Low-temperature propellant in-orbit low-loss storage system and method for deep space probe

Abstract

The invention relates to the technical field of deep space exploration, in particular to a cryogenic propellant on-orbit low-loss storage system and method for a deep space probe. After the low-temperature propellant is injected into the storage tank through the injection pipe, along with continuous accumulation of external leaked heat, the first pressure sensor detects that the pressure in the storage tank is continuously increased, and when the numerical value of the first pressure sensor exceeds the preset pressure, the cooling assembly is started to cool the low-temperature propellant in the storage tank, so that the external leaked heat is consumed; before the engine needs to supply the low-temperature propellant, the low-temperature propellant in the storage tank is in a supercritical state, and the storage temperature is increased in a high-pressure storage mode, so that the temperature difference between the storage tank and the outside and the heat leakage amount are reduced, and the requirement for the refrigerating capacity of the cooling assembly is reduced; when the low-temperature propellant is conveyed, due to the fact that the low-temperature propellant is in a supercritical state and free of gas-liquid phase separation, the interior of the whole storage box is in a homogeneous state, the stable conveying flow of the low-temperature propellant can be guaranteed, and stable output of an engine is also facilitated.

Description

Technical Field

[0001] The present invention relates to the technical field of deep space exploration, and particularly to a cryogenic propellant on-orbit low-loss storage system and method for a deep space probe. Background Art

[0002] Cryogenic propellants (such as liquid methane, liquid hydrogen, liquid oxygen, etc.) have significant advantages in deep space exploration missions. They have high energy density, can provide strong thrust for the probe, greatly improving the carrying capacity; the combustion products are clean and pollution-free, effectively avoiding interference with the environment of the detection target; in addition, the cost is relatively low and the resource consumption is less, meeting the requirements of long-distance and large-load deep space exploration, and becoming the core power choice for deep space exploration.

[0003] However, in deep space exploration missions, controlling the evaporation loss of cryogenic propellants during on-orbit storage faces severe challenges. Due to the complex space environment, cryogenic propellants are extremely prone to heat evaporation. Taking liquid methane as an example, its boiling point is only -161.5°C under normal pressure. The extremely hot environment encountered during on-orbit flight will cause a large amount of cryogenic propellants to evaporate, which will seriously restrict the on-orbit operation time of deep space probes. At the same time, deep space probes need to exhaust regularly during flight to maintain the tank pressure, and it is difficult to effectively separate the gas-liquid mixture (i.e., the state of cryogenic propellants in the tank is in a gas-liquid mixed state) in the microgravity environment of space. Therefore, a large amount of liquid cryogenic propellants will be entrained during the exhaust process, which will further exacerbate the loss of cryogenic propellants.

[0004] Therefore, there is an urgent need for a cryogenic propellant on-orbit low-loss storage system and method for a deep space probe to solve the above technical problems. Summary of the Invention

[0005] The embodiments of the present invention provide a cryogenic propellant on-orbit low-loss storage system and method for a deep space probe, which can achieve on-orbit low-loss storage of cryogenic propellants.

[0006] In a first aspect, the embodiments of the present invention provide a cryogenic propellant on-orbit low-loss storage system for a deep space probe, including a storage tank for containing cryogenic propellants. An adiabatic insulation layer is provided outside the storage tank. The storage tank is connected to a filling pipe, a discharge pipe, and a cooling component. The discharge pipe is sequentially connected to a throttling delivery pipe, a heat exchange pipe, and a supply pipe along the delivery direction of the cryogenic propellants. The throttling delivery pipe and the supply pipe are both provided outside the adiabatic insulation layer. The heat exchange pipe is provided between the storage tank and the adiabatic insulation layer. The supply pipe is connected to the engine of the deep space probe. A first pressure sensor is provided on the discharge pipe. A throttle valve and a regulating valve are provided on the throttling delivery pipe. A second pressure sensor and a flow sensor are provided on the supply pipe; After the cryogenic propellant is filled into the storage tank through the filling pipe, with the continuous accumulation of external heat leakage, the first pressure sensor detects that the pressure in the storage tank is continuously rising. When the value of the first pressure sensor exceeds the preset pressure, the cooling component is started to cool the cryogenic propellant in the storage tank; When the engine needs to supply cryogenic propellant, the cryogenic propellant is sequentially supplied to the engine through the discharge pipe, the throttle conveying pipe, the heat exchange pipe and the supply pipe, and the supply pressure and supply flow of the cryogenic propellant are adjusted through the throttle valve and the regulating valve respectively; wherein, before the engine needs to supply cryogenic propellant, the cryogenic propellant in the storage tank is in a supercritical state, and the preset pressure is higher than the minimum pressure when the cryogenic propellant is in a supercritical state.

