JP7490227B2 - Gas supply and propulsion systems - Google Patents

Description

The present invention relates to a gas supply system and a propulsion system.

In recent years, universities and companies have been developing small artificial satellites. To reduce the cost of launching them using rockets, small artificial satellites are lightweight, weighing between 1 and 100 kg, compared to the masses of conventional artificial satellites, which range from several hundred kg to several tons.

The reduction of the structural mass, which is the mass of the components that make up this small artificial satellite, is an issue. For orbital control and attitude control, a thruster needs to be installed. In a general method, the fuel for the thruster is sealed in a high-pressure tank at a pressure of 1 MPa to 10 MPa and is supplied using a high-pressure gas valve or the like. In this method, the pipes and tanks that can withstand high pressure are used, so the structure is robust. Therefore, it is difficult to reduce the structural mass. For example, in Non-Patent Document 1, the structural mass of a gas supply system equipped with a tank for storing 890 g of xenon is 2840 g. Since the mass of a small artificial satellite is 1 to 100 kg, this is a major constraint on the installation of a thruster. If orbital change and attitude change are not possible without a thruster, it will hinder the use of the small artificial satellite. Therefore, there is a demand for a reduction in the structural mass of the gas supply system. There is also a demand for further miniaturization of the tank in Non-Patent Document 1.

Metal-organic frameworks (MOFs) have the property of adsorbing gases. For this reason, MOFs are used for small, high-density storage and for removing specific gases from mixed gases. Patent Document 1 discloses an airtight container equipped with a metal-organic framework.

Japanese Patent No. 5074035

Journal of the Japan Society for Aeronautical and Space Sciences, History, Current Status, and Prospects of Small Ion Thruster Research and Development, vol. 66, No. 11, p. 7

However, the method disclosed in Patent Document 1 uses a pressure of 1 to 300 bar to ensure the amount of gas stored. As a result, as with conventional storage methods, gas is stored at high pressure, and the pressure resistance strength of the tank needs to be increased, so there is almost no effect in reducing the structural mass.

The present invention was made in consideration of the above problems, and aims to provide a lightweight and compact gas supply system.

In order to solve the above problems, the present invention proposes the following means.
(1) A gas supply system according to one aspect of the present invention includes a metal-organic framework filling tank filled with a metal-organic framework that adsorbs a gas, and the pressure of the metal-organic framework filling tank is equal to or greater than 0 Pa and equal to or less than 0.1 MPa .
(2) In the gas supply system described in (1) above, the pressure may be 0.01 Pa or more.
(3) In the gas supply system described in (1) or (2) above, the pressure may be 0.1 Pa or more.
(4 ) In the gas supply system according to any one of (1) to ( 3 ) above, the gas may be xenon.
( 5 ) In the gas supply system according to any one of (1) to ( 4 ) above, the metal organic framework may be MOF-74.
( 6 ) A propulsion system according to one aspect of the present invention includes the gas supply system according to any one of (1) to ( 5 ) above.

The above aspect of the present invention provides a lightweight and compact gas supply system.

1 is a schematic diagram of a gas supply system according to an embodiment of the present invention; FIG. 4 is a schematic diagram of a gas supply system according to another embodiment of the present invention. FIG. 4 is a schematic diagram of a gas supply system according to another embodiment of the present invention. FIG. 1 is a diagram showing the relationship between gas pressure and gas adsorption amount of MOF. FIG. 1 is a diagram showing the relationship between gas pressure and gas adsorption amount in MOF-74-Co and MOF-74-Mg. FIG. 1 is a schematic diagram of a conventional gas supply system.

First Embodiment
Hereinafter, a gas supply system 100 according to a first embodiment of the present invention will be described with reference to FIG.
The gas supply system 100 includes a metal-organic framework filled tank (MOF filled tank) 1, a first pressure sensor 2, a valve 3, a regulator valve 4, a second pressure sensor 5, an accumulator tank 6, a thruster valve 7, an orifice 8, a control unit (not shown), and pipes 30a, 30b, 30c, 30d, 30e, and 30f. Each part will be described below. The propulsion system 200 includes a thruster 9 in addition to the gas supply system 100.

