A method for reducing the loss of liquid hydrogen during refueling

Abstract

This invention relates to the field of ground testing technology for hydrogen-oxygen rocket engines, and discloses a method for reducing liquid hydrogen refueling losses. The method includes: surrounding a liquid hydrogen container with a jacket; connecting the jacket to a first refueling valve, which in turn connects to a liquid nitrogen tanker via a second refueling valve; installing a temperature sensor inside the jacket to obtain the temperature of the inner wall of the jacket in real time; opening the first and second refueling valves to refuel the jacket with liquid nitrogen from the tanker; and stopping the refueling of liquid nitrogen into the jacket when the temperature obtained by the temperature sensor reaches -196℃±5℃ and is maintained at -196℃±5℃ for more than 30 minutes. This application pre-cools the liquid hydrogen container by adding liquid nitrogen into the jacket, ensuring that the liquid hydrogen container starts filling with liquid hydrogen in the liquid nitrogen temperature range on the day of the liquid hydrogen refueling test. This fundamentally reduces heat exchange and pre-cooling losses during the refueling process, significantly reducing test costs; and simultaneously ensuring the stability of the liquid hydrogen refueling process.

Description

Technical Field

[0001] This invention relates to the field of ground testing technology for hydrogen-oxygen rocket engines, and specifically to a method for reducing liquid hydrogen refueling losses. Background Technology

[0002] During the ground tests of hydrogen-oxygen rocket engines, liquid hydrogen is used as the core propellant. Due to its extremely low boiling point of approximately -252.87°C, liquid hydrogen is prone to heat exchange with the external environment during the refueling process, resulting in vaporization loss. This leads to high test costs and also affects the stability of the liquid hydrogen refueling process. Summary of the Invention

[0003] In view of this, the present invention provides a method for reducing the loss of liquid hydrogen during refueling, in order to solve the problem that in the existing liquid hydrogen refueling process, liquid hydrogen is easily subjected to heat exchange with the external environment, resulting in vaporization loss, which leads to high test costs and affects the stability of the liquid hydrogen refueling process.

[0004] This invention provides a method for reducing liquid hydrogen refueling losses, comprising:

[0005] A jacket is fitted and surrounded on the outside of the liquid hydrogen container; the jacket is connected to a first filling valve, which is connected to a liquid nitrogen tanker via a second filling valve.

[0006] A temperature sensor is provided on the inner wall of the jacket, and the temperature sensor is adapted to obtain the temperature of the inner wall of the jacket in real time.

[0007] Open the first and second filling valves to fill the jacket with liquid nitrogen from the liquid nitrogen tanker.

[0008] When the temperature sensor detects a temperature of -196℃±5℃ and maintains this temperature for at least 30 minutes, the first and second filling valves are closed, stopping the addition of liquid nitrogen to the jacket. Beneficial effects: This application employs the above technical solution, pre-cooling the liquid hydrogen container by adding liquid nitrogen to the jacket. This ensures that on the day of the liquid hydrogen filling test, the container starts filling with liquid hydrogen within the liquid nitrogen temperature range, fundamentally reducing heat exchange and pre-cooling losses during the filling process and significantly lowering test costs; simultaneously, it ensures the stability of the liquid hydrogen filling process.

[0009] Optionally, when the interval between liquid hydrogen refueling tests is ≤7 days, liquid nitrogen refueling shall be initiated from 14:00 to 18:00 on the day before the liquid hydrogen refueling test, and liquid nitrogen shall be added into the jacket at a rate of 32m³. 3 The injection rate is 5m 3 / h~8m 3 / h. Beneficial effects: This application adopts the above technical solution and develops a specially optimized liquid nitrogen refueling scheme for different test intervals in the ground liquid hydrogen refueling test of hydrogen-oxygen rocket engine, which shortens the liquid hydrogen refueling time on the test day, reduces the amount of liquid hydrogen loss, and achieves efficient pre-cooling of the liquid hydrogen container.