[0007] In a second aspect, an embodiment of the present invention provides a method for on-orbit low-loss storage of cryogenic propellant for a deep space probe, which is applied to the system described in the above embodiment. The method includes a cryogenic propellant filling stage, a cryogenic propellant storage stage and a cryogenic propellant delivery stage in sequence, wherein: The cryogenic propellant storage stage includes: The initial pressure inside the storage tank after filling is one atmosphere, and the start stage of the storage stage relies on the passive heat insulation of the heat insulation layer; With the continuous accumulation of external heat leakage, the pressure inside the storage tank is continuously rising. When the pressure inside the storage tank exceeds the preset pressure, the cooling component is started to cool the cryogenic propellant in the storage tank, so as to consume the external heat leakage.

[0008] The present invention has at least the following beneficial effects compared with the related art: According to the cryogenic propellant on-orbit low-loss storage system and method for deep space probes provided by the embodiments of the present invention, after the cryogenic propellant is filled into the storage tank through the filling pipe, with the continuous accumulation of external heat leakage, the first pressure sensor detects that the pressure in the storage tank is continuously rising. When the value of the first pressure sensor exceeds the preset pressure, the cooling component is started to cool the cryogenic propellant in the storage tank, so as to consume the external heat leakage; before the engine needs to supply the cryogenic propellant, the cryogenic propellant in the storage tank is in a supercritical state. By storing it in a high-pressure manner, the storage temperature is increased, thereby reducing the temperature difference and heat leakage between the storage tank and the outside world. Furthermore, the refrigeration capacity requirement of the cooling component will also be reduced; when the cryogenic propellant is transported, due to being in a supercritical state, there is no distinction between gas and liquid phases, and the entire interior of the storage tank is in a homogeneous state. In this way, the transportation flow rate of the cryogenic propellant can be ensured to be stable, which is also beneficial to the stable output of the engine; by controlling the opening degrees of the throttle valve and the regulating valve, the supply pressure and supply flow rate of the cryogenic propellant are adjusted. The temperature of the cryogenic propellant after throttling and pressure reduction drops, and when the cryogenic propellant flows through the heat exchange pipe, it can exchange heat with the wall surface of the storage tank, thereby reducing the power consumption of the cooling component. Therefore, the above technical solution can achieve on-orbit low-loss storage of cryogenic propellants. Brief Description of the Drawings

[0009] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the following drawings are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0010] Figure 1 It is a schematic structural diagram of the cryogenic propellant on-orbit low-loss storage system for deep space probes provided by the embodiments of the present invention; Figure 2 is Figure 1 a schematic structural diagram of the heat exchanger in the on-orbit low-loss storage system shown.

[0011] Reference Signs: 1 - storage tank; 2 - adiabatic insulation layer; 3 - filling pipe; 4 - discharge pipe; 5 - cooling component; 6 - throttling and transportation pipe; 7 - heat exchange pipe; 8 - supply pipe; 9 - first pressure sensor; 10 - throttle valve; 11 - regulating valve; 12 - second pressure sensor; 13 - flow sensor; 14 - temperature sensor; 15 - overpressure discharge pipe; 16 - safety valve; 17 - active discharge pipe; 18 - stop valve; 51 - refrigerator; 52 - heat exchanger; 53 - circulation pump; 511 - cold head; 521 - heat exchange inlet; 522 - heat exchange outlet; 523 - copper foam. Detailed Embodiments

[0012] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of them. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts belong to the scope of protection of the present invention.

