Dynamic sealing and axial force self-balancing device and method for hydrogen environment mechanical property detection

Abstract

The invention discloses a dynamic sealing and axial force self-balancing device and method for hydrogen environment mechanical property detection, and belongs to the technical field of material testing. The device comprises a mechanical loading mechanism, a reaction kettle, an atmosphere supply and control system and an integrated cooling and force balancing unit, the core of the unit is a cooling gas cabin arranged around a loading pull rod and a cooling pressurization system for providing pressure-adjustable cooling gas. When cooling gas flows through the cooling gas cabin, two functions are executed at the same time: one function is that a loading pull rod and a dynamic sealing area are cooled through convective heat exchange; secondly, reverse thrust is generated on the pull rod through gas pressure so as to dynamically balance axial force generated by high-pressure gas in the reaction kettle; the device is further provided with a temperature closed-loop control module, and cooling parameters are adjusted in real time according to temperature feedback of a dynamic sealing area. According to the invention, the coupling problem of dynamic seal cooling and axial force balance in an extreme hydrogen environment is solved, and the test safety, stability and measurement precision are significantly improved.

Description

Device and method for dynamic sealing and axial force self-balancing for testing mechanical properties in hydrogen environments Technical Field

[0001] This invention belongs to the field of material mechanical property testing technology, specifically relating to a dynamic seal and axial force self-balancing device and method for testing mechanical properties in a hydrogen environment. Background Technology

[0002] High-temperature hydrogen-sensitive components in hydrogen-fueled aero-engines and gas turbines operate at temperatures ranging from 1100℃ to 1200℃, with gas pressures exceeding 4 MPa. Unlike aerospace engines, these components are exposed to high-temperature, high-pressure hydrogen atmospheres for extended periods. The materials in these high-temperature components are prone to hydrogen embrittlement and corrosion, leading to severe hydrogen-induced damage and potentially significant performance degradation or even complete failure. Therefore, constructing a high-temperature, high-pressure hydrogen environment closely resembling service conditions, obtaining mechanical property data for hydrogen-sensitive materials under near-service conditions, revealing their performance evolution, and assessing their service life and safety are crucial for the research, development, and engineering applications of hydrogen-fueled aero-engines and gas turbines.

[0003] Currently, existing mechanical property testing devices for hydrogen environment materials are mainly designed for the petrochemical industry. The tested objects are primarily materials used in low- and medium-temperature components such as hydrogen storage tanks and hydrogen-blending pipelines. The test temperatures generally do not exceed 650℃, far below the actual service temperatures of hot-end components in aero-engines and gas turbines. Existing mechanical property testing devices for hydrogen environment materials mainly create a relatively sealed high-temperature, high-pressure hydrogen atmosphere through a reactor. Due to limitations in sealing materials and the design of the test chamber and sample clamps, these devices cannot meet the mechanical property testing requirements under higher temperature and higher pressure hydrogen environments. Specifically, existing high-temperature, high-pressure hydrogen environment mechanical testing technology faces two major bottlenecks: First, the temperature resistance limit of dynamic seals is low. A dynamic seal is required between the loading rod of the testing machine and the external environment to prevent high-pressure hydrogen leakage. Currently, rubber O-ring dynamic seals are commonly used, with a temperature resistance limit typically not exceeding 250℃. When the temperature inside the reactor far exceeds this limit, heat conduction will cause the seal to soften, age, or even fail rapidly, leading to hydrogen leakage and serious safety hazards. Second, axial force interference causes load control distortion. The high-pressure gas inside the reactor generates a huge reverse axial thrust on the end face of the loading rod. This thrust varies with temperature, pressure and atmosphere concentration, causing fluctuations in the test loading load and making it difficult to control the loading accuracy. Furthermore, an impact is generated at the moment the sample breaks, which seriously interferes with the readings of the load sensor of the testing machine, reduces the loading control accuracy, and may damage the expensive precision loading mechanism.

[0004] Existing technologies attempt to address these problems separately. For example, some solutions use a water-cooling jacket around the sealing area for cooling, but this is passive cooling, with limited efficiency and unable to solve the axial force problem. Other solutions attempt to counteract the axial force through complex piston and balance chamber structures, but these structures often fail to consider the impact of high temperatures on the sealing elements, and their reliability is questionable at extreme temperatures. All these solutions treat sealing cooling and axial force balancing as two independent problems, using two separate systems to handle them, resulting in complex equipment structures, high costs, and poor coordination.