[0010] Optionally, when the interval between liquid hydrogen refueling tests is 7 to 15 days, liquid nitrogen refueling is initiated from 8:00 to 18:00 on the day before the liquid hydrogen refueling test, and liquid nitrogen is added into the jacket at a rate of 60m³. 3 The injection rate is 5m 3 / h~8m 3 / h. Beneficial effects: This application adopts the above technical solution and develops a specially optimized liquid nitrogen refueling scheme for different test intervals in the ground liquid hydrogen refueling test of hydrogen-oxygen rocket engine, which shortens the liquid hydrogen refueling time on the test day, reduces the amount of liquid hydrogen loss, and achieves efficient pre-cooling of the liquid hydrogen container.

[0011] Optionally, when the interval between liquid hydrogen refueling tests is >15 days, liquid nitrogen refueling shall be initiated from 8:00 to 18:00 two days before the liquid hydrogen refueling test, and liquid nitrogen shall be added into the jacket at a rate of 33m³. 3 Maintain the temperature of the inner wall of the jacket at -196℃±5℃ and let it stand for 24 hours; then, on the day before the test, add 60ml of liquid nitrogen into the jacket between 10:00 and 18:00. 3 This stabilizes the temperature of the inner wall of the jacket at -196℃±5℃. Beneficial effects: This application employs the above technical solution to develop a specially optimized liquid nitrogen refueling scheme for different test intervals during ground liquid hydrogen refueling tests of hydrogen-oxygen rocket engines. Liquid nitrogen is added one day before the test, shortening the liquid hydrogen refueling time on the test day, reducing liquid hydrogen loss, and achieving efficient pre-cooling of the liquid hydrogen container.

[0012] Optionally, it also includes:

[0013] One day before the liquid hydrogen filling test, from 14:00 to 17:00, liquid nitrogen was added into the jacket until it overflowed, and then left to stand for 20 minutes.

[0014] Liquid nitrogen was repeatedly injected into the jacket, with each injection lasting 10 to 15 seconds, at a rate of 8 m / s. 3 / h~10m 3 / h; After each addition of liquid nitrogen, let it stand for 20 minutes and monitor the temperature change of the inner wall of the jacket using a temperature sensor until the temperature of the inner wall of the jacket stabilizes at -196℃±5℃.

[0015] Optionally, the temperature of the jacket inner wall is stabilized to -196℃±5℃ at 18:00 the day before the liquid hydrogen refueling test. Beneficial effects: This application adopts the above technical solution to precisely control the time and temperature conditions for refueling completion. It adjusts the traditional mode where the liquid nitrogen replenishment completion time is not fixed the day before the test to complete replenishment at 18:00 the day before the test, ensuring the pre-cooling temperature. By shortening the interval between the replenishment completion time and the test time, the pre-cooling effect of the liquid hydrogen container is significantly improved, achieving efficient pre-cooling of the liquid hydrogen container and further reducing liquid hydrogen loss.

[0016] Optionally, the jacket is elastic, and the volume of the jacket is 1 / 5 to 1 / 3 of the volume of the liquid hydrogen container; the temperature sensor is a platinum resistance temperature sensor.

[0017] Optionally, the liquid hydrogen container is connected to a filling pipeline via a third filling valve; a composite insulation structure is provided around the outer periphery of the filling pipeline;

[0018] The composite insulation structure includes:

[0019] A vacuum insulation layer is wrapped around the outer periphery of the filling pipe; the vacuum insulation layer is a stainless steel shell, and a vacuum is drawn inside the stainless steel shell;

[0020] A glass wool layer is wrapped around the outer periphery of the vacuum insulation layer, and the glass wool layer is a porous structure formed by glass wool.

[0021] A sealing and protective layer, made of polytetrafluoroethylene (PTFE) film, is wrapped around the outer periphery of the glass wool layer using a hot-press sealing process. Beneficial effects: This application employs the above technical solution, which, through a composite insulation structure, significantly improves the heat resistance and insulation performance of the filling pipeline, reduces the heat exchange rate between the filling pipeline and the external environment, and significantly reduces the vaporization loss of liquid hydrogen during the filling process. Specifically, the vacuum environment of the vacuum insulation layer blocks the conduction and convection paths of heat, the porous structure of the glass wool layer enhances its ability to block radiative heat transfer, and the sealing and protective layer prevents external water vapor from seeping in and causing a decrease in insulation performance, while also resisting mechanical friction damage to the inner structure.