(MOF filling tank)
The MOF tank 1 is a gas tank filled with a metal-organic framework (MOF). Here, the metal-organic framework is a porous material formed by coordinate bonds between metal ions and an organic substance. The MOF tank 1 is connected to a valve 3 via a pipe 30a.

Materials for the MOF-filled tank 1 include Ti, Ti alloys, Al alloys, Mg alloys, and carbon fiber reinforced plastic (CFRP).

Gases that can be filled into the MOF filling tank 1 include xenon, krypton, argon, neon, helium, hydrogen, oxygen, nitrogen, and chlorine.

The filling rate of the MOF is not particularly limited, but is preferably 60% or more of the total volume of the MOF-filled tank 1. A more preferred filling rate of the MOF-filled tank 1 is 70% or more of the total volume of the MOF-filled tank 1. An even more preferred filling rate of the MOF-filled tank 1 is 75% or more of the total volume of the MOF-filled tank 1.

The MOF to be filled in the MOF filling tank 1 is not particularly limited, and examples thereof include SBMOF-1, SBMOF-2, Ni-MOF-74, Co ₃ (HCOO) ₆ , HKUST-1, MOF-5, FMOF-Cu, MRJ-4I, MOF-505, SIFSIX-3-Ni, SIFSIX-3-Fe, CROFOUR-1-Ni, UIO-66, PCN-14, NOTT-100, NOTT-103, MOF-74-Co, MOF-74-Mg, etc. In particular, MOF-74 such as MOF-74-Mg and MOF-74-Co, which have a high density of coordinatively unsaturated metal sites (open metal sites) on the pore surface, are preferred.

The BET surface area of the MOF is not particularly limited, but is preferably 1000 m ² /g or more, and more preferably 1400 m ² /g or more. The upper limit of the BET surface area of the MOF is not particularly limited, and may be, for example, 6500 m ² /g.

MOFs are formed from metal salts and organic ligands. The raw materials for MOFs are metal salts that can produce metal ions in solution, and organic ligands. This means that at least one type of both the metal salt and the organic ligand are used as raw materials. Furthermore, if necessary, raw materials other than metal salts and organic ligands can also be used.

Metal salts used as MOF raw materials can be selected from those containing various metal elements. Examples of metal elements contained in the metal salt include Cu, Zn, Co, In, Al, Fe, V, Mg, Mn, Ni, Ru, Mo, Cr, W, Rh, and Pd. Mg and Co are particularly preferred.

Organic ligands that form coordinate bonds with metal ions include 2-aminoterephthalic acid, 2,5-diaminoterephthalic acid, 2,5-dihydroxyterephthalic acid, 1,2,4,5-tetrakis(4-carboxyphenyl)benzene, 1,3,5-tris(4'-carboxy[1,1'-biphenyl]-4-yl)benzene, 1,3,5-tris(4-carboxyphenyl)benzene, 2,6-naphthalenedicarboxylic acid, 2-hydroxyterephthalic acid, 3,3' ,5,5'-tetracarboxydiphenylmethane, 4,4',4"-S-triazine-2,4,6-tolyl-tribenzoic acid, 9,10-anthracenedicarboxylic acid, biphenyl-3,3',5,5'-tetracarboxylic acid, biphenyl-3,4',5-tricarboxylic acid, terephthalic acid, trimesic acid, [1,1':4',1"]terphenyl-3,3',5,5'-tetracarboxylic acid, imidazole, 2-methylimidazole, etc. are particularly preferred. 2,5-dihydroxyterephthalic acid is particularly preferred.

The MOF material can be identified by measuring it using, for example, infrared spectroscopy (IR), time-of-flight secondary ion mass spectrometry (TOF-SIMS), solid-state nuclear magnetic resonance analysis (solid-state NMR), etc.