[0013] As Figure 1 shown, an in-orbit low-loss storage system for cryogenic propellants of a deep space probe provided by an embodiment of the present invention includes a storage tank 1 for containing cryogenic propellants. An adiabatic insulation layer 2 is provided outside the storage tank 1. The storage tank 1 is connected to a filling pipe 3, a discharge pipe 4 and a cooling assembly 5. The discharge pipe 4 is sequentially connected to a throttling conveying pipe 6, a heat exchange pipe 7 and a supply pipe 8 along the conveying direction of the cryogenic propellants. Both the throttling conveying pipe 6 and the supply pipe 8 are provided outside the adiabatic insulation layer 2. The heat exchange pipe 7 is provided between the storage tank 1 and the adiabatic insulation layer 2. The supply pipe 8 is connected to the engine of the deep space probe. A first pressure sensor 9 is provided on the discharge pipe 4. A throttle valve 10 and a regulating valve 11 are provided on the throttling conveying pipe 6. A second pressure sensor 12 and a flow sensor 13 are provided on the supply pipe 8; After the cryogenic propellants are filled into the storage tank 1 through the filling pipe 3, with the continuous accumulation of external heat leakage, the first pressure sensor 9 detects that the pressure in the storage tank 1 is continuously rising. When the value of the first pressure sensor 9 exceeds the preset pressure, the cooling assembly 5 is started to cool the cryogenic propellants in the storage tank 1; When the engine needs to be supplied with cryogenic propellants, the cryogenic propellants are sequentially supplied to the engine through the discharge pipe 4, the throttling conveying pipe 6, the heat exchange pipe 7 and the supply pipe 8, and the supply pressure and supply flow rate of the cryogenic propellants are adjusted through the throttle valve 10 and the regulating valve 11 respectively. Among them, before the engine needs to be supplied with cryogenic propellants, the cryogenic propellants in the storage tank 1 are in a supercritical state, and the preset pressure is higher than the minimum pressure when the cryogenic propellants are in a supercritical state.

[0014] In this embodiment, after the cryogenic propellant is filled into the storage tank 1 through the filling pipe 3, as the external heat leakage accumulates continuously, the first pressure sensor 9 detects that the pressure in the storage tank 1 is rising continuously. When the value of the first pressure sensor 9 exceeds the preset pressure, the cooling assembly 5 is started to cool the cryogenic propellant in the storage tank 1, so as to consume the external heat leakage. Before the engine needs to supply the cryogenic propellant, the cryogenic propellant in the storage tank 1 is in a supercritical state. By storing it in a high-pressure manner, the storage temperature is increased, thereby reducing the temperature difference and heat leakage between the storage tank 1 and the outside world. Furthermore, the cooling capacity requirement of the cooling assembly 5 will also be reduced. When the cryogenic propellant is being transported, since it is in a supercritical state and there is no distinction between gas and liquid phases, the entire interior of the storage tank is in a homogeneous state. In this way, the stable flow rate of the cryogenic propellant can be ensured, which is also beneficial to the stable output of the engine. By controlling the opening degrees of the throttle valve 10 and the regulating valve 11, the supply pressure and supply flow rate of the cryogenic propellant are adjusted. The temperature of the cryogenic propellant after throttling and pressure reduction drops, and when the cryogenic propellant flows through the heat exchange tube 7, it can exchange heat with the wall surface of the storage tank 1, thereby reducing the power consumption of the cooling assembly 5. Therefore, the above technical solution can achieve low-loss in-orbit storage of cryogenic propellants.

[0015] In an embodiment of the present invention, the storage tank 1 is made of a carbon fiber composite material, and the maximum allowable pressure of the storage tank 1 is greater than the preset pressure. With such a setting, it can not only meet the requirement that the storage tank 1 has a higher maximum allowable pressure for facilitating storage at a higher pressure, but also reduce the self-weight of the storage tank 1, thereby further extending the service life of the cryogenic propellant.

[0016] In an embodiment of the present invention, the difference between the maximum allowable pressure and the preset pressure is less than the difference between the preset pressure and the minimum pressure. With such a setting, the preset pressure can be made closer to the maximum allowable pressure, thereby further increasing the storage temperature and reducing the cooling capacity requirement.

