A displacement filling device and method based on low-temperature medium property measurement

Abstract

The application relates to the technical field of low-temperature medium, in particular to a displacement filling device and method based on low-temperature medium property measurement. In the technical scheme, the device comprises a core cavity, a first displacement air inlet channel arranged at a high position area of the core cavity, a second displacement air inlet channel arranged at a low position area, a state monitoring assembly for acquiring real-time state parameters of residual medium and a control unit; the control unit determines the actual density of the residual medium based on the real-time state parameters, and controls the first or second displacement air inlet channel to be opened to inject displacement gas according to the relative size of the actual density and the density of the displacement gas. The application dynamically matches the air inlet mode, uses the density difference to form a stable layered interface, and improves the displacement completeness and safety.

Description

Technical Field

[0001] This invention relates to the field of cryogenic media technology, and in particular to a displacement filling device and method based on cryogenic media property measurement. Background Technology

[0002] In the measurement and storage of cryogenic media, it is often necessary to switch between different types of cryogenic media. Current technologies typically select either top or bottom inlet gas intake based on the density difference between the replacement gas and the residual medium under standard conditions, or use a fixed intake mode. However, the temperature and pressure of cryogenic media change drastically under actual operating conditions, and their actual density differs significantly from the standard density. This renders judgments based on standard density ineffective, or the fixed intake mode unsuitable for varying operating conditions. This can easily cause turbulent flow fields during replacement, resulting in incomplete removal of residual media, leading to safety risks from mixing of old and new media, or ice blockage on the inner walls of pipelines, affecting the normal operation of equipment and measurement accuracy. Summary of the Invention

[0003] To address the problems of incomplete replacement and high safety risks in the existing technology during cryogenic medium replacement due to mismatch between air intake method and operating conditions, the present invention provides a replacement filling device and method based on cryogenic medium property measurement, which realizes dynamic air intake switching based on the real-time actual density of the residual medium, thereby improving replacement efficiency and safety.

[0004] In a first aspect, embodiments of the present invention provide a displacement filling device based on cryogenic medium property measurement, comprising: The core cavity is used to contain the cryogenic medium to be tested; The first replacement air intake channel is located in the high area of ​​the core cavity; The second replacement air intake channel is located in the lower part of the core cavity; The status monitoring component is configured to acquire real-time status parameters of the residual medium within the core cavity; The control unit is communicatively connected to the first replacement intake channel, the second replacement intake channel, and the status monitoring component. The control unit is configured to: determine the actual density of the residual medium based on real-time state parameters, and control the opening of the first or second replacement gas inlet channel according to the relative magnitude of the actual density and the replacement gas density, so as to inject replacement gas into the core cavity.

[0005] Secondly, embodiments of the present invention provide a displacement filling method based on cryogenic medium property measurement, applied to the apparatus described in the above embodiments, comprising: Obtain real-time status parameters of the residual medium within the core cavity; The actual density of the residual medium is determined based on real-time state parameters. By comparing the relative density of the actual density with that of the replacement gas, the first or second replacement gas inlet channel is opened based on the comparison result to inject replacement gas into the core cavity for replacement.

[0006] This invention provides a displacement filling device and method based on cryogenic medium property measurement. A state monitoring component acquires real-time state parameters such as temperature and pressure of the residual medium within the core cavity, and determines its actual density under current operating conditions, overcoming the shortcomings of existing technologies that rely on standard state densities or fixed air intake modes. The control unit dynamically selects high- or low-position air intake channels based on the relative magnitude of the actual density and the density of the displacement gas. Utilizing the piston-like pushing effect formed by the fluid density difference, a stable stratified interface is created between the displacement gas and the residual medium, significantly improving the thoroughness of displacement and effectively eliminating the risk of combustion and explosion and ice blockage caused by the mixing of different media. Attached Figure Description

[0007] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0008] Figure 1 This is a schematic diagram of the displacement filling device based on the measurement of the physical properties of a cryogenic medium provided in an embodiment of the present invention.

