Liquid immersion cooling network system for spacecraft and its control method

Abstract

To provide a liquid immersion cooling network system for a space machine that has enhanced environmental resistance, can obtain high cooling efficiency, and facilitates layout design.SOLUTION: A liquid immersion cooling network system includes: at least one of radiators 101a, 101b that performs heat exchange of a refrigerant; a plurality of pressure vessels G1-G3 that perform liquid immersion cooling by the refrigerant with an electronic apparatus placed inside; a heat transport network configured by connecting the plurality of pressure vessels and the radiator by a flexible pipe 103 through which the refrigerant flows; and forced flow generators P1, P2 that force the refrigerant to circulate through the heat transport network. The heat transport network includes at least one of control valves VL1, VL2. The control valve can adjust a flow rate of the refrigerant between different pressure vessels or between the radiator and the plurality of pressure vessels.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a technology for cooling electronic devices mounted on spacecraft. [Background Art]

[0002] It is expected that electronic devices mounted on spacecraft such as artificial satellites, particularly computers including CPUs (Central Processing Units) or processors, will reach a power consumption of 300 W or more in the future. For this reason, how to efficiently discharge heat generated by computers mounted on spacecraft is an extremely important issue.

[0003] For general electronic devices, for example, Patent Document 1 proposes a cooling system called a Loop Heat Pipe (LHP). An LHP is a cooling system that repeats a cycle in which a working fluid is circulated between an evaporator and a condenser, the working fluid is vaporized in the evaporator to cool electronic devices, and the working fluid vaporized in the condenser dissipates heat and liquefies. Patent Document 2 also discloses a cooling system that forcibly circulates a cooling liquid and adjusts the flow rate of the cooling liquid according to the calorific value for each electronic unit to be cooled.

[0004] As another cooling method, immersion cooling, in which electronic devices such as computers themselves are immersed in a refrigerant tank for cooling, has attracted attention in recent years. For example, Patent Document 3 discloses an immersion cooling apparatus that improves the cooling efficiency in a refrigerant tank by immersing an electronic device in the refrigerant tank filled with a first refrigerant, causing a second refrigerant to flow from the outside into a liquid-cooling jacket for cooling the electronic device, and causing the first refrigerant in the refrigerant tank to flow by a liquid flow generator in the refrigerant tank. In addition, Patent Document 4 discloses an immersion cooling apparatus that moves a refrigerant by a pump, and describes an example in which heat from electronic components is efficiently dissipated through convection and boiling of the refrigerant.

[0005] Furthermore, as a heat dissipation system installed on a spacecraft, a pump-type heat dissipation system is disclosed in Patent Document 5. In this pump-type heat dissipation system, a pump, an evaporator, and a condenser are connected three-dimensionally via piping. The refrigerant in liquid phase is forcibly circulated through the piping by the pump. That is, the refrigerant discharged from the pump vaporizes in the evaporator to become a two-phase gas-liquid flow, and the two-phase flow of refrigerant is then heated in the condenser, liquefied, and returned to the pump. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2014-052110 [Patent Document 2] Japanese Patent Publication No. 2022-064480 [Patent Document 3] Patent No. 6720752 [Patent Document 4] U.S. Patent No. 9750159B2 [Patent Document 5] Japanese Patent Publication No. 2021-097179 [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] However, in the cooling systems disclosed in Patent Documents 1 and 2, it is difficult to obtain high heat dissipation efficiency because the heat from the electronic equipment is dissipated by heat conduction between multiple components. Similarly, the heat dissipation system for spacecraft disclosed in Patent Document 5 also cools the electronic equipment by circulating a refrigerant between an evaporator and a condenser, making it difficult to obtain high heat dissipation efficiency.

[0008] Furthermore, the immersion cooling devices described in Patent Documents 3 and 4 are cooling methods intended for normal use on Earth. For this reason, they are not designed for use in environments with large vibrations, such as those experienced during rocket launches or in a weightless environment. In particular, in the weightless environment of space, convection of the refrigerant does not occur, so boiling bubbles do not detach from the heat dissipation fins, resulting in a dry-out phenomenon. In addition, the structure and manufacturing process become complicated because they require means to circulate a first refrigerant to immerse the electronic equipment and means to circulate a second refrigerant to cool the first refrigerant.

[0009] Furthermore, the electronic devices used as heat sources described in Patent Documents 1-4 are intended for consumer use and are not designed for use in harsh environments. Therefore, if use in environments where temperature, pressure, vibration, etc., are outside the normal range is expected, environmental resistance enhancement (ruggedization) technology is essential. No efficient cooling system for such environmentally resistant electronic devices is described in any patent document.

[0010] Furthermore, mounting equipment on a spacecraft requires integrating many devices into a limited space. The heat dissipation system described in Patent Document 5 requires electronic equipment to be placed in piping through which the refrigerant flows. This makes it difficult to freely arrange a large number of electronic devices, resulting in an unfavorable design.

