Full-scale low-temperature medium dynamic characteristic test filling and pressurizing system

Abstract

A full-size low-temperature medium dynamic characteristic test filling and pressurizing system uses low-temperature liquid nitrogen to replace low-temperature propellant as test medium, realizes filling and recovery of liquid nitrogen in a test pipeline system through a liquid nitrogen filling and recovery subsystem, and realizes pressurized flow and pressure control of liquid nitrogen in the test pipeline system through a nitrogen pressurizing and exhaust subsystem. The filling and pressurizing system comprises a measurement and control subsystem, the liquid nitrogen filling and recovery subsystem and the nitrogen pressurizing and exhaust subsystem. Liquid nitrogen is filled into the test system through a liquid nitrogen tank truck before the test, and is pressurized and exhausted into a liquid nitrogen recovery tank after each test state ends, so that liquid nitrogen can be pressurized and filled into the test system from the recovery tank for the next test state, realizing recycling of liquid nitrogen and reducing test cost.

Description

Technical Field

[0001] This invention belongs to the field of dynamic characteristic testing, specifically relating to a full-scale cryogenic medium dynamic characteristic testing filling and pressurization system, used for the filling, pressurization and medium circulation of cryogenic medium in cryogenic dynamic characteristic testing of liquid rocket propellant delivery systems. Background Technology

[0002] In the field of aerospace launch vehicles, the propulsion system of a liquid rocket mainly consists of the delivery system and the engine system, and is one of the most important subsystems of a liquid rocket. The engine provides power for rocket flight; the delivery system mainly consists of propellant tanks, main delivery pipelines, accumulators, and branch delivery pipelines. As a crucial system ensuring the reliable operation of the liquid rocket engine, it is also of great significance to the overall reliability and safety of the liquid rocket, and to a certain extent, constrains the development of the aerospace industry.

[0003] With the rapid development of modern aerospace technology and the continuous improvement of rocket carrying capacity, the size of rockets and their propellant delivery systems is also constantly increasing. The widespread use of cryogenic propellants has brought greater challenges to delivery systems and imposed more stringent technical requirements. During a certain period of flight, the thrust pulsations of the bottom engine of a liquid rocket can excite longitudinal vibrations in the rocket body structure, which in turn excite the liquid propellant in the propellant delivery pipeline. If the longitudinal modal frequencies of the rocket body structure and the liquid propellant in the delivery system are close, resonance will occur, causing uneven outflow of the liquid propellant. This leads to intensified thrust pulsations from the engine, further aggravating the longitudinal vibrations of the rocket body structure. The vibration magnitude increases, resulting in vibration divergence. As propellant is consumed and the rocket mass decreases, the resonant frequencies gradually diverge, and the vibration weakens until it disappears. This resonance phenomenon is called "Pogo vibration." During Pogo vibration, the peak resonance vibration magnitude can reach a level that damages onboard equipment and threatens flight safety. Especially for manned spacecraft, this low-frequency, high-magnitude vibration can cause severe discomfort to astronauts and even threaten their lives. Therefore, reducing or eliminating Pogo vibration to ensure the flight safety of liquid rockets necessitates Pogo vibration suppression design. The dynamic characteristic parameters of the delivery system are key parameters for Pogo vibration suppression design, and conducting full-scale ground-based dynamic characteristic tests of the delivery system to obtain these parameters is essential for the aerospace industry. Currently, the dynamic characteristic parameters of delivery systems are mainly studied through numerical simulations and small-scale ambient temperature delivery system dynamic characteristic tests. Newer launch vehicles, which are larger-scale cryogenic delivery systems, cannot accurately obtain data that closely approximates real-world operating conditions, thus posing numerous limitations to the Pogo vibration suppression design of these new launch vehicles.

[0004] For dynamic characteristic testing of large-scale cryogenic delivery systems, liquid nitrogen is generally used as the test medium. The entire system must be adequately insulated, but heat leakage still occurs in some areas. Heat leakage can cause liquid nitrogen to vaporize, resulting in gas entrainment and altering the system's dynamic characteristics. In this case, the measured test data cannot reflect the dynamic characteristics under actual flight conditions. Therefore, during the test, the liquid nitrogen must be kept in a pressurized flow state to remove heat and maintain the cryogenic temperature, preventing gas entrainment and ensuring the accuracy of the dynamic characteristic test data. Summary of the Invention

[0005] Based on the above problems, this invention proposes a full-scale cryogenic medium dynamic characteristic testing and pressurization system. This system utilizes cryogenic liquid nitrogen instead of cryogenic propellant, enabling liquid nitrogen refueling, pressurization of liquid nitrogen with nitrogen gas, and flow of liquid nitrogen between the delivery pipeline system and the refueling and pressurization system at specified pressures and flow rates. High-precision sensors monitor the system's temperature, pressure, and flow rate to ensure correct operation. Tests are conducted under these conditions to obtain parameters that more closely approximate the dynamic characteristics under real-world operating conditions.