The shape of the MOF to be filled can be, for example, powder or pellets. For ease of handling, it is preferable that the MOF to be filled is molded into pellets.

The pressure during gas storage in the MOF filled tank 1 is 0 Pa or more and less than 1 MPa. If the pressure during gas storage is less than 1.0 MPa, the thickness of the tank can be made thinner than when it is compatible with, for example, 3.0 MPa, and the structural mass can be reduced. In addition, if the gas pressure is less than 1 MPa, for example, in Japan, the Japanese High Pressure Gas Safety Act does not apply, and the handling of the gas tank becomes easier, so the manufacturing and management costs can be reduced. Normally, in preparation for unforeseen circumstances, the accumulator tank 6 and the like are designed to withstand high pressure, but since the pressure of the MOF filled tank 1 is low in the gas supply system 100, the accumulator tank 6 and the like can be made to a low pressure specification, and the weight can be reduced compared to the conventional gas supply system 100. A more preferable pressure during gas storage is 0.2 MPa or less. If the pressure during gas storage is 0.2 MPa or less, the structural mass can be further reduced. More preferably, the first gas pressure is 0.1 MPa or less. The pressure during gas storage is preferably 1 kPa or more.

(First pressure sensor)
The first pressure sensor 2 is provided in the pipe 30a connecting the MOF filling tank 1 and the valve 3. The first pressure sensor 2 measures the pressure of the gas on the MOF filling tank 1 side and sends information on the pressure on the MOF filling tank 1 side to a control unit not shown.

(valve)
The opening and closing of the valve 3 is controlled by a control unit (not shown). The regulator valve 4 reduces the pressure of the gas sent through the pipe 30b. The pressure of the gas sent from the MOF-filled tank 1 is finely adjusted by the valve 3 and the regulator valve 4 to, for example, about 0.03 MPa.

(Second pressure sensor)
The second pressure sensor 5 is provided in a pipe 30c that connects the regulator valve 4 and the accumulator tank 6. The second pressure sensor 5 measures the pressure of the gas on the accumulator tank 6 side, and sends information about the pressure on the accumulator tank 6 side to a control unit (not shown).

(Accumulator tank)
The accumulator tank reduces the pressure and stores the gas sent from the MOF filling tank 1. The accumulator tank 6 is connected to the thruster valve 7 via a pipe 30d.

(Thruster valve)
The thruster valve 7 controls the ON/OFF supply of gas to the thruster 9 by opening and closing the valve.

(Orifice)
The flow rate of the gas is restricted by the orifice 8. The gas passes through the orifice 8 and is sent to the thruster 9. The gas pressure here is not particularly limited and may be, for example, 0 Pa or 1 kPa. The orifice 8 is equipped with a filter.

(Control Unit)
A control unit (not shown) controls the valve 3, the regulator valve 4, and the thruster valve 7. The gas pressure is controlled based on information obtained from the first pressure sensor 2 and the second pressure sensor 5.

Gas pressure control during thruster operation will now be described. When thruster 9 is operating, valve 3 and thruster valve 7 are always open. A control unit (not shown) monitors the pressure of second pressure sensor 5, and when the gas pressure reaches the lower threshold, feedback control is used to open regulator valve 4 for a fixed period of time, filling accumulator tank 6 with gas, which is fuel. This gas filling process is repeated every time the gas pressure reaches the lower threshold while thruster 9 is operating.

The first embodiment of the present invention has been described above. In the gas supply system 100 according to the first embodiment, only one system of gas pressure control mechanisms (valve 3 and regulator valve 4) from the MOF filling tank 1 to the accumulator tank 6 is provided, but one or more systems of gas pressure control mechanisms may be provided to provide redundancy. Also, an orifice that controls the flow rate may be further provided between the regulator valve 4 and the accumulator tank 6. The gas supply system 100 may have two or more first pressure sensors 2 and two or more second pressure sensors 5 to provide redundancy.