[0011] Therefore, the object of the present invention is to provide a liquid immersion cooling network system for spacecraft and a control method thereof, which enhances environmental resistance, achieves high cooling efficiency, and facilitates layout design. [Means for solving the problem]

[0012] According to one aspect of the present invention, an immersion cooling network system mounted on a spacecraft cools electronic equipment by circulating a refrigerant, The refrigerant is used for heat exchange. multiple A radiator, a plurality of pressure vessels in which electronic equipment is placed inside and immersion cooling is performed by the refrigerant, and a flexible pipe through which the refrigerant flows between the plurality of pressure vessels and the multiple It is configured by connecting a radiator. , equipped with at least one control valve It comprises a heat transport network and a forced flow generator that forcibly circulates the refrigerant through the heat transport network, When the cooling capacity of the first radiator among the plurality of radiators falls below a predetermined value, the control valve is controlled to switch to the second radiator whose cooling capacity has not decreased, thereby adjusting the flow rate of refrigerant between different pressure vessels or between the plurality of radiators and the plurality of pressure vessels. It is characterized by the following: According to one aspect of the present invention, a control method for an immersion cooling network system mounted on a spacecraft that cools electronic equipment by flowing a refrigerant, wherein the immersion cooling network system exchanges heat with the refrigerant. multiple A radiator, a plurality of pressure vessels in which electronic equipment is placed inside and immersion cooling is performed by the refrigerant, and the plurality of pressure vessels and multiple The system comprises a heat transport network configured by connecting a radiator with a flexible pipe through which the refrigerant flows, and a forced flow generator that forcibly flows the refrigerant through the heat transport network, each of the plurality of pressure vessels having a refrigerant inlet and a refrigerant outlet connected to the flexible pipe, the refrigerant flowing in from the refrigerant inlet flowing over the surface of the electronic equipment and flowing out from the refrigerant outlet, the heat transport network comprising at least one control valve, the control valve capable of adjusting the flow rate of the refrigerant between different pressure vessels, and the control method comprising a control unit located in at least one of the plurality of pressure vessels monitoring the temperature in the plurality of pressure vessels, and the control unit adjusting at least one of the refrigerant distribution amount of the control valve and the refrigerant flow amount of the forced flow generator according to the temperature of each of the different pressure vessels. When the cooling capacity of the first radiator falls below a predetermined value, it switches to the second radiator, which does not have reduced cooling capacity. Control between the different pressure vessels or the multiple The method is characterized by controlling the refrigerant flow rate between the radiator and the plurality of pressure vessels. [Effects of the Invention]

[0013] According to the present invention, it is possible to provide a liquid immersion cooling network system for spacecraft that offers enhanced environmental resistance, high cooling efficiency, and easy layout design. [Brief explanation of the drawing]

[0014] [Figure 1] Figure 1 is a schematic diagram of a liquid immersion cooling network system according to one embodiment of the present invention. [Figure 2] Fig. 2 is a perspective view showing a schematic configuration of a pressure vessel (network grid) in the present embodiment. [Figure 3] Fig. 3 is a connection diagram showing an example of a heat transport network in the present embodiment. [Figure 4] Fig. 4 is a block configuration diagram showing the heat transport network and a valve control system in the present embodiment. [Figure 5] Fig. 5 is a side cross-sectional view showing a schematic configuration of an axial flow pump in the present embodiment. [Figure 6] Fig. 6 is a partial configuration diagram showing a first example of a valve control system in the heat transport network in the present embodiment. [Figure 7] Fig. 7 is a partial configuration diagram showing a second example of a valve control system in the heat transport network in the present embodiment. [Figure 8] Fig. 8 is a partial configuration diagram showing a first example of a control method for a heat transport network in the present embodiment. [Figure 9] Fig. 9 is a partial configuration diagram showing a second example of a control method for a heat transport network in the present embodiment. [Figure 10] Fig. 10 is a side cross-sectional view schematically showing an example of a pressure vessel in the present embodiment. [Figure 11] Fig. 11 is a cross-sectional view taken along line I-I of the pressure vessel shown in Fig. 10. DESCRIPTION OF EMBODIMENTS

[0015] <Outline of Embodiment> According to embodiments of the present invention, a plurality of pressure vessels, radiators, and flexible pipes constitute a heat transport network as network elements. Each pressure vessel has a refrigerant inlet and a refrigerant outlet connected to a flexible pipe, and the refrigerant flowing in from the refrigerant inlet flows over the surface of the electronic equipment and flows out from the refrigerant outlet. The refrigerant is forced to circulate through the heat transport network, causing it to flow through each pressure vessel and immersion-cooling the electronic equipment in each pressure vessel. In particular, by providing control valves in the heat transport network, it becomes possible to connect / disconnect or adjust the flow rate between the pressure vessels or between the pressure vessels and radiators, thereby enabling control of thermal interactions. The electronic equipment located in each pressure vessel is connected by an internal satellite network, and at least one of the electronic equipment includes a main computer that controls the heat transport network.