[0017] In some embodiments, the maximum allowable pressure is 75 MPa and the preset pressure is 70 MPa.

[0018] For example, the traditional method for storing methane cryogenic propellant uses low-pressure (such as 0.3 MPa) liquid storage. The boiling point of liquid methane at 0.3 MPa is 126.71 K, and the density of liquid methane is 399.38 kg / m 3 , and according to a 90% filling rate of the storage tank, the storage density of the storage tank is 359.44 kg / m 3 . The storage temperature of the cryogenic propellant is positively correlated with the storage pressure of the storage tank. When the storage pressure is increased to 75 MPa, the storage density is 359.44 kg / m 3Under the condition, the storage temperature of methane is 238.5K. Compared with the traditional low-pressure liquid storage method, the above technical solution adopts the high-pressure supercritical state storage method, which can increase the storage temperature by more than 111K. Thus, the higher the storage temperature, the smaller the temperature difference with the outside world, the lower the heat leakage, and the smaller the cooling capacity requirement.

[0019] In addition, in a microgravity environment, due to the extremely weak gravitational field, the gravitational forces on the gas and liquid can be almost ignored, and it is impossible to achieve natural stratification and separation of the gas and liquid relying on gravity as on Earth. Therefore, in the traditional low-pressure liquid storage method (0.3MPa, 126.71K), the inside of the storage tank is often in a gas-liquid mixed state under microgravity conditions, and gas-liquid mixed transportation is inevitably caused during the transportation process, resulting in fluctuations in the flow rate of cryogenic propellant transportation and affecting the stable output of the engine. However, for cryogenic high-pressure storage (75.0MPa, 238.5K), at this time methane is in a supercritical state, there is no distinction between gas and liquid phases, the entire tank interior is in a homogeneous state, and the supply flow rate of cryogenic propellant is more stable, which is conducive to the stable output of the engine.

[0020] The supply pressure of the cryogenic propellant required by the thrust engine used in deep space probes is usually small, generally at 0.2MPa. It needs to be throttled and depressurized through a throttle valve first and then supplied to the propulsion engine. The temperature drop generated during the throttling process is recovered through a heat exchange tube, thereby reducing the power consumption of the refrigeration system.

[0021] In an embodiment of the present invention, the storage tank 1 is further connected with a temperature sensor 14, and the temperature sensor 14 is used to detect the real-time temperature of the cryogenic propellant in the storage tank 1; Based on the pressure detected by the first pressure sensor 9 and the temperature detected by the temperature sensor 14, determine the current remaining amount of the cryogenic propellant in the storage tank 1.

[0022] In an embodiment of the present invention, the discharge pipe 4 is further connected with an overpressure discharge pipe 15, and a safety valve 16 is provided on the overpressure discharge pipe 15; When the external heat leakage is greater than the cooling capacity of the cooling component 5, the safety valve 16 opens.

[0023] In an embodiment of the present invention, the discharge pipe 4 is further connected with an active discharge pipe 17, and stop valves 18 are provided on the filling pipe 3, the throttling and transportation pipe 6 and the active discharge pipe 17; When filling the cryogenic propellant, the stop valves 18 on the filling pipe 3 and the active discharge pipe 17 are both opened; When the safety valve 16 fails, the stop valve 18 on the active discharge pipe 17 is opened; When the engine needs to supply cryogenic propellant, the stop valve 18 on the throttling and transportation pipe 6 is opened.

[0024] In one embodiment of the present invention, the cooling assembly 5 includes a refrigerator 51, a heat exchanger 52 and a circulating pump 53 which are connected in sequence through pipelines. The refrigerator 51 is arranged outside the thermal insulation layer 2, and the heat exchanger 52 and the circulating pump 53 are both arranged inside the tank 1 and are both located on the central axis of the tank 1. The circulating pump 53 is used to suck the cryogenic propellant from the bottom of the tank 1 and send it into the heat exchanger 52. The refrigerator 51 is used to cool the cryogenic propellant entering the heat exchanger 52 so that the cooled cryogenic refrigerant is discharged horizontally from both sides of the heat exchanger 52.