[0022] Optionally, the thickness of the stainless steel casing ranges from 2 mm to 3 mm; the stainless steel casing is evacuated to a vacuum level of 10. -3 Below Pa; the density range of the glass wool is 60 kg / m³. 3 ~80kg / m 3 The thickness of the glass wool layer ranges from 50 mm to 80 mm; the thickness of the polytetrafluoroethylene film ranges from 0.1 mm to 0.2 mm.

[0023] Optionally, the liquid hydrogen container is connected to a liquid outlet valve and a pressure relief valve; the jacket is connected to a venting valve;

[0024] When adding liquid nitrogen into the jacket, open the first filling valve, the second filling valve, and the venting valve, and close the liquid outlet valve;

[0025] When stopping the addition of liquid nitrogen into the jacket, close the first filling valve, the second filling valve, and the venting valve. Attached Figure Description

[0026] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0027] Figure 1 This is a schematic diagram of the connection setup involved in the method for reducing liquid hydrogen refueling loss provided in an embodiment of the present invention.

[0028] Explanation of reference numerals in the attached figures:

[0029] 1. Liquid nitrogen tanker; 2. First pressure gauge; 3. First filling valve; 4. Filter; 5. Second filling valve; 6. Second pressure gauge; 7. Discharge valve; 8. Third filling valve; 9. Liquid hydrogen container; 10. Level gauge; 11. Venting valve; 12. Pressure boosting valve; 13. Jacket; 14. Filling pipeline. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0031] Existing technologies cannot systematically optimize pipeline insulation, container precooling, and supplemental cooling strategies, resulting in persistently high liquid hydrogen refueling losses. This not only significantly increases testing costs but may also affect the accuracy of test results due to insufficient liquid hydrogen supply stability. Therefore, this application proposes a method to specifically address the above problems and reduce liquid hydrogen refueling losses. Through multi-dimensional optimization, it achieves efficient liquid hydrogen refueling and cost control, meeting the urgent needs of the hydrogen-oxygen rocket engine testing field.

[0032] like Figure 1One specific embodiment of the method for reducing liquid hydrogen refueling losses, as shown, includes:

[0033] A jacket 13 is fitted and surrounds the outside of a liquid hydrogen container 9; the liquid hydrogen container 9 can be a high-pressure liquid hydrogen container 9. The jacket 13 is internally connected to a first filling valve 3, which is connected to a liquid nitrogen tanker 1 via a second filling valve 5. A temperature sensor is installed on the inner wall of the jacket 13, suitable for real-time monitoring of the temperature of the inner wall of the jacket 13. The first filling valve 3 and the second filling valve 5 are opened, and liquid nitrogen is added to the jacket 13 from the liquid nitrogen tanker 1; when the temperature obtained by the temperature sensor reaches -196℃±5℃ and is maintained at -196℃±5℃ for more than 30 minutes, the first filling valve 3 and the second filling valve 5 are closed, stopping the addition of liquid nitrogen to the jacket 13. The jacket 13 has a cavity capable of containing liquid nitrogen. The first filling valve 3 is DN50.

[0034] The method for reducing liquid hydrogen refueling losses described in this application can be applied to ground tests of hydrogen-oxygen rocket engines.

[0035] Furthermore, a first pressure gauge 2 can be installed on the connecting pipeline between the second filling valve 5 and the liquid nitrogen tanker 1. The first pressure gauge 2 is adapted to obtain the pressure of the liquid nitrogen output from the liquid nitrogen tanker 1. A filter 4 is provided between the first filling valve 3 and the second filling valve 5. The filter 4 is adapted to filter the liquid nitrogen flowing from the second filling valve 5 to the first filling valve 3. A second pressure gauge 6 is provided inside the jacket 13 and between it and the first filling valve 3. The second pressure gauge 6 is adapted to obtain the pressure of the liquid nitrogen input into the jacket 13.

