Liquid hydrogen heat exchange experimental device

Abstract

The invention discloses a liquid hydrogen heat exchange experimental device, which relates to the field of aero-engines and comprises a liquid hydrogen loop, a nitrogen heating loop, a test section, a measurement and control module and a safety protection module, wherein the liquid hydrogen loop is used for providing supercritical hydrogen meeting a preset working condition; the nitrogen heating loop is used for heating nitrogen to a target working condition temperature and providing a convection heating environment for the test section; the test section comprises a straight pipe type sealing sleeve, supercritical hydrogen circulates in an inner pipe of the straight pipe type sealing sleeve, and high-temperature nitrogen circulates in an outer pipe of the straight pipe type sealing sleeve; the measurement and control module comprises a controller, and the controller and the heater are configured to dynamically adjust the flow of hydrogen and nitrogen and the heating power of nitrogen so as to simulate transient working conditions; the safety protection module is used for conducting steady state judgment and safety monitoring according to data collected by the liquid hydrogen side sensor and the nitrogen side sensor. According to the invention, the convective heat transfer performance of supercritical hydrogen can be accurately measured under low-temperature, high-pressure and safe conditions, and reliable experimental support is provided for thermal management of a hydrogen fuel aero-engine.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of aeroengines, in particular to a liquid hydrogen heat exchange experimental device. BACKGROUND

[0002] With the development of hydrogen fuel aeroengines, the use of liquid hydrogen in the engine is not only limited to fuel, but also plays an important role in cooling and energy management. Among them, the tail nozzle as a high-temperature component of the engine, heating hydrogen fuel is a key link to ensure the stability of combustion and propulsion performance. Therefore, it is of great significance to master the heat transfer law of supercritical hydrogen under convective heat transfer conditions for engine thermal management and fuel utilization efficiency.

[0003] At present, the heat transfer research of supercritical fluid at home and abroad is relatively rich, especially in supercritical carbon dioxide, water and hydrocarbon fuel working medium, a relatively systematic experimental and theoretical results have been formed. However, due to the low temperature of supercritical hydrogen, and easy to burn and explode, the heat transfer characteristics of supercritical hydrogen under the conditions of extremely low temperature, high pressure and severe thermal property change are still relatively limited. The existing experimental measurement device cannot meet the low temperature and safety requirements of liquid hydrogen, therefore, the development of an experimental device that can accurately and safely measure the convective heat transfer performance of supercritical hydrogen under real working conditions is an urgent need in the development of hydrogen fuel aeroengine thermal management technology.

[0004] In the prior art, a device is provided to make supercritical fuel flow in the inner circular pipe, high-temperature and high-pressure air flows through the outer cavity, and forms a convective heat transfer environment with the fuel pipe wall, so as to simulate the third type of boundary condition under the main cooling condition of the engine. And through the recessed groove on the outer wall of the circular pipe, the infrared window and the infrared thermal imager are used for wall temperature measurement. The technical scheme has improved the experimental reality compared with the traditional isoflux boundary condition device, but still has certain limitations. First, the accuracy of temperature measurement by the infrared thermal imager through the infrared window is easily affected by the transmittance of the window material, pollution and self-heating radiation, and the recessed groove on the outer wall of the circular pipe may change the local heat conduction characteristics, resulting in errors in the temperature measurement results. Secondly, the experimental conditions are complex and the cost is high, the device needs to have high-pressure air source, air heater and infrared window at the same time, and the sealing and heat insulation design of the cavity under high temperature and high pressure also brings great engineering difficulty. In addition, supercritical fuel and high-temperature air coexist in the experimental environment, which has the potential risk of fuel cracking, carbon deposition and even leakage and combustion, and the safety and stability need to be additionally guaranteed.