[0009] Figure label: 10-Vacuum chamber, 11-Cryogenic intermediate chamber, 12-Core chamber, 21-Cryogenic medium filling valve, 31-Upper inlet valve for replacement gas, 32-Lower inlet valve for replacement gas, 41-Temperature sensor, 51-Top gas analysis valve, 52-Bottom gas analysis valve, 53-Analytical testing pressure sensor, 54-Analyzer inlet valve, 55-Online analyzer, 61-First cryogenic gas valve, 62-Cryogenic gas pressure sensor, 63-Cryogenic gas temperature sensor, 64-Heat exchanger, 65-Second gas pressure sensor, 66-Second gas temperature sensor, 67-Second cryogenic gas valve, 68-Cryogenic gas recovery container, 71-Medium pressure sensor, 72-Medium temperature sensor, 73-Cryogenic medium valve, 74-Cryogenic medium recovery container. Detailed Implementation

[0010] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments. 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 of the present invention.

[0011] like Figure 1 As shown, this embodiment provides a displacement filling device based on cryogenic medium property measurement. This device is mainly used to achieve efficient and safe medium replacement through intelligent air intake control during the switching process of different types of cryogenic media. The displacement filling device based on cryogenic medium property measurement includes a core cavity 12, a first displacement air intake channel, a second displacement air intake channel, a status monitoring component, and a control unit.

[0012] The core cavity 12 is used to contain the cryogenic medium to be tested and serves as the physical carrier for the entire replacement and filling process. In practice, the core cavity 12 is typically designed as a cryogenic and pressure-resistant sealed container structure, with its internal space forming the reaction zone for medium storage and replacement. It should be understood that the specific shape of the core cavity 12 is not limited to the cylindrical shape shown in the figure; it can also be designed as a sphere, ellipsoid, or other geometric shapes adapted to the characteristics of cryogenic fluids, as long as it can provide a stable medium-containing space.

[0013] The first displacement air intake channel is located in the high region of the core cavity 12, and the second displacement air intake channel is located in the low region of the core cavity 12. In one specific implementation, the first displacement air intake channel corresponds to a pipe connected to the top of the core cavity 12, which is equipped with a displacement gas upper inlet valve 31; the second displacement air intake channel corresponds to a pipe connected to the lower part or bottom of the side wall of the core cavity 12, which is equipped with a displacement gas lower inlet valve 32. The terms "high region" and "low region" are relative to the orientation of the core cavity 12 in the direction of gravity, and are intended to distinguish the differences in the distribution of air intakes in the vertical dimension. In other embodiments not shown, the first and second displacement air intake channels can also take the form of spray pipes, distributors, etc., extending into the cavity, or be located at different heights on the side wall of the cavity. The core is to construct two air intake nodes with a significant height difference to provide a physical basis for subsequent flow field control.

[0014] The condition monitoring component is configured to acquire real-time condition parameters of the residual medium within the core cavity 12. This component may include various sensors, such as temperature sensors 41, pressure sensors, level gauges, or density gauges, arranged inside or on the outer wall of the core cavity 12. Through these sensors, the system can perceive the thermodynamic state of the residual medium within the cavity under current operating conditions in real time, rather than relying solely on theoretical values ​​under standard conditions. This real-time sensing capability is a prerequisite for accurate replacement, because the physical property changes of the cryogenic medium during temperature and pressure variations are non-linear; only by mastering the real-time condition parameters can the current physical properties of the medium be accurately characterized.

[0015] The control unit is communicatively connected to the first and second displacement inlet channels and the status monitoring component. The control unit is configured to: determine the actual density of the residual medium based on real-time status parameters, and control the opening of either the first or second displacement inlet channel according to the relative magnitude of the actual density and the displacement gas density, to inject displacement gas into the core cavity 12. Specifically, the control unit receives a data stream from the status monitoring component, processes it to obtain the actual density value of the residual medium in the core cavity 12 at the current moment. Subsequently, the control unit compares this actual density with a preset or real-time acquired displacement gas density. When the determination result shows that the displacement gas density is less than the actual density of the residual medium, it means that the displacement gas is lighter. At this time, the control unit opens the first displacement inlet channel located at the higher position, allowing the lighter gas to enter from the top and smoothly push the heavier residual medium below from top to bottom using buoyancy. Conversely, when the displacement gas density is greater than or equal to the actual density of the residual medium, it means that the displacement gas is heavier or equivalent. At this time, the control unit opens the second displacement inlet channel located at the lower position, allowing the heavier gas to enter from the bottom and lift and displace the lighter residual medium above from bottom to top.