[0016] The flexible pipe is detachably connected to the refrigerant inlet and outlet of the pressure vessel and radiator by fittings at both ends.

[0017] Since the electronic equipment is immersed in a liquid coolant within a pressure vessel, its environmental resistance is enhanced by the pressure vessel walls and the coolant, and efficient cooling of the electronic equipment is possible through immersion. Furthermore, because multiple pressure vessels are detachably connected by flexible pipes to circulate the coolant, it becomes possible to lay out many electronic devices relatively freely even in the limited space of a spacecraft. This makes it possible to construct a cooling system within a spacecraft that has enhanced environmental resistance, high cooling efficiency, and facilitates layout design.

[0018] Embodiments of the present invention will be described in detail below with reference to the drawings. However, the components, their shapes, dimensions, dimensional ratios, and arrangements described in the following embodiments are illustrative examples for illustrating these embodiments and are not intended to limit the technical scope of the present invention to them alone.

[0019] 1. Structure As illustrated in Figure 1, the satellite 100, which is a spacecraft, is equipped with a radiator 101 for dissipating heat into space, and various mission equipment 102a and 102b. The radiator 101 may include multiple radiators, as will be described later. In addition, the main electronic equipment such as computers inside the satellite 100 is immersed in a coolant in pressure vessels G1 to G3 for liquid immersion cooling. Each pressure vessel Gi has a coolant inlet IL i and refrigerant outlet OL i A valve is provided (where i is any integer greater than or equal to 1, but here i=1, 2, or 3). The pressure vessels G1 to G3, radiator 101, and control valves VL1 and VL2 form a heat transport network through a plurality of flexible pipes 103 through which the refrigerant flows.

[0020] The heat transport network should be configured to ensure efficient immersion cooling in each pressure vessel. The refrigerant that has undergone heat exchange in the radiator 101 flows into each pressure vessel, and the refrigerant that flows out of each pressure vessel returns to the radiator 101. In particular, the control valves (VL1 and VL2) are controlled to ensure that the required amount of refrigerant is supplied to the pressure vessel that needs cooling. The network configuration shown in Figure 1 is an example.

[0021] In Figure 1, control valve VL1 distributes the refrigerant flowing out of radiator 101a's refrigerant outlet RO1 between pressure vessels G1 and G3. The refrigerant flowing from control valve VL1 to the refrigerant inlet IL1 of pressure vessel G1 immerses and cools the electronic equipment in pressure vessel G1 before flowing out of refrigerant outlet OL1 to control valve VL2. The refrigerant flowing from control valve VL1 to the refrigerant inlet IL3 of pressure vessel G3 immerses and cools the electronic equipment in pressure vessel G3 before flowing from refrigerant outlet OL3 to the refrigerant inlet RI1 of radiator 101a.

[0022] The refrigerant flowing out from the refrigerant outlet RO2 of radiator 101b flows into the refrigerant inlet IL2 of pressure vessel G2, immersing and cooling the electronic equipment in pressure vessel G2, and then flows out from the refrigerant outlet OL2 to the control valve VL2. The control valve VL2 causes the refrigerant flowing in from pressure vessels G1 and G2 to flow out to the refrigerant inlet RI2 of radiator 101b.

[0023] A forced flow generator for circulating refrigerant in the heat transport network is provided in a flexible pipe 103 connected to the refrigerant outlet of radiator 101. Here, an axial flow pump P1 is provided as a forced flow generator in the flexible pipe 103 connecting the refrigerant outlet RO1 of radiator 101a and the control valve VL1. Additionally, an axial flow pump P2 is provided in the flexible pipe 103 connecting the refrigerant outlet RO2 of radiator 101b and the refrigerant inlet IL2 of pressure vessel G2.

[0024] In this embodiment, the electronic equipment (mission edge) connected to mission equipment 102a is housed in pressure vessel G1, the electronic equipment (mission edge) connected to mission equipment 102b is housed in pressure vessel G2, and the electronic equipment (OBC: On-Board Computer) that controls the entire satellite is housed in pressure vessel G3. The electronic equipment in each pressure vessel can communicate with the electronic equipment in other pressure vessels or with mission equipment 102a and 102b via the satellite network NET. Furthermore, as will be described later, the OBC in pressure vessel G3 controls the control valves VL1 and VL2 via the satellite network NET or another network.

[0025] 2. Pressure vessel (for liquid immersion cooling) Hereafter, each of the pressure vessels G1 to G3 will be referred to as "pressure vessel G," and the structure of pressure vessel G will be explained with reference to Figure 2.

[0026] As illustrated in Figure 2, the pressure vessel G for liquid immersion cooling consists of a sealed cylindrical container body 201, with a lid 202 fixed to the bottom surface of the container body 201, and a refrigerant 203 sealed inside the pressure vessel. The lid 202 is provided with a refrigerant inlet IL through which the refrigerant flows into the container and a refrigerant outlet OL through which it flows out to the outside. Inside the pressure vessel G, a support part 204 is provided, fixed to the lid 202, and electronic equipment 205 is fixed to the support part 204. Therefore, the refrigerant flows in from the refrigerant inlet IL, flows over the electronic equipment 205, moves heat or bubbles, and flows out to the outside from the refrigerant outlet OL.