[0005] It can be seen that although the existing heat exchange experimental device for supercritical carbon hydrogen fuel can simulate the third type of boundary condition under the condition of external air flow, when the research object turns to supercritical hydrogen, there is obvious inapplicability. First, the temperature of liquid hydrogen is extremely low, and it is difficult for conventional devices to simultaneously meet the sealing performance and material reliability under low temperature environment, and frost formation, brittle fracture and sealing failure are prone to occur; second, liquid hydrogen has strong permeability and extremely high risk of flammability and explosiveness, and the existing device measures by opening grooves on the pipe wall or infrared transparent windows on the outer cavity, which will bring leakage points and significantly increase the risk of hydrogen leakage and explosion; third, using high temperature air as the external working medium is not suitable for simultaneous operation with the liquid hydrogen test section, and if hydrogen leakage occurs, it will cause serious safety hazards. Therefore, a supercritical hydrogen convective heat transfer measurement device capable of operating under low temperature and safe conditions is urgently needed to obtain reliable heat transfer and flow parameters under the premise of ensuring sealing performance and safety. SUMMARY

[0006] The present application provides a liquid hydrogen heat exchange experimental device to overcome at least one technical problem in the prior art.

[0007] The present application provides a liquid hydrogen heat exchange experimental device, comprising: a liquid hydrogen circuit, a nitrogen heating circuit, a test section, a measurement and control module, and a safety protection module; wherein, The liquid hydrogen circuit is used to provide supercritical hydrogen that meets a predetermined working condition; includes a liquid hydrogen side sensor, which is used to collect the temperature, pressure, pressure difference, and flow of the liquid hydrogen circuit; The nitrogen heating circuit is used to heat nitrogen to a target working condition temperature to provide a convective heating environment for the test section; includes a nitrogen side sensor and a heater, the nitrogen side sensor is used to collect the temperature and pressure of the nitrogen heating circuit, and the heater is used to heat the nitrogen; The test section includes a straight pipe type sealing sleeve, the inner tube of the straight pipe type sealing sleeve flows through the supercritical hydrogen, and the outer tube flows through high temperature nitrogen; The measurement and control module includes a controller, which is configured to dynamically adjust the flow rates of hydrogen and nitrogen, and the heating power of nitrogen to simulate transient working conditions; The safety protection module is used for steady state determination and safety monitoring according to the data collected by the liquid hydrogen side sensor and the nitrogen side sensor.

[0008] Optionally, the predetermined working condition is defined as: the pressure is not less than 3 MPa, the temperature is as low as 20 K, and the flow rate is adjustable within the range of 0-6 g / s.

[0009] Optionally, the controller includes a nitrogen flow controller and a hydrogen flow controller; The nitrogen flow controller is located in the nitrogen heating circuit and is used to adjust the flow rate of nitrogen; The hydrogen flow controller is located in the liquid hydrogen circuit and used for adjusting the hydrogen flow.

[0010] Optionally, the inner tube of the straight tube sealing sleeve is made of GH4169 high-temperature alloy material.

[0011] Optionally, the experimental device comprises a plurality of hydrogen pipelines for circulating hydrogen, and the hydrogen pipelines are made of low-temperature anti-brittleness material.

[0012] Optionally, the hydrogen pipeline and the liquid hydrogen side sensor are connected by welding, and a low-temperature deformation compensation structure is arranged at the liquid hydrogen side sensor interface and the weld.

[0013] Optionally, The liquid hydrogen side sensor comprises: A Coriolis mass flowmeter connected to the liquid hydrogen circuit and used for measuring the liquid hydrogen mass flow; A special gold-iron thermocouple connected to the hydrogen inlet end of the inner tube and used for measuring the hydrogen temperature flowing into the inner tube; A hydrogen temperature sensor connected to the hydrogen outlet end of the inner tube and used for measuring the hydrogen temperature flowing out of the inner tube; Two hydrogen pressure sensors connected to two ends of the inner tube through air pipes respectively and used for measuring the pressure of the liquid hydrogen circuit; A differential pressure sensor connected to the inlet of the inner tube at one end and connected to the outlet of the inner tube at the other end and used for measuring the pressure difference; The nitrogen side sensor comprises: A nitrogen pressure sensor connected to the nitrogen heating circuit and used for judging the sealing performance of the test section; Two nitrogen temperature sensors connected to two ends of the outer tube respectively and used for measuring the temperature of the nitrogen heating circuit.

[0014] Optionally, a purging unit is further included, which is used for purging and replacing the liquid hydrogen circuit with nitrogen before and after the experiment.

