Lightweight propellant tank on-orbit venting device based on regenerative liquid collector

Abstract

A kind of light-weight propellant tank exhaust device based on regenerative liquid collector in orbit, including cryogenic propellant tank, cryogenic propellant tank top is equipped with electromagnetic regulating valve and pressure sensor, electromagnetic regulating valve is connected with booster gas source;Cryogenic propellant tank inside is equipped with tube-shell heat exchanger and the liquid collector connected therewith;Liquid collector outlet is connected with cryogenic stop valve inlet by liquid delivery pipe;Cryogenic stop valve outlet is connected with circulating pump inlet, circulating pump outlet connects the inlet of shunt, the main stream outlet of shunt and the shell side of tube-shell heat exchanger are connected, the branch stream outlet of shunt is connected through throttle valve, first exhaust coil pipe in liquid collector and second exhaust coil pipe in tube-shell heat exchanger, second exhaust coil pipe outlet is connected with exhaust valve;Tube-shell heat exchanger top end is arranged with spray rod;The present application realizes the organic combination of exhaust coil pipe and liquid collector, significantly reduces the mass of exhaust system while improving its operation reliability.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of on-orbit exhaust of cryogenic propellant tank, and particularly relates to a lightweight propellant tank on-orbit exhaust device based on a regenerative liquid collector. BACKGROUND

[0002] Cryogenic propellant has been widely used in new generation of launch vehicles, and is an inevitable choice for future new upper stages, which will support future large-scale space projects such as moon landing and fire exploration. However, the problems of low temperature, low boiling point, easy evaporation and difficult storage of cryogenic propellant make it necessary to control the pressure of cryogenic propellant tank during on-orbit period, and exhaust pressure control is one of the most effective solutions. Under the condition of space microgravity, the distribution of gas and liquid is no longer significantly constrained by gravity, and presents the characteristics of chaotic distribution and easy disturbance by weak force. The liquid phase may cover the exhaust port, and if directly exhausted, the liquid phase may be discharged, causing waste of propellant and even attitude instability of the spacecraft. Researchers have proposed a thermodynamic exhaust system (Flachbart RH, Hastings LJ, Hedayat A, et al. Testing of a spray-bar thermodynamic vent system in liquid nitrogen [J]. AIP conference proceedings, 2006, 823(1): 240-247.), which mainly consists of a circulating pump, a throttle valve, a heat exchanger, an exhaust pipe and a spray rod. A small part of fluid (liquid or gas-liquid two-phase) is throttled, completely gasified by the heat exchanger and then discharged, realizing safe exhaust without dependence on gas-liquid phase relocation.

[0003] At present, the thermodynamic exhaust system is still in the ground experiment stage, and a mature scheme with engineering application ability has not been formed. The main limitation is that the circulating pump of the system still needs a stable supply of single-phase liquid, that is, it needs to be combined with a stable and reliable liquid acquisition device to ensure the stable operation of the thermodynamic exhaust system in orbit. However, the in-orbit gas-liquid separation technology of low-temperature fluid is also one of the key bottlenecks to be solved. The most feasible liquid acquisition devices such as liquid collection basket, flow trap, screen channel (Hartwig J W. A Detailed Historical Review of Propellant Management Devices for Low Gravity Propellant Acquisition [C] / / 52nd AIAA / SAE / ASEE Joint Propulsion Conference. July 25-27, 2016, Salt Lake City, UT) all have problems such as complex structure, large size, heavy mass, high risk of thermal sensitivity failure, etc., and do not have the engineering application of meeting the load economy. In order to accelerate the application of cold low-temperature propulsion system in future large space missions and improve the maturity of in-orbit management technology of low-temperature propellant, it is urgent to develop a lightweight propellant tank in-orbit exhaust device to improve the reliability, safety and economy of the low-temperature propulsion system. SUMMARY

[0004] In order to overcome the shortcomings of the prior art, the purpose of the present application is to provide a lightweight propellant tank in-orbit exhaust device based on a regenerative liquid collector, which combines the exhaust pipe of the thermodynamic exhaust system with the screen type liquid acquisition device, effectively reduces the additional mass of the liquid acquisition device, further utilizes the exhaust cold of the thermodynamic exhaust system to supercool the circulating pump inflow liquid, reduces the thermal sensitivity of the low-temperature thermodynamic exhaust system, and improves the long-term in-orbit performance of the low-temperature propulsion system, and improves the reliability, safety and economy of the low-temperature propulsion system.