[0016] This embodiment establishes an adaptive replacement mechanism based on real-time property matching through the above configuration. Unlike traditional fixed-intake methods or methods based on standard density judgment, this mechanism can dynamically adapt to the drastic changes in medium density under low-temperature conditions, ensuring that the injected replacement gas can form a stable density stratification interface with the residual medium at any time. This stratification interface acts like an invisible "piston," effectively suppressing turbulent mixing and vortex generation during the pushing process, thereby significantly improving the thoroughness of replacement. It fundamentally eliminates the risk of combustion and explosion and ice blockage caused by medium mixing, while also reducing the ineffective consumption of replacement gas and improving overall operational efficiency and safety.

[0017] In one implementation, the condition monitoring component includes a temperature sensor 41 and a pressure sensor. Specifically, the temperature sensor 41 preferably adopts an insertion structure, with its temperature probe extending into the core cavity 12. It can measure the temperature at three different heights (upper, middle, and lower) within the core cavity 12 to comprehensively reflect the temperature field distribution of the medium inside the cavity, avoiding density calculation errors caused by local temperature differences. The pressure sensor is used to acquire the absolute pressure value inside the core cavity 12 in real time. Although the pressure sensor is not separately marked in the attached figure, in actual engineering implementation, it can be integrated into the wall of the core cavity 12, or implemented through a high-precision pressure transmitter or other device connected to the core cavity 12 via a pipeline. In cryogenic thermodynamic systems, the density of the medium is a binary function of its temperature and pressure. Especially in the region near the critical point or saturation line, even small temperature and pressure fluctuations can cause drastic changes in density. Therefore, simultaneously acquiring high-precision temperature and pressure data is a necessary prerequisite for accurately characterizing the current true physical state of the residual medium inside the core cavity 12.

[0018] The control unit is configured to determine the actual density based on temperature data collected by temperature sensor 41 and pressure data collected by pressure sensor 41. In this process, the control unit receives real-time analog or digital signals from the sensors, filters and calibrates them, and then inputs them as state variables into a preset property calculation model. Because the properties of cryogenic media are highly nonlinear, relying solely on empirical formulas or table values ​​under standard conditions often results in significant errors. Calculations based on real-time temperature and pressure data can accurately pinpoint the thermodynamic state of the medium to the current operating point, thus obtaining the actual density value that reflects the true fluid characteristics. This actual density value serves as the benchmark for all subsequent control decisions, and its accuracy directly determines the effectiveness of the replacement strategy.

[0019] Based on this, the control unit executes the following specific channel switching judgment logic: when the density of the replacement gas is less than the actual density, the first replacement gas inlet channel is opened; when the density of the replacement gas is greater than or equal to the actual density, the second replacement gas inlet channel is opened. The essence of this logic is to use the density stratification stability principle in hydrostatics to construct the optimal replacement flow field. Specifically, when it is determined that the density of the replacement gas is less than the actual density of the residual medium in the core cavity 12, it means that the injected gas is relatively light. If the gas is introduced from the bottom, the light gas is very likely to pass through the heavy medium layer quickly to the top due to buoyancy, forming "gas channeling" or "short-circuit flow", resulting in a large amount of residual medium remaining at the bottom and not being replaced. Therefore, the control unit automatically selects the first replacement gas inlet channel located at the high position (i.e., the pipeline where the replacement gas inlet valve 31 is located), so that the light gas enters slowly from the top, relying on the balance of gravity and buoyancy to form a stable pushing interface from top to bottom, like a piston, orderly discharging the heavy residual medium below. Conversely, when the density of the replacement gas is determined to be greater than or equal to the actual density of the residual medium, it means that the injected gas is heavier or equivalent to the residual medium. In this case, if the gas is introduced from the top, the heavy gas will directly sink to the bottom, while the light residual medium at the top may form a "dead zone" due to lack of driving force. Therefore, the control unit automatically switches to the second replacement gas inlet channel located at the lower position (i.e., the pipeline where the replacement gas lower inlet valve 32 is located), so that the heavy gas is injected from the bottom, lifting and replacing the light medium above from bottom to top, or achieving overall displacement through momentum transfer under the condition of equal density.

[0020] This embodiment concretizes the abstract density comparison logic into automatic control actions based on temperature and pressure parameters, enabling the device to adaptively cope with complex fluid characteristics under low-temperature variable operating conditions. For example, during the process of liquid hydrogen replacing liquid nitrogen, the density relationship between the two may reverse with changes in temperature and pressure, inevitably rendering the fixed gas intake method ineffective. However, the dynamic switching mechanism of this embodiment can capture this reversal in real time and adjust the gas intake strategy, maintaining the stability of the replacement interface at all times. This fundamentally eliminates the risk of medium mixing caused by flow field turbulence, significantly improving replacement efficiency and safety.