[0005] Therefore, there is an urgent need for a technical solution that can simultaneously, efficiently, and adaptively address the issues of dynamic seal reliability and axial force balance under high temperature and high pressure hydrogen conditions within an integrated structure. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a dynamic sealing and axial force self-balancing device and method for testing the mechanical properties of a hydrogen environment. Through innovative integrated design, this device utilizes the same cooling medium and system to simultaneously achieve reliable cooling of the dynamic sealing area and dynamic self-balancing of the axial force on the loading rod. This ensures that mechanical testing can be conducted long-term, stably, safely, and with high precision in extreme hydrogen environments with temperatures not lower than 650°C and pressures not lower than 4 MPa.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] In a first aspect, the present invention provides a dynamic sealing and axial force self-balancing device for testing the mechanical properties of a hydrogen environment. The device is designed to operate in a hydrogen environment with a temperature not lower than 650°C and a pressure not lower than 4 MPa. The device includes a mechanical loading mechanism, a reaction vessel, an atmosphere supply and control system, and an integrated cooling and force balancing unit. The integrated cooling and force balancing unit includes: a cooling gas chamber disposed between the bottom of the reaction vessel and the main base of the mechanical loading mechanism, surrounding the loading rod; a cooling pressurization system for providing adjustable-pressure cooling gas; and a gas pipeline connecting the two, which constitutes a circulation path for the cooling gas. When the cooling gas flows through the cooling gas chamber, it is... The device is configured to perform two functions simultaneously: first, to cool the loading rod through convective heat transfer; second, to generate a reverse thrust on the bearing surface of the loading rod through the pressure of the cooling gas, which is used to dynamically balance the axial force exerted on the loading rod by the test gas in the reactor. The device also includes a temperature closed-loop control module, which includes a temperature sensor and an intelligent controller located near the dynamic sealing area. The intelligent controller is configured to dynamically adjust the output of the cooling pressurization system (such as cooling power, gas pressure, or flow rate) according to the feedback signal from the temperature sensor, thereby controlling the temperature of the dynamic sealing area within a safe range and helping to maintain the balance of the axial force.

[0009] In a preferred embodiment, the cooling gas chamber has cooling air inlets and exhaust outlets on its wall, which are connected to the cooling pressurization system via cooling gas pipelines and cooling gas circuits, respectively, to form a closed gas cooling circulation loop.

[0010] In a preferred embodiment, the intelligent controller is further configured to receive a pressure signal inside the reactor and, by regulating the gas pressure output by the cooling and pressurizing system, enable the reverse thrust to dynamically follow and counteract the axial force, thereby achieving high-precision force balance.

[0011] Regarding the structural implementation, the loading tie rod may have a cooling channel inside the section corresponding to the cooling gas chamber; or, the cooling gas chamber may be an annular sealed cavity formed within the main unit base and surrounding the loading tie rod.

[0012] In addition, the device may also include a combined sealing system, which includes a static sealing structure for sealing the reactor and a dynamic sealing structure for sealing the relative movement between the loading rod and the main unit base.

[0013] Secondly, the present invention provides a method for testing the mechanical properties of hydrogen environment based on the above-mentioned device. The method includes the following steps: Sample installation and atmosphere preparation step: The sample is installed in the reaction vessel and sealed. After evacuating and replacing the gas in the reaction vessel, a hydrogen-based test atmosphere of a preset composition is introduced; Integrated system start-up and pre-equilibrium step: The cooling and pressurization system is started, and cooling gas with a preset pressure is introduced into the cooling gas chamber; At the same time, the temperature closed-loop control module is started for real-time monitoring; Environment establishment and dynamic equilibrium step: The reaction vessel is heated and pressurized until the target test temperature and pressure are reached, wherein the target temperature is not lower than the target pressure. At 650℃, the target pressure is not less than 4MPa. During this process and in steady state, the intelligent controller dynamically adjusts the cooling gas parameters based on the feedback from the temperature sensor to control the temperature of the dynamic sealing area. At the same time, the dynamic balance of the axial force is maintained by adjusting the cooling gas pressure. Mechanical loading and data acquisition steps: Under the condition of maintaining the hydrogen environment and the aforementioned dynamic balance, the mechanical loading mechanism is activated to perform mechanical property tests on the sample (such as slow strain rate tensile test, fatigue test, creep test, or endurance strength test), and the corresponding mechanical data is collected. Test completion steps: After the test is completed, the cooling, depressurization, and system shutdown operations are performed in sequence.

[0014] Preferably, in the integrated system startup and pre-balancing step, the preset pressure is set to a value matching the target test pressure. In the environment setup and dynamic balancing step, the intelligent controller compares the real-time temperature with a preset safe temperature threshold and adjusts the cooling power and / or gas flow rate of the cooling booster system to stabilize the temperature of the dynamic sealing area below the safe temperature threshold. The cooling gas is preferably an inert gas such as nitrogen, argon, or helium.