[0006] Working principle: A full-size cryogenic medium dynamic characteristic test filling and pressurization system, including: liquid nitrogen filling and recovery subsystem, nitrogen pressurization and exhaust subsystem, and measurement and control subsystem; The liquid nitrogen filling and recovery subsystem also includes a liquid nitrogen recovery tank, a liquid nitrogen tanker, a liquid nitrogen filling pipe, and a liquid nitrogen recovery pipe. Flow meters, regulating valves, and shut-off valves are arranged on the liquid nitrogen filling pipe and the liquid nitrogen recovery pipe, and flow meters, pressure sensors, and temperature sensors are also installed. A transition tee is installed at the bottom of the test pipeline system. The liquid nitrogen recovery pipe is connected to one interface of the transition tee, and the other interface of the tee is connected to the test excitation system. The multiple liquid nitrogen recovery pipes are combined and connected to the adjustable pressure liquid nitrogen recovery tank. The liquid nitrogen recovery tank is connected to the storage tank through the liquid nitrogen filling pipe, realizing the liquid nitrogen pressurization and filling function. A filling interface is reserved on the liquid nitrogen filling pipe for connecting the liquid nitrogen tanker to fill liquid nitrogen. The nitrogen pressurization and exhaust subsystem also includes a liquid nitrogen tanker, a liquid nitrogen container, an ambient temperature vaporizer, a nitrogen buffer tank, a nitrogen pressurization pipe, and an exhaust pipe. The liquid nitrogen tanker is connected to the adjustable pressure liquid nitrogen container via pipelines. After liquid nitrogen is added from the tanker to the container, the tanker leaves. The liquid nitrogen in the container is pressurized and enters the ambient temperature vaporizer, where it vaporizes into cryogenic nitrogen. The nitrogen then enters the nitrogen buffer tank, which serves as the pressurization source for the test pipeline system, storing high-pressure nitrogen. The nitrogen pressurization pipe extends from the nitrogen buffer tank to the top storage tank to pressurize the test pipeline system. The storage tank is equipped with three exhaust pipes that directly discharge to the atmosphere for pressure regulation and depressurization operations. Two of these pipes are equipped with pneumatic shut-off valves, and the third pipe is equipped with a pneumatic regulating valve to adjust the exhaust flow rate. The measurement and control subsystem includes temperature sensors, pressure sensors, flow meters, control cabinets, operating consoles, and measurement and control software. It is used to control various valves in the system pipelines and to display various test parameters in real time. The subsystem remotely controls the pneumatic shut-off valves according to test requirements and uses the flow rates collected by the flow meters on each pipeline as the basis for judgment. The control software outputs control signals to the regulating valves to adjust the valve opening and the flow rate of the cryogenic liquid nitrogen, thus achieving the operation control and safety interlock of the liquid nitrogen filling and pressurization system.

[0007] Furthermore, the storage tank is equipped with a liquid nitrogen filling port, a liquid nitrogen venting port, a nitrogen pressurization port, and a nitrogen exhaust port. The tank volume is greater than the capacity of the medium consumed in a complete test. The tank pressure meets the maximum pressure conditions during the test and has a safety factor. The liquid nitrogen exhaust port, liquid nitrogen pressurization port, and liquid nitrogen pressure measuring port are designed according to the tank size, system vaporization rate, and pressurization requirements. The tank must be insulated to ensure that the temperature change of the medium inside the tank within 5 minutes before and after the formal test does not exceed 0.3K. The tank is equipped with a temperature sensor, a pressure sensor, and a differential pressure level gauge to monitor the tank temperature, pressure, and real-time liquid level. A safety valve is installed on the tank as a safety protection measure. An anti-vortex device must be installed at the bottom outlet of the tank to prevent vortexing when the medium flows out. The bottom interface of the tank is connected to the main pipeline through a flange. The side wall of the tank is equipped with a support interface and locally reinforced, and connected and fixed to the support device.