The gas supply system 100 according to the first embodiment of the present invention includes only one thruster-side gas pressure control mechanism (thruster valve 7 and orifice 8), but may include two or more thruster-side gas pressure control mechanisms. The gas supply system 100 may further include a valve for filling fuel. The gas supply system 100 according to this embodiment includes only a pressure sensor, but may further include a temperature sensor.

Second Embodiment
A gas supply system 100A according to a second embodiment of the present invention will be described below with reference to FIG.
The gas supply system 100A includes a metal-organic framework filled tank (MOF filled tank) 1, a first pressure sensor 2a, a latch valve 10, a proportional flow control valve 11, a third pressure sensor 12, a control unit (not shown), and pipes 30g, 30h, and 30i. Each part will be described below. The propulsion system 200A further includes a thruster 9 in addition to the gas supply system 100A. Hereinafter, the description of the same configuration and the same functions as the gas supply system 100A according to the first embodiment will be omitted, and only the differences will be described.

(First pressure sensor)
The first pressure sensor 2a is provided in a pipe 30g connecting the MOF filling tank 1 and the latch valve 10. The first pressure sensor 2a measures the pressure of the gas on the MOF filling tank 1 side and sends information on the pressure on the MOF filling tank 1 side to a control unit (not shown).

(Latch valve)
The latch valve 10 opens and closes to control the ON/OFF supply of gas to the proportional flow control valve 11. The latch valve 10 is connected to the proportional flow control valve 11 through a pipe 30h.

(Proportional flow control valve)
The proportional flow control valve 11 controls the flow rate of the gas sent through the latch valve 10 .

(Third pressure sensor)
The third pressure sensor 12 is provided in a pipe 30i connecting the proportional flow control valve 11 and the thruster 9. The third pressure sensor 12 measures the pressure of the gas sent from the proportional flow control valve 11, and sends information on the pressure to a control unit (not shown).

(Control Unit)
A control unit (not shown) controls the latch valve 10 and the proportional flow control valve 11. The gas pressure is controlled based on information obtained from the first pressure sensor 2a and the third pressure sensor 12.

The second embodiment of the present invention has been described above. The gas supply system 100A according to the second embodiment has only one gas pressure control mechanism (latch valve 10) from the MOF filling tank 1 to the proportional flow control valve 11, but may have two or more gas pressure control mechanisms to provide redundancy. The gas supply system 100A according to the second embodiment may further include a temperature sensor near the first pressure sensor 2a. The gas supply system 100A according to the second embodiment may further include a temperature sensor near the third pressure sensor 12. Two or more first pressure sensors 2a and third pressure sensors 12 may be provided to provide redundancy. The gas supply system 100A may further include a valve for filling fuel. The gas supply system 100A according to the second embodiment may include a thermo throttle that controls the flow rate by utilizing thermal expansion instead of the proportional flow control valve 11.

The propulsion system 200A according to the first embodiment of the present invention has only one thruster-side gas pressure control mechanism (proportional flow control valve 11 and thruster 9), but may have two or more thruster-side gas pressure control mechanisms.

Third Embodiment
Next, a gas supply system 100B according to a third embodiment of the present invention will be described with reference to FIG.
In the third embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and their description is omitted. Only the differences are described. The gas supply system 100B includes a MOF-filled tank 1b, a valve 15, a pipe 30j, and a control unit (not shown). Each component will be described below.

The MOF filling tank 1a is a gas tank filled with a metal-organic framework (MOF). The MOF filling tank 1a is connected to the vacuum device 20 via a pipe 30j. A valve 15 is provided on the pipe 30j.

Materials for the MOF-filled tank 1a include Ti, Ti alloys, Al alloys, Mg alloys, carbon fiber reinforced plastic (CFRP), Fe, Fe alloys, etc.

Gases that can be filled into the MOF filling tank 1a include xenon, krypton, argon, neon, helium, hydrogen, oxygen, nitrogen, and chlorine.