[0036] The existing liquid hydrogen container 9 lacks a pre-cooling mechanism, and no pre-cooling scheme has been established for it to match the test interval. Before adding liquid hydrogen, the body temperature of the liquid hydrogen container 9 is much higher than the liquid hydrogen temperature range, and violent heat exchange and vaporization occur immediately after the liquid hydrogen is injected; moreover, the temperature of the liquid hydrogen container 9 rises rapidly during the test interval, further aggravating liquid hydrogen loss. Therefore, this application further proposes the following implementation method. Based on the test interval time of the hydrogen-oxygen rocket engine, this application has determined the following three differentiated pre-cooling schemes through statistical analysis of more than 20 sets of orthogonal experiments.

[0037] Specifically, when the interval between liquid hydrogen refueling tests is ≤7 days, the liquid nitrogen tanker 1 will be in place one day before the test, and liquid nitrogen refueling will be initiated between 14:00 and 18:00, adding liquid nitrogen into jacket 13 at a rate of 32m³. 3 The injection rate is 5m 3 / h~8m 3 / h, ensuring that the temperature of the inner wall of jacket 13 is stable at -196℃±5℃ after filling.

[0038] Specifically, when the interval between liquid hydrogen refueling tests is 7 to 15 days, liquid nitrogen refueling is initiated from 8:00 to 18:00 on the day before the test, with liquid nitrogen being added to jacket 13 at a rate of 60m³. 3 The injection rate is 5m 3 / h~8m 3 / h. The above implementation compensates for the temperature rise of the liquid hydrogen container 9 over a longer interval by increasing the filling volume.

[0039] Existing cooling strategies are unreasonable. Traditional liquid nitrogen replenishment has no fixed completion time, and the timing of replenishment is poorly matched with the commissioning time, resulting in unstable pre-cooling effect of liquid hydrogen container 9. This can lead to increased liquid hydrogen loss due to insufficient pre-cooling or waste of liquid nitrogen due to excessive replenishment. Therefore, this application proposes the following implementation method.

[0040] Specifically, when the interval between liquid hydrogen refueling tests is greater than 15 days, the refueling is carried out in two stages. First, two days before the liquid hydrogen refueling test, from 8:00 to 18:00, liquid nitrogen refueling is initiated, adding liquid nitrogen to jacket 13 at a rate of 33m³. 3 Maintain the temperature of the inner wall of jacket 13 at -196℃±5℃ and let it stand for 24 hours; then, on the day before the test, add 60ml of liquid nitrogen into jacket 13 from 10:00 to 18:00. 3 This ensures that the temperature of the inner wall of jacket 13 is stabilized at -196℃±5℃.

[0041] By matching the test interval and selecting the corresponding pre-cooling implementation method, it is ensured that the temperature difference between the liquid hydrogen container 9 and the liquid hydrogen temperature zone is ≤10℃ before liquid hydrogen injection, thus avoiding violent vaporization during the initial injection of liquid hydrogen.

[0042] Furthermore, the method for reducing liquid hydrogen refueling loss described in this application also includes: one day prior to the liquid hydrogen refueling test, from 14:00 to 17:00, adding liquid nitrogen to jacket 13 until overflow, allowing it to stand for 20 minutes, during which time the temperature of jacket 13 rises to -180℃±5℃ due to environmental heat exchange. Then, initiating an intermittent pulsed replenishment program, specifically: repeatedly adding liquid nitrogen to jacket 13, each injection lasting 10 to 15 seconds, at a rate of 8m / s. 3 / h~10m 3 / h; After each addition of liquid nitrogen, let it stand for 20 minutes and monitor the temperature change of the inner wall of jacket 13 using a temperature sensor until the temperature of the inner wall of jacket 13 stabilizes at -196℃±5℃.

[0043] Based on different test intervals of hydrogen-oxygen rocket engines, this application formulates the above three differentiated liquid nitrogen refueling schemes to replace the traditional single mode of uniform liquid nitrogen refueling the day before the test. By matching the test intervals and selecting the corresponding scheme, the liquid hydrogen container 9 is pre-cooled more fully, improving the temperature stability of liquid hydrogen, shortening the liquid hydrogen refueling time, reducing liquid hydrogen loss and test costs.

[0044] Furthermore, at 18:00 one day before the liquid hydrogen refueling test, the temperature of the inner wall of jacket 13 was stabilized at -196℃±5℃. This ensured that the liquid hydrogen container 9 was fully immersed in a low-temperature environment after refueling and before the test run, preventing the temperature from rising again.