[0025] In this embodiment, the cryogenic propellant is sucked from the bottom of the tank 1 by the circulation pump 53, sent to the heat exchanger 52 located at the top of the tank 1, and heat is exchanged with the cold head of the refrigerator 51, and the cooled cryogenic propellant is discharged horizontally from the side. This specially designed suction and discharge form will form a circulation in the vertical direction of the tank 1, break the fluid temperature stratification inside the tank 1, promote the mixing of the fluid, ensure the temperature uniformity of the cryogenic propellant in the tank, and improve the absorption speed of the refrigeration system with external heat leakage.

[0026] like Figure 2 As shown, in one embodiment of the present invention, the heat exchanger 52 includes a vertically arranged heat exchange inlet 521, two horizontally arranged heat exchange outlets 522, and a foam copper 523 respectively connected to the heat exchange inlet 521 and the heat exchange outlet 522. The cold head 511 of the refrigerator 51 is inserted into the foam copper 523, and the cryogenic propellant enters the foam copper 523 through the heat exchange inlet 521, and is discharged horizontally through the two heat exchange outlets 522 after heat exchange at the cold head 511.

[0027] In summary, different from the traditional liquid storage idea, the above technical solution uses a composite material high-pressure tank as a container to store methane cryogenic propellant at low temperature and high pressure, ensuring storage density and reducing the temperature difference of heat leakage from the inner tank to the outside, thereby reducing the demand for refrigeration capacity; cooperate with the internal circulation system of the refrigerator to absorb heat leakage and break the temperature stratification inside the tank; throttle and regulate the pressure of the transportation system, recover cold energy through the cold screen, and reduce the power consumption of the refrigeration system; it is expected to achieve low-power, low-loss or even zero-loss storage of methane cryogenic propellant in space orbit.

[0028] In addition, an embodiment of the present invention further provides a low-loss on-orbit storage method for cryogenic propellant for a deep space probe, which is applied to the system mentioned in the above embodiment. The method includes a cryogenic propellant filling stage, a cryogenic propellant storage stage and a cryogenic propellant delivery stage in sequence, wherein: The cryogenic propellant storage phase includes: The initial pressure inside the tank 1 after filling is one atmosphere, and the initial stage of the storage phase relies on the passive insulation of the thermal insulation layer 2; As the external heat leakage continues to accumulate, the pressure inside the tank 1 continues to rise. When the pressure inside the tank 1 exceeds the preset pressure, the cooling component 5 is started to cool the cryogenic propellant in the tank 1, thereby absorbing the external heat leakage.

[0029] In one embodiment of the present invention, the cryogenic propellant delivery stage includes: The opening of the throttle valve 10 and the regulating valve 11 is controlled to adjust the supply pressure and supply flow rate of the cryogenic propellant; wherein, the temperature of the cryogenic propellant after throttling and depressurization decreases, and when the cryogenic propellant flows through the heat exchange tube 7, it can exchange heat with the wall surface of the tank 1; Based on the pressure detected by the first pressure sensor 9 and the second pressure sensor 12 and the flow rate detected by the flow rate sensor 13, the openings of the throttle valve 10 and the regulating valve 11 are controlled to maintain the stability of the supply pressure and the supply flow rate.

[0030] It can be understood that the on-orbit low-loss storage method of cryogenic propellant for deep space probes provided in the embodiments of the present invention and the on-orbit low-loss storage system of cryogenic propellant for deep space probes provided in the above embodiments are based on the same inventive concept, and therefore both have the same beneficial effects. The beneficial effects of the on-orbit low-loss storage method of cryogenic propellant for deep space probes will not be elaborated herein.

[0031] The specific workflow is described below.

