Propellant plant system

Abstract

Provided is a propellant plant system that enables efficient production, storage and replenishment of propellant in outer space. The propellant plant system is provided with: a water intake device that collects a water resource and stores the water resource as liquid water; an electrolysis device that electrolyzes the water to generate hydrogen gas and oxygen gas; a liquefaction device that liquefies a target gas that is at least one of the hydrogen gas and the oxygen gas; a storage tank that stores a target liquid that is the liquefied target gas; a first refrigerator that cools the storage tank; a first radiator that exchanges heat with the first refrigerator; and a power generation device that can be installed in a sunlit region within a lunar polar region and generates power by solar irradiation to supply power to at least one of the electrolysis device, the liquefaction device, and the first refrigerator. When the first radiator is installed in a shaded region within the lunar polar region, the first radiator dissipates heat into the shaded region to cool the first refrigerator using the ambient temperature in the shaded region.

Description

Propellant Plant System

[0001] The present disclosure relates to propellant plant systems.

[0002] In recent years, there has been discussion about installing facilities in outer space for the production, storage, and replenishment of propellants such as liquid hydrogen and liquid oxygen, which serve as fuel for interorbital transfer vehicles traveling between the Earth and a space station or a geostationary satellite, etc. For example, Patent Document 1 discloses a propellant production and storage device that produces liquid hydrogen and liquid oxygen in outer space from water stored in a water tank.

[0003] Japanese Patent Application Publication No. 3-186500

[0004] However, the device of Patent Document 1 requires transporting water into space, and a large amount of energy is required to cool the liquefied gas storage tank and liquefaction machine, leaving cost issues unresolved.

[0005] The present disclosure is intended to solve the above-mentioned problems, and aims to provide a propellant plant system that enables efficient production, storage, and replenishment of propellant in space.

[0006] In order to achieve the above-mentioned object, a propellant plant system according to one aspect of the present disclosure includes a water intake device that recovers a water resource and stores it as liquid water, an electrolysis device that electrolyzes the water to produce hydrogen gas and oxygen gas, a liquefaction device that liquefies a target gas that is at least one of the hydrogen gas and the oxygen gas, a storage tank that stores the target liquid that is the liquefied target gas, a first refrigerator that cools the storage tank, a first radiator that exchanges heat with the first refrigerator, and a power generation device that can be installed in a sunny region of a lunar polar region and generates electricity by irradiation with sunlight to supply power to at least one of the electrolysis device, the liquefaction device, and the first refrigerator, and when installed in a shaded region of the lunar polar region, the first radiator rejects heat to the shaded region and cools the first refrigerator at the ambient temperature in the shaded region.

[0007] According to the present disclosure, propellant can be efficiently manufactured, stored, and replenished in space.

[0008] Fig. 1 is a schematic diagram showing the general configuration of a propellant plant system according to this embodiment. Fig. 2 is a schematic diagram showing the general configuration of a hydrogen liquefaction device shown in Fig. 1. Fig. 3 is a schematic diagram showing the general configuration of an oxygen liquefaction device shown in Fig. 1. Fig. 4 is a schematic diagram showing an example of the arrangement of radiators shown in Fig. 1. Fig. 5 is a schematic diagram showing another example of the arrangement of radiators shown in Fig. 1.

[0009] (Embodiments) Hereinafter, embodiments according to the present disclosure will be described in detail with reference to the drawings. Note that the present invention is not limited to these embodiments. Furthermore, the components in the following embodiments include those that are easily replaceable by those skilled in the art, those that are substantially identical, or those that are equivalent. Furthermore, the components in the following embodiments can be variously omitted, replaced, or modified without departing from the gist of the present disclosure. In the following embodiments, components necessary for illustrating the embodiments will be described, and other components will be omitted. The same components will be assigned the same reference numerals, and different components will be assigned different reference numerals.

[0010] FIG. 1 is a schematic diagram showing the overall configuration of a propellant plant system according to this embodiment. The propellant plant system 1 shown in FIG. 1 is a system used on the lunar surface. When installed in the lunar polar regions, the propellant plant system 1 is a facility that produces liquid hydrogen and liquid oxygen, which serve as propellants, by utilizing the resources and environment of the moon. The lunar polar regions refer to the region on the lunar surface that is between 60 degrees and 90 degrees latitude, including the poles, preferably between 85 degrees and 90 degrees latitude, and more preferably between 89 degrees and 90 degrees latitude. The following description will be given taking as an example a case in which the propellant plant system 1 is deployed on the lunar surface.

[0011] Although the propellant plant system 1 is described as being installed in the lunar polar regions, the present disclosure is not limited thereto and can be applied to other planets or satellites as long as the environment is similar. A similar environment includes having a water resource, having a sunny area and a shaded area, and an environmental temperature in the shaded area of ​​4 K or higher and 200 K or lower, preferably 20 K or higher and 100 K or lower. It is also preferable that the sunny area and the shaded area do not frequently switch positions.