[0008] Furthermore, sealing devices must be installed at all connection points of the refueling and pressurization system, and a room temperature airtightness check must be performed after the connection is completed. After the room temperature check meets the requirements, thermal insulation layers are added to the storage tank, liquid nitrogen filling pipe, liquid nitrogen recovery pipe, and all areas through which liquid nitrogen flows, according to the heat leakage of the refueling and pressurization system, to reduce the heat exchange between the system and the outside. Then, liquid nitrogen is added into the refueling and pressurization system for a low temperature airtightness check and system test. After all tests are passed, the test is carried out according to the test procedure.

[0009] Furthermore, the liquid nitrogen filling pipe and liquid nitrogen recovery pipe are equipped with movable supports to accommodate the "arched" bending deformation caused by the presence of liquid nitrogen in the lower part of the horizontal pipe section and the absence of liquid nitrogen in the upper part during the initial filling stage.

[0010] Furthermore, corrugated pipes are installed on the main pipeline, liquid nitrogen filling pipe, nitrogen pressurization pipe, and liquid nitrogen recovery pipe.

[0011] Furthermore, based on the system's heat leakage situation, thermal insulation layers were installed on the storage tank, liquid nitrogen filling pipe, liquid nitrogen recovery pipe, and all areas through which liquid nitrogen flows.

[0012] A full-scale cryogenic medium dynamic characteristic test injection and pressurization test includes the following steps: Step 1: Check the status of all valves and sensors in the system to confirm that the system is functioning normally; Step 2: Connect the liquid nitrogen tanker; Step 3: Liquid nitrogen filling begins. Liquid nitrogen is transferred from the tanker truck through the filling and pressurization system into the test pipeline system. Sensor data is monitored during this process, and filling is stopped when the liquid level reaches the required level. Step 4: Adjust the opening of the regulating valve on the liquid nitrogen recovery pipe to the specified value, and at the same time pressurize the test pipeline system with nitrogen until the pressure reaches the required level; Step 5: Open the shut-off valve on the liquid nitrogen recovery pipe, and liquid nitrogen will begin to leak out. The experiment will then begin. Step 6: Liquid nitrogen is drained into the recovery tank, completing one test. Step 7: Pressurize the liquid nitrogen recovery tank and add liquid nitrogen from the liquid nitrogen recovery tank to the test pipeline system. After the addition is completed, conduct the next test and repeat steps 4 to 6.

[0013] The beneficial effects of this invention are as follows: This invention utilizes a liquid nitrogen recovery tank to achieve the reuse of liquid nitrogen. Liquid nitrogen, added to the system via a liquid nitrogen tanker, is pressurized and discharged into the liquid nitrogen recovery tank after each test phase. It can then enter the system from the recovery tank for the next phase, thus realizing the recycling of liquid nitrogen and reducing costs.

[0014] This invention addresses the cold deformation problem in cryogenic systems by installing expandable corrugated pipes and movable supports. Cryogenic pipelines undergo expansion and contraction, as well as bending deformation, upon cooling. The corrugated pipes release the internal stress generated by expansion and contraction, while the movable supports release the internal stress generated by bending deformation, thereby improving system safety.

[0015] This invention employs a system-wide thermal insulation method to suppress the "geyser" phenomenon. The "geyser" phenomenon in low-temperature systems can damage the structure. By adding an insulation layer to the entire system, heat exchange between the system and the outside environment is reduced, thereby suppressing the occurrence of "geysers" to a certain extent and improving system safety and reliability.

[0016] This invention regulates and stabilizes the pressure within the delivery pipeline system by installing an exhaust port on the storage tank. The exhaust port on the storage tank discharges a large amount of nitrogen gas from the "geyser" within the system, and the pressure within the storage tank is stabilized by adjusting the regulating valve on the exhaust pipeline, thus achieving pressure control.

[0017] This invention achieves flow control through a combination of a flow meter, a regulating valve, and a shut-off valve. By pre-setting the opening degree of the regulating valve, the shut-off valve opens rapidly, ensuring both accurate flow control and rapid attainment of flow, thus saving on the consumption of cryogenic media. Attached Figure Description

[0018] Figure 1 This is a diagram showing the composition of the pipeline system and the pressurization system for testing the dynamic characteristics of low-temperature media.

[0019] Figure 2 This is a diagram of the control interface of the measurement and control subsystem.

[0020] Figure 3 This is the experimental flowchart.