[0027] The cover 202 is also provided with terminals 206 and 207 for connecting to the satellite network NET. The electronic equipment 205 can communicate with other electronic equipment G or mission equipment in other pressure vessels through terminals 206 and 207. In this embodiment, the satellite network NET is an optical network consisting of optical fibers, but is not limited thereto. For example, it may be a local area network that communicates using electrical signals. Alternatively, terminal 206 may be an optical terminal for the optical network and terminal 207 may be an electrical terminal for the local area network.

[0028] Furthermore, the refrigerant 203 is a liquid that has electrical insulation and thermal conductivity, and it is particularly desirable that it contains hydrogen atoms to slow down and shield neutron radiation. As such a refrigerant 203, for example, a liquid such as a fluorocarbon substitute or polyester can be used.

[0029] 3. Heat transport network and fluid control system Next, with reference to Figure 3, a heat transport network using the flexible pipe 103 will be described.

[0030] Figure 3 shows two pressure vessels Gi and bGj, a 1-input, 2-output control valve VL, and flexible pipes 103a, 103b, and 103c for connecting them. Each of these flexible pipes consists of a high-vacuum hose and is equipped with a watertight fitting at both ends for detachable connection. Hereinafter, i, j, p, and q are any integers greater than or equal to 1 and are used as suffixes to indicate any pressure vessel or control valve.

[0031] The flexible pipe 103a, equipped with an axial flow pump P, has joints 104a and 105a at both ends, with joint 104a connected to the refrigerant outlet RO of the radiator 101 and joint 105a connected to the refrigerant inlet of the control valve VL. The flexible pipe 103b has joints 104b and 105b at both ends, with joint 104b connected to the first refrigerant outlet of the control valve VL and joint 105b connected to the refrigerant inlet IL of the pressure vessel Gj. jSimilarly, the flexible pipe 103c has joints 104c and 105c at both ends, with joint 104c connected to the second refrigerant outlet of the control valve VL and joint 105c connected to the refrigerant inlet IL of the pressure vessel Gi. i It is connected to the radiator. The joints provided at both ends of each flexible pipe must be resistant to temperature, pressure, and vacuum environments. The refrigerant flowing out of the radiator 101 is then flowed in the direction of the arrow by the axial flow pump P. The control valve VL can supply controlled amounts of refrigerant to the pressure vessels Gi and Gj, respectively. Flow rate control of the control valve VL will be described later.

[0032] The number of pressure vessels G, the number of mission equipment, and the distribution configuration of control valves VL are not limited to those shown in Figures 1 and 3. A generalized heat transport network and flow control system are shown in Figure 4.

[0033] As illustrated in Figure 4, the heat transport network 110 is assumed to consist of k pressure vessels G1 to Gk and a radiator 101, and n control valves VL1 to VLn and axial flow pumps P1 to On. Here, the electronic equipment of pressure vessels G1, G2 and Gi is assumed to be connected to mission equipment 102a, 102b and 102c, respectively. Furthermore, the electronic equipment of pressure vessel Gk has a computer that controls the control valves and includes a control unit 210 and a valve control unit 211.

[0034] Control valve VL1 distributes refrigerant from radiator 101 between pressure vessels G1 and G2, supplying a controlled amount of refrigerant to each. Similarly, control valve VLn supplies a controlled amount of refrigerant to pressure vessels Gi, Gj, and Gk, respectively. The refrigerant flowing out of each pressure vessel returns to radiator 101 via a path not shown. Note that the refrigerant distribution of control valve VL may be 1 input m (>3) output or multiple inputs and multiple outputs.

[0035] Each pressure vessel G has sensors to measure the temperature T and pressure Pr inside the vessel. The control unit 210 of pressure vessel Gn collects the measurements of each pressure vessel via the satellite network NET. The control unit 210 monitors the temperature T of each pressure vessel G and controls the bubble control unit 211 according to the temperature of each pressure vessel, supplying more refrigerant to pressure vessels with particularly high temperatures. More specifically, if the temperature of pressure vessel Gn exceeds a predetermined value and the temperatures of pressure vessels Gi and Gj are below a predetermined value, the corresponding control valve VLk is controlled to increase the flow rate of refrigerant to the pressure vessel Gn. In addition to controlling the control valve VLk, or independently, the flow rate of the axial flow pump Pn that flows refrigerant to the corresponding control valve VLn may be controlled to increase. The same control is also performed with the 1-input 2-output control valve VL1.

[0036] As illustrated in Figure 5, the axial flow pump P is installed inside the flexible pipe 103. The axial flow pump P consists of a motor 111 and a fan 112 attached to the rotating shaft of the motor 111. By rotating the fan 112, a flow 113 of refrigerant is generated inside the flexible pipe 103. The rotation speed of the motor 111 can be controlled, for example, by a control unit 210 provided in the pressure vessel Gk.