[0045] The above-mentioned supplementary implementation method can reduce liquid nitrogen waste by about 15% to 20% while ensuring the cryogenic state of liquid hydrogen container 9, thus balancing precooling effect and economy.

[0046] In summary, this application reduces the initial liquid hydrogen injection loss rate by 40% to 50% through the aforementioned differentiated precooling method; combined with intermittent pulse replenishment, the total liquid hydrogen loss rate throughout the experiment is reduced by 30% to 40%.

[0047] Specifically, the jacket 13 is elastic, and its volume is 1 / 5 to 1 / 3 of the volume of the liquid hydrogen container 9; the temperature sensor is a platinum resistance temperature sensor. Three to five platinum resistance temperature sensors are evenly arranged on the inner wall of the jacket 13, and the measurement accuracy of the platinum resistance temperature sensors is ±0.5℃.

[0048] Furthermore, the liquid hydrogen container 9 is connected to the filling pipe 14 via the third filling valve 8.

[0049] Existing refueling pipes 14 generally employ a single insulation layer design, which has limited heat resistance and insulation capabilities. The heat exchange effect between the refueling pipe 14 and the external environment is significant, leading to a large amount of liquid hydrogen vaporizing and being lost during transportation; that is, the insulation performance of the refueling pipe 14 is insufficient. Therefore, this application incorporates a composite insulation structure around the outer periphery of the refueling pipe 14. This replaces the original single insulation layer on the refueling pipe 14 with a composite insulation structure. Liquid hydrogen can be added to the liquid hydrogen container 9 through the third refueling valve 8 and the refueling pipe 14. The original single insulation layer is typically a 50 mm thick polyurethane insulation layer. The total length of the refueling pipe 14 is typically 20 meters.

[0050] Specifically, the composite insulation structure includes a vacuum insulation layer, a glass wool layer, and a sealing and protective layer. The vacuum insulation layer wraps around the outer periphery of the filling pipe 14; the vacuum insulation layer is a stainless steel shell, and a vacuum is drawn inside the stainless steel shell. The stainless steel shell can be made of 304 stainless steel. The glass wool layer wraps around the outer periphery of the vacuum insulation layer, and the glass wool layer has a porous structure formed by glass wool. The glass wool is ultrafine glass wool. The sealing and protective layer wraps around the outer periphery of the glass wool layer, and the sealing and protective layer is a polytetrafluoroethylene (PTFE) film, which is wrapped around the outer periphery of the glass wool layer through a hot-press sealing process. That is, the vacuum insulation layer is the inner layer, the glass wool layer can be a middle layer of ultrafine glass wool, and the sealing and protective layer is the outer layer. Through the above-mentioned composite insulation structure, this application can reduce the heat exchange coefficient between the filling pipe 14 and the external environment by 40%–50%, and reduce the liquid hydrogen loss rate during pipeline transportation by 25%–35%, significantly reducing the vaporization loss of liquid hydrogen during transportation.

[0051] Specifically, the thickness of the stainless steel shell ranges from 2 mm to 3 mm; the stainless steel shell is evacuated to a vacuum level of 10. -3 Below Pa; the density range of the glass wool is 60 kg / m³. 3 ~80kg / m 3 The thickness of the glass wool layer ranges from 50 mm to 80 mm; the thickness of the polytetrafluoroethylene film ranges from 0.1 mm to 0.2 mm.

[0052] Specifically, the liquid hydrogen container 9 is connected to a pressure relief valve. A level gauge 10 is also installed on the liquid hydrogen container 9, which is adapted to obtain the liquid hydrogen level within the container. The jacket 13 is connected to a vent valve 11 and a liquid outlet valve 7; the liquid outlet valve 7 is adapted to discharge liquid nitrogen from the jacket 13. The vent valve 11 is connected and positioned near the top of the jacket 13. The jacket 13 is also connected to a pressure boosting valve 12, which is also connected and positioned near the top of the jacket 13. The liquid outlet valve 7 has a specification of DN40; the pressure relief valve has a set pressure of 0.8 MPa.

