61 can be guided to the thruster 20. Therefore, the boil-off gas can be used as fuel for the thruster 20. Furthermore, even if the oxidizer in the thruster 20 is lost, the boil-off gas can be released directly from the thruster 20 to obtain thrust. Therefore, it is possible to provide a rocket system 1 that can effectively utilize the evaporated gas of the fuel.

[0073] The rocket system 1 of the fourth aspect of the present disclosure is a rocket system 1 of any of the first to third aspects, and further comprises a first insulating material 100 applied to the outer peripheral surface of the cylinder portion 611 of the fuel tank 61, and a second insulating material 200 provided on the outer peripheral surface of the first insulating material 100.

[0074] According to this configuration, by covering the fuel tank 61 with two types of heat insulating material, it is possible to prevent heat from entering from the outside. This makes it possible to appropriately reduce the amount of fuel evaporation in the fuel tank 61. Therefore, it is possible to provide a rocket system 1 that can effectively utilize the evaporated fuel gas while reducing the amount of fuel evaporation.

[0075] The rocket system 1 according to the fifth aspect of the present disclosure is a rocket system 1 according to any one of the first to fourth aspects, and further comprises a first insulating material 100 applied to the outer peripheral surface of the dome portion 612 of the fuel tank 61, and a third insulating material provided on the outer peripheral surface of the first insulating material 100.

[0076] According to this configuration, by covering the dome portion 612 of the fuel tank 61 with two types of heat insulating material, it is possible to prevent heat from entering from the outside. As a result, it is possible to appropriately reduce the amount of fuel evaporation from the fuel tank 61. Therefore, it is possible to provide a rocket system 1 that can effectively utilize the evaporated fuel gas while reducing the amount of fuel evaporation.

[0077] A rocket system 1 according to a sixth aspect of the present disclosure is a rocket system 1 according to any one of the first to fifth aspects, and includes a refrigerator 65 that cools the fuel filled in the fuel tank 61, a cooling pipe 63, and a heat exchange unit 64 that is connected to a refrigerant pipe 66 through which the refrigerant of the refrigerator 65 flows, and exchanges heat between the boil-off gas flowing through the cooling pipe 63 and the refrigerant flowing through the refrigerant pipe 66, and the boil-off gas flowing through the cooling pipe 63 cools the refrigerant in the heat exchange unit 64, and then cools the fuel tank 61.

[0078] With this configuration, boil-off gas generated when the fuel in the fuel tank 61 evaporates can be used to recover the waste heat of the refrigerant in the refrigerator 65, and then used to cool the fuel tank 61. This reduces the boil-off gas generated by the rise in fuel temperature, and therefore provides a rocket system 1 that can effectively utilize the evaporated gas from the fuel.

[0079] The rocket system 1 according to the seventh aspect of the present disclosure is the rocket system 1 according to the sixth aspect, further comprising a solar cell panel 67 that is provided on the dome portion 612 of the fuel tank 61 and generates electricity using sunlight, and the refrigerator 65 comprises a compressor that compresses the refrigerant, and the compressor is driven by the electricity generated by the solar cell panel 67.

[0080] With this configuration, the compressor can be driven by the power generated by the solar panel 67. This allows the refrigerator 65 to appropriately cool the fuel in the fuel tank 61. This makes it possible to provide a rocket system 1 that can effectively utilize the evaporated fuel gas while reducing the amount of fuel evaporation.

[0081] The rocket system 1 according to the eighth aspect of the present disclosure is the rocket system 1 according to the seventh aspect, in which the solar cell panel 67 comprises a solar cell that converts sunlight into electricity and a back electrode that serves as the substrate for the solar cell, and a third insulating material is provided on the side of the back electrode on which the solar cell is not provided.

[0082] With this configuration, the third insulating material can prevent heat generated by power generation by the solar cell from being transmitted to the fuel tank 61. Therefore, it is possible to provide a rocket system 1 that can effectively utilize the evaporated fuel gas while reducing the amount of fuel evaporation.

[0083] A rocket system 1 according to a ninth aspect of the present disclosure is a rocket system 1 according to any one of the first to eighth aspects, and the rocket system 1 according to the present disclosure comprises an oxidizer tank 50 filled with an oxidizer for oxidizing fuel, the oxidizer tank 50 comprising a cylindrical cylinder portion 511 and a hemispherical dome portion 512 connected to both ends of the cylinder portion 511, a first insulating material 100 applied to the outer surface of the cylinder portion 511 of the oxidizer tank 50, and a third insulating material provided on the outer surface of the first insulating material 100.

[0084] According to this configuration, by covering the cylinder portion 511 of the oxidant tank 50 with two types of insulating materials, it is possible to prevent heat input from the outside. Therefore, it is possible to appropriately reduce the amount of evaporation of the oxidant in the oxidant tank 50.

[0085] A rocket system 1 according to a tenth aspect of the present disclosure is a rocket system 1 according to any one of the first to ninth aspects, and includes an oxidizer tank 50 filled with an oxidizer for oxidizing fuel and having a cylindrical cylinder portion 511 and a hemispherical dome portion 512 connected to both ends of the cylinder portion 511, a first insulating material 100 applied to the outer surface of the dome portion 512 of the oxidizer tank 50, and a third insulating material provided on the outer surface of the first insulating material 100.