[0012] The propellant plant system 1 shown in FIG. 1 includes a power generation device 10 , a water intake device 20 , an electrolysis device 30 , a liquefaction device 40 , a storage tank 80 , and a control device 100 .

[0013] The power generation device 10 generates electricity using renewable energy. The power generation device 10 of this embodiment is installed in the lunar polar regions and generates electricity using sunlight irradiated in the sunny areas of the lunar polar regions. The moon has a thin atmosphere, allowing sunlight to reach it directly, making it possible to generate electricity efficiently. The power generation device 10 includes a solar panel 12 and a power storage device 14.

[0014] The solar panel 12 has multiple solar cell modules that generate electricity by receiving sunlight. The solar panel 12 is installed in a sunny area. Because sunlight shines from a substantially horizontal direction in the lunar polar regions, the light-receiving surface of the solar panel 12 is preferably inclined from the horizontal at an angle of 0 degrees to 90 degrees, and preferably 0 degrees to 80 degrees. In this case, the solar panel 12 is preferably capable of changing its position so that the light-receiving surface faces the sun, and is preferably rotatable, for example, around a vertical axis.

[0015] The power storage device 14 is charged with power generated by the solar panel 12. The power generated by the solar panel 12 may be converted by a power conditioner (not shown) into power suitable for storage in the power storage device 14. The power storage device 14 supplies power for operating each component of the propellant plant system 1. Destinations to which the power stored in the power storage device 14 is supplied are exemplified by the targets indicated by the broken line arrows in Figures 1, 2, and 3. The power storage device 14 includes a secondary battery, for example, a lithium ion battery (LiB).

[0016] The water intake device 20 collects water resources from the site where the propellant plant system 1 is installed and stores them as liquid water. The water intake device 20 of this embodiment, which is installed in the lunar polar regions, collects water resources that are thought to exist in shaded areas of the lunar polar regions, particularly in permanent shade such as inside craters in the lunar polar regions. The water resources are contained underground or on the earth's surface, and are attached to or contained within sand, gravel, rocks, etc. as ice or frost. The water intake device 20 includes, for example, an ice collection device 22, a separation and purification device 24, and a water storage tank 26.

[0017] The ice collecting device 22 collects ice and frost together with sand, gravel, and rocks from underground or on the ground. The ice collecting device 22 may be realized, for example, by a stationary excavator, an elevator, a transport vehicle, or a transfer conveyor, or may be realized by a mobile robot having a drill or a robotic arm.

[0018] The separation and purification device 24 separates pure water from the sand, gravel, rocks, ice, and frost collected by the ice collection device 22. The separation and purification device 24 includes, for example, a crusher for crushing rocks, a heater for melting ice and frost, a filtration device, a distiller for removing impurities, etc. Solar radiation in a sunny area may be used as a heating means for the heater and distiller.

[0019] The water storage tank 26 stores the pure water separated by the separation and purification device 24. The pure water stored in the water storage tank 26 is in liquid form. The pure water stored in the water storage tank 26 is sent to the electrolysis device 30 via a water supply line 28.

[0020] The electrolysis device 30 electrolyzes the pure water supplied from the water storage tank 26 to produce hydrogen gas and oxygen gas. The electrolysis device 30 of this embodiment is a solid polymer water electrolysis device that uses pure water and is a high-pressure electrolysis device that electrolyzes high-pressure water to produce high-pressure hydrogen gas and oxygen gas. The electrolysis device 30 includes a high-pressure water supply pump 32, an electrolytic cell 34, and a gas tank 36.

[0021] The high-pressure water supply pump 32 pressurizes the pure water supplied from the water storage tank 26 and delivers the high-pressure water. The high-pressure water is pure water at room temperature that has been pressurized to a pressure of 0.1 MPa or more and 100 MPa or less, preferably 0.1 MPa or more and 90 MPa or less. Room temperature refers to a temperature of 5°C or more and 80°C or less, preferably 20°C or more and 50°C or less. The high-pressure water supply pump 32 delivers the high-pressure water at room temperature to the anode side of the electrolytic cell 34.

[0022] The electrolytic cell 34 contains an anode, a cathode, an electrolyte membrane separating the anode side and the cathode side, and a catalyst. When a predetermined voltage is applied between the electrodes, the electrolytic cell 34 electrolyzes pure water supplied to the anode side, producing hydrogen gas on the cathode side and oxygen gas on the anode side. Power supplied to the electrolytic cell 34 is supplied from the power storage device 14. In the electrolytic cell 34, the reaction represented by reaction formula (1) occurs on the anode side, and the reaction represented by reaction formula (2) occurs on the cathode side, resulting in an overall reaction represented by reaction formula (3).