[0005] In order to achieve the above purpose, the present application adopts the following technical scheme:

[0006] A lightweight propellant tank in-orbit exhaust device based on a regenerative liquid collector, comprising a low-temperature propellant tank 1, an electromagnetic regulating valve 16 and a pressure sensor 17 are arranged at the top of the low-temperature propellant tank 1, and the electromagnetic regulating valve 16 is connected with a pressurizing gas source 18; a shell-and-tube heat exchanger 11 and a liquid collector 2 connected therewith are arranged in the low-temperature propellant tank 1.

[0007] The outlet of the liquid collector 2 is connected with the inlet of the low-temperature stop valve 6 through the liquid delivery pipe 5; the outlet of the low-temperature stop valve 6 is connected with the inlet of the circulating pump 7, the outlet of the circulating pump 7 is connected with the inlet of the flow divider 8, the main flow outlet 8a of the flow divider 8 is connected with the shell side of the tube-shell heat exchanger 11, the branch flow outlet 8b of the flow divider 8 is connected with the throttling valve 9, the first exhaust coil 10 in the liquid collector 2 and the second exhaust coil 12 in the tube-shell heat exchanger 11, and the outlet of the second exhaust coil 12 is connected with the exhaust valve 15; the top of the tube-shell heat exchanger 11 is provided with the spray rod 13, and the spray rod 13 is provided with the jet hole 14.

[0008] The liquid collector 2 is arranged at the bottom of the low-temperature propellant storage tank 1, has a cylindrical structure, the upper cover plate 2a and the lower cover plate 2b of the liquid collector 2 are both solid wall surfaces, the upper cover plate 2a is provided with the outlet pipe 10b of the first exhaust coil 10, the lower cover plate 2b is provided with the liquid delivery pipe 5, the liquid delivery pipe 5 is arranged with the inlet pipe 10a of the first exhaust coil 10; the side wall surface of the liquid collector 2 is provided with a layer of metal screen 3 having a porous medium structure feature; the volume of the liquid collector 2 is determined according to the area of the metal screen 3 required by the flow of the circulating pump 7 in the actual task.

[0009] The liquid collector 2 is arranged with the temperature sensor 4 and the pressure sensor 17, which monitor and judge the gas-liquid phase distribution state in the liquid collector 2; when the fluid temperature measured by the temperature sensor 4 is higher than the low-temperature propellant saturation temperature corresponding to the pressure of the low-temperature propellant storage tank 1 measured by the pressure sensor 17, the electromagnetic regulating valve 16 is opened to carry out pre-pressurization exhaust circulation, so as to realize the elimination of the gas phase in the liquid collector 2 and full-liquid filling.

[0010] The first exhaust coil 10 has a spiral coil structure, and the outer diameter is the same as the inner diameter of the liquid collector 2, and the metal screen 3 arranged in the middle section of the liquid collector 2 is supported.

[0011] The flow ratio of the main flow outlet 8a side to the branch flow outlet 8b side of the flow divider 8 is (40-60):1.

[0012] The throttling valve 9 is a Joule-Thomson valve, which is designed in the throttling working condition by combining the inversion temperature and the inversion curve, so as to ensure that the low-temperature propellant always has a refrigeration effect in the throttling process.

[0013] The size and number of the spray rod 13, the aperture, the number and the spacing parameters of the jet hole 14 need to be determined according to the specific conditions of the tank size, the jet flow, the tank pressure in the actual task.

[0014] Compared with the prior art, the present application has the following beneficial effects:

[0015] The application effectively utilizes the exhaust pipe structure of the thermodynamic exhaust system. Compared with the sleeve exhaust pipe of the conventional thermodynamic exhaust system, the first exhaust coil can be used as the structural support of the metal screen of the liquid collector. Based on the liquid collector structure of the spiral exhaust coil, on the one hand, compared with the conventional liquid acquisition device, the independent metal wall surface is not needed as the structural support of the metal screen, only the screen surface and the upper and lower sealing plates and other assembly structures are needed, the additional mass of the liquid collector system is significantly reduced, and then the weight reduction of the overall design of the exhaust device is facilitated; the metal screen arranged in the cylindrical structure has the advantage of smaller sealing surface on the sealing structure compared with the planar arrangement, and the engineering application feasibility of the designed exhaust system is comprehensively improved.