The filling rate of the MOF is not particularly limited, but is preferably 60% or more of the total volume of the MOF-filled tank 1a. A more preferred filling rate of the MOF-filled tank 1a is 70% or more of the total volume of the MOF-filled tank 1a. An even more preferred filling rate of the MOF-filled tank 1a is 75% or more of the total volume of the MOF-filled tank 1a.

The MOF filled in the MOF filled tank 1a is not particularly limited, and examples thereof include SBMOF-1, SBMOF-2, Ni-MOF-74, Co ₃ (HCOO) ₆ , HKUST-1, MOF-5, FMOF-Cu, ZIF-8, MRJ-4I, MOF-505, SIFSIX-3-Ni, SIFSIX-3-Fe, CROFOUR-1-Ni, UIO-66, PCN-14, NOTT-100, NOTT-103, MOF-74-Co, MOF-74-Mg, etc. The MOF filled in the MOF filled tank 1a can be appropriately selected depending on the type of gas to be adsorbed.

The BET surface area of the MOFs packed in the MOF-packed tank 1a is not particularly limited, but is preferably 1000 m ² /g or more, and more preferably 1400 m ² /g or more. The upper limit of the BET surface area of the MOFs is not particularly limited, and may be, for example, 6500 m ² /g.

The metal salt used as the MOF raw material can be selected from those containing various metal elements, such as Cu, Zn, Co, In, Al, Fe, V, Mg, Mn, Ni, Ru, Mo, Cr, W, Rh, and Pd.

Organic ligands that form coordinate bonds with metal ions include 2-aminoterephthalic acid, 2,5-diaminoterephthalic acid, 2,5-dihydroxyterephthalic acid, 1,2,4,5-tetrakis(4-carboxyphenyl)benzene, 1,3,5-tris(4'-carboxy[1,1'-biphenyl]-4-yl)benzene, 1,3,5-tris(4-carboxyphenyl)benzene, 2,6-naphthalenedicarboxylic acid, 2-hydroxyterephthalic acid, 3,3' , 5,5'-tetracarboxydiphenylmethane, 4,4',4"-S-triazine-2,4,6-tolyl-tribenzoic acid, 9,10-anthracenedicarboxylic acid, biphenyl-3,3',5,5'-tetracarboxylic acid, biphenyl-3,4',5-tricarboxylic acid, terephthalic acid, trimesic acid, [1,1':4',1"]terphenyl-3,3',5,5'-tetracarboxylic acid, imidazole, 2-methylimidazole, etc.

The shape of the MOF filled into the MOF filling tank 1a may be, for example, powder or pellet form. For ease of handling, it is preferable that the MOF filled be molded into pellet form.

The pressure during gas storage in the MOF-filled tank 1a is 0 Pa or more and less than 1 MPa. If the pressure during gas storage is less than 1 MPa, the thickness of the tank can be made thinner than when it is compatible with, for example, 3.0 MPa, and the structural mass can be reduced. In addition, if the pressure is within this range, the amount of gas adsorbed by the MOF can be increased, and a larger amount of gas can be stored than in conventional gas tanks. Therefore, the MOF-filled tank 1a can be made smaller. If the gas pressure is less than 1 MPa, pressure resistance testing of the gas tank is simplified, and the manufacturing cost can be reduced. A more preferable pressure during gas storage is 0.2 MPa or less. If the pressure during gas storage is 0.2 MPa or less, the structural mass can be further reduced. More preferably, the pressure during gas storage is 0.1 MPa or less. The lower limit of the pressure during gas storage is not particularly limited, but is, for example, 0.01 Pa or 0.1 Pa.

(valve)
The opening and closing of the valve 15 is controlled by a control unit (not shown). By opening and closing the valve 15, the pressure of the gas sent from the MOF filling tank 1a is adjusted.

(Control Unit)
A control unit (not shown) controls the valve 15. The control is based on information obtained from a pressure sensor, a temperature sensor, and the like (not shown) provided near the valve 15. The pressure sensor and the temperature sensor may be, for example, a high pressure sensor and a temperature sensor that monitor the MOF tank 1a, and a low pressure sensor and a temperature sensor that monitor the vacuum device 20.