[0015] Optionally, The steady state determination specifically refers to that when the fluctuation value of the liquid hydrogen outlet temperature is less than a preset threshold value and maintained for a preset time length, it is determined that the system is in a steady state; The safety monitoring specifically refers to that when any one of the following conditions is monitored, an alarm is triggered and the experiment is immediately stopped: the hydrogen concentration exceeds the limit, the test section pipe wall over-temperature, or the nitrogen pressure fluctuation exceeds the threshold value.

[0016] Optionally, a plurality of wall temperature sensors are further included, which are located on the inner tube wall of the sealing sleeve and fixed on the outer tube wall through a sleeve and used for measuring the wall surface temperature of the inner tube.

[0017] The innovation points of the embodiment of the present application include: (1) In this embodiment, the low temperature, high pressure and safety requirements of supercritical hydrogen are specially designed, which can realize stable operation under real or equivalent third boundary conditions, and through reasonable temperature measurement and monitoring scheme, the wall temperature and fluid parameters can be obtained without damaging the test section structure, which ensures the authenticity and repeatability of experimental data, which is one of the innovations of the embodiment of the application.

[0018] (2) In this embodiment, the device avoids the risk of direct contact between hydrogen and air during operation, reduces the risk of combustion and explosion, and significantly improves the safety of the experiment. It can be seen that the application can accurately measure the convective heat transfer performance of supercritical hydrogen under low temperature, high pressure and safe conditions, and can be used for combustion chamber cooling, liquid hydrogen heat exchanger performance evaluation and other low temperature fluid heat transfer research, and provides reliable experimental support for hydrogen fuel aircraft engine thermal management, which is one of the innovations of the embodiment of the application.

[0019] (3) In this embodiment, the convective heat transfer performance of supercritical hydrogen can be accurately measured under low temperature, high pressure and safe conditions, and can be used for combustion chamber cooling, liquid hydrogen heat exchanger performance evaluation and other low temperature fluid heat transfer research, and provides reliable experimental support for hydrogen fuel aircraft engine thermal management, which is one of the innovations of the embodiment of the application. BRIEF DESCRIPTION OF DRAWINGS

[0020] In order to more clearly illustrate the technical solutions of the embodiments of the application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiment or prior art description. Obviously, the drawings in the following description are only some embodiments of the application, and those skilled in the art can obtain other drawings according to these drawings without creative labor.

[0021] Figure 1 A structural schematic diagram of the liquid hydrogen heat exchange experimental device provided by the embodiment of the application; Figure 2 A schematic diagram of the wall temperature sensor provided by the embodiment of the application in the inner tube. DETAILED DESCRIPTION

[0022] The technical solutions in the embodiments of the application will be described clearly and completely in the following with reference to the drawings in the embodiments of the application. Obviously, the described embodiments are only some of the embodiments of the application, not all. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the application.

[0023] It is to be understood that the terms "including", "comprising", "having" and any change thereof used herein, are intended to be inclusive in a manner similar to the term "comprising" and are not intended to be limiting. For example, a process, method, system, product, or apparatus that comprises a list of steps or elements is not necessarily limited to the listed steps or elements, but can include additional steps or elements that are not expressly listed or inherent to such process, method, system, product, or apparatus.

[0024] The embodiment of the present application discloses a liquid hydrogen heat exchange experimental device and method. The following are described in detail.

[0025] Figure 1 A structural schematic diagram of the liquid hydrogen heat exchange experimental device provided by the embodiment of the present application is shown in Figure 1 The liquid hydrogen heat exchange experimental device provided by the embodiment of the present application comprises a liquid hydrogen loop, a nitrogen heating loop, a test section, a measurement and control module, and a safety protection module. The liquid hydrogen loop is used to provide supercritical hydrogen meeting a predetermined working condition, and comprises a liquid hydrogen side sensor for collecting the temperature, pressure, pressure difference, and flow of the liquid hydrogen loop. The nitrogen heating loop is used to heat nitrogen to a target working condition temperature to provide a convection heating environment for the test section, and comprises a nitrogen side sensor and a heater, wherein the nitrogen side sensor is used to collect the temperature and pressure of the nitrogen heating loop, and the heater is used to heat nitrogen. The test section comprises a straight pipe type sealing sleeve, wherein the inner pipe of the straight pipe type sealing sleeve flows supercritical hydrogen, and the outer pipe flows high-temperature nitrogen. The measurement and control module comprises a controller, and the controller and the heater are configured to dynamically adjust the flow of hydrogen and nitrogen and the heating power of nitrogen to simulate transient working conditions. The safety protection module is used to make steady state determination and safety monitoring according to the data collected by the liquid hydrogen side sensor and the nitrogen side sensor.