[0021] Figure 4 It is a diagram showing the relationships between the various systems. Detailed Implementation

[0022] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection claimed by the present invention.

[0023] A full-scale cryogenic medium dynamic property test fueling and pressurization system addresses the problem by using cryogenic liquid nitrogen instead of cryogenic propellant. It employs a liquid nitrogen fueling and recovery subsystem and a nitrogen pressurization and exhaust subsystem to achieve liquid nitrogen fueling, recovery, and pressurized flow within the full-scale test system. The fueling and pressurization system includes: a liquid nitrogen fueling and recovery system, a nitrogen pressurization and exhaust system, and a measurement and control subsystem; the pressurization system is shown in the attached figure. Figure 1 As shown.

[0024] The liquid nitrogen filling and recovery subsystem also includes a liquid nitrogen recovery tank, a liquid nitrogen tanker, a liquid nitrogen filling pipe, and a liquid nitrogen recovery pipe. Flow meters, regulating valves, and shut-off valves are installed on the liquid nitrogen filling and recovery pipes, along with flow meters, pressure sensors, and temperature sensors. A connecting tee is installed at the bottom of the test pipeline system. The liquid nitrogen recovery pipe connects to one port of the connecting tee, and the other port connects to the test vibration system. Multiple liquid nitrogen recovery pipes are combined and connected to an adjustable-pressure liquid nitrogen recovery tank. The liquid nitrogen recovery tank is connected to a storage tank via a liquid nitrogen filling pipe, thus realizing the liquid nitrogen pressurization and filling function (recovery and reuse). A pre-reserved filling port on the liquid nitrogen filling pipe is used to connect to the liquid nitrogen tanker for filling liquid nitrogen (initial filling or supplementary filling). The nitrogen pressurization and exhaust subsystem also includes a liquid nitrogen tanker, a liquid nitrogen container, an ambient temperature vaporizer, a nitrogen buffer tank, a nitrogen pressurization pipe, and an exhaust pipe. The liquid nitrogen tanker is connected to the adjustable pressure liquid nitrogen container via pipelines. After the liquid nitrogen in the tanker is added to the liquid nitrogen container, the tanker leaves. The liquid nitrogen in the container is pressurized and enters the ambient temperature vaporizer, where it is vaporized into cryogenic nitrogen. The nitrogen enters the nitrogen buffer tank (which serves as the pressurization pressure source for the test pipeline system and stores high-pressure nitrogen). The nitrogen pressurization pipe starts from the nitrogen buffer tank and connects to the top storage tank to pressurize the test pipeline system. The storage tank is equipped with three exhaust pipes that directly discharge to the atmosphere for pressure regulation and depressurization operations of the test pipeline system. Two of these pipes are equipped with pneumatic shut-off valves, and the third pipe is equipped with a pneumatic regulating valve to adjust the exhaust flow rate. The measurement and control subsystem includes temperature sensors, pressure sensors, flow meters, control cabinets, operating consoles, and measurement and control software. It is used to control various valves in the system pipelines and to display various test parameters in real time. The subsystem remotely controls the pneumatic shut-off valves according to test requirements and uses the flow rates collected by the flow meters on each pipeline as the basis for judgment. The control software outputs control signals to the regulating valves to adjust the valve opening and the flow rate of the cryogenic liquid nitrogen, thus achieving the operation control and safety interlock of the liquid nitrogen filling and pressurization system.

[0025] The tank should be designed according to the test requirements, ensuring its volume and pressure resistance. It should include a liquid nitrogen filling port, a liquid nitrogen vent, a nitrogen pressurization port, and a nitrogen exhaust port. The tank volume must be greater than the volume of media consumed in a single complete test. The tank pressure must meet the maximum pressure conditions during the test and have a safety factor. The exhaust port, pressurization port, and pressure measuring port should be designed according to the tank dimensions, system vaporization rate, and pressurization requirements. The tank must be insulated to ensure that the temperature change of the medium inside the tank within 5 minutes before and after the formal test does not exceed 0.3K. The tank should be equipped with temperature sensors, pressure sensors, and a differential pressure level gauge to monitor the tank temperature, pressure, and real-time liquid level. A safety valve should be installed on the tank as a safety protection measure. An anti-vortex device must be installed at the bottom outlet of the tank to prevent vortex formation when the medium flows out. The bottom interface of the tank should be connected to the main pipeline via a flange. The side wall of the tank should have a support interface with local reinforcement, connected and fixed to the support device.