[0032] a. Ground filling of cryogenic propellants: Before refueling, ensure that all valves of the storage system are closed, connect the ground vacuum unit to the active discharge pipe, connect the nitrogen source to the filling pipe, open the stop valve on the active discharge pipe, turn on the ground vacuum unit, and evacuate to a pressure below 0.1Pa. Close the ground vacuum unit and the stop valve on the active discharge pipe, open the stop valve on the filling pipe and the ground nitrogen source, and pressurize the storage tank to 0.3MPa. Repeat the vacuuming and pressurizing operations more than three times until the gas in the pipe is completely replaced. Disconnect the ground vacuum unit and the nitrogen source, and connect the filling pipe to the liquid methane tank truck. Open the stop valve on the active discharge pipe and release the pressure in the pipe to the ambient pressure (i.e. one atmosphere). Open the stop valve on the filling pipe and the liquid outlet valve of the methane tank truck until 90% of the remaining volume is in the pipe. Close the stop valve on the filling pipe and the stop valve on the active discharge pipe, and disconnect the liquid methane tank truck.

[0033] b. Cryogenic propellant storage: The maximum working pressure of the tank is 75MPa. After filling, the initial pressure in the tank is one atmosphere. In the initial stage of storage, it only relies on the passive insulation of the composite insulation layer. As the external heat leakage continues to accumulate, the pressure in the tank continues to rise. When the pressure in the tank exceeds 70MPa, the refrigerator and circulation pump are turned on to start cooling the cryogenic propellant in the tank to absorb the external heat leakage.

[0034] c. Low-temperature propellant delivery: Open the globe valve on the throttle delivery pipe to output the low-temperature propellant outward, adjust the opening degrees of the throttle valve and the regulating valve, and adjust the output flow rate and pressure of the low-temperature propellant. The throttling and decompression process will cause the temperature of the low-temperature propellant to drop suddenly. The low-temperature propellant flows into the heat exchange pipe and exchanges heat with the wall surface of the storage tank to realize cold energy recovery and reduce the power consumption of the entire storage system. Through the pressure detection values of the first pressure sensor and the second pressure sensor and the flow detection value of the flow sensor, feedback control is performed on the opening degrees of the throttle valve and the regulating valve to maintain the stability of the delivery pressure and flow rate.

[0035] It should be noted that in this article, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "comprising an..." does not exclude the presence of additional identical elements in the process, method, article or device comprising the said element.

[0036] Finally, it should be noted that the above description is only a preferred embodiment of the present invention, and is only used to illustrate the technical solution of the present invention, and is not used to limit the protection scope of the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention are all included within the protection scope of the present invention.

Claims

1. A cryogenic propellant on-orbit low-loss storage system for deep space probes, characterized in that, It includes a storage tank (1) for containing cryogenic propellant. An adiabatic insulation layer (2) is provided outside the storage tank (1). The storage tank (1) is connected with a filling pipe (3), a discharge pipe (4) and a cooling assembly (5). The discharge pipe (4) is sequentially connected with a throttling conveying pipe (6), a heat exchange pipe (7) and a supply pipe (8) along the conveying direction of the cryogenic propellant. Both the throttling conveying pipe (6) and the supply pipe (8) are arranged outside the adiabatic insulation layer (2). The heat exchange pipe (7) is arranged between the storage tank (1) and the adiabatic insulation layer (2). The supply pipe (8) is connected with the engine of the deep space probe. A first pressure sensor (9) is arranged on the discharge pipe (4). A throttle valve (10) and a regulating valve (11) are arranged on the throttling conveying pipe (6). A second pressure sensor (12) and a flow sensor (13) are arranged on the supply pipe (8). After the cryogenic propellant is filled into the storage tank (1) through the filling pipe (3), with the continuous accumulation of external heat leakage, the first pressure sensor (9) detects that the pressure in the storage tank (1) is continuously rising. When the value of the first pressure sensor (9) exceeds the preset pressure, the cooling assembly (5) is started to cool the cryogenic propellant in the storage tank (1). When the engine needs to supply cryogenic propellant, the cryogenic propellant is sequentially supplied to the engine through the discharge pipe (4), the throttling conveying pipe (6), the heat exchange pipe (7) and the supply pipe (8), and the supply pressure and supply flow of the cryogenic propellant are respectively adjusted through the throttle valve (10) and the regulating valve (11). Wherein, before the engine needs to supply cryogenic propellant, the cryogenic propellant in the storage tank (1) is in a supercritical state, and the preset pressure is higher than the minimum pressure when the cryogenic propellant is in a supercritical state.