[0026] Specifically, the liquid hydrogen heat exchange experimental device provided by the embodiment of the present application comprises a test section, and in order to provide a convection heating channel for hydrogen and nitrogen, the test section comprises a straight pipe type sealing sleeve, the inner pipe of the straight pipe type sealing sleeve is used as a hydrogen channel, supercritical hydrogen flows in the inner pipe, the outer pipe is coaxial with the inner pipe and forms an annular space, the annular space is used as a nitrogen channel, high-temperature nitrogen flows in the annular space to heat the inner pipe, thereby forming a convection heat exchange channel. Figure 1

[0027] ​In addition, since the temperature of the supercritical hydrogen flowing into the inner tube is extremely low, the inner tube of the straight tube sealing sleeve in the embodiment is made of the same GH4169 high-temperature alloy material as the engine, which has excellent toughness and ductility, can not only avoid the problem of low-temperature brittle fracture of the inner tube, but also make the heat exchange boundary conditions of the experiment similar to the real engine, which is conducive to improving the authenticity of the experimental data.

[0028] On the other hand, although the temperature inside the inner tube is extremely low, the outside of the inner tube needs to be heated by high-temperature nitrogen. It can be seen that the inner tube not only needs to resist low temperature, but also needs to resist high temperature. Therefore, the same GH4169 high-temperature alloy material as the engine is selected to ensure that the inner tube will not deform due to high temperature under the condition of nitrogen heating.

[0029] Since hydrogen is extremely easy to leak, the interface of the straight tube sealing sleeve in the present application is sealed by full-welded metal, thereby avoiding leakage caused by low-temperature deformation.

[0030] The experimental device also includes a nitrogen heating circuit (the route is indicated by a dashed line in the figure). In order to heat the nitrogen to the target working condition temperature and thus provide a convection heating environment for the test section, the present application has a heater in the circuit. The nitrogen flowing to the test section is heated by the heater to meet the target working condition. The heater needs to heat 5.0g / s of nitrogen to above 900K, as far as possible to ensure the same temperature as the gas temperature in the engine exhaust nozzle, so as to simulate the actual working condition, avoid the risk of combustion and explosion caused by the coexistence of hydrogen and air, and realize safe operation under high temperature and high heat flux density.

[0031] It should be noted that, in order to avoid the problem of device damage or precision decline caused by the existence of pollutants in the nitrogen heating circuit, the present application also provides a nitrogen filter at the nitrogen inlet of the nitrogen heating circuit, which filters out the pollutants in the heating circuit.

[0032] In order to ensure that the system can operate stably, a nitrogen side sensor, such as a nitrogen pressure sensor and a nitrogen temperature sensor, is also provided in the nitrogen heating circuit. The nitrogen pressure sensor is connected to the nitrogen heating circuit, and the pressure state of the nitrogen heating circuit itself can be monitored in real time through the nitrogen pressure sensor, so as to avoid the problem of leakage. In addition, when the inner tube of the test section breaks or the sealing is poor, the leakage of high-pressure hydrogen will cause abnormal nitrogen pressure, so the nitrogen pressure sensor can also be used to judge the sealing performance of the test section.

[0033] The nitrogen side sensor further comprises two nitrogen temperature sensors, one of which is connected to the nitrogen inlet end of the outer tube, and by installing the nitrogen temperature sensor here, the nitrogen temperature applied to the test section can be directly measured, so as to determine whether the nitrogen temperature meets the working condition requirements, and provide data support for controlling the heating power. The other nitrogen temperature sensor is connected to the nitrogen outlet end of the outer tube, and by setting the nitrogen temperature sensor here, the nitrogen temperature flowing out of the test section can be measured, so that the temperature difference between the inlet and outlet of the nitrogen can be calculated, and data support is provided for the calculation of the heat transfer performance.