[0015] Beneficial effects: Compared with the prior art, the beneficial effects of the present invention are as follows: 1. The present invention utilizes adjustable pressure cooling gas to simultaneously solve the two independent problems of sealed cooling and axial force balance in a compact cooling gas chamber, replacing the traditional two independent systems and reducing complexity and cost.

[0016] 2. This invention achieves precise management of sealing temperature (preventing overheating failure) and real-time dynamic compensation of axial force (improving load accuracy) through closed-loop feedback control of temperature and pressure, and the system has strong self-adaptive capability.

[0017] 3. This invention ensures that the sealing material operates in a safe temperature range for a long time through active cooling, fundamentally avoiding the risks of high-temperature failure and hydrogen leakage; the dynamic balance of axial force effectively protects the precision loading mechanism from impact, extends the equipment life, and greatly improves the reliability and safety of the equipment.

[0018] 4. This invention significantly increases the upper limits of temperature and pressure for mechanical property testing, making it possible to conduct long-term, stable mechanical property testing in extreme hydrogen environments with temperatures not lower than 650℃ (which can be stabilized up to 1100℃) and pressures not lower than 4MPa. This fills the technological gap in high-end testing equipment in this field and provides key data support for the research and development of hydrogen energy equipment materials. Attached Figure Description

[0019] Figure 1 is a schematic diagram of the overall layout of the test system for the dynamic sealing and axial force self-balancing device for testing the mechanical properties of a hydrogen environment provided in an embodiment of the present invention; Figure 2 is a three-dimensional structural schematic diagram of the mechanical property testing device in Figure 1; Figure 3 is a cross-sectional structural schematic diagram of the device shown in Figure 2; Figure 4 is a cross-sectional structural schematic diagram of the reactor base and its related components in an embodiment of the present invention; Figure 5 is a top view of the reactor in an embodiment of the present invention; Figure 6 is a cross-sectional structural schematic diagram of the connection between the cooling gas pipeline and the cooling gas chamber in an embodiment of the present invention; Figure 7 is a cross-sectional structural schematic diagram of the thermocouple temperature measurement system in an embodiment of the present invention; Figure 8 is a partially enlarged structural schematic diagram of the cooling gas chamber in an embodiment of the present invention; In the figures, 1-hydrogen concentration detector, 2-flame detector, 3-smoke alarm, 4-intelligent control system, 5-vacuum pump, 6-hydrogen source, 7-nitrogen source, 8-hydrogen mixing chamber, 9-cooling pressurization system, 10-mechanical testing machine, 11-cooling gas pipeline, 12-cooling gas circuit, 1 3-Mixed gas pipeline, 14-Valve, 15-Hydrogen pipeline, 16-Nitrogen pipeline, 17-Booster pump, 101-Crossbeam, 102-Reaction vessel body, 103-Reaction vessel base, 104-Support column, 105-Loading tie rod, 106-Guide column, 107-Sample, 108-Clamp, 109-Reaction frame, 110-Cooling gas chamber, 111-Reaction vessel base, 112-Main unit base, 113-Main unit base, 114-First cooling inlet, 11 5- Bolt, 116- Second cooling air inlet, 117- Nitrogen port, 118- Mixed gas port, 119- First-stage static seal, 120- Second-stage static seal, 121- Displacement measurement port, 122- Thermocouple temperature measurement port, 123- Threaded hole, 124- Exhaust port, 125- Dynamic seal temperature measurement port, 126- Pressure detector, 127- Pressure relief valve, 128- Flange, 129- Dynamic seal, 130- Cooling water port, 131- Resistance wire, 132- Thermal insulation cotton. Detailed Implementation

[0020] The embodiments of this application will now be described in detail with reference to the accompanying drawings.

[0021] The following specific examples illustrate the implementation of this application. Those skilled in the art can easily understand other advantages and effects of this application from the content disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. This application can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this application. It should be noted that, in the absence of conflict, the following embodiments and features in the embodiments can be combined with each other. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0022] It should be noted that, unless otherwise defined, the technical or scientific terms used in this invention should have the ordinary meaning understood by one of ordinary skill in the art to which this invention pertains. The terms "first," "second," and similar words used in this invention do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Words such as "comprising" or "including" mean that the element or object preceding the word encompasses the elements or objects listed following the word and their equivalents, without excluding other elements or objects.

[0023] As shown in Figure 1, the dynamic sealing and axial force self-balancing device for testing mechanical properties in a hydrogen environment provided in this embodiment of the invention is a complete testing system. This system mainly includes: an explosion-proof safety monitoring unit, an intelligent control system 4, an atmosphere supply and control system, a reaction vessel, a core mechanical loading mechanism, and an integrated cooling and force balancing unit. The entire system works collaboratively to safely and accurately test the mechanical properties of materials in a hydrogen environment with a temperature not lower than 650℃ and a pressure not lower than 4MPa. Specifically, the explosion-proof safety monitoring unit includes a hydrogen concentration detector 1, a flame detector 2, and a smoke alarm 3 located in key positions, which monitor environmental safety in real time, and the signals are connected to the intelligent control system 4.