[0023] 2H ２ O → O ２ +4H ＋ +4e － ...(1)

[0024] 4H ＋ +4e － →2H ２ ...(2)

[0025] 2H ２ O → O ２ +2H ２ ...(3)

[0026] The gas generated by electrolyzing water in the electrolytic cell 34 is defined as the target gas. In this case, the target gas generated in the electrolytic cell 34 is sent to the gas tank 36 and stored therein. The target gas here is at least one of hydrogen gas and oxygen gas. More specifically, in this embodiment, the gas tank 36 is provided with a hydrogen gas tank 36h that stores hydrogen gas and an oxygen gas tank 36o that stores oxygen gas. However, the gas tank 36 is not limited to having both the hydrogen gas tank 36h and the oxygen gas tank 36o, and may include at least one of the hydrogen gas tank 36h and the oxygen gas tank 36o.

[0027] In this embodiment, hydrogen gas generated on the cathode side of the electrolytic cell 34 is delivered to the hydrogen gas tank 36h. Oxygen gas generated on the anode side of the electrolytic cell 34 is delivered to the oxygen gas tank 36o. Note that, for example, back pressure valves (not shown) are provided between the electrolytic cell 34 and the hydrogen gas tank 36h, and between the electrolytic cell 34 and the oxygen gas tank 36o.

[0028] The hydrogen gas tank 36h stores the hydrogen gas produced in the electrolytic cell 34. The hydrogen gas stored in the hydrogen gas tank 36h is at room temperature and is a high-pressure gas with a pressure of 1 MPa or more and 100 MPa or less. The hydrogen gas stored in the hydrogen gas tank 36h is sent to a hydrogen liquefaction device 40h via a high-pressure hydrogen gas line 38h.

[0029] The oxygen gas tank 36o stores the oxygen gas produced in the electrolytic cell 34. The oxygen gas stored in the oxygen gas tank 36o is at room temperature and is a high-pressure gas with a pressure of 1 MPa or more and 100 MPa or less. The oxygen gas stored in the oxygen gas tank 36o is sent to the oxygen liquefaction device 40o via a high-pressure oxygen gas line 38o.

[0030] The liquefaction device 40 liquefies the target gas to produce a target liquid, which is the liquefied target gas. In this embodiment, the liquefaction device 40 includes a hydrogen liquefaction device 40h that liquefies hydrogen gas to produce liquid hydrogen, and an oxygen liquefaction device 40o that liquefies oxygen gas to produce oxygen-hydrogen. However, the gas tank 36 is not limited to having both the hydrogen liquefaction device 40h and the oxygen liquefaction device 40o, and may include at least one of the hydrogen liquefaction device 40h and the oxygen liquefaction device 40o.

[0031] Figure 2 is a schematic diagram showing the overall configuration of the hydrogen liquefaction apparatus shown in Figure 1. Hereinafter, the configuration of a hydrogen liquefaction apparatus 40h will be described as an example of the liquefaction apparatus 40. The hydrogen liquefaction apparatus 40h shown in Figures 1 and 2 liquefies room-temperature, high-pressure hydrogen gas supplied from a hydrogen gas tank 36h to produce liquid hydrogen. The hydrogen liquefaction apparatus 40h includes a first heat exchanger 50h, an expansion turbine 60, and a second heat exchanger 70h.

[0032] The first heat exchanger 50h cools the room-temperature, high-pressure hydrogen gas supplied from the high-pressure hydrogen gas line 38h. The first heat exchanger 50h cools the hydrogen gas using the ambient temperature in the shaded region of the lunar polar region. In this embodiment, the first heat exchanger 50h exchanges heat between the hydrogen gas in the high-pressure hydrogen gas line 38h and the refrigerant circulating through the refrigerant line 52. The hydrogen gas is cooled by the refrigerant cooled by the ambient temperature in the shaded region of the lunar polar region, and is cooled to a temperature of 4 K or higher and 200 K or lower, preferably 20 K or higher and 100 K or lower. In this embodiment, the temperature is, for example, 140 K. The refrigerant is heated by the hydrogen gas.

[0033] A conversion unit 54h containing a catalyst for promoting the conversion of ortho-hydrogen to para-hydrogen is provided downstream of the high-pressure hydrogen gas line 38h. Because the hydrogen gas rapidly cooled in the first heat exchanger 50h contains an excessive amount of ortho-hydrogen remaining, the conversion of ortho-hydrogen to para-hydrogen is promoted in the conversion unit 54h. The catalyst includes, for example, a paramagnetic substance such as ferric hydroxide or chromium oxide.

[0034] The refrigerant line 52 connects the first heat exchanger 50h and the radiator 56. The refrigerant circulating through the refrigerant line 52 is, for example, an antifreeze liquid such as silicone oil, ethylene glycol, a fluorine-based liquid, or an ether-based liquid, or helium (He), nitrogen (N ２ ), argon (Ar), methane (CH ４ ), ethane (C ２ H ６The refrigerant heated by the hydrogen gas is discharged in the radiator 56. The radiator 56 includes a radiator. The refrigerant heated by the hydrogen gas in the first heat exchanger 50h flows through the radiator 56, and the refrigerant flowing through the radiator 56 is cooled by the ambient temperature. The radiator 56 is installed in a shaded region of the lunar polar region. The radiator 56 is exposed to a high vacuum region in the shaded region of the lunar polar region, dissipates heat by radiation, and cools the refrigerant by the ambient temperature in the shaded region of the lunar polar region. The radiator 56 cools the refrigerant to approximately this temperature, i.e., to a temperature between 100 K and 200 K. Alternatively, the radiator 56 may cool the refrigerant to a temperature between 150 K and 250 K. In this embodiment, for example, the ambient temperature in the shaded region is 100 K, and the refrigerant temperature is 120 K. It is preferable that the heat dissipation surface of the radiator 56 is inclined from the horizontal at an angle of 0 to 90 degrees, preferably 0 to 80 degrees, which prevents dust and other particles from accumulating on the heat dissipation surface and reduces the decrease in heat dissipation efficiency.