[0016] On the other hand, the liquid collector with the first exhaust coil is equivalent to a regenerative heat exchanger before the circulating pump. The low-temperature and low-pressure fluid after throttling enters the first exhaust coil, can continuously cool the single-phase liquid in the liquid collector, reduces the risk of two-phase fluid caused by the leakage heat in the liquid collector, thereby improves the reliability of the single-phase liquid input of the circulating pump, and then improves the stability and safety of the exhaust device. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 is a structural schematic diagram of an embodiment of the application. DETAILED DESCRIPTION

[0018] The technical solutions of the application will be further described below in combination with the drawings and embodiments.

[0019] Referring to Figure 1 A light-weight propellant tank on-orbit exhaust device based on a regenerative liquid collector, comprising a low-temperature propellant tank 1, an electromagnetic regulating valve 16 and a pressure sensor 17 are arranged at the top of the low-temperature propellant tank 1, and the electromagnetic regulating valve 16 is connected with a pressurizing gas source 18; a tube-shell heat exchanger 11 and a liquid collector 2 connected therewith are arranged inside the low-temperature propellant tank 1.

[0020] The outlet of the liquid collector 2 is connected with the inlet of a low-temperature stop valve 6 through a liquid delivery pipe 5; the outlet of the low-temperature stop valve 6 is connected with the inlet of a circulating pump 7, the outlet of the circulating pump 7 is connected with the inlet of a flow divider 8, the main flow outlet 8a of the flow divider 8 and the shell side of the tube-shell heat exchanger 11 are connected, and the main flow liquid flowing through the main flow outlet 8a side enters the shell side of the tube-shell heat exchanger 11; the branch flow outlet 8b of the flow divider 8 is connected with a throttling valve 9, a first exhaust coil 10 in the liquid collector 2 and a second exhaust coil 12 in the tube-shell heat exchanger 11, the branch flow liquid flowing through the second outlet 8b side first enters the first exhaust coil 10 in the liquid collector 2 through the throttling valve 9, and then enters the second exhaust coil 12 in the tube-shell heat exchanger 11; the outlet of the second exhaust coil 12 is connected with an exhaust valve 15; a spray rod 13 is arranged at the top end of the tube-shell heat exchanger 11, and jet holes 14 are punched on the spray rod 13.

[0021] The liquid collector 2 is located at the bottom of the cryogenic propellant tank 1 and has a cylindrical structure. The upper sealing plate 2a and the lower sealing plate 2b of the liquid collector 2 are both solid walls. The upper sealing plate 2a is provided with the outlet pipe 10b of the first exhaust coil 10, and the lower sealing plate 2b is installed with the liquid delivery pipe 5. The inlet pipe 10a of the first exhaust coil 10 is arranged inside the liquid delivery pipe 5. A layer of metal screen 3 with porous media structure is installed on the side wall of the liquid collector 2. The volume of the liquid collector 2 needs to be determined according to the area of ​​the metal screen 3 required by the flow rate design of the circulating pump 7 in the actual mission.

[0022] The liquid collector 2 is equipped with a temperature sensor 4, which, together with the pressure sensor 17 arranged on the top of the cryogenic propellant tank 1, monitors and determines the gas-liquid phase distribution state inside the liquid collector 2. When the fluid temperature measured by the temperature sensor 4 is higher than the cryogenic propellant saturation temperature corresponding to the pressure of the cryogenic propellant tank 1 measured by the pressure sensor 17, the electromagnetic regulating valve 16 is opened to perform pre-pressurization and exhaust circulation, thereby eliminating the gas phase and filling the liquid collector 2 with liquid.

[0023] The first exhaust coil 10 is a spiral coil structure with an outer diameter that is the same as the inner diameter of the liquid collector 2, supporting the metal screen 3 arranged in the middle section of the liquid collector 2.

[0024] The diverter 8 is a three-way structure, with the flow ratio between the main outlet 8a and the branch outlet 8b being (40-60):1.