[0024] Intelligent Control System 4 (i.e., Intelligent Controller): This is the brain of the entire test system. It integrates the acquisition and processing of signals such as temperature, pressure, load, and displacement, and executes closed-loop control logic for subsystems such as heating, cooling, loading, and atmosphere.

[0025] Atmosphere supply and control system: This includes a vacuum pump 5, a hydrogen source 6, a nitrogen source 7, a hydrogen mixing chamber 8, and corresponding pipelines (hydrogen pipeline 15, nitrogen pipeline 16, and mixed gas pipeline 13), valves 14, and a booster pump 17. The hydrogen source 6 is connected to the hydrogen pipeline 15, and the nitrogen source 7 is connected to the nitrogen pipeline 16. The hydrogen pipeline 15 and nitrogen pipeline 16 are connected to the hydrogen mixing chamber 8 via the booster pump 17. The hydrogen mixing chamber 8 is connected to the reactor via the mixed gas pipeline 13. Valves are installed on the hydrogen pipeline 15, nitrogen pipeline 16, and mixed gas pipeline 13. The vacuum pump 5 is also connected to the reactor via a pipeline (with valves) to provide a vacuum environment for the reactor. The function of the atmosphere supply and control system is to provide a pure, proportionally controllable experimental atmosphere to the reactor and to perform vacuuming and purging before and after the experiment.

[0026] Mechanical loading mechanism: a mechanical testing machine 10, used to apply controllable loads or displacements to the specimen.

[0027] As shown in Figures 2 and 3, the main frame of the mechanical testing machine 10 includes a main unit base 113, a main unit base 112, a support column 104, a loading tie rod 105, a guide column 106, and a crossbeam 101 that can move up and down on the guide column 106. The movement of the crossbeam 101 is controlled by a precision servo drive system (not shown in the figure, but part of the mechanical loading mechanism), which is the execution end for realizing tensile, compressive, and other mechanical loading.

[0028] As shown in Figures 1-8, the reactor is the core container for creating a high-temperature, high-pressure hydrogen environment. It includes an upper lid and a lower bottom. The lid is fixedly connected to a crossbeam 101. The lid includes a reactor body 102. During the test preparation stage, the reactor body 102 can be fixed to the main frame via the reactor base 103 at the bottom. The flange 128 of the lid and the flange (not shown in the figures) of the bottom have circumferentially distributed threaded holes 123, which are diagonally tightened with bolts 115 to form a sealed connection. A first-stage static sealing ring 119 and a second-stage static sealing ring 120 are used to maintain airtightness between the lid and the bottom. The static sealing rings are preferably made of fluororubber, which can be used in a wide temperature range with an upper temperature resistance of approximately 250℃. A pressure relief valve 127 and a pressure detector 126 are installed on the upper part of the lid. The pressure detector 126 transmits the internal pressure of the reactor to the intelligent control system 4 in real time. When overpressure occurs, the pressure relief valve 127 automatically releases pressure to ensure safe operation. The reactor base 111 is located at the bottom of the reactor vessel and is connected to the main unit base 112. Furthermore, both the reactor body 102 and the reactor bottom are equipped with cooling water holes 130, allowing cooling water to flow through them. The circulating cooling water effectively reduces the temperature of the outer wall of the body and the static sealing area. As shown in Figure 4, the reactor base 111 has a nitrogen port 117, through which an external pipeline can be directly connected to a nitrogen source, providing nitrogen directly to the reactor. The reactor base 111 also has a mixed gas port 118, which connects to a mixed gas pipeline 13 for introducing a hydrogen-nitrogen mixed gas into the reactor. The reactor base 111 also has a thermocouple temperature measuring port 122, as shown in Figure 7. The thermocouple extends into the reactor through the thermocouple temperature measuring port 122 at the bottom of the vessel, forming a thermocouple temperature measuring system for real-time monitoring of the sample temperature. The reactor base 111 is also provided with a displacement measuring hole 121, through which a displacement sensor is inserted to measure the deformation of the sample 107 during the test.

[0029] Heating and insulation system: A resistance wire 131 is arranged inside the reactor body 102 as a heating element to heat the sample 107 and the internal test atmosphere through thermal radiation. The resistance wire 131 is covered with heat insulation cotton 132 to reduce heat loss, ensure uniform internal temperature, reduce the temperature of the outer wall of the cylinder, and protect external components.