[0035] The high-pressure hydrogen gas line 38h is connected to a first cooled hydrogen gas line 58h. The hydrogen gas cooled in the first heat exchanger 50h and whose conversion to para-hydrogen has been promoted in the conversion unit 54h is sent to the expansion turbine 60 via the first cooled hydrogen gas line 58h.

[0036] The expansion turbine 60 adiabatically expands the high-pressure hydrogen gas cooled to approximately this temperature in the first heat exchanger 50h by using the ambient temperature in the shaded region of the lunar polar region. As a result, the hydrogen gas is cooled as well as its pressure is reduced. The hydrogen gas at the outlet of the expansion turbine 60 has a pressure of 0.1 MPa or more and 10 MPa or less and a temperature of 20 K or more and 150 K or less. The hydrogen gas decompressed and cooled by the expansion turbine 60 is sent to the second heat exchanger 70h via a second cooled hydrogen gas line 68h.

[0037] The second heat exchanger 70h further cools the hydrogen gas cooled in the first heat exchanger 50h and the expansion turbine 60 and supplied from the second cooled hydrogen gas line 68h. The second heat exchanger 70h liquefies the hydrogen gas by cooling it to a temperature below its boiling point, preferably between 20 K and 30 K. The second heat exchanger 70h of this embodiment exchanges heat between the hydrogen gas in the second cooled hydrogen gas line 68h and the liquid or gas on the low-temperature side of the refrigerator 72. The hydrogen gas is cooled in the refrigerator 72. The refrigerator 72 is heated by the hydrogen gas.

[0038] A conversion section 74h containing a catalyst for promoting the conversion of ortho-hydrogen to para-hydrogen is provided downstream of the second cooled hydrogen gas line 68h. Because the liquid hydrogen rapidly cooled and liquefied in the second heat exchanger 70h contains an excessive amount of ortho-hydrogen, the conversion of ortho-hydrogen to para-hydrogen is promoted in the conversion section 74h. The catalyst includes, for example, a paramagnetic substance such as ferric hydroxide or chromium oxide.

[0039] The refrigerator 72 transfers heat using the heat pump principle, cooling the liquid or gas on the low-temperature side and heating the high-temperature side. The power supplied to the refrigerator 72 is supplied from the power storage device 14. The high-temperature side of the refrigerator 72 is connected to a heat sink 76, which dissipates heat. The heat sink 76 includes a radiator. The heat sink 76 cools the liquid or gas on the high-temperature side of the refrigerator 72 at the ambient temperature. The heat sink 76 is installed in a shaded region of the lunar polar region. The heat sink 76 is exposed to a high vacuum region in the shaded region of the lunar polar region and dissipates heat by radiation, cooling the liquid or gas on the high-temperature side of the refrigerator 72 at the ambient temperature in the shaded region of the lunar polar region. The heat sink 76 cools the liquid or gas on the high-temperature side of the refrigerator 72 to approximately the target temperature, i.e., between 4 K and 200 K, preferably between 20 K and 100 K.

[0040] The second cooled hydrogen gas line 68h is connected to a liquid hydrogen line 78h. The liquid hydrogen is further cooled and liquefied in the second heat exchanger 70h, and the conversion to para-hydrogen is promoted in the conversion unit 74h. The liquid hydrogen is then sent to a liquid hydrogen storage tank 80h via the liquid hydrogen line 78h.

[0041] Figure 3 is a schematic diagram showing the overall configuration of the oxygen liquefaction apparatus shown in Figure 1. Hereinafter, the configuration of the oxygen liquefaction apparatus 40o will be described as the liquefaction apparatus 40. The oxygen liquefaction apparatus 40o shown in Figures 1 and 3 liquefies room-temperature, high-pressure oxygen gas supplied from an oxygen gas tank 36o to produce liquid oxygen. Note that in the configuration of the oxygen liquefaction apparatus 40o, components similar to those of the hydrogen liquefaction apparatus 40h shown in Figure 2 are designated by the same reference numerals, and descriptions thereof will be omitted as appropriate. The oxygen liquefaction apparatus 40o includes a first heat exchanger 50o, an expansion turbine 60, and a second heat exchanger 70o.