[0034] The experimental device further comprises a liquid hydrogen circuit (the route is indicated by a solid line in the figure), in order to make the hydrogen enter the test section in a supercritical state, it is necessary to measure the state of the hydrogen in the liquid hydrogen circuit in real time, and ensure that it is in a supercritical state, therefore, the liquid hydrogen side sensor is arranged in the liquid hydrogen circuit, after the liquid hydrogen enters the liquid hydrogen circuit from the storage tank through the liquid hydrogen inlet, the temperature, pressure, pressure difference and flow of the hydrogen are measured by the liquid hydrogen side sensor.

[0035] It should be noted that liquid hydrogen is an extremely low-temperature, easily-leakage medium, and its purity is required to be high, therefore, the hydrogen filter is further arranged in the liquid hydrogen circuit, the hydrogen filter is located at the liquid hydrogen inlet, after the liquid hydrogen enters the liquid hydrogen circuit from the storage tank through the liquid hydrogen inlet, the solid particles carried in the liquid hydrogen are filtered out through the hydrogen filter, so as to avoid the solid particles flowing into the test section and affecting the experimental data.

[0036] In the embodiment, the liquid hydrogen side sensor comprises a Coriolis mass flowmeter connected after the hydrogen filter, after the hydrogen working medium filtered by the hydrogen filter flows through the Coriolis mass flowmeter, the mass flow of the hydrogen working medium is measured by the Coriolis mass flowmeter, so as to calculate the heat absorption of the hydrogen working medium, and thus the heat transfer performance of the supercritical hydrogen is measured.

[0037] The heat transfer performance of the supercritical hydrogen needs to be measured, therefore, it is necessary to ensure that the hydrogen entering the test section is in a supercritical state. Therefore, it is necessary to measure the pressure value of the hydrogen entering the test section in real time, for example, when the pressure of the hydrogen is not lower than 3MPa, it can be ensured that it is in a supercritical state. Based on this, the liquid hydrogen side sensor comprises two hydrogen pressure sensors in the embodiment, one of which is installed at the inlet end of the inner tube, and is used to monitor the hydrogen pressure value entering the test section, and the back pressure valve adjusts the pressure according to the measurement data, so as to ensure the stability of the pressure of the test section, and thus ensure that the hydrogen is in a supercritical state.

[0038] Another hydrogen pressure sensor is installed at the outlet end of the inner tube, through which the pressure of hydrogen at the outlet of the test section can be monitored, so as to determine whether the system is stable according to the inlet pressure and the outlet pressure. It should be noted that since the temperature of the supercritical hydrogen is very low (for example, 20K), if the hydrogen pressure sensor is directly connected to the hydrogen pipeline, it may fail due to low temperature. In order to avoid this problem, the present application connects the two hydrogen pressure sensors to the two ends of the inner tube through the air guide pipe. In this way, the low-temperature hydrogen can be warmed up through the air guide pipe before measurement, so as to ensure that the hydrogen pressure sensor can work normally.

[0039] Although the pressure measured by the hydrogen pressure sensors connected at the two ends of the inner tube can be calculated to obtain the pressure drop of the test section, when any one of the hydrogen pipe pressure sensors fails, the pressure drop cannot be accurately obtained. Therefore, the liquid hydrogen side sensor provided by the present application further comprises a differential pressure sensor, one end of which is connected to the inlet of the inner tube and the other end of which is connected to the outlet of the inner tube. In this way, the pressure drop of the test section can be directly measured, so as to evaluate the heat exchange performance of the test section. Similarly, the differential pressure sensor is also connected to the two ends of the inner tube through the air guide pipe.