[0037] 4. Example of a heat transport network As described above, according to this embodiment, the heat transport network 110 can be thermally connected to or disconnected from the pressure vessel G and radiator 101 for liquid immersion cooling, and the thermal interaction between them can be controlled. Below, a simplified heat transport network will be illustrated to avoid complicating the explanation, and its configuration and control method will be described.

[0038] 4.1) First Example As illustrated in Figure 6, the heat transport network 110 includes a radiator 101, pressure vessels Gi and Gj, and control valves VLp and VLq. The axial flow pump P is omitted. Control valve VLp distributes refrigerant from radiator 101 to pressure vessel Gi and control valve VLq, supplying a controlled amount of refrigerant to each. Pressure vessel Gi cools electronic equipment by immersion cooling by circulating the refrigerant flowing in from control valve VLp. Refrigerant flowing out of pressure vessel Gi flows into control valve VLq.

[0039] The control valve VLq directs the refrigerant flowing in from the control valve VLp and the pressure vessel Gi, respectively, to the pressure vessel Gj and the radiator 101 in controlled quantities. The pressure vessel Gj immerses the electronic equipment by circulating the refrigerant flowing in from the control valve VLq. The refrigerant flowing out from the pressure vessel Gj flows into the radiator 101.

[0040] The control unit 210 monitors the temperatures of pressure vessels Gi and Gj. When the temperature of pressure vessel Gi rises above a predetermined value, the valve control unit 211 controls the control valve VLp to increase the refrigerant flow rate to pressure vessel Gi. This allows for individual control of the temperatures of pressure vessels Gi and Gj. Furthermore, when the temperature of pressure vessel Gj rises above a predetermined value, the valve control unit 211 controls the control valves VLp and VLq to decrease the refrigerant flow rate to pressure vessel Gi and increase the refrigerant flow rate to pressure vessel Gj. This ensures that refrigerant is supplied from the relatively lower-temperature pressure vessel Gi to the higher-temperature pressure vessel Gj, thereby equalizing the temperature of the pressure vessels as a whole.

[0041] In this way, by adjusting the degree of opening and closing of the control valves between the containers in the heat transport network 110, the temperature can be controlled differently for each container, enabling uniform or individual temperature control of multiple pressure vessels. For example, even if the permissible temperatures of the internal electronic equipment differ, the temperature of each pressure vessel can be controlled individually to maintain each electronic device within its permissible temperature range.

[0042] 4.2) Second Case As illustrated in Figure 7, the heat transport network 110 includes two radiators 101a and 101b, control valves VLi and VLj, and a partial network 111. The partial network 111 consists of multiple pressure vessels and control valves and constitutes part of the heat transport network 110. The radiators 101a and 101b are installed on opposite or differently oriented sides of the satellite's outer surface. Therefore, as the satellite's attitude changes the side exposed to sunlight, the heat dissipation capacity of one of the radiators 101a and 101b decreases while the heat dissipation capacity of the other increases. The control unit 210 can detect changes in heat dissipation capacity or cooling capacity, for example, by monitoring the temperature of the refrigerant flowing out of the radiators.

[0043] In the second example shown in Figure 7, the control valve VLi has two input ports and one output port, and can supply refrigerant from the refrigerant outlets ROa and ROb of radiators 101a and 101b, respectively, to the partial network 111 at a controlled flow rate. The control valve VLj also has one input port and two output ports, and can discharge refrigerant flowing in from the partial network 111 to the refrigerant inlets RIa and RIb of radiators 101a and 101b, respectively, at a controlled flow rate.

[0044] The control unit 210 monitors the temperature of the refrigerant flowing out of radiators 101a and 101b. If sunlight hits the radiator 101a and, for example, the cooling capacity of radiator 101a decreases, the control unit 210 controls control valves VLi and VLj to open the refrigerant flow path from radiator 101b to partial network 111. As a result, the refrigerant cooled by radiator 101b flows into partial network 111 through control valve VLi, and then returns from partial network 111 to radiator 101b through control valve VLj. Since radiator 101b is not exposed to sunlight and maintains its cooling capacity, the flow of refrigerant from radiator 101b into partial network 111 enables more effective immersion cooling.

[0045] By controlling the control valves VLi and VLj in this manner, the refrigerant flow path to the partial network 111 can be switched between radiator 101a and radiator 101b. Alternatively, the refrigerants from radiator 101a and radiator 101b can be mixed and supplied to the partial network 111 for recovery.

[0046] Furthermore, if the entire satellite is not exposed to sunlight and is subjected to a low-temperature environment for an extended period, control valves VLi and VLj that pass through the radiator can be closed to maintain temperature. In this case, the coolant may be circulated within the partial network 111.