[0042] The first heat exchanger 50o cools the room-temperature, high-pressure oxygen gas supplied from the high-pressure oxygen gas line 38o. The first heat exchanger 50o cools the oxygen gas using the ambient temperature in the shaded region of the lunar polar region. In this embodiment, the first heat exchanger 50o exchanges heat between the oxygen gas in the high-pressure oxygen gas line 38o and the refrigerant circulating through the refrigerant line 52. The oxygen gas is cooled by the refrigerant cooled by the ambient temperature in the shaded region of the lunar polar region, and is cooled to a temperature between 4 K and 200 K, preferably between 20 K and 100 K. In this embodiment, the temperature is, for example, 140 K. The refrigerant is heated by the oxygen gas.

[0043] The refrigerant line 52 connects the first heat exchanger 50o and the radiator 56. The configurations and functions of the refrigerant line 52, the refrigerant circulating through the refrigerant line 52, and the radiator 56 are similar to those of the refrigerant line 52, the refrigerant circulating through the refrigerant line 52, and the radiator 56 for cooling hydrogen gas shown in Figure 2, so description thereof will be omitted. The high-pressure oxygen gas line 38o communicates with a first cooled oxygen gas line 58o. The oxygen gas cooled in the first heat exchanger 50o is sent to the expansion turbine 60 via the first cooled oxygen gas line 58o.

[0044] The configuration and function of the expansion turbine 60 of the oxygen liquefaction device 40o are equivalent to the configuration and function of the expansion turbine 60 of the hydrogen liquefaction device 40h. The expansion turbine 60 of the oxygen liquefaction device 40o adiabatically expands high-pressure oxygen gas cooled to approximately that temperature by cooling it using the ambient temperature in the shaded region of the lunar polar region in the first heat exchanger 50o. As a result, the oxygen gas is cooled as well as its pressure is reduced. The oxygen gas at the outlet of the expansion turbine 60 has a pressure of 0.1 MPa or more and 10 MPa or less and a temperature of 90 K or more and 200 K or less. The oxygen gas decompressed and cooled by the expansion turbine 60 is sent to the second heat exchanger 70o via the second cooled oxygen gas line 68o.

[0045] The second heat exchanger 70o further cools the oxygen gas cooled in the first heat exchanger 50o and the expansion turbine 60 and supplied from the second cooled oxygen gas line 68o. The second heat exchanger 70o liquefies the oxygen gas by cooling it to a temperature below its boiling point, preferably between 90 K and 100 K. The second heat exchanger 70o of this embodiment exchanges heat between the oxygen gas in the second cooled oxygen gas line 68o and the liquid or gas on the low-temperature side of the refrigerator 72. The oxygen gas is cooled in the refrigerator 72. The refrigerator 72 is heated by the oxygen gas.

[0046] The configuration and function of the refrigerator 72 and the radiator 76 that dissipates heat from the refrigerator 72 are similar to those of the refrigerator 72 and radiator 76 that cool and liquefy hydrogen gas shown in Figure 2, and therefore a description thereof will be omitted. The second cooled oxygen gas line 68o communicates with a liquid oxygen line 78o. The liquid oxygen that has been further cooled and liquefied in the second heat exchanger 70o is sent to a liquid oxygen storage tank 80o via the liquid oxygen line 78o.

[0047] Storage tank 80 stores a target liquid, which is the target gas liquefied in liquefaction device 40. In this embodiment, storage tank 80 includes a liquid hydrogen storage tank 80h that stores liquid hydrogen obtained by liquefying hydrogen gas, and a liquid oxygen storage tank 80o that stores liquid oxygen obtained by liquefying oxygen gas. However, storage tank 80 is not limited to having both the liquid hydrogen storage tank 80h and the liquid oxygen storage tank 80o, and may include at least one of the liquid hydrogen storage tank 80h and the liquid oxygen storage tank 80o.

[0048] 1 and 2 stores liquid hydrogen liquefied in the hydrogen liquefaction device 40h. The liquid hydrogen stored in the liquid hydrogen storage tank 80h has a temperature of 20 K or higher and 33 K or lower, and a pressure of 0.1 MPa or higher and 3.3 MPa or lower.

[0049] The liquid hydrogen stored in the liquid hydrogen storage tank 80h is cooled by a refrigerator 82 to prevent evaporation. The configurations and functions of the refrigerator 82 and the radiator 86 that dissipates heat from the refrigerator 82 are similar to those of the refrigerator 72 and the radiator 76 shown in Fig. 2, and therefore a description thereof will be omitted. That is, power supplied to the refrigerator 82 is supplied from the power storage device 14. The radiator 86 is installed in a shaded area of ​​the lunar polar region.

[0050] Vaporized hydrogen gas in the liquid hydrogen storage tank 80h is returned to the hydrogen gas tank 36h via a return hydrogen gas line 88h. The liquid hydrogen stored in the liquid hydrogen storage tank 80h is sucked into a transfer pump 90 and supplied to the propellant tank RTh of the inter-orbital transfer vehicle R via a liquid hydrogen transfer line 98h. The power supplied to the transfer pump 90 is supplied from the power storage device 14.