[0021] In one implementation, the control unit is configured to calculate the actual density based on temperature and pressure data by querying a pre-set property database or invoking a state equation. Specifically, the system can employ differentiated density acquisition strategies for different types of cryogenic media and operating conditions. When querying the pre-set property database, the control unit internally stores a discrete data table covering the thermodynamic properties of the target medium over a wide temperature and pressure range, such as a two-dimensional lookup table built based on the NIST standard fluid thermophysical property database. During actual operation, the control unit uses real-time acquired temperature and pressure data as index coordinates and extracts the corresponding density value from the data table using bilinear interpolation or cubic spline interpolation algorithms. This method has a low computational load and fast response speed, making it particularly suitable for common cryogenic media (such as liquid nitrogen and liquid oxygen) with complex property changes but for which mature experimental data already exists. As another equivalent implementation, the control unit can also call a pre-set state equation to calculate the actual density. For example, for media with significant quantum effects, such as hydrogen and helium, or those near the critical region, simple table lookup methods may introduce errors due to sparse data points. In such cases, the control unit can run the Peng-Robinson equation, the Benedict-Webb-Rubin (BWR) equation, or a modified cryogenic equation of state, directly substituting real-time temperature and pressure into the equation to solve for density. Although this method involves relatively large computational loads, it provides continuous and high-precision property predictions, effectively avoiding computational failures caused by operating conditions exceeding the database coverage. It should be understood that the above two methods are not mutually exclusive and can be used in combination in practical systems. That is, under normal operating conditions, table lookup is prioritized to ensure efficiency, while under extreme operating conditions or when table lookup overflows, the system automatically switches to equation of state calculation, thus balancing the system's real-time performance and robustness.

[0022] In practice, the actual density can be calculated using the following real gas law form: in, This represents the actual density of the residual medium (kg / m³). The absolute pressure value (Pa) inside the core cavity of the pressure sensor. The molar mass of the medium is (kg / mol). The compressibility factor (dimensionless, its value reflects the degree to which the cryogenic medium deviates from the ideal gas behavior under the current temperature and pressure conditions, and can be obtained by looking up a table or empirical formula). It is the universal gas constant (8.314 J / (mol·K)). The absolute temperature value (K) collected by the temperature sensor. This formula directly maps the real-time collected temperature and pressure data to the true density of the medium, providing an accurate physical property reference for subsequent intake channel switching decisions.

[0023] Simultaneously, to achieve physical switching of the intake channels, the first replacement intake channel is equipped with a first intake valve, and the second replacement intake channel is equipped with a second intake valve. The control unit controls the opening and closing of the first or second intake valve to open the first or second replacement intake channel. In this embodiment, the first intake valve is specifically manifested as the upper inlet valve 31 of the replacement gas, which is connected in series on the high-level intake pipeline connected to the top of the core cavity 12; the second intake valve is specifically manifested as the lower inlet valve 32 of the replacement gas, which is connected in series on the low-level intake pipeline connected to the lower part or bottom of the side wall of the core cavity 12. These two valves are preferably low-temperature resistant pneumatic shut-off valves or electric regulating valves, with fast response and zero-leakage sealing performance to meet the requirements of frequent switching of low-temperature media. The control unit drives the valve actuator to act by outputting electrical signals or pneumatic control signals, thereby precisely controlling the on / off state of the corresponding pipeline. For example, when the control unit needs to open the first replacement intake channel, it sends an opening command to the upper inlet valve 31 of the replacement gas, while keeping the lower inlet valve 32 of the replacement gas closed; and vice versa. This structural design, which uses independent valves to control the high and low intake channels separately, not only automates the replacement strategy but also provides redundant safety isolation measures for the system. Specifically, during non-replacement periods, both valves can be closed simultaneously, completely cutting off the connection between the external air source and the core cavity 12, preventing the risk of media contamination due to misoperation or valve leakage. This embodiment concretizes the abstract density calculation logic into an executable algorithm module and transforms control decisions into reliable mechanical actions, providing solid underlying engineering support for the intelligent replacement function of the entire device.