[0040] To calculate the heat exchange characteristics, the temperature of the inflow and outflow hydrogen must be known. Therefore, the present application is provided with temperature measuring sensors at the hydrogen inlet end and the hydrogen outlet end of the inner tube for measuring the hydrogen temperature. Since the temperature of the supercritical hydrogen flowing into the test section is very low, in order to ensure the measurement accuracy, the temperature measuring sensor at the inlet end adopts a low-temperature special thermocouple, such as a specially made gold-iron thermocouple, for measuring the temperature of the low-temperature hydrogen flowing into the test section. The temperature of the hydrogen at the outlet end is warmed up after heat exchange, so the hydrogen temperature sensor at this position adopts a general thermocouple, which is used to measure the temperature of the hydrogen flowing out of the inner tube.

[0041] In the liquid hydrogen circuit, various devices are connected through the hydrogen pipeline. Since the supercritical hydrogen flowing in the hydrogen pipeline is at an extremely low temperature, the present embodiment is provided with a low-temperature anti-brittleness material for the hydrogen pipeline, so as to avoid the problem of low-temperature brittle fracture of the hydrogen pipeline. At the same time, according to the difference in contraction coefficient, a full-welding structure is designed between the hydrogen pipeline and the liquid hydrogen side sensor, and a low-temperature deformation compensation structure is provided at the liquid hydrogen side sensor interface and the weld, so as to realize the structure and material integrated anti-brittleness and anti-leakage design.

[0042] Through the above-mentioned liquid hydrogen circuit, supercritical hydrogen meeting the predetermined working condition can be provided. The predetermined working condition is defined, for example, as follows: the pressure is not less than 3MPa, the temperature is as low as 20K, and the flow rate is adjustable within the range of 0-6g / s. It should be noted that since the temperature of the liquid hydrogen circuit is extremely low, the liquid hydrogen side sensor needs to be calibrated at low temperature, for example, liquid nitrogen (77K) can be used as the calibration medium, so as to ensure the measurement accuracy.

[0043] In order to make the experimental device can simulate a variety of different working conditions, the application also sets up a measurement and control module, which is provided with a controller, such as a nitrogen flow controller and a hydrogen flow controller. During the experiment, the flow of nitrogen can be dynamically adjusted by the nitrogen flow controller, and the flow of hydrogen can be dynamically adjusted by the hydrogen flow controller. At the same time, the heating power of nitrogen can also be adjusted by the heater, so as to simulate the coordinated change of supercritical pressure (above 3MPa) and gas temperature (273~900K) of the engine under various different transient conditions, in order to study the supercritical hydrogen heat transfer performance under different working conditions.

[0044] Among them, the nitrogen flow controller is arranged in the nitrogen heating circuit, and the hydrogen flow controller is arranged in the liquid hydrogen circuit, which can be referred to in detail Figure 1 . The nitrogen flow controller is arranged between the nitrogen pressure sensor and the heater. The nitrogen flow can be quickly and accurately adjusted to the target value by the nitrogen flow controller without manual adjustment of the valve by the staff, which is beneficial to improve the experimental efficiency and accuracy. The hydrogen flow controller is arranged between the back pressure valve and the exhaust pipe, and works cooperatively with the back pressure valve. By adjusting the opening degree, the flow in the test section is assisted to be adjusted.

[0045] Since hydrogen is flammable and explosive, and the experiment is in an extreme supercritical condition, in order to prevent accidents, the application also sets up a safety protection module. The safety protection module can make self-steady state judgment and safety monitoring according to the data collected by the liquid hydrogen side sensor and the nitrogen side sensor, and form a full working condition safety closed loop for the hydrogen environment. For example, when the fluctuation value of the liquid hydrogen outlet temperature is less than a preset threshold and maintains for a preset time length, it is determined that the system is in a steady state. When any one of the conditions of hydrogen concentration exceeding the limit, test section pipe wall overtemperature or nitrogen pressure fluctuation exceeding the threshold is monitored, the alarm is triggered and the experiment is immediately stopped, so as to ensure the safety of the system.

[0046] It should be noted that the hydrogen concentration can be detected by a concentration sensor. If the concentration of hydrogen exceeds the concentration threshold, an alarm is immediately issued and the experiment is stopped.