[0051] 1 and 3 stores the liquid oxygen liquefied in the oxygen liquefaction device 40. The liquid oxygen stored in the liquid oxygen storage tank 80 has a temperature of 90 K or higher and 155 K or lower, and a pressure of 0.1 MPa or higher and 5.0 MPa or lower.

[0052] The liquid oxygen stored in the liquid oxygen storage tank 80o is cooled by a refrigerator 82 to prevent evaporation. The configurations and functions of the refrigerator 82 and the radiator 86 that dissipates heat from the refrigerator 82 are similar to those of the refrigerator 72 and the radiator 76 shown in Fig. 3, and therefore a description thereof will be omitted. That is, power supplied to the refrigerator 82 is supplied from the power storage device 14. The radiator 86 is also installed in a shaded area of ​​the lunar polar region.

[0053] The oxygen gas that has vaporized in the liquid oxygen storage tank 80o is returned to the oxygen gas tank 36o via a return oxygen gas line 88o. The liquid oxygen stored in the liquid oxygen storage tank 80o is sucked into a transfer pump 90 and supplied to the propellant tank RTo of the inter-orbital transfer vehicle R via a liquid oxygen transfer line 98o. The power supplied to the transfer pump 90 is supplied from the power storage device 14.

[0054] The liquid hydrogen transfer line 98h and the liquid oxygen transfer line 98o of the propellant plant system 1 can be connected and disconnected at a connection point C provided on the outer hull of the orbital transfer vehicle R. The connection point C is realized by, for example, a well-known quick disconnect.

[0055] 1 , the high-pressure hydrogen gas line 38h, the liquid hydrogen line 78h, the return hydrogen gas line 88h, the liquid hydrogen transfer line 98h, the high-pressure oxygen gas line 38o, the liquid oxygen line 78o, the return oxygen gas line 88o, and the liquid oxygen transfer line 98o are provided with shutoff valves V. Note that the shutoff valves V are not limited to being located in the positions shown in the figure and may be provided at appropriate locations. Furthermore, each line in the propellant plant system 1 may be provided with a bypass flow path, a bypass valve, or the like as appropriate.

[0056] The control device 100 is a controller that controls each part of the propellant plant system 1. The control device 100 controls each part of the propellant plant system 1, thereby producing liquefied hydrogen and liquefied oxygen as propellants using the resources and environment of the moon. The control device 100 may be, for example, a computer having an arithmetic circuit such as a CPU (Central Processing Unit), memory and storage, an interface, etc. The control device 100 may be configured with multiple computers divided into several functions, or may exist separately via a network.

[0057] In the following description, when there is no need to distinguish between the hydrogen gas tank 36h and the oxygen gas tank 36o, they will simply be referred to as the gas tank 36. When there is no need to distinguish between the high-pressure hydrogen gas line 38h and the high-pressure oxygen gas line 38o, they will simply be referred to as the high-pressure gas line 38. When there is no need to distinguish between the hydrogen liquefaction device 40h and the oxygen liquefaction device 40o, they will simply be referred to as the liquefaction device 40. When there is no need to distinguish between the first heat exchanger 50h and the first heat exchanger 50o, they will simply be referred to as the first heat exchanger 50. When there is no need to distinguish between the first cooled hydrogen gas line 58h and the first cooled oxygen gas line 58o, they will simply be referred to as the first cooled gas line 58. When there is no need to distinguish between the second cooled hydrogen gas line 68h and the second cooled oxygen gas line 68o, they will simply be referred to as the second cooled gas line 68. When there is no need to distinguish between the second heat exchanger 70h and the second heat exchanger 70o, they will simply be referred to as the second heat exchanger 70. Furthermore, when there is no particular distinction between the liquid hydrogen line 78h and the liquid oxygen line 78o, they are simply referred to as the liquid line 78. When there is no particular distinction between the liquid hydrogen storage tank 80h and the liquid oxygen storage tank 80o, they are simply referred to as the storage tank 80. When there is no particular distinction between the return hydrogen gas line 88h and the return oxygen gas line 88o, they are simply referred to as the return gas line 88. When there is no particular distinction between the liquid hydrogen transfer line 98h and the liquid oxygen transfer line 98o, they are simply referred to as the transfer line 98. When there is no particular distinction between the propellant tank RTh and the propellant tank RTo, they are simply referred to as the propellant tank RT.

[0058] (Example of heat radiator arrangement) Fig. 4 is a schematic diagram showing an example of the arrangement of the heat radiator shown in Fig. 1. As an example, an example of the arrangement of the heat radiator 86 that dissipates heat from the refrigerator 82 that cools the storage tank 80 will be described below, but this example of the arrangement may be applied not only to the heat radiator 86 but also to the heat radiator 56 and the heat radiator 76 shown in Figs. 2 and 3.