[0086] According to this configuration, by covering the dome portion 512 of the oxidant tank 50 with two types of insulating materials, it is possible to prevent heat input from the outside. Therefore, the amount of evaporation of the oxidant in the oxidant tank 50 can be appropriately reduced.

[0087] A fuel tank system 6 according to an eleventh aspect of the present disclosure includes a fuel tank 61 filled with fuel and a cooling pipe 63 through which boil-off gas of the fuel in the fuel tank 61 flows, and the boil-off gas flowing through the cooling pipe 63 cools the fuel tank 61.

[0088] According to this configuration, the fuel tank 61 can be appropriately cooled by circulating the boil-off gas through the cooling pipe 63. Therefore, it is possible to provide a fuel tank system 6 that can effectively utilize the evaporated gas of the fuel.

[0089] Although the embodiments of the present invention have been described above, the embodiments are not limited to the contents of these embodiments. Furthermore, the above-described components include those that can be easily imagined by a person skilled in the art, those that are substantially the same, and those that are within the scope of what is called equivalents. Furthermore, the above-described components can be combined as appropriate. Furthermore, various omissions, substitutions, or modifications of the components can be made without departing from the spirit of the above-described embodiments. [Explanation of symbols]

[0090] 1. Rocket System 11 Fairing 12 Second stage rocket (rocket body) 13 First Stage Rocket 14 Solid Rocket Boosters 2. Rocket body 3. Rocket Engine 4 frames 5. Oxidizer Tank System 51 Oxidizer Tank 511 Cylinder section 512 Dome 6 Fuel Tank System 61 Fuel Tank 611 Cylinder section 612 Dome 62 Skirt Club 63 Cooling piping 64 Heat Exchange Unit 65 Refrigeration Machine 66 Refrigerant piping 67 Solar Panels 7. Air Storage Tank 8 Load support section 9. Load separation section 10 Payload 20 thrusters 100 First insulation material 200 Secondary insulation 210 Film 220 spacer 230 Fiber-reinforced plastics 300 Vacuum Pump

Claims

1. a fuel tank filled with fuel; a cooling pipe connected to the fuel tank and through which boil-off gas of the fuel flows; Equipped with The boil-off gas flowing through the cooling pipe cools the fuel tank. Rocket system.

2. the fuel tank includes a cylindrical cylinder portion and a semispherical dome portion connected to both ends of the cylinder portion, the cooling pipe is wound around an inner surface of a cylindrical skirt portion connected to one end of the cylinder portion of the fuel tank; The rocket system of claim 1 .

3. a thruster for controlling the attitude of the rocket body by thrust, The cooling pipe is connected to the thruster, and the boil-off gas is guided to the thruster via the cooling pipe.

3. A rocket system according to claim 1 or 2.

4. a first insulating material applied to an outer peripheral surface of a cylinder portion of the fuel tank; Further provided with a second insulating material provided on the outer peripheral surface of the first insulating material, 3. The rocket system of claim 2.

5. a first insulating material applied to an outer peripheral surface of a dome portion of the fuel tank; Further comprising a third insulating material provided on the outer peripheral surface of the first insulating material, 5. A rocket system according to claim 2 or 4.

6. a refrigerator that cools the fuel filled in the fuel tank; a heat exchange unit connected to the cooling pipe and a refrigerant pipe through which a refrigerant of the refrigerator flows, and performing heat exchange between the boil-off gas flowing through the cooling pipe and the refrigerant flowing through the refrigerant pipe; and The boil-off gas flowing through the cooling pipe cools the refrigerant in the heat exchange unit and then cools the fuel tank.

3. A rocket system according to claim 1 or 2.

7. The fuel tank further includes a solar cell panel that is provided on a dome portion of the fuel tank and generates electricity using sunlight, The refrigerator includes a compressor that compresses a refrigerant, The compressor is driven by the power generated by the solar panel.

7. The rocket system of claim 6.

8. The solar cell panel includes a solar cell that converts sunlight into electricity and a back electrode that serves as a substrate for the solar cell, a third heat insulating material is provided on the surface of the back electrode on which the solar cell is not provided; 8. The rocket system of claim 7.

9. an oxidizer tank filled with an oxidizer for oxidizing the fuel, the oxidizer tank including a cylindrical cylinder portion and semispherical dome portions connected to both ends of the cylinder portion; a first insulating material applied to an outer peripheral surface of the cylinder portion of the oxidizer tank; A third insulating material provided on the outer peripheral surface of the first insulating material, 3. A rocket system according to claim 1 or 2.

10. an oxidizer tank filled with an oxidizer for oxidizing the fuel, the oxidizer tank including a cylindrical cylinder portion and semispherical dome portions connected to both ends of the cylinder portion; a first insulating material applied to an outer peripheral surface of the dome portion of the oxidizer tank; A third insulating material provided on the outer peripheral surface of the first insulating material, 3. A rocket system according to claim 1 or 2.

11. a fuel tank filled with fuel; a cooling pipe through which boil-off gas of the fuel in the fuel tank flows; Equipped with The boil-off gas flowing through the cooling pipe cools the fuel tank. Fuel tank system.

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