[0047] In order to measure the temperature of the test section pipe wall, a plurality of wall temperature sensors are arranged on the inner pipe wall of the sealing sleeve, which can be referred to in detail Figure 1 and Figure 2 , Figure 2A schematic diagram of a wall temperature sensor provided in an inner tube according to an embodiment of the present application. In order to ensure the accuracy of temperature measurement, the most direct thermocouple temperature measurement method is usually used, but the outer tube will involve sealing problems. If a thermocouple wire is used for temperature measurement, the wire is exposed to strong erosion environment, and the thin wire is easy to be bent and broken, especially the K-type, E-type or thin wire platinum rhodium thermocouple, which is more prone to failure due to vibration and stress concentration; and in high-temperature high-speed airflow, the thermocouple itself will be heated to a higher temperature than the pipe wall, and even there is a superposition effect of radiation and convection, the output potential can no longer truly reflect the pipe wall temperature, thereby generating systematic measurement error.

[0048] But if a armored thermocouple is used for temperature measurement, the front end is thick, it is difficult to fix the thermocouple at a fixed position on the pipe wall under the erosion airflow, therefore, the wall temperature sensor in the embodiment uses an armored thermocouple with a bare front end, in this way, the thermocouple wire can be protected under the erosion airflow, and since the front end of the thermocouple wire is exposed, it can be welded to the inner tube wall and fixed to the outer tube wall by a sleeve, as shown in Figure 2 , so the temperature measurement position can be fixed, thereby effectively measuring the wall temperature of the inner tube. At the same time, it avoids recess processing or windowing on the pipe wall, fundamentally reduces the hydrogen leakage channel, and improves the overall sealing and long-term reliability of the device Before the experiment starts, the liquid hydrogen circuit may be filled with air, so that hydrogen entering after that can easily cause the risk of explosion. Therefore, the present application is provided with a purging unit, which uses nitrogen to purge the liquid hydrogen circuit before the experiment starts, to drive out the air in the circuit and prevent hydrogen from mixing with air to form an explosive substance after entering. After the experiment is completed, there may still be hydrogen gas remaining in the liquid hydrogen circuit, therefore, after the experiment is completed, the purging unit uses nitrogen to drive out and replace the remaining hydrogen gas, so that the circuit is in a state of no combustible material, improving safety.

[0049] The liquid hydrogen heat exchange experimental device provided by the present application is specially designed for the low temperature, high pressure and safety requirements of supercritical hydrogen, can realize stable operation under real or equivalent third type boundary conditions, and can obtain wall temperature and fluid parameters without damaging the structure of the test section through reasonable temperature measurement and monitoring scheme, thereby ensuring the authenticity and repeatability of experimental data.

[0050] The device avoids the risk of direct contact between hydrogen and air during operation, reduces the risk of explosion, and significantly improves the safety of the experiment. It can be seen that the present application can accurately measure the convective heat transfer performance of supercritical hydrogen under low temperature, high pressure and safe conditions, and can be popularized for combustion chamber cooling, liquid hydrogen heat exchanger performance evaluation and other low temperature fluid heat transfer research, to provide reliable experimental support for hydrogen fuel aircraft engine thermal management.

[0051] Those skilled in the art can understand that the modules or flows in the drawings are not necessarily required for implementing the present application.

[0052] Those skilled in the art can understand that the modules in the devices in the embodiments can be distributed in the devices in the embodiments as described in the embodiments, or can be changed to be located in one or more devices different from the embodiments. The modules in the above embodiments can be combined into one module, or can be further split into multiple sub-modules.