[0059] As described above, the radiator 86 is installed in the shaded region DR in the lunar polar region, and utilizes the low temperature of the shaded region DR to efficiently dissipate heat. In the lunar polar region, the sunlit region and the shaded region move in long cycles. Places that are permanently shaded, such as the inside of a crater, may not be suitable for installing the radiator 86. Therefore, it is preferable that the radiator 86 be installed in a movable manner so that heat can always be dissipated in the shaded region DR in response to the moving shaded region.

[0060] 4, the heat sink 86 is fixed to a sliding base 86S that is movable on guide rails 86G. The guide rails 86G are provided in a range such that at least one of the guide rails 86G always falls within the shaded region DR. This allows the installation location of the heat sink 86 to be periodically changed in accordance with the movement of the sunny region SR and the shaded region DR.

[0061] The movement of the sliding base 86S is controlled, for example, by the control device 100. The control device 100 stores in advance, for example, the hours of sunlight at each point in the lunar polar regions, and moves the radiator 86 and the sliding base 86S to the shaded region DR based on the hours of sunlight. The control device 100 may also control the movement points and timing of the movement so that the frequency of movement of the sliding base 86S is reduced.

[0062] FIG. 5 is a schematic diagram showing another example of the arrangement of the radiator shown in FIG. 1 . In the example shown in FIG. 5 , the radiator 86 is fixed to a rotating base 86R. A vertical wall 86W extends from the rotating base 86R. One side of the vertical wall 86W faces the sun, forming a shaded area DR on the other side. As a result, the radiator 86 can always be located in the shaded area DR formed by the vertical wall 86W by rotating the rotating base 86R around the vertical axis.

[0063] In the example shown in FIG. 5 , a solar panel 12 may also be combined. To improve power generation efficiency, the solar panel 12 is preferably always installed in the sunny region SR. The solar panel 12 is fixed to a rotating base 86R on the opposite side of the radiator 86, separated by a vertical wall 86W. That is, by periodically rotating the rotating base 86R so that the radiator 86 is always positioned in the shaded region DR defined by the vertical wall 86W, the solar panel 12 can be oriented in the direction of sunlight irradiating the sunny region SR. For example, by combining the rotating base 86R with the guide rail 86G shown in FIG. 4 and providing a movable base 86R, it is possible to adjust the solar panel 12 so that it is always located in the sunny region SR and the radiator 86 is always located in the shaded region DR.

[0064] The rotation of the rotating base 86R is controlled, for example, by the control device 100. The control device 100 stores, for example, the sunshine hours at each point in the lunar polar regions in advance and, based on the sunshine hours, rotates the rotating base 86R so that the radiator 86 faces the shaded region DR and the solar panel 12 faces the sunny region SR. In other words, the control device 100 rotates the rotating base 86R so that one surface of the standing wall 86W facing the solar panel 12 faces the direction of irradiation from the sun. The control device 100 may also control the rotation angle and timing of the rotating base 86R to reduce the rotation frequency. As another example, instead of the rotating base 86R shown in FIG. 5 , the solar panel 12, the power storage device 14, and the radiator 86 may be mounted on a mobile body having a standing wall 86W. The mobile body is, for example, a vehicle that can move straight and turn on the surface of the earth in the lunar polar regions.

[0065] (Operation and Effect of the Embodiment) The propellant plant system 1 described in the embodiment can be understood, for example, as follows.

[0066] The propellant plant system 1 according to the first aspect includes a water intake device 20 that collects water resources and stores them as liquid water, an electrolysis device 30 that electrolyzes water to produce hydrogen gas and oxygen gas, a liquefaction device 40 that liquefies a target gas that is at least one of hydrogen gas and oxygen gas, a storage tank 80 that stores the target liquid that is the liquefied target gas, a first refrigerator (refrigerant 82) that cools the storage tank 80, a first radiator (radiator 86) that exchanges heat with the first refrigerator, and a power generation device 10 that can be installed in a sunny region of the lunar polar region and that generates electricity using irradiation by sunlight and supplies the electricity to at least one of the electrolysis device 30, the liquefaction device 40, and the first refrigerator, and when installed in a shaded region of the lunar polar region, the first radiator rejects heat to the shaded region to cool the first refrigerator at the ambient temperature of the shaded region.

[0067] When installed in the lunar polar regions, the propellant plant system 1 according to the first aspect can recover water, which is used as a raw material for producing liquid hydrogen and liquid oxygen propellants, from water resources in the lunar polar regions, eliminating the need to transport water to outer space and reducing costs. Furthermore, the environmental temperature in the shaded regions of the lunar polar regions is used to exhaust heat from the first refrigerator to prevent the target liquid from vaporizing, improving cooling efficiency and achieving energy savings. The propellant plant system 1 obtains power through solar power generation using sunlight irradiated in the sunny regions of the lunar polar regions. However, by improving cooling efficiency by utilizing the environmental temperature in the shaded regions of the lunar polar regions, the amount of power required can be reduced, allowing the system to operate sufficiently with the amount of power generated by solar power.

[0068] The propellant plant system 1 according to the second aspect is the propellant plant system 1 according to the first aspect, in which the electrolysis device 30 electrolyzes pressurized water to generate hydrogen gas and oxygen gas. This reduces the power required for pressurization compared to pressurizing the hydrogen gas and oxygen gas after electrolysis, thereby achieving energy savings.