2. The system according to claim 1, wherein The storage tank (1) is made of carbon fiber composite material, and the maximum allowable pressure of the storage tank (1) is greater than the preset pressure.

3. The system according to claim 2, wherein The difference between the maximum allowable pressure and the preset pressure is less than the difference between the preset pressure and the minimum pressure.

4. The system according to claim 1, wherein The storage tank (1) is further connected with a temperature sensor (14), and the temperature sensor (14) is used to detect the real-time temperature of the cryogenic propellant in the storage tank (1). Based on the pressure detected by the first pressure sensor (9) and the temperature detected by the temperature sensor (14), the current remaining amount of the cryogenic propellant in the storage tank (1) is determined.

5. The system according to claim 1, characterized in that The discharge pipe (4) is further connected with an overpressure discharge pipe (15), and a safety valve (16) is arranged on the overpressure discharge pipe (15). When the external heat leakage is greater than the cooling capacity of the cooling assembly (5), the safety valve (16) opens.

6. The system according to claim 5, wherein The discharge pipe (4) is further connected with an active discharge pipe (17), and stop valves (18) are arranged on the filling pipe (3), the throttling conveying pipe (6) and the active discharge pipe (17). When filling the cryogenic propellant, the stop valves (18) on the filling pipe (3) and the active discharge pipe (17) are both opened. When a failure occurs in the safety valve (16), the stop valve (18) on the active discharge pipe (17) opens; When the engine needs to be supplied with cryogenic propellant, the stop valve (18) on the throttle delivery pipe (6) opens.

7. The system according to any one of claims 1-6, characterized in that, The cooling assembly (5) includes a refrigerator (51), a heat exchanger (52), and a circulation pump (53) that are sequentially connected by pipelines. The refrigerator (51) is disposed outside the heat insulation layer (2), and both the heat exchanger (52) and the circulation pump (53) are disposed inside the storage tank (1) and are located on the central axis of the storage tank (1). The circulation pump (53) is used to suck cryogenic propellant from the bottom of the storage tank (1) and send it into the heat exchanger (52). The refrigerator (51) is used to cool the cryogenic propellant entering the heat exchanger (52) so that the cooled cryogenic refrigerant is discharged horizontally from both sides of the heat exchanger (52).

8. The system according to claim 7, characterized in that, The heat exchanger (52) includes a vertically arranged heat exchange inlet (521), two horizontally arranged heat exchange outlets (522), and a copper foam (523) that is respectively connected to the heat exchange inlet (521) and the heat exchange outlets (522). The cold head (511) of the refrigerator (51) is inserted into the copper foam (523). The cryogenic propellant enters the copper foam (523) through the heat exchange inlet (521) and is discharged horizontally through the two heat exchange outlets (522) after heat exchange with the cold head (511).

9. A method for on-orbit low-loss storage of cryogenic propellants for deep space probes, characterized in that, Applied to the system according to any one of claims 1-8, the method includes successively progressive cryogenic propellant filling stage, cryogenic propellant storage stage, and cryogenic propellant delivery stage, wherein: The cryogenic propellant storage stage includes: The initial pressure inside the storage tank (1) after filling is one atmosphere, and the start stage of the storage stage relies on the passive heat insulation of the heat insulation layer (2); As the external heat leakage accumulates continuously, the pressure inside the storage tank (1) rises continuously. When the pressure inside the storage tank (1) exceeds the preset pressure, the cooling assembly (5) is started to cool the cryogenic propellant in the storage tank (1) so as to consume the external heat leakage.

10. The method according to claim 9, wherein The cryogenic propellant delivery stage includes: Controlling the opening degrees of the throttle valve (10) and the regulating valve (11) to adjust the supply pressure and supply flow rate of the cryogenic propellant; wherein, the temperature of the cryogenic propellant after throttling and pressure reduction drops, and the cryogenic propellant can exchange heat with the wall surface of the storage tank (1) when flowing through the heat exchange pipe (7); Based on the pressures detected by the first pressure sensor (9) and the second pressure sensor (12) and the flow rate detected by the flow sensor (13), controlling the opening degrees of the throttle valve (10) and the regulating valve (11) to maintain the stability of the supply pressure and supply flow rate.

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