[0024] In one implementation, the displacement filling device based on cryogenic medium property measurement also includes a medium recovery pipeline connected to the core cavity 12. The medium recovery pipeline is equipped with a recovery status monitoring component and a recovery control valve. Specifically, the medium recovery pipeline constitutes a physical channel for the discharge of residual medium within the core cavity 12. Its inlet end connects to the bottom or low-lying area of ​​the side wall of the core cavity 12, and its outlet end extends to an external collection container or processing system. It should be understood that although the accompanying drawings schematically show recovery branches for the gas and liquid phases respectively, at the general architecture level of this embodiment, the medium recovery pipeline is a higher-level concept encompassing all discharge paths. Its specific form can be a single drain pipe, a single vent pipe, a multi-functional pipeline for both gas and liquid phases, or a combination of separate branches as described in subsequent embodiments. The recovery status monitoring component is arranged on the pipeline or at key nodes associated with it to sense the fluid or equipment status during the recovery process in real time; the recovery control valve is connected in series in the pipeline as an actuator to cut off the flow of medium. This structural design ensures that the system has the capability for controlled media removal after the replacement operation is completed or in case of an emergency, while also providing the hardware foundation for subsequent safety interlocks.

[0025] The control unit communicates with the recovery status monitoring component and the recovery control valve, and is configured to close the recovery control valve when the recovery status parameter detected by the recovery status monitoring component exceeds a preset safety threshold. This interlocking logic constitutes the last line of defense for the safe operation of the device. Specifically, the recovery status parameter is not limited to a specific physical quantity, but refers to various indicators that can characterize the safety of the recovery process, such as fluid pressure, temperature, and flow rate in the pipeline, or the liquid level of the recovery container and valve opening feedback. The preset safety threshold is a critical value pre-calibrated based on the pressure resistance level, temperature resistance limit, or process safety window of the downstream recovery equipment. During operation, the control unit continuously receives data streams from the recovery status monitoring component. Once it is determined that the current parameter exceeds the safety boundary, meaning that continued discharge may lead to equipment damage or a safety accident, the control unit will immediately send a closing command to the recovery control valve to forcibly cut off the medium flow. For example, the interlocking mechanism will be triggered when an abnormal increase in downstream pressure in the recovery pipeline exceeds the design pressure of the container, or when the pipeline temperature is detected to be too low, potentially causing material embrittlement.

[0026] This embodiment achieves proactive safety protection during the media recovery process through the aforementioned general safety interlock architecture. Unlike traditional methods that rely on manual monitoring or passive pressure relief, this mechanism pre-emptively and automatically assesses safety, responding to abnormal conditions within milliseconds. This effectively prevents risks such as overpressure bursts, cryogenic freezing, or media leaks caused by operational errors, fluctuations in operating conditions, or equipment malfunctions. More importantly, this architecture employs a decoupling design approach for parameters and logic. Both the "recovery status parameters" and the "preset safety thresholds" are configurable variables. This allows the same hardware platform to flexibly adapt to the recovery safety standards of different cryogenic media such as liquid nitrogen, liquid hydrogen, and liquid oxygen through software parameter adjustments. It meets diverse safety compliance requirements without requiring modifications to the mechanical structure, significantly improving the device's versatility and inherent safety level.

[0027] In one implementation, the medium recovery pipeline includes a gas recovery branch, which is sequentially equipped with a cryogenic gas valve, a heat exchanger, a gas pressure sensor, and a gas temperature sensor. Specifically, this gas recovery branch constitutes the channel for the discharge of gaseous medium from the core cavity 12. In this embodiment, the cryogenic gas valve is specifically manifested as a first cryogenic gas valve 61 and a second cryogenic gas valve 67 arranged in series. The first cryogenic gas valve 61 is located closer to the core cavity 12 and serves as the main discharge valve, while the second cryogenic gas valve 67 is located downstream of the heat exchanger 64 and serves as a safety shut-off valve. The heat exchanger 64 is preferably an ambient air vaporizer, which uses the heat of the ambient air to reheat the discharged cryogenic gas, raising its temperature to near ambient temperature to prevent the cryogenic fluid from directly entering the downstream container and causing material damage. Crucially, the second gas pressure sensor 65 and the second gas temperature sensor 66 are specifically arranged on the pipe section between the heat exchanger 64 and the second cryogenic gas valve 67, i.e., after the reheating process and before entering the recovery container. This layout ensures that the data collected by the sensors accurately reflects the gas state before it enters the cryogenic gas recovery container 68, rather than the extreme low-temperature state immediately after exiting the core cavity 12, thus providing an accurate basis for subsequent safety assessments. It should be understood that while this embodiment demonstrates a preferred scheme using two cryogenic gas valves in combination, in other embodiments, only one cryogenic gas valve with both regulation and shut-off functions may be provided, as long as it meets the dual requirements of flow control and safety isolation.