[0069] The propellant plant system 1 according to the third aspect is the propellant plant system 1 according to the first aspect, wherein the liquefaction device 40 includes a first heat exchanger 50 having a second radiator (radiator 56) that exchanges heat with the target gas, an expansion turbine 60 that cools the target gas cooled in the first heat exchanger 50 by adiabatic expansion, a second heat exchanger 70 that cools and liquefies the target gas by exchanging heat between the target gas cooled in the expansion turbine 60 and a second refrigerator (refrigerator 72), and a third radiator (radiator 76) that exchanges heat with the second refrigerator, and when the second radiator is installed in a shaded region of the lunar polar region, it rejects heat to the shaded region to cool the target gas at the ambient temperature of the shaded region, and when the third radiator is installed in a shaded region of the lunar polar region, it rejects heat to the shaded region to cool the second refrigerator at the ambient temperature of the shaded region.

[0070] The propellant plant system 1 according to the third aspect cools and liquefies the target gas in stages. In this case, the environmental temperature in the shaded area of ​​the lunar polar region is used to cool the target gas in the first stage, thereby improving cooling efficiency and achieving energy savings. Furthermore, the environmental temperature in the shaded area of ​​the lunar polar region is also used to exhaust heat from the second refrigerator, which cools the target gas to an even lower temperature for liquefaction, thereby improving cooling efficiency and achieving energy savings.

[0071] The propellant plant system 1 according to a fourth aspect is the propellant plant system 1 according to any one of the first to third aspects, wherein the first radiator (radiator 86) is movably provided. This allows the first radiator to always radiate heat to a shaded area, suppressing a decrease in cooling efficiency and achieving energy savings.

[0072] The propellant plant system 1 according to the fifth aspect is the propellant plant system 1 according to the fourth aspect, and further includes a control device 100 that stores the sunshine hours in the lunar polar regions in advance and controls the movement of the first radiator (radiator 86) based on the sunshine hours. This allows the first radiator to be moved to an appropriate movement location at an appropriate time, thereby reducing the frequency of movement to shaded areas and reducing the power required for movement, thereby achieving energy conservation.

[0073] 1 Propellant plant system 10 Power generation device 12 Solar panel 14 Power storage device 20 Water intake device 22 Ice collection device 24 Separation and purification device 26 Water storage tank 28 Water supply line 30 Electrolysis device 32 High-pressure water supply pump 34 Electrolyzer 36 Gas tank 38 High-pressure gas line 40 Liquefaction device 50 First heat exchanger 52 Refrigerant line 56 Radiator 58 First cooled gas line 60 Expansion turbine 68 Second cooled gas line 70 Second heat exchanger 72 Refrigerator 76 Radiator 78 Liquid line 80 Storage tank 82 Refrigerator 86 Radiator 88 Return gas line 90 Transfer pump 98 Transfer line 100 Control device C Connection R Orbital transfer vehicle RT Propellant tank V Shut-off valve

Claims

1. A propellant plant system comprising: a water intake device that recovers water resources and stores them as liquid water; an electrolysis device that electrolyzes the water to produce hydrogen gas and oxygen gas; a liquefaction device that liquefies a target gas, which is at least one of the hydrogen gas and the oxygen gas; a storage tank that stores the target liquid that is the liquefied target gas; a first refrigerator that cools the storage tank; a first radiator that exchanges heat with the first refrigerator; and a power generation device that can be installed in a sunny region of a lunar polar region and generates electricity using irradiation by sunlight to supply power to at least one of the electrolysis device, the liquefaction device, and the first refrigerator, wherein when the first radiator is installed in a shaded region of the lunar polar region, it rejects heat to the shaded region and cools the first refrigerator at the ambient temperature of the shaded region.

2. The propellant plant system according to claim 1, wherein the electrolysis device electrolyzes the water under pressure to produce the hydrogen gas and the oxygen gas.

3. The propellant plant system according to claim 1, wherein the liquefaction device comprises: a first heat exchanger having a second radiator that exchanges heat with the target gas; an expansion turbine that adiabatically expands and cools the target gas cooled in the first heat exchanger; a second heat exchanger that cools and liquefies the target gas by exchanging heat between the target gas cooled in the expansion turbine and a second refrigerator; and a third radiator that exchanges heat with the second refrigerator, wherein when the second radiator is installed in a shaded region of the lunar polar region, it rejects heat to the shaded region to cool the target gas at an ambient temperature in the shaded region, and when the third radiator is installed in a shaded region of the lunar polar region, it rejects heat to the shaded region to cool the second refrigerator at an ambient temperature in the shaded region.

4. A propellant plant system according to any one of claims 1 to 3, wherein the first radiator is provided movably.

5. The propellant plant system according to claim 4, further comprising a control device that stores in advance the hours of sunlight in the lunar polar regions and controls the movement of the first radiator based on the hours of sunlight.

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