[0030] Sample clamping system: The sample 107 to be tested is connected to the force loading mechanism via clamp 108 and fixed to the center of the reactor base 111 via reaction frame 109. The reaction frame 109 is a key component that bears the loading reaction force. The reaction frame 109 is located at the center of the reactor bottom. The upper end of the reaction frame 109 has a threaded groove that connects to the upper end of the sample 107. The lower end of the sample 107 is connected to the upper end of the loading rod 105. The loading rod 105 drives the sample 107 to move axially, and the mechanical loading of the sample is achieved through the reaction frame 109.

[0031] Force transmission path: The force is guided by the crossbeam 101 and guide column 106, and transmitted to the lower end of the sample 107 through the loading rod 105. The loading rod 105 is a key moving part connecting the external loading mechanism and the internal high-temperature environment sample. Its upper end extends into the high-temperature zone and connects to the sample 107, and its lower end passes through the reactor base 111 and the main unit base 112.

[0032] Integrated cooling and force balancing unit: Its main structure is concentrated in the area where the loading rod 105 passes through the reactor base 111 and the main unit base 112. Specifically, it includes: Cooling gas chamber 110: As shown in the partial enlarged views of Figures 3, 6, and 8, this is a key functional cavity. In this embodiment, it is formed within the space jointly enclosed between the lower part of the reactor base 111 and the upper part of the main unit base 112, and is an annular sealed cavity surrounding the loading rod 105. The side wall of the cooling gas chamber 110 has a first cooling air inlet 114 and a second cooling air inlet 116, both for introducing cooling gas; an exhaust port 124 is also provided on the side wall for discharging gas.

[0033] Cooling and pressurizing system 9: This system provides adjustable-pressure cooling gas (high-purity nitrogen is used in this embodiment). It is connected to nitrogen source 7 via pipeline and communicates with intelligent control system 4, receiving control signals and feeding back pressure information. Cooling and pressurizing system 9 is connected to cooling gas chamber 110 via gas pipeline, forming a cooling gas circulation path. Specifically, the gas pipeline includes cooling gas pipeline 11 and cooling gas circuit 12. Low-temperature, high-pressure nitrogen (cooling gas) enters cooling gas chamber 110 via cooling gas pipeline 11, from the first cooling inlet 114 and the second cooling inlet 116. During its flow within cooling gas chamber 110, the cooling gas undergoes intense forced convection heat exchange with the surface of the loading rod 105, which has become incandescent due to heat conduction from the high-temperature reactor, achieving efficient cooling of the loading rod 105. The heated gas exits from exhaust port 124 and returns to cooling and pressurizing system 9 via cooling gas circuit 12. After cooling and pressurization, it is recycled, thus forming a closed-loop gas cooling circulation circuit.

[0034] As the cooling gas flows through the cooling gas chamber 110, it is configured to perform two functions simultaneously: cooling function: directly reducing the temperature of the loading rod 105 through convective heat transfer. Due to heat conduction, the temperature of the dynamic seal 129 region adjacent to the loading rod is also significantly reduced, thereby ensuring that the dynamic seal material (such as fluororubber) can operate within its safe temperature range.

[0035] Axial force balancing function: Low-temperature, high-pressure nitrogen gas is introduced into the chamber, and its pressure acts perpendicularly on an annular boss surface (or equivalent pressure-bearing surface) at the lower end of the loading rod 105, generating an upward reverse thrust (F_cool). Simultaneously, high-pressure hydrogen gas (test gas) in the reactor acts on the pressure-bearing surface at the upper end of the loading rod, generating a downward axial force (F_H2). The intelligent control system 4 receives the pressure signal from the reactor and, by precisely controlling the gas pressure output by the cooling and pressurizing system 9, enables the reverse thrust F_cool to dynamically follow and counteract the axial force F_H2, thereby achieving self-balancing of the axial force. This greatly improves the load measurement accuracy and protects the loading mechanism.

[0036] To ensure absolute reliability of the dynamic seal, the device described in this embodiment of the invention incorporates a temperature closed-loop control module. As shown in Figure 8, a dedicated dynamic seal temperature measurement hole 125 is provided on the main unit base 112. A temperature sensor (such as a type K thermocouple) probe is inserted through this hole, with its measuring end positioned near the dynamic seal area (e.g., as close as possible to the dynamic seal 129 without interfering with its movement), to monitor the temperature (T_seal) of this critical area in real time. The temperature sensor is communicatively connected to the intelligent control system 4, together forming the temperature closed-loop control module.

[0037] The intelligent control system 4 is configured to dynamically adjust the output of the cooling booster system 9 based on feedback signals from the temperature sensor to control the temperature of the dynamic sealing area. Specifically, the temperature sensor signal is fed back to the intelligent control system 4 in real time, and the intelligent control system 4 presets a safe temperature threshold (T_max, e.g., 200℃) for the dynamic sealing material. When T_seal approaches T_max, the intelligent control system 4 automatically increases the cooling power and / or gas circulation flow rate of the cooling booster system 9 to enhance the cooling effect; conversely, it adjusts appropriately to save energy. This process constitutes a dynamic closed-loop temperature control system with the temperature of the dynamic sealing area as the control target.