[0028] The recovery control valve includes a cryogenic gas valve, and the recovery status monitoring components include a gas pressure sensor and a gas temperature sensor. In this configuration, the second cryogenic gas valve 67 acts as the final safety barrier in the gas recovery branch, while the second gas pressure sensor 65 and the second gas temperature sensor 66 act as the "sensory nerves" of this barrier in real time. The control unit continuously receives signals from these two sensors and compares them with a preset safety window. This preset safety window is a two-dimensional safety domain enclosed by an upper pressure limit and a lower temperature limit; the system only allows continued emission when the gas state falls within this area simultaneously.

[0029] The control unit is configured to close the cryogenic gas valve when the gas pressure sensor reading exceeds a preset pressure threshold or the gas temperature sensor reading falls below a preset temperature threshold. This dual interlocking logic addresses two typical risks in the gas recovery process. The first risk is overpressure during reheating. If the heat exchanger 64's heat exchange efficiency decreases or the back pressure of the downstream cryogenic gas recovery container 68 abnormally increases, causing the gas pressure in the pipeline to exceed the preset pressure threshold, continued discharge may lead to pipeline rupture or container overpressure. In this case, the control unit immediately closes the second cryogenic gas valve 67, forcibly cutting off the gas flow to prevent the pressure accident from escalating. The second risk is cryogenic brittleness. If the heat exchanger 64 is blocked by frost or the ambient temperature is too low, resulting in insufficient reheating and the temperature of the outflowing gas still being below the preset temperature threshold (e.g., -4°C), allowing the gas to enter a recovery container or pipeline designed for ambient temperature could easily cause cryogenic brittle fracture of the metal materials. Through temperature interlocking, the system can intercept the cold gas before it reaches vulnerable components. After the heat exchanger 64 resumes normal operation or auxiliary heating measures are taken to raise the gas temperature above the safety line, the valve is reopened to resume discharge. This embodiment combines the monitoring of both pressure and temperature to construct a safety defense network covering both thermodynamic and fluid dynamic risks. It effectively solves the potential equipment damage caused by fluctuations in operating conditions during the cryogenic gas recovery process, and significantly improves the reliability and intrinsic safety level of the device in long-term operation.

[0030] In one implementation, the media recovery pipeline includes a media recovery branch, which is equipped with a media pressure sensor, a media temperature sensor, and a cryogenic media valve. Specifically, the media recovery branch forms a channel for the discharge of liquid media from the core cavity 12, and its inlet end is connected to the lowest point of the bottom of the core cavity 12 to ensure that the liquid media can be completely discharged by gravity. In this embodiment, the cryogenic media valve 73 is connected in series on this branch as an actuator to control the flow of media; the media pressure sensor 71 and the media temperature sensor 72 are arranged on the upstream or downstream pipe section of the cryogenic media valve 73 to collect the pressure and temperature status of the liquid media flowing through this branch in real time. It should be understood that although the figure shows a preferred layout in which the sensor is located upstream of the valve, in other embodiments, the sensor can also be located downstream of the valve near the cryogenic media recovery container 74, or a composite transmitter integrating temperature and pressure measurement functions can be used, as long as it can accurately characterize the state of the media about to enter the recovery container. In addition, the cryogenic medium valve 73 is preferably a pneumatic shut-off valve or electric ball valve that is resistant to low temperature and high pressure, and has fast response and bidirectional sealing performance to cope with the water hammer effect or pressure fluctuation that may occur in the liquid medium.