[0053] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that the technical solutions recorded in the foregoing embodiments can still be modified, or some technical features can be replaced by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A liquid hydrogen heat exchange experiment device, characterized by, The liquid hydrogen heat exchange experimental device comprises a liquid hydrogen circuit, a nitrogen heating circuit, a test section, a measurement and control module, and a safety protection module, wherein The liquid hydrogen circuit is used to provide supercritical hydrogen meeting a predetermined working condition, and comprises a liquid hydrogen side sensor for collecting the temperature, pressure, pressure difference, and flow of the liquid hydrogen circuit. The nitrogen heating circuit is used to heat nitrogen to a target working condition temperature, and to provide a convection heating environment for the test section, and comprises a nitrogen side sensor and a heater, wherein the nitrogen side sensor is used to collect the temperature and pressure of the nitrogen heating circuit, and the heater is used to heat nitrogen. The test section comprises a straight pipe type sealing sleeve, an inner pipe of the straight pipe type sealing sleeve flows the supercritical hydrogen, and an outer pipe of the straight pipe type sealing sleeve flows high-temperature nitrogen. The measurement and control module comprises a controller, and the controller and the heater are configured to dynamically adjust the flow of hydrogen and nitrogen and the heating power of nitrogen to simulate a transient working condition. The safety protection module is used to make a steady state determination and safety monitoring according to the data collected by the liquid hydrogen side sensor and the nitrogen side sensor. The predetermined working condition is defined as a pressure not lower than 3 MPa, a temperature as low as 20 K, and a flow adjustable in a range of 0-6 g / s.

2. The liquid hydrogen heat exchange experiment device according to claim 1, characterized by, The controller comprises a nitrogen flow controller and a hydrogen flow controller.

3. The liquid hydrogen heat exchange experiment device according to claim 1, characterized by, The nitrogen flow controller is located in the nitrogen heating circuit and is used to adjust the flow of nitrogen. The hydrogen flow controller is located in the liquid hydrogen circuit and is used to adjust the flow of hydrogen. The inner pipe of the straight pipe type sealing sleeve is made of GH4169 high-temperature alloy material.

4. The liquid hydrogen heat exchange experiment device according to claim 1, characterized by, The experimental device comprises a plurality of hydrogen pipelines for flowing hydrogen, and the hydrogen pipelines are made of low-temperature anti-brittleness material.

5. The liquid hydrogen heat exchange experiment device according to claim 1, characterized in that, The hydrogen pipelines and the liquid hydrogen side sensor are connected by welding, and a low-temperature deformation compensation structure is arranged at the liquid hydrogen side sensor interface and the weld.

6. The liquid hydrogen heat exchange experiment device according to claim 5, characterized in that, 7. The liquid hydrogen heat exchange experimental device according to claim 1, wherein The liquid hydrogen side sensor comprises: a Coriolis mass flowmeter connected to the liquid hydrogen circuit and used to measure the mass flow of liquid hydrogen; a special gold-iron thermocouple connected to the hydrogen inlet end of the inner pipe and used to measure the temperature of hydrogen flowing into the inner pipe; a hydrogen temperature sensor connected to the hydrogen outlet end of the inner pipe and used to measure the temperature of hydrogen flowing out of the inner pipe; two hydrogen pressure sensors connected to the two ends of the inner pipe through gas guide pipes respectively and used to measure the pressure of the liquid hydrogen circuit; a pressure difference sensor having one end connected to the inlet of the inner pipe and the other end connected to the outlet of the inner pipe and used to measure the pressure difference. The nitrogen side sensor comprises: a nitrogen pressure sensor connected to the nitrogen heating circuit and used to determine the sealing performance of the test section; two nitrogen temperature sensors connected to the two ends of the outer pipe respectively and used to measure the temperature of the nitrogen heating circuit. The experimental device further comprises a purging unit used to purge and replace the liquid hydrogen circuit with nitrogen before and after the experiment.

8. The liquid hydrogen heat exchange experiment device according to claim 1, wherein 9. The liquid hydrogen heat exchange experimental device according to claim 1, wherein The steady state determination is specifically that when the fluctuation value of the liquid hydrogen outlet temperature is less than a preset threshold value and is maintained for a preset time length, it is determined that the system is in a steady state. ​ The safety monitoring specifically comprises: when any one of the following conditions is monitored, triggering an alarm and immediately stopping the experiment: hydrogen concentration exceeding the limit, test section pipe wall over-temperature, or nitrogen pressure fluctuation exceeding the threshold.

10. The liquid hydrogen heat exchange experiment device according to claim 1, wherein The wall temperature sensors are arranged on the inner tube wall of the sealing sleeve and fixed on the outer tube wall through a sleeve, and used for measuring the wall surface temperature of the inner tube.

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