[0047] 5. Examples of flow rate control According to this embodiment, the heat transport network 110 can control the thermal interaction between the pressure vessel G for liquid immersion cooling and the radiator 101. The refrigerant flow rate control of the liquid immersion cooling network system will be described below. The refrigerant flow rate control described below is performed by the control unit 210 and valve control unit 211 shown in Figure 4. The control unit 210 and valve control unit 211 illustrated in Figure 4 are implemented in a processor (or CPU), which is an electronic device located inside the pressure vessel Gk. The processor can realize the functions of the control unit 210 and valve control unit 211 by executing a program stored in a memory (not shown).

[0048] 5.1) First Case In Figure 8, the control unit 210 monitors the temperature of each pressure vessel G by pre-setting the permissible temperature range set for the electronic equipment of the multiple pressure vessels G1-Gk (operation S10). If there is a pressure vessel Gi whose temperature exceeds the first threshold T1 (YES in operation S11), the control unit 210 determines whether the temperature of a nearby pressure vessel Gj is below the second threshold T2 (operation S12). The nearby pressure vessel Gj is a pressure vessel that can supply refrigerant to pressure vessel Gi through a control valve. The first threshold T1 is a temperature lower than the upper limit of the permissible temperature range of the pressure vessel Gi, and the second threshold T2 is a temperature lower than the first threshold T1 but higher than the lower limit of the permissible temperature range.

[0049] If the temperature of the pressure vessel Gj is below the second threshold T2 (YES in operation S12), the control unit 210 controls the corresponding control valve so that refrigerant is supplied from the pressure vessel Gj to Gi (operation S13). If the temperature of the pressure vessel Gj is not below the second threshold T2 (NO in operation S12), the control unit 210 supplies refrigerant from the radiator to the pressure vessel Gj (operation S14).

[0050] If no pressure vessels exceed the first threshold T1 (NO in operation S11), the control unit 210 determines whether the temperature of all pressure vessels is below the third threshold T3 (operation S15). The third threshold T3 is lower than the second threshold T2 and higher than the lower limit of the allowable temperature range. If the temperature of all pressure vessels is below the third threshold T3 (YES in operation S15), the control unit 210 closes the control valve that goes through the radiator to shut off the radiator (operation S16). After operations S13, S14, or S16, or if the temperature of all pressure vessels is higher than the third threshold T3 (NO in operation S15), operations S10 to S16 are repeated.

[0051] 5.2) Second Case In Figure 9, the control unit 210 monitors the cooling capacity of multiple radiators by detecting the temperature of the refrigerant outlet of each radiator (operation S20). If the temperature of the refrigerant outlet of the current radiator exceeds a predetermined value and a decrease in cooling capacity is determined (operation S21, YES), the control unit 210 determines whether the cooling capacity of all radiators has decreased (operation S22). If there is a radiator whose cooling capacity has not decreased (operation S22, NO), the control unit 210 controls the control valves VLi and VLj to switch to the radiator whose cooling capacity has not decreased (operation S23). If the cooling capacity of the current radiator has not decreased (operation S21, NO), or if the cooling capacity of all radiators has decreased, the above operations S20 to S23 are repeated.

[0052] 6. Other examples of pressure vessels 6.1) Configuration Other examples of pressure vessels for immersion cooling used in this embodiment will be described below with reference to Figures 6 and 7. In the pressure vessel illustrated in Figure 2, a refrigerant inlet and outlet and signal terminals 206 and 207 were provided on one lid 202, but this is not the case. In the following examples, a refrigerant inlet and outlet are provided on one lid of the vessel body, and signal terminals are provided on the other lid.

[0053] In Figures 10 and 11, the immersion cooling system consists of a pressure vessel 300 and a heat transport network 400. The pressure vessel 300 consists of a cylindrical vessel body 301 and detachable first lid 310 and second lid 320 provided on opposing openings of the vessel body 301, respectively, and a refrigerant 330 is sealed inside the pressure vessel. The first lid 310 and the second lid 320 are airtightly joined to the openings on both sides of the vessel body 301 by a plurality of joining members 302 such as bolts. Here, the first lid 310 is used for the refrigerant system and the second lid 320 is used for the electrical system.

[0054] Mounting flanges 303 and 304 are provided at the center of both ends of the container body 301, and a plate 340, described later, is fixed to these mounting flanges 303 and 304 as mounting members. In addition, flanges 305 and 306 that protrude outward are provided at both open ends of the container body 301, and the first lid 310 and the second lid 320 are joined to these flanges, respectively.

[0055] The first lid 310 has a refrigerant outlet 311 through which the refrigerant 330 flows out, and a refrigerant inlet 312 through which the refrigerant 330, whose temperature has been regulated via the heat transport network 400, flows in. Furthermore, a sensor 313 for detecting the pressure and temperature inside the pressure vessel 300 is provided between the refrigerant outlet 311 and the refrigerant inlet 312, closer to the refrigerant outlet 311. The first lid 310 is also provided with a flange 314 that protrudes inward so as to contact the mounting flange 303 of the vessel body 301, located between the pressure / temperature sensor 313 and the refrigerant inlet 312. Thus, the flange 314 and the mounting flange 303 constitute a partition wall that separates the upper and lower parts of the pressure vessel 300 on the first lid 310 side (upper and lower parts of the paper in Figure 10) (see Figure 11). This prevents the refrigerant 330 flowing in from the refrigerant inlet 312 from flowing directly to the pressure / temperature sensor 313 and the refrigerant outlet 311. Furthermore, the opening of the first lid 310 is provided with a flange 315 that protrudes outward, and is joined to the flange 105 of the container body 301 by a joining member 302.