[0038] The static and dynamic sealing structures described above in this embodiment of the invention constitute a combined sealing system. Specifically, it includes a first-stage static sealing ring 119 and a second-stage static sealing ring 120 for sealing between the reactor lid and bottom, ensuring that high-pressure hydrogen does not leak from the static connection of the reactor body. It also includes a dynamic sealing structure 129 located at the relatively moving part between the loading rod 105 and the main unit base 112. This dynamic seal is typically a high-temperature resistant O-ring (such as fluororubber) to prevent hydrogen leakage along the movement gap of the rod. Through the aforementioned active cooling, this embodiment of the invention ensures the long-term reliability of the dynamic seal.

[0039] This invention also provides a method for testing the mechanical properties of a hydrogen environment using the above-mentioned device, comprising the following steps: (1) Sample installation and atmosphere preparation steps: The processed sample 107 is installed in the center of the reactor using the clamp 108 and the reaction frame 109. The height of the crossbeam 101 is lowered, the reactor lid is closed, and the flange 128 is tightened diagonally with bolts 115. Initial sealing is achieved using the first-stage static sealing ring 119 and the second-stage static sealing ring 120. The vacuum pump 5 is started, and the reactor is evacuated to a high vacuum (e.g., below 10 Pa) through the pipeline. Then, high-purity nitrogen is introduced into the reactor to atmospheric pressure through the nitrogen source 7 and the pipeline connected to the nitrogen port 117 for gas replacement; the vacuum is then evacuated again, and this process is repeated 2-3 times to fully replace the residual air until the oxygen concentration in the reactor is lower than the preset target. Finally, according to the test requirements, the test gases supplied by hydrogen source 6 and nitrogen source 7 are pressurized by booster pump 17 and mixed in hydrogen mixing chamber 8 according to the atmosphere ratio set for the test (e.g., 5% H2 + 95% N2). The mixture is then introduced into the reactor through mixing gas pipeline 13 connected to mixing gas port 118 to the predetermined initial pressure, providing a hydrogen environment atmosphere for the sample. It should be noted that the 5% hydrogen and 95% nitrogen mixing ratio used in the above example is a commonly used test condition that follows relevant test standards and balances safety and cost. The capability of the device of this invention is by no means limited to this mixing ratio. The atmosphere supply and control system can provide and precisely control any preset ratio of hydrogen-based test atmosphere, from low concentration to 100% pure hydrogen. The integrated cooling and force balancing unit of this embodiment solves the problems of dynamic seal high-temperature failure and axial force interference, which are particularly prominent and critical under extreme conditions of pure hydrogen, high pressure, and high temperature. Therefore, the apparatus of this invention is particularly suitable for conducting stringent mechanical performance tests in a pure hydrogen environment, with a maximum temperature of not less than 650°C and a maximum pressure of not less than 4 MPa, which is difficult to achieve with existing technologies. The use of a mixed gas in the embodiments is for illustrative purposes only and should not be construed as limiting the scope of application of this invention.

[0040] (2) Integrated System Start-up and Pre-Balancing Steps: The cooling pressurization system 9 is activated. Gas supplied by nitrogen source 7 enters the cooling pressurization system 9 through pipelines. After cooling and pressurization, a cooling gas with a preset pressure is formed. This cooling gas is then introduced into the cooling gas chamber 110 to provide a low-temperature heat exchange medium. Specifically, cooling gas (nitrogen) with a preset pressure is introduced into the cooling gas chamber 110 through cooling gas pipeline 11. This preset pressure is usually set to a value that matches the target test pressure (e.g., 4.2 MPa) of subsequent steps, so as to pre-balance the axial force before pressurization and reduce the initial offset of the tie rod. Simultaneously, the temperature closed-loop control module is activated to begin monitoring the temperature of the dynamic seal area.