[0053] When adding liquid nitrogen into the jacket 13, open the first filling valve 3, the second filling valve 5, and the venting valve 11, and close the liquid outlet valve 7. When stopping the addition of liquid nitrogen into the jacket 13, close the first filling valve 3, the second filling valve 5, and the venting valve 11.

[0054] When the interval between liquid hydrogen refueling tests is ≤7 days, specifically, the liquid nitrogen tanker truck 1 can be in place one day before the test, and the liquid nitrogen refueling can be started at 14:00. The second refueling valve 5 is slightly opened, the first refueling valve 3 is opened, the vent valve 11 is opened, the liquid outlet valve 7 is closed, and 32m³ of liquid nitrogen is added to the jacket 13. 3 The injection rate is 6m 3During the test, the reading of the second pressure gauge 6 was observed in real time and did not exceed 0.2 MPa. At 17:00, the inner wall temperature of the jacket 13 dropped to -194℃ and stabilized. Refilling was stopped, and the second refill valve 5, the first refill valve 3, and the vent valve 11 were closed. One day before the test, liquid nitrogen was added until overflow at 17:30. After standing for 20 minutes, the inner wall temperature of the jacket 13 rose back to -181℃. The pulse replenishment program was started, with each addition lasting 12 seconds, followed by a 20-minute stand, repeated three times until the inner wall temperature of the jacket 13 stabilized at -194℃. Refilling was completed at 17:50. The connection between the liquid nitrogen tanker 1 and the pipeline was disconnected, and the liquid nitrogen tanker 1 was removed. On the day of the test, the outlet valve 7 was opened first to drain the liquid nitrogen from the jacket 13, and then the outlet valve 7 was closed. Open the liquid hydrogen filling valve 8 to fill the liquid hydrogen container 9 with liquid hydrogen. The filling time is 4.5 hours, while the traditional method requires 6.8 hours. After filling is complete, close the liquid hydrogen filling valve 8. The total liquid hydrogen loss rate is 8.2%, while the total liquid hydrogen loss rate using the traditional method is 13.5%. The embodiment of this application saves 9m³ of liquid hydrogen. 3 The total cost was 180,000 yuan.

[0055] When the interval for liquid hydrogen refueling tests is 7 to 15 days, liquid nitrogen refueling is initiated at 8:00 AM the day before the test, with liquid nitrogen being added to jacket 13 at a rate of 60 m³. 3 The injection rate is 7m 3 At 16:30, the inner wall temperature of jacket 13 dropped to -196℃ and stabilized. Refilling was stopped, and the second refill valve 5, the first refill valve 3, and the vent valve 11 were closed. One day before the test, at 17:00, liquid nitrogen was added until overflow, then allowed to stand for 20 minutes. The inner wall temperature of jacket 13 rose back to -179℃. The pulse replenishment program was then started, with each refill lasting 15 seconds, followed by a 20-minute stand, repeated four times until the inner wall temperature of jacket 13 stabilized at -196℃. Refilling was completed at 17:55. The connection between the liquid nitrogen tanker 1 and the pipeline was disconnected, and the liquid nitrogen tanker 1 was removed. On the day of the test, liquid hydrogen refilling took 4.8 hours, compared to 7.2 hours using the traditional method. After refilling, the liquid hydrogen refill valve 8 was closed. The total liquid hydrogen loss rate was 9.5%, compared to 15.2% using the traditional method. This embodiment saves 7m³ of liquid hydrogen. 3 The total cost was 140,000 yuan.

[0056] When the interval between liquid hydrogen refueling tests is greater than 15 days, liquid nitrogen refueling shall be initiated at 8:00 AM two days before the test, and liquid nitrogen shall be added to jacket 13 at a rate of 33m³. 3 The injection rate is 6m 3 / h, at 10:00, the inner wall temperature of jacket 13 dropped to -191℃, and it was left to stand for 24 hours; 60m³ of liquid nitrogen was added at 8:00 the day before the test. 3 The injection rate is 7m 3At 16:40, the inner wall temperature of jacket 13 dropped to -196℃ and stabilized. Refilling was stopped, and the second refill valve 5, the first refill valve 3, and the vent valve 11 were closed. One day prior to the test, at 17:10, liquid nitrogen was added until overflow. After standing for 20 minutes, the inner wall temperature of jacket 13 rose back to -182℃. The pulse replenishment program was then initiated, with each refill lasting 13 seconds, followed by a 20-minute stand, repeated three times until the inner wall temperature of jacket 13 stabilized at -196℃. Refilling was completed at 17:48. The connection between the liquid nitrogen tanker 1 and the pipeline was disconnected, and the liquid nitrogen tanker 1 was removed. On the day of the test, the liquid hydrogen refilling time was 5.0 hours, compared to 7.5 hours using the traditional method. The total liquid hydrogen loss rate was 10.3%, while the total liquid hydrogen loss rate using the traditional method was 16.8%. The embodiment of this application saved 8m³ of liquid hydrogen. 3 The total cost was 160,000 yuan.