[0056] The second lid 320 has a hermetic terminal 321 in its approximate center, which is an electrical terminal for transmitting and receiving signals to and from the outside and for supplying power. The hermetic terminal 321 is connected to a connector 323 through a cable 322 inside the refrigerant 330, and the connector 323 is connected to a connector 342 provided on the circuit board 341. The opening of the second lid 320 is also provided with a flange 324 that protrudes outward, and is joined to the flange 306 of the container body 301 by a joining member 302.

[0057] A plate 340 is fixed inside the pressure vessel 300, supported at both ends by mounting flanges 303 and 304, which serve as mounting members. A circuit board 341 is fixed to the surface of the plate 340 on the refrigerant outlet 311 side, and a heat dissipation fin 343 is fixed to the surface on the refrigerant inlet 312 side. A connector 342 is provided at the end of the circuit board 341 on the second lid 320 side, and as described above, it is connected to a hermetic terminal 321 through a connector 323 and a cable 322. Therefore, by connecting the hermetic terminal 321 to the satellite network NET, it becomes possible to transmit and receive signals and supply power between the circuit board 341 and the outside. The circuit board 341 is an electronic device consisting of a semiconductor integrated circuit, and includes a computer such as an OBC.

[0058] The heat transport network 400 consists of a flexible pipe 401 connected to a refrigerant outlet 311 and a refrigerant inlet 312, a control valve 402 located near the refrigerant outlet 311, an axial flow pump 403 which is a forced flow generator located near the refrigerant inlet 312, and a heat sink 405 which acts as a radiator radiated to the flexible pipe 401. When the axial flow pump 403 is driven, the refrigerant 330 in the pressure vessel 300 flows from the refrigerant outlet 311 through the control valve 402 and the flexible pipe 401, and the heat of the refrigerant flowing through the flexible pipe 401 is discharged to the outside by the heat sink 405.

[0059] The refrigerant, thus dissipated heat, flows into the pressure vessel 300 from the refrigerant inlet 312 through the axial flow pump 403 and cools by flowing over the heat dissipation fins 343 and circuit board 341. At this time, even if the refrigerant 330 vaporizes and bubbles BB are formed due to the heat generated by the heat dissipation fins 343 and circuit board 341, the refrigerant 430 is forcibly flowed by the axial flow pump 403, so the bubbles BB flow with the refrigerant 330 and condense back into a liquid near the inner wall of the pressure vessel 300. In this way, the refrigerant 330 circulates through the flexible pipes 401 of the heat transport network 400 between the inside of the pressure vessel 300 and the refrigerant outlet 311 and refrigerant inlet 312.

[0060] As shown in Figure 6, the pressure vessel 300 described above is fixed to the mounting panel 500 of a satellite or the like by legs 501 and 502. The control valve 402 and heat sink 405 are also fixed to the mounting panel 500 by support members (not shown) to prevent them from coming loose due to vibration or the like. Even with the pressure vessel 300 and control valve 402 fixed in this way, the heat transport network can be configured relatively freely using the flexible pipe 401.

[0061] The refrigerant 330 is a liquid that has electrical insulating and thermal conductive properties, and it is particularly desirable that it contains hydrogen atoms to slow down and shield neutron radiation. As such a refrigerant 330, liquids such as alternative fluorocarbons or polyester can be used. When the temperature of the entire pressure vessel 300 is controlled to 60°C or below, the boiling point of the refrigerant 330 is, for example, about 76°C.

[0062] 6.2) Effects As described above, in the pressure vessel 300 illustrated in Figures 10 and 11, the area around the circuit board 341, which is an electronic device inside the vessel, is filled with flowing coolant 330, enabling efficient cooling. Furthermore, since the circuit board 341 is surrounded by the pressure vessel 300 and the coolant 330, its resistance to large vibrations and harsh environments such as space is enhanced.

[0063] Furthermore, since the flexible pipe 401 constitutes the heat transport network, the arrangement of the pressure vessel 300, control valve 402, and heat sink 405 can be designed with relatively freedom.

[0064] Furthermore, the pressure vessel 300 is divided into three parts: the vessel body 301, the first lid (for the refrigerant system), and the second lid (for the electrical system). By dividing the two lids in this way, one for the refrigerant system and the other for the electrical system, the design of the mechanical configuration of the vessel, the design of the thermal control system, and the design of the electrical system can be separated, making it easier to derive the optimal solution as a liquid immersion cooling device.