[0025] The throttling valve 9 is a Joule-Thomson valve, designed for throttling conditions based on the conversion temperature and conversion curve, ensuring that the cryogenic propellant throttling process always has a cooling effect.

[0026] The size and quantity of the spray rods 13, the diameter, number and spacing of the jet holes 14, and other parameters need to be determined according to the specific conditions such as the tank size, jet flow rate and tank pressure in the actual task. Existing orifice discharge flow models can be used for calculation and design.

[0027] The working principle of this invention is:

[0028] During the long-term on-orbit operation of the cryogenic propellant tank 1, the continuous heat leakage causes the temperature of the cryogenic propellant to rise continuously, resulting in the continuous increase of the pressure in the tank. When the pressure sensor 17 detects that the pressure in the cryogenic propellant tank 1 reaches the upper limit of the pressure control, and the temperature sensor 4 detects that the temperature of the fluid is always lower than the saturation temperature of the cryogenic propellant corresponding to the pressure detected by the pressure sensor 17, the cryogenic stop valve 6 and the exhaust valve 15 are opened, and the circulating pump 7 is started. Under the pumping action of the circulating pump 7, the liquid in the cryogenic propellant tank 1 will penetrate the metal screen 3 into the liquid collector 2 under the wetting action, and flow along the liquid delivery pipe 5 to the circulating pump 7. The metal screen 3 soaked by the liquid can block the gas phase within a certain pressure difference range by relying on the surface tension, realizing gas-liquid separation, so as to ensure that the circulating pump 7 is supplied with single-phase liquid. The liquid pumped by the circulating pump 7 is divided into two streams in the flow divider 8. The main stream liquid on the outlet 8a side of the main stream enters the shell side of the tube-in-shell heat exchanger 11, and the other stream on the outlet 8b side of the branch stream passes through the throttle valve 9. The low-temperature and low-pressure branch stream after throttling enters the first exhaust coil 10 and exchanges heat with the high-temperature fluid in the liquid collector 2, and the liquid collector 2 can continuously provide the circulating pump 7 with single-phase liquid at a lower temperature under the regenerative cooling effect. The branch stream after absorbing heat then enters the second exhaust coil 12, exchanges heat with the main stream high-temperature liquid in the tube-in-shell heat exchanger 11, and is completely gasified to complete the discharge of single-phase gas through the exhaust valve 15. The main stream fluid exchanges heat in the tube-in-shell heat exchanger 11, and the temperature gradually decreases, and finally enters the spray rod 13 at a lower temperature, and is sprayed to the gas pillow area and the liquid area of the cryogenic propellant tank 1 through the jet hole 14. The low-temperature jet flow mixes with the fluid in the cryogenic propellant tank 1 which has a higher temperature, and exchanges heat, so as to reduce the pressure in the tank by eliminating thermal stratification, increasing the supercooling degree of the liquid, and promoting the condensation of the gas pillow temperature. When the pressure sensor 17 detects that the pressure in the cryogenic propellant tank 1 decreases to the safe storage pressure range, the cryogenic stop valve 6, the circulating pump 7 and the exhaust valve 15 are closed, and the exhaust device stops working.

[0029] During the long-term on-orbit operation of the cryogenic propellant tank 1, when the temperature sensor 4 detects that the temperature of the fluid in the liquid collector 2 is higher than the saturation temperature of the cryogenic propellant corresponding to the pressure of the cryogenic propellant tank 1 detected by the pressure sensor 17, it indicates that the liquid in the liquid collector 2 is gasified, and cannot provide the circulating pump 7 with single-phase liquid. At this time, the electromagnetic regulating valve 16 is opened, the cryogenic propellant tank 1 is pressurized by the pressurizing gas source 18, the pressure of the cryogenic propellant tank 1 is increased to exceed the saturation pressure corresponding to the temperature detected by the temperature sensor 4 within the upper limit of the pressure, so that the gas existing in the liquid collector 2 is supercooled and liquefied under high pressure, and then the cryogenic stop valve 6, the circulating pump 7 and the exhaust valve 15 are opened, so as to realize the supply of single-phase liquid to the circulating pump 7. During the operation of the exhaust system, the fluid in the liquid collector 2 is also circulated and updated, and maintains a low temperature state under the regenerative precooling effect of the first exhaust coil 10, so as to ensure the safe and stable operation of the exhaust device.