[0057] Experimental verification has shown that, before the liquid hydrogen refueling test of the hydrogen-oxygen rocket engine, the method described in this application for reducing liquid hydrogen refueling loss—by pre-filling liquid nitrogen into the jacket 13 to pre-cool the liquid hydrogen container 9 to the liquid nitrogen temperature range, and then draining the liquid nitrogen from the jacket 13 before refueling with liquid hydrogen on the day of the test—can significantly save liquid hydrogen compared to the traditional method of directly pre-cooling the liquid hydrogen container 9 with liquid nitrogen. (At 45m...) 3 Taking the high-pressure liquid hydrogen container 9 as an example, a single test can shorten the liquid hydrogen filling time by about 2 hours and save about 7 cubic meters of liquid hydrogen. 3 ~10m 3 Based on the market price of liquid hydrogen of 20,000 yuan / m³ 3 Calculations show that this would reduce expenditures by approximately 140,000 to 200,000 yuan; simultaneously, it would save approximately 50 Nm³ of hydrogen used for gas sealing. 3 And save approximately 30 Nm of helium gas used for purging. 3 This method significantly reduces costs. Furthermore, the method described in this application for reducing liquid hydrogen refueling losses can shorten the pre-cooling time of the liquid hydrogen container 9 on the day of a liquid hydrogen refueling test for a hydrogen-oxygen rocket engine from the traditional 3-4 hours to approximately 1 hour. This improves the efficiency of the test process and optimizes the time arrangement of each stage on the test day, providing greater flexibility in the test process arrangement while reducing the risk of test delays due to pre-cooling delays. The process efficiency is significantly improved, and resources for gas sealing hydrogen and purging helium are saved. Simultaneously, the method described in this application for reducing liquid hydrogen refueling losses requires virtually no structural modification to the existing liquid hydrogen refueling system's pipelines, valves, and control units. It can be achieved solely through insulation structure optimization and operational process adjustments. The modification cycle for a single system is as short as 3-5 days, and the cost per system is low, generally not exceeding 100,000 yuan. It has the advantages of simple operation, reliable operation, and good economy. It can be innovatively optimized based on the original operational process, can be quickly implemented, and can be further extended to the liquid hydrogen refueling of the high-pressure liquid hydrogen container 9 in ground test systems for hydrogen-oxygen rocket engines and related components.

[0058] Although embodiments of the invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the invention, and such modifications and variations all fall within the scope defined by this application.