[0065] Regarding the support rigidity of the circuit board 341 mounted inside the pressure vessel 300, dedicated mounting flanges 303 and 304 are provided on both sides of the vessel body 301, and both ends of the plate 340 on which the circuit board is mounted are fixed to these flanges. This ensures the support rigidity required to meet vibration resistance requirements, for example, during rocket launch.

[0066] In this embodiment, a first lid 310 for the refrigerant system and a second lid 320 for the electrical system are provided on both sides of the container body 301, but the invention is not limited to this configuration. The first lid 310 and the second lid 320 can also be placed adjacent to each other if implementation is feasible.

[0067] Although the present invention has been described in detail based on its embodiments, it goes without saying that the present invention is not limited to the embodiments described above, and can be modified in various ways without departing from its essence. [Industrial applicability]

[0068] This invention is applicable to systems for cooling electronic devices such as computers used in harsh environments such as extremely cold / extremely hot regions or outer space. [Explanation of Symbols]

[0069] 100 satellites 101, 101a, 101b Radiators 102a, 102b Mission equipment G, G1-G3 pressure vessels OL1-OL3 refrigerant outlet IL1-IL3 refrigerant inlet NET satellite network RO1, RO2 radiator refrigerant outlet Refrigerant inlets for RI1 and RI2 radiators 201 Container body 202 Lid 203 Refrigerant 204 Support part 205 Electronic equipment 206, 207 Signal terminals

Claims

1. A liquid immersion cooling network system installed on a spacecraft that cools electronic equipment by circulating a coolant, Multiple radiators that exchange heat with the refrigerant, Multiple pressure vessels, each having electronic equipment placed inside and being cooled by liquid immersion using the refrigerant, A heat transport network is constructed by connecting the plurality of pressure vessels and the plurality of radiators with flexible pipes through which the refrigerant flows, and is equipped with at least one control valve. A forced flow generator that forcibly circulates the refrigerant through the heat transport network, Equipped with, When the cooling capacity of the first radiator among the plurality of radiators falls below a predetermined value, the control valve is controlled to switch to the second radiator whose cooling capacity has not decreased, thereby adjusting the flow rate of refrigerant between different pressure vessels or between the plurality of radiators and the plurality of pressure vessels. A liquid immersion cooling network system characterized by the following:

2. The immersion cooling network system according to claim 1, characterized in that the control valve distributes the refrigerant discharged from the radiator to the different pressure vessels at an adjusted flow rate.

3. The immersion cooling network system according to claim 1 or 2, wherein the electronic equipment disposed in at least one of the plurality of pressure vessels includes a control unit that monitors the temperature inside the plurality of pressure vessels and controls at least one of the refrigerant distribution amount of the control valve and the refrigerant flow rate of the forced flow generator according to the respective temperature of each of the different pressure vessels.

4. The immersion cooling network system according to claim 3, characterized in that the control unit controls the flow rate of the refrigerant to maintain the temperature of each pressure vessel within its respective allowable range.

5. The liquid immersion cooling network system according to claim 1 or 2, characterized in that the electronic equipment of the plurality of pressure vessels is connected to the satellite network via their respective signal terminals.

6. The immersion cooling network system according to claim 1 or 2, characterized in that the forced flow generator is an axial flow pump provided in at least one flexible pipe in the heat transport network, and the axial flow pump generates a flow of the refrigerant through the plurality of pressure vessels.

7. A control method for a liquid immersion cooling network system installed on a spacecraft that cools electronic equipment by circulating a refrigerant, The liquid immersion cooling network system comprises a plurality of radiators that exchange heat with a refrigerant, a plurality of pressure vessels in which electronic equipment is placed and liquid immersion cooling is performed by the refrigerant, a heat transport network formed by connecting the plurality of pressure vessels and the plurality of radiators with flexible pipes through which the refrigerant flows, and a forced flow generator that forcibly flows the refrigerant through the heat transport network, each of the plurality of pressure vessels having a refrigerant inlet and a refrigerant outlet connected to the flexible pipe, the refrigerant flowing in from the refrigerant inlet flowing over the surface of the electronic equipment and flowing out from the refrigerant outlet, the heat transport network comprising at least one control valve, the control valve capable of adjusting the flow rate of the refrigerant between different pressure vessels, The control method described above is: A control unit located in at least one of the plurality of pressure vessels monitors the temperature inside the plurality of pressure vessels. The control unit controls at least one of the refrigerant distribution amount of the control valve and the refrigerant flow rate of the forced flow generator according to the temperature of each of the different pressure vessels, and switches to a second radiator whose cooling capacity has not decreased when the cooling capacity of the first radiator in the plurality of radiators falls below a predetermined value, thereby controlling the refrigerant flow rate between the different pressure vessels or between the plurality of radiators and the plurality of pressure vessels. A control method for a liquid immersion cooling network system, characterized by the following features.

8. The control method for an immersion cooling network system according to claim 7, characterized in that the control unit controls the refrigerant flow rate to maintain the temperature of each pressure vessel within its respective allowable range.

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