(Vacuum device)
The vacuum device 20 connected to the MOF filling tank 1a is not particularly limited as long as it has a mechanism for supplying gas under a vacuum environment. Examples of such a vacuum device 20 include a vacuum deposition device and a dry etching device.

(Relationship between gas pressure and gas adsorption amount)
Next, the relationship between the gas adsorption amount of MOF and the gas pressure will be described. Here, the relationship between the gas pressure of Xe and the adsorption amount of Xe to MOF will be described. FIG. 4 is a diagram showing the relationship between the gas pressure and the adsorption amount of gas when MOF (MOF-74-Co) is filled in the MOF filling tank 1. The solid line in FIG. 4 is the result obtained by fitting the measurement results of the adsorption amount of Xe up to 1 MPa with the BET (Brunauer, Emmett, Teller) adsorption isotherm represented by the following formula (1). In the following formula (1), w indicates the adsorption amount, wm indicates the adsorption amount when adsorbed as a single molecule, p indicates the pressure, p0 indicates the vapor pressure of the adsorbent, c indicates parameters related to the heat of adsorption, etc. The vertical axis of FIG. 4 indicates the adsorption amount of Xe to MOF 1g (g _xe /g _MOF ), and the horizontal axis indicates the gas pressure of Xe (MPa). Here, point a in FIG. 4 means gas pressure: 0.1 MPa, adsorption amount: 0.80 g _xe /g _MOF , point b means gas pressure: 3 MPa, adsorption amount: 1.57 g _xe /g _MOF , point c means gas pressure: 1 MPa, adsorption amount: 1.27 g _xe /g _MOF , and point d means gas pressure: 0 MPa, adsorption amount: 0 g _xe /g _MOF .

Conventionally, since it was used between a and b, the gas pressure changes between 0.1 MPa and 3 MPa, and the gas adsorption amount changes between 0.80 g _xe /g _MOF and 1.57 g _xe /g _MOF . That is, in the conventional case, 0.77 g of gas can be stored for 1 g of MOF. On the other hand, when it is used between a and c, the gas pressure changes between 0 MPa and 1 MPa, and the adsorption amount changes between 0 g _xe /g _MOF and 1.27 g _xe /g _MOF . That is, by using it between a gas pressure of 0 MPa and 1 MPa, 1.27 g of gas can be stored for 1 g of MOF. Since space is a vacuum, the adsorbed gas can be released even at less than 1 MPa. Therefore, there is no problem even if the upper limit pressure of the gas is reduced, and the structural mass of the MOF-filled tank 1 can be reduced. Similarly, in the case of the vacuum device 20, the adsorbed gas can be released at less than 1 MPa, so the structural mass of the MOF-filled tank 1a can be reduced. In addition, the MOF-filled tanks 1 and 1a utilize a pressure range in which the change in the amount of gas adsorbed by MOFs is large, and therefore can store more gas than the tanks of conventional gas supply systems such as those in Non-Patent Document 1. This allows the tank volume to be reduced. As a result, the gas supply systems 100, 100A, and 100B can be made smaller than conventional gas supply systems.

As described above, the gas supply system according to this embodiment is lighter and smaller than conventional systems.

Although the preferred embodiment of the present invention has been described in detail above, the present invention is not limited to the specific embodiment, and various modifications and variations are possible within the scope of the present invention described in the claims. For example, the components in the above embodiment can be replaced with well-known components as appropriate, and the components of the above-mentioned modified examples can be combined as appropriate.

The present invention will be described in detail below with reference to examples, but the present invention is not limited to these.