[0041] (3) Environmental setup and dynamic equilibrium steps: Start the heating program of resistance wire 131 in the reactor to heat up the reactor. At the same time, slowly increase the hydrogen pressure in the reactor through the cooling pressurization system 9 to pressurize the reactor. Monitor the sample temperature (through the thermocouple in the thermocouple measuring hole 122) and the pressure in the reactor (through the pressure detector 126) in real time until the target test temperature and pressure are reached. The target temperature is not lower than 650℃ and the target pressure is not lower than 4MPa. For example, the target temperature is 1100℃ and the target pressure is 4.2MPa. During the entire heating and steady-state maintenance process, the intelligent control system 4 performs dual closed-loop control: Temperature control loop: The intelligent control system 4 dynamically adjusts the cooling gas parameters according to the feedback of the temperature sensor to control the temperature of the dynamic seal area. Specifically, the intelligent control system 4 compares the real-time temperature value (T_seal) monitored by the temperature sensor from the dynamic seal measuring hole 125 with the preset safe temperature threshold (e.g., 180℃). The cooling power and / or gas flow rate of the cooling booster system 9 are dynamically adjusted by a PID algorithm to dynamically adjust the parameters of the cooling gas, thereby controlling the temperature of the dynamic sealing area and keeping the temperature T_seal of the dynamic sealing area stably below the safe temperature threshold.

[0042] Force balance control loop: Simultaneously, the intelligent control system 4 maintains the dynamic balance of axial force by adjusting the cooling gas pressure. Specifically, the intelligent control system 4 receives the real-time pressure signal (P_H2) from the pressure detector 126, and through calculation, adjusts the gas pressure (P_cool) output by the cooling booster system 9, so that P_cool... A ≈ P_H2 A (where A is the effective bearing area of ​​the tie rod) is used to maintain the dynamic balance of axial forces. The pressure relief valve 127, as a safety redundancy, automatically opens when the system is overpressured.

[0043] (4) Mechanical loading and data acquisition steps: In this step, under the condition of maintaining the hydrogen environment and the dynamic equilibrium, the mechanical loading mechanism is started to test the mechanical properties of the sample and collect the corresponding mechanical data. Specifically, when the temperature and pressure in the reactor reach the preset values ​​and stabilize, and the cooling and force balance system runs smoothly, the loading program of the mechanical testing machine 10 is started. The crossbeam 101 moves down at a constant rate under servo control (or performs cyclic loading or constant load control), and applies load to the sample 107 through the loading tie rod 105. Since the axial force has been dynamically balanced, the actual load acting on the sample is accurately measured by the high-precision load sensor of the testing machine (usually located in the crossbeam 101 or actuator, not separately marked in the figure). At the same time, the deformation of the sample is measured through the displacement measuring hole 121 and other mechanisms. The data is collected and recorded in real time for subsequent calculation of the material's strength, plasticity, fatigue life or creep rate and other performance indicators. This mechanical property test includes at least one of slow strain rate tensile test, fatigue test, creep test or endurance strength test.

[0044] (5) Test Completion Procedure: After the sample test is completed (e.g., fracture or reaching the predetermined number of cycles / times), first stop the mechanical loading. Then, operate in the following safety procedure sequence: turn off the heating power supply and allow the reactor to cool naturally or by forced cooling. After the temperature drops to a safe range, slowly release the high-pressure gas inside the reactor through the controllable pressure relief valve. After confirming that the pressure has dropped to atmospheric pressure, turn off the cooling pressurization system 9 and the atmosphere supply and control system in sequence. Finally, open the reactor, remove the sample and fixtures for subsequent analysis.

[0045] Experimental Verification: Using the device described in this embodiment of the invention, a long-term tensile test exceeding 200 hours was successfully conducted in a hydrogen environment at 1100℃ and 4.2MPa. Throughout the process, the temperature of the dynamic seal area was stably controlled at (180±10)℃, with zero hydrogen leakage. The load sensor readings were stable, and no impact peak appeared at the moment of specimen fracture, verifying the effectiveness of the axial force dynamic balance. Compared with traditional devices without active cooling and force balancing, this device increases the dynamic seal life from less than 10 hours to thousands of hours, and reduces load measurement fluctuations from typically over ±5% to within ±0.8%.

[0046] Other embodiments: The above embodiments describe a preferred embodiment of the present invention in detail. Those skilled in the art will understand that various modifications can be made without departing from the core concept of the present invention. For example, the cooling gas is not limited to nitrogen; it can also be an inert gas such as argon or helium introduced into the cooling gas chamber.

[0047] The material of the dynamic seal 129 can be selected according to the target temperature. Fluororubber can be selected for temperatures below 250°C, while perfluoroether rubber or polytetrafluoroethylene composite material can be selected for higher temperatures.

[0048] The structure of the cooling gas chamber 110 can be formed between the base and the pedestal, or it can be achieved by machining a spiral or annular cooling channel inside the loading tie rod 105.

[0049] In addition to PID, the control algorithm of the intelligent control system 4 can also adopt advanced algorithms such as fuzzy control and adaptive control.