[0026] All connection points of the system must be equipped with sealing devices, and a room temperature airtightness check must be performed after the connection is completed. After the room temperature check meets the requirements, heat insulation layers are added to the storage tank, liquid nitrogen filling pipe, liquid nitrogen recovery pipe, and all areas through which liquid nitrogen flows, according to the system's heat leakage situation, to reduce the heat exchange between the system and the outside world. Then, liquid nitrogen is added into the filling and pressurization system for low temperature airtightness check and system testing. After all tests are passed, the test is carried out according to the test procedure.

[0027] Movable supports are installed on the liquid nitrogen filling pipe and liquid nitrogen recovery pipe to accommodate the "arched" bending deformation that occurs when there is liquid nitrogen in the lower part of the horizontal pipe section but not in the upper part during the initial filling stage.

[0028] The main pipeline, liquid nitrogen filling pipe, nitrogen pressurization pipe, and liquid nitrogen recovery pipe are equipped with corrugated pipes to solve the problem of pipe shrinkage when cold.

[0029] Based on the system's heat leakage situation, thermal insulation layers were installed on the storage tank, liquid nitrogen filling pipe, liquid nitrogen recovery pipe, and all areas through which liquid nitrogen flows.

[0030] A full-scale cryogenic medium dynamic characteristic test injection and pressurization test includes the following steps, as shown in the attached figure. Figure 3 As shown: Step 1: Check the status of all valves and sensors in the system to confirm that the system is functioning normally; Step 2: Connect the liquid nitrogen tanker; Step 3: Liquid nitrogen filling begins. Liquid nitrogen is transferred from the tanker truck through the filling and pressurization system into the test pipeline system. Sensor data is monitored during this process, and filling is stopped when the liquid level reaches the required level. Step 4: Adjust the opening of the regulating valve on the liquid nitrogen recovery pipe to the specified value, and at the same time pressurize the test pipeline system with nitrogen until the pressure reaches the required level; Step 5: Open the shut-off valve on the liquid nitrogen recovery pipe, and liquid nitrogen will begin to leak out. The experiment will then begin. Step 6: Liquid nitrogen is drained into the recovery tank, completing one test. Step 7: Pressurize the liquid nitrogen recovery tank and add liquid nitrogen from the liquid nitrogen recovery tank to the test pipeline system. After the addition is completed, conduct the next test and repeat steps 4 to 6.

[0031] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A full-scale cryogenic medium dynamic characteristic test filling and pressurization system, characterized in that, include: Liquid nitrogen filling and recovery subsystem, nitrogen pressurization and exhaust subsystem, measurement and control subsystem; The liquid nitrogen filling and recovery subsystem also includes a liquid nitrogen recovery tank, a liquid nitrogen tanker, a liquid nitrogen filling pipe, and a liquid nitrogen recovery pipe. Flow meters, regulating valves, and shut-off valves are arranged on the liquid nitrogen filling pipe and the liquid nitrogen recovery pipe, and flow meters, pressure sensors, and temperature sensors are also installed. A transition tee is installed at the bottom of the test pipeline system. The liquid nitrogen recovery pipe is connected to one interface of the transition tee, and the other interface of the tee is connected to the test excitation system. The multiple liquid nitrogen recovery pipes are combined and connected to the adjustable pressure liquid nitrogen recovery tank. The liquid nitrogen recovery tank is connected to the storage tank through the liquid nitrogen filling pipe, realizing the liquid nitrogen pressurization and filling function. A filling interface is reserved on the liquid nitrogen filling pipe for connecting the liquid nitrogen tanker to fill liquid nitrogen. The nitrogen pressurization and exhaust subsystem also includes a liquid nitrogen tanker, a liquid nitrogen container, an ambient temperature vaporizer, a nitrogen buffer tank, a nitrogen pressurization pipe, and an exhaust pipe. The liquid nitrogen tanker is connected to the adjustable pressure liquid nitrogen container via pipelines. After liquid nitrogen is added from the tanker to the container, the tanker leaves. The liquid nitrogen in the container is pressurized and enters the ambient temperature vaporizer, where it vaporizes into cryogenic nitrogen. The nitrogen then enters the nitrogen buffer tank, which serves as the pressurization source for the test pipeline system, storing high-pressure nitrogen. The nitrogen pressurization pipe extends from the nitrogen buffer tank to the top storage tank to pressurize the test pipeline system. The storage tank is equipped with three exhaust pipes that directly discharge to the atmosphere for pressure regulation and depressurization operations. Two of these pipes are equipped with pneumatic shut-off valves, and the third pipe is equipped with a pneumatic regulating valve to adjust the exhaust flow rate. The measurement and control subsystem includes temperature sensors, pressure sensors, flow meters, control cabinets, operating consoles, and measurement and control software. It is used to control various valves in the system pipelines and to display various test parameters in real time. The subsystem remotely controls the pneumatic shut-off valves according to test requirements and uses the flow rates collected by the flow meters on each pipeline as the basis for judgment. The control software outputs control signals to the regulating valves to adjust the valve opening and the flow rate of the cryogenic liquid nitrogen, thus achieving the operation control and safety interlock of the liquid nitrogen filling and pressurization system.