(Evaluation of adsorption amount in MOF)
The MOFs used were MOF-74-Co and MO-74-Mg manufactured by Atomics. Each MOF molded into a pellet shape was filled into a separate tank, and the amount of Xe adsorbed per 1 g of MOF was measured when the pressure was changed from 0.004 MPa to 1000 MPa at room temperature. The results are shown in FIG. 5. The horizontal axis of FIG. 5 indicates pressure (kPa), and the vertical axis indicates the amount of Xe adsorbed per 1 g of MOF (g _xe /g _MOF ). When the Xe pressure was gradually increased from vacuum, both MOF-74-Co and MOF-74-Mg adsorbed about 0.7 g to 0.8 g of Xe per 1 g of MOF at 100 kPa. At 1000 kPa, MOF-74-Co and MOF-74-Mg adsorbed about 1.2 g to 1.4 g of Xe per 1 g of MOF. Therefore, if the lower limit of gas pressure is 1 atmosphere (100 kPa), as in the past, only about 0.7 g of Xe can be extracted per 1 g of MOF. On the other hand, it was found that if the pressure is reduced to 1 kPa, as in the case of use in space, almost all of the adsorbed Xe can be extracted.

(Gas supply system mass comparison)
A comparison of mass between a conventional gas supply tank and the fuel tank of this embodiment will be described.

(Conventional gas supply system)
Before comparing masses, a conventional gas supply system will be described. FIG. 6 shows a conventional gas supply system 300. The gas supply system of FIG. 6 is a two-stage pressure adjustment type gas supply system in combination with a mechanical modulator. This gas supply system 300 includes a high-pressure tank 20, a mechanical regulator 21, a solenoid valve 22, an accumulator 23, a thruster valve 24, and a flow controller 25. In this gas supply system 300, the mechanical regulator 21 reduces the pressure to 0.1 MPa, and then the solenoid valve 22 finely adjusts the gas pressure in the accumulator 23 to 0.03 MPa. The finely adjusted gas pressure is adjusted to 1 kPa by the thruster valve 24 and the flow controller 25, and sent to the thruster. When high-pressure gas is used, multiple pressure adjustment mechanisms are required, as described above, and the structural mass becomes high.

Table 1 shows a mass comparison between the gas supply system of this embodiment and a conventional gas supply system.

As shown in Table 1, the fuel tank, which was previously about 1,453 g, is now about 900 g. In this embodiment, the mass of the MOF is 640 g of the fuel tank. The fuel tank is made of low-pressure material instead of high-pressure material, so the mass of the fuel tank without the MOF is 260 g instead of 1,453 g. In addition, a regulator and a high-pressure drain valve are no longer necessary, so the mass is reduced compared to the conventional gas supply system. In addition, the tubes such as piping are also changed from the conventional high-pressure specification to a low-pressure specification of 1 MPa or less. In terms of volumetric ratio, the tank volume of the conventional fuel tank is 2 L, but when the MOF is used, it is 0.8 L, so the volume can be reduced by more than 50%. The reduction in volume also made it possible to reduce the weight of the bracket. As a result of the above weight reduction effect, the fuel mass/structural mass ratio, which was 30% in the conventional method, has been improved to 56% in the gas supply system of this embodiment.

The gas supply system according to this embodiment is lightweight and compact, making it highly applicable industrially.

REFERENCE SIGNS LIST 1 MOF filling tank 2 First pressure sensor 3 Valve 4 Regulator valve 5 Second pressure sensor 6 Accumulator tank 7 Thruster valve 8 Orifice 9 Thrusters 30a, 30b, 30c, 30d, 30e, 30f Piping 100 Gas supply system 200 Propulsion system

Claims (6)

A metal-organic framework filling tank is provided which is filled with a metal-organic framework that adsorbs a gas,
The pressure of the metal-organic framework filling tank is 0 Pa or more and 0.1 MPa or less .
Gas supply system. The gas supply system of claim 1, wherein the pressure is 0.01 Pa or more. The gas supply system according to claim 1 or 2, wherein the pressure is 0.1 Pa or more. The gas supply system according to any one of claims 1 to 3 , wherein the gas is xenon. The gas supply system according to any one of claims 1 to 4 , wherein the metal-organic framework is MOF-74. A propulsion system comprising a gas supply system according to any one of claims 1 to 5 .

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