[0050] In summary, this invention, through the design of an adjustable-pressure cooling gas and a cooling gas chamber, deeply integrates active cooling and dynamic force balancing, successfully solving the challenges of sealing safety and load accuracy in mechanical testing under extreme hydrogen environments. Specifically, this invention achieves efficient cooling and long-term reliable sealing of the dynamic seal under high-temperature and high-pressure hydrogen environments through circulating cooling gas, online temperature monitoring, and intelligent control adjustment. Furthermore, it achieves axial force balancing through the reverse axial force generated by the cooling gas, thereby significantly improving the stability and loading accuracy of the test.

[0051] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, various modifications and variations can be made to the embodiments of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A dynamic seal and axial force self-balancing device for testing the mechanical properties in a hydrogen environment, characterized in that, The device is designed to operate in a hydrogen environment with a temperature not lower than 650℃ and a pressure not lower than 4MPa. The device includes a mechanical loading mechanism, a reaction vessel, an atmosphere supply and control system, and an integrated cooling and force balancing unit. The integrated cooling and force balancing unit includes a cooling gas chamber located between the bottom of the reaction vessel and the main base of the mechanical loading mechanism, surrounding the loading rod of the mechanical loading mechanism; a cooling pressurization system for providing adjustable-pressure cooling gas; and a gas pipeline connecting the cooling pressurization system and the cooling gas chamber to form a cooling gas circulation path. The cooling gas flows through the cooling... When the gas chamber is in use, it is configured to perform two functions simultaneously: first, to cool the loading rod through convective heat transfer; second, to generate a reverse thrust on the pressure-bearing surface of the loading rod through the pressure of the cooling gas, in order to dynamically balance the axial force exerted on the loading rod by the test gas in the reactor; the device also includes a temperature closed-loop control module, which includes a temperature sensor located near the dynamic sealing area and an intelligent controller. The intelligent controller is configured to dynamically adjust the output of the cooling pressurization system according to the feedback signal of the temperature sensor to control the temperature of the dynamic sealing area.

2. The apparatus according to claim 1, characterized in that: The cooling gas chamber has cooling air inlets and exhaust outlets on its walls, which are connected to the cooling pressurization system through cooling gas pipelines and cooling gas circuits, respectively, forming a closed gas cooling circulation loop.

3. The apparatus according to claim 1, characterized in that: The intelligent controller is also configured to receive the pressure signal inside the reactor and, by adjusting the gas pressure output by the cooling and pressurizing system, make the reverse thrust dynamically follow and counteract the axial force.

4. The apparatus according to claim 1, characterized in that: The loading rod has a cooling channel inside the section corresponding to the cooling gas chamber; or, the cooling gas chamber is an annular sealed cavity formed in the main unit base and surrounding the loading rod.

5. The apparatus according to claim 1, characterized in that: The device also includes a combined sealing system, comprising a static sealing structure for sealing the reactor and a dynamic sealing structure for sealing the relative movement between the loading rod and the main unit base.

6. A method for testing the mechanical properties of a device in a hydrogen environment based on any one of claims 1 to 5, characterized in that, Includes the following steps: Sample Installation and Atmosphere Preparation Steps: Install the sample in the reactor and seal it. After evacuating and purging the reactor, fill it with a hydrogen-based test atmosphere of the preset composition. Integrated System Start-up and Pre-Balance Steps: Start the cooling and pressurizing system and introduce cooling gas with a preset pressure into the cooling gas chamber. Simultaneously, start the temperature closed-loop control module for real-time monitoring. Environment Establishment and Dynamic Balancing Steps: Heat and pressurize the reactor until the target test temperature and pressure are reached, where the target temperature is not lower than 650℃ and the target pressure is not lower than 4MPa. During this process and in steady state, the intelligent controller dynamically adjusts the cooling gas parameters based on the feedback from the temperature sensor to control the temperature of the dynamic sealing area. At the same time, the dynamic balance of the axial force is maintained by adjusting the cooling gas pressure. Mechanical Loading and Data Acquisition Steps: Under the condition of maintaining the hydrogen environment and the dynamic balance, start the mechanical loading mechanism to test the mechanical properties of the sample and collect the corresponding mechanical data. Test Completion Steps: After the test is completed, perform cooling, depressurization, and system shutdown operations in sequence.

7. The method according to claim 6, characterized in that: In the integrated system startup and pre-balancing step, the preset pressure is set to a value that matches the target test pressure.

8. The method according to claim 6, characterized in that: In the environment establishment and dynamic balancing step, the intelligent controller compares the real-time temperature value monitored by the temperature sensor with the preset safe temperature threshold, and adjusts the cooling power and / or gas flow of the cooling booster system to keep the temperature of the dynamic sealing area stable below the safe temperature threshold.

9. The method according to claim 6, characterized in that: The mechanical property tests include at least one of slow strain rate tensile test, fatigue test, creep test, or endurance strength test.

10. The method according to claim 6, characterized in that: The cooling gas is an inert gas, including nitrogen, argon, or helium.

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