2. The refueling and pressurization system according to claim 1, characterized in that, The storage tank is equipped with a liquid nitrogen filling port, a liquid nitrogen vent, a nitrogen pressurization port, and a nitrogen exhaust port. The tank volume is greater than the capacity of the medium consumed in a complete test. The tank pressure meets the maximum pressure conditions during the test and has a safety factor. The liquid nitrogen exhaust port, liquid nitrogen pressurization port, and liquid nitrogen pressure measuring port are designed according to the tank size, system vaporization rate, and pressurization requirements. The tank must be insulated to ensure that the temperature change of the medium inside the tank within 5 minutes before and after the formal test does not exceed 0.3K. The tank is equipped with a temperature sensor, a pressure sensor, and a differential pressure level gauge to monitor the tank temperature, pressure, and real-time liquid level. A safety valve is installed on the tank as a safety protection measure. An anti-vortex device must be installed at the bottom outlet of the tank to prevent vortexing when the medium flows out. The bottom interface of the tank is connected to the main pipeline through a flange. The side wall of the tank is equipped with a support interface and locally reinforced, and connected and fixed to the support device.

3. The refueling and pressurization system according to claim 1, characterized in that, All connection points of the refueling and pressurization system must be equipped with sealing devices. After the connection is completed, a room temperature airtightness test must be performed. After the room temperature test meets the requirements, according to the heat leakage of the refueling and pressurization system, heat insulation layers should be added to the storage tank, liquid nitrogen filling pipe, liquid nitrogen recovery pipe, and all areas through which liquid nitrogen flows to reduce the heat exchange between the system and the outside. Then, liquid nitrogen is added into the refueling and pressurization system for a low temperature airtightness test and system testing. After all tests are passed, conduct the tests according to the test procedures.

4. The refueling and pressurization system according to claim 1, characterized in that, The liquid nitrogen filling pipe and liquid nitrogen recovery pipe are equipped with movable supports to accommodate the "arched" bending deformation that occurs when there is liquid nitrogen in the lower part of the horizontal pipe section but not in the upper part during the initial filling stage.

5. The refueling and pressurization system according to claim 1, characterized in that, The main pipeline, liquid nitrogen filling pipe, nitrogen pressurization pipe and liquid nitrogen recovery pipe are equipped with corrugated pipes.

6. The system according to claim 1, characterized in that, Based on the system's heat leakage situation, thermal insulation layers were installed on the storage tank, liquid nitrogen filling pipe, liquid nitrogen recovery pipe, and all areas through which liquid nitrogen flows.

7. A full-scale cryogenic medium dynamic characteristic test injection and pressurization test, characterized in that, The steps include the following: Step 1: Check the status of all valves and sensors in the system to confirm that the system is functioning normally; Step 2: Connect the liquid nitrogen tanker; Step 3: Liquid nitrogen filling begins. Liquid nitrogen is transferred from the tanker truck through the filling and pressurization system into the test pipeline system. Sensor data is monitored during this process, and filling is stopped when the liquid level reaches the required level. Step 4: Adjust the opening of the regulating valve on the liquid nitrogen recovery pipe to the specified value, and at the same time pressurize the test pipeline system with nitrogen until the pressure reaches the required level; Step 5: Open the shut-off valve on the liquid nitrogen recovery pipe, and liquid nitrogen will begin to leak out. The experiment will then begin. Step 6: Liquid nitrogen is drained into the recovery tank, completing one test. Step 7: Pressurize the liquid nitrogen recovery tank and add liquid nitrogen from the liquid nitrogen recovery tank to the test pipeline system. After the addition is completed, conduct the next test and repeat steps 4 to 6.

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