Claims

1. A method for reducing liquid hydrogen refueling losses, characterized in that, include: A jacket (13) is fitted and surrounded on the outside of the liquid hydrogen container (9); the jacket (13) is connected to the first filling valve (3) inside, and the first filling valve (3) is connected to the liquid nitrogen tanker (1) through the second filling valve (5); A temperature sensor is provided on the inner wall of the jacket (13), and the temperature sensor is adapted to obtain the temperature of the inner wall of the jacket (13) in real time; Open the first filling valve (3) and the second filling valve (5) to fill liquid nitrogen into the jacket (13) from the liquid nitrogen tanker (1); When the temperature obtained by the temperature sensor reaches -196℃±5℃ and is maintained at -196℃±5℃ for more than 30 minutes, the first filling valve (3) and the second filling valve (5) are closed to stop the filling of liquid nitrogen into the jacket (13); When the interval between liquid hydrogen refueling tests is ≤7 days, liquid nitrogen refueling shall be initiated from 14:00 to 18:00 on the day before the liquid hydrogen refueling test, and liquid nitrogen shall be added into the jacket (13) at a rate of 32m³. 3 The injection rate is 5m 3 / h~8m 3 / h; The liquid hydrogen container (9) is connected to a liquid outlet valve (7) and a pressure safety valve; the jacket (13) is connected to a vent valve (11) and a liquid outlet valve (7). When adding liquid nitrogen into the jacket (13), open the first filling valve (3), the second filling valve (5) and the venting valve (11), and close the liquid outlet valve (7); When the liquid nitrogen is stopped being added to the jacket (13), the first filling valve (3), the second filling valve (5) and the venting valve (11) are closed. On the day of the test, first open the liquid outlet valve (7) to drain the liquid nitrogen in the jacket (13) and close the liquid outlet valve (7); open the liquid hydrogen filling valve (8) to fill the liquid hydrogen container (9) with liquid hydrogen for 4.5 hours. After the filling is completed, close the liquid hydrogen filling valve (8). When the interval between liquid hydrogen refueling tests is 7 to 15 days, liquid nitrogen refueling is initiated from 8:00 to 18:00 on the day before the liquid hydrogen refueling test, and liquid nitrogen is added into the jacket (13) at a rate of 60m³. 3 The injection rate is 5m 3 / h~8m 3 / h; When the interval between liquid hydrogen refueling tests is >15 days, liquid nitrogen refueling is initiated from 8:00 to 18:00 two days before the liquid hydrogen refueling test. Liquid nitrogen is added into the jacket (13) at a rate of 33m³. 3 Maintain the temperature of the inner wall of the jacket (13) at -196℃±5℃ and let it stand for 24 hours; then, on the day before the test, add 60ml of liquid nitrogen into the jacket (13) from 10:00 to 18:

00. 3 This stabilizes the temperature of the inner wall of the jacket (13) at -196℃±5℃; Also includes: One day before the liquid hydrogen filling test, from 14:00 to 17:00, liquid nitrogen was added into the jacket (13) until it overflowed, and then left to stand for 20 minutes. Initiate the intermittent pulse replenishment program, specifically: repeatedly inject liquid nitrogen into the jacket (13), with each injection lasting 10 to 15 seconds and an injection rate of 8 m / s. 3 / h~10m 3 / h; After each addition of liquid nitrogen, let stand for 20 minutes and monitor the temperature change of the inner wall of the jacket (13) using a temperature sensor until the temperature of the inner wall of the jacket (13) stabilizes at -196℃±5℃; The liquid hydrogen container (9) is connected to the filling pipe (14) via the third filling valve (8); a composite insulation structure is wrapped around the outer periphery of the filling pipe (14); The composite insulation structure includes: A vacuum insulation layer is wrapped around the outer periphery of the filling pipe (14); the vacuum insulation layer is a stainless steel shell, and a vacuum is drawn inside the stainless steel shell; A glass wool layer is wrapped around the outer periphery of the vacuum insulation layer, and the glass wool layer is a porous structure formed by glass wool. A sealing and protective layer is wrapped around the outer periphery of the glass wool layer. The sealing and protective layer is a polytetrafluoroethylene film, which is wrapped around the outer periphery of the glass wool layer by a hot-press sealing process.

2. The method for reducing liquid hydrogen refueling losses according to claim 1, characterized in that, At 18:00 one day before the liquid hydrogen refueling test, the temperature of the inner wall of the jacket (13) stabilized at -196℃±5℃.

3. The method for reducing liquid hydrogen refueling losses according to claim 1, characterized in that, The jacket (13) is elastic, and the volume of the jacket (13) is 1 / 5 to 1 / 3 of the volume of the liquid hydrogen container (9); the temperature sensor is a platinum resistance temperature sensor.

4. The method for reducing liquid hydrogen refueling losses according to claim 1, characterized in that, The thickness of the stainless steel shell ranges from 2 mm to 3 mm; the stainless steel shell is evacuated to 10 mm. -3 Below Pa; the density range of the glass wool is 60 kg / m³. 3 ~80kg / m 3 The thickness of the glass wool layer ranges from 50 mm to 80 mm; the thickness of the polytetrafluoroethylene film ranges from 0.1 mm to 0.2 mm.

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