[0030] The above examples only illustrate the basic principles and characteristics of the present application, and the present application is not limited to the above examples. Without departing from the spirit and scope of the present application, various changes and modifications can be made to the present application, and all modifications directly derived or thought of by those skilled in the art from the content disclosed in the present application should be considered as falling within the scope of the present application.

Claims

1. A lightweight propellant tank on-orbit venting device based on a regenerating liquid collector, comprising a cryogenic propellant tank (1), characterized in that: The cryogenic propellant tank (1) is equipped with an electromagnetic regulating valve (16) and a pressure sensor (17) on the top. The electromagnetic regulating valve (16) is connected to a pressurizing gas source (18). The cryogenic propellant tank (1) is equipped with a shell-and-tube heat exchanger (11) and a liquid collector (2) connected to it. The outlet of the liquid collector (2) is connected to the inlet of the cryogenic shut-off valve (6) through the liquid delivery pipe (5); the outlet of the cryogenic shut-off valve (6) is connected to the inlet of the circulating pump (7); the outlet of the circulating pump (7) is connected to the inlet of the distributor (8); the main outlet (8a) of the distributor (8) is connected to the shell side of the shell-and-tube heat exchanger (11); the branch outlet (8b) of the distributor (8) is connected to the first exhaust coil (10) in the liquid collector (2) and the second exhaust coil (12) in the shell-and-tube heat exchanger (11) through the throttle valve (9); the outlet of the second exhaust coil (12) is connected to the exhaust valve (15); a spray bar (13) is arranged at the top of the shell-and-tube heat exchanger (11); the spray bar (13) has jet holes (14) punched on it. The liquid collector (2) is equipped with a temperature sensor (4) and a pressure sensor (17) to monitor and determine the gas-liquid phase distribution state inside the liquid collector (2). When the fluid temperature measured by the temperature sensor (4) is higher than the cryogenic propellant saturation temperature corresponding to the pressure of the cryogenic propellant tank (1) measured by the pressure sensor (17), the electromagnetic regulating valve (16) is opened to perform pre-pressurization and exhaust circulation, thereby eliminating the gas phase and filling the liquid in the liquid collector (2).

2. The lightweight propellant tank on-orbit venting device based on a regenerative liquid collector according to claim 1, characterized in that: The liquid collector (2) is located at the bottom of the cryogenic propellant tank (1) and has a cylindrical structure. The upper sealing plate (2a) and the lower sealing plate (2b) of the liquid collector (2) are both solid walls. The upper sealing plate (2a) is provided with the outlet pipe (10b) of the first exhaust coil (10), and the lower sealing plate (2b) is equipped with a liquid delivery pipe (5). The inlet pipe (10a) of the first exhaust coil (10) is arranged inside the liquid delivery pipe (5). A layer of metal screen (3) with porous media structure is installed on the side wall of the liquid collector (2). The volume of the liquid collector (2) needs to be determined according to the area of ​​the metal screen (3) required by the flow rate design of the circulating pump (7) in the actual task.

3. The lightweight propellant tank on-orbit venting device based on a regenerative liquid collector according to claim 1, characterized in that: The first exhaust coil (10) is a spiral coil structure with an outer diameter that is the same as the inner diameter of the liquid collector (2), supporting the metal screen (3) arranged in the middle section of the liquid collector (2).

4. The lightweight propellant tank on-orbit venting device based on a regenerative liquid collector according to claim 1, characterized in that: The diverter (8) is a three-way structure, and the flow ratio between the main outlet (8a) and the branch outlet (8b) is (40-60):

1.

5. The lightweight propellant tank on-orbit venting device based on a regenerative liquid collector according to claim 1, characterized in that: The throttling valve (9) is a Joule-Thomson valve, which is designed for throttling conditions by combining the conversion temperature and conversion curve to ensure that the cryogenic propellant throttling process always has a cooling effect.

6. The lightweight propellant tank on-orbit venting device based on a regenerative liquid collector according to claim 1, characterized in that: The size and quantity of the spray bar (13), and the parameters of the diameter, number and spacing of the jet holes (14) need to be determined according to the specific conditions of the tank size, jet flow rate and tank pressure in the actual task.

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