[0031] The recovery control valve includes a cryogenic medium valve, and the recovery status monitoring components include a medium pressure sensor and a medium temperature sensor. In this configuration, the cryogenic medium valve 73 acts as a critical safety barrier on the medium recovery branch, while the medium pressure sensor 71 and the medium temperature sensor 72 sense the thermodynamic state of the medium in real time, providing data support for interlock judgment. Unlike gas recovery, the core risk of medium recovery lies in the volume expansion and pressure surge caused by phase change. If the cryogenic medium absorbs ambient heat or its temperature rises due to throttling and pressure reduction during transportation, it is highly susceptible to flash evaporation or partial vaporization, and its volume can expand hundreds of times instantaneously, thereby generating destructive overpressure in closed pipelines or containers. At the same time, the cryogenic medium recovery container 74 itself has a clearly defined design pressure limit; exceeding this limit may lead to container deformation or even rupture. Therefore, the safety monitoring of the medium must simultaneously consider both the absolute pressure value and the risk of temperature-induced phase change.

[0032] The control unit is configured to close the cryogenic medium valve when the detected value of the medium pressure sensor exceeds a preset pressure threshold, or when the detected value of the medium temperature sensor exceeds a preset medium temperature threshold. This dual interlocking logic addresses two typical failure modes in the medium recovery process. The first is direct overpressure risk. When the medium pressure sensor 71 detects that the pressure in the pipeline or container exceeds the preset pressure threshold (this threshold is usually set to 8% to 9% of the design pressure of the cryogenic medium recovery container 74, with a safety margin), it indicates that the system is approaching its pressure limit. At this time, the control unit immediately closes the cryogenic medium valve 73, cutting off the medium source and preventing a burst accident caused by a further increase in pressure due to continuous liquid intake. The second is vaporization overpressure risk. Even if the current pressure has not exceeded the limit, if the medium temperature sensor 72 detects that the medium temperature exceeds the preset medium temperature threshold (this threshold is usually set to the medium saturation temperature at the current pressure minus a certain supercooling margin), it means that the medium is in a superheated state or is about to undergo violent vaporization. In this case, although the pressure gauge may not show an abnormality due to response lag, the potential phase change energy is sufficient to pose a threat. By interlocking temperature in advance, the system can cut off the flow path before vaporization actually occurs and causes a pressure surge, fundamentally eliminating the risk of pipeline rupture or container damage caused by medium vaporization.

[0033] In practical implementation, the preset pressure resistance threshold and the preset medium temperature threshold can be determined as follows: in, The preset withstand voltage threshold (Pa) is used. This is a safety factor (ranging from 0.8 to 0.9, used to reserve a safety margin). Design pressure (Pa) for cryogenic medium recovery container; The preset medium temperature threshold (K) is used. This represents the saturation temperature (K) of the medium under the current pressure. This is a supercooling margin (ranging from 3K to 1K, used to prevent the medium from entering an overheated state due to temperature fluctuations). The above formula provides a quantitative engineering calculation basis for the safety interlock threshold, enabling the system to automatically calibrate the safety boundary according to different media types and container specifications.

[0034] This embodiment, through the interlocking mechanism based on the characteristics of the medium described above, forms a complementary parallel defense system with the gas recovery interlocking in Embodiment 5. This differentiated design fully considers the essential differences in the thermodynamic behavior of gas and liquid two-phase fluids, avoiding potential protection blind spots caused by applying a single logic to all operating conditions. For example, during the discharge process of liquid hydrogen replacing liquid nitrogen, if high-temperature nitrogen gas enters the liquid phase pipeline due to operational errors, the medium temperature will rise rapidly, triggering the temperature interlock. Even if the pressure is still within the safe range, the system can stop the damage in time, preventing the risk of subsequent gas-liquid mixing and explosion. At the same time, the preset pressure resistance threshold and preset medium temperature threshold are parameters that can be flexibly configured according to the actual medium type and container specifications, enabling the same hardware platform to adapt to the safe recovery needs of various cryogenic media such as liquid oxygen, liquid nitrogen, and liquid hydrogen, significantly improving the versatility and intrinsic safety level of the device.

[0035] In one implementation, the replacement filling device based on cryogenic medium property measurement also includes an online analysis component. The online analysis component includes an analysis pipeline, an analyzer inlet valve 54, and an online analyzer 55. One end of the analysis pipeline is connected to the core cavity 12, and the other end is connected to the online analyzer 55 via the analyzer inlet valve 54. Specifically, the analysis pipeline forms a sampling channel from the core cavity 12 to the online analyzer 55. Its inlet end is connected to a specific sampling point in the core cavity 12, and its outlet end is connected to the detection chamber of the online analyzer 55 via the analyzer inlet valve 54. The analyzer inlet valve 54 is preferably a cryogenic pneumatic shut-off valve or solenoid valve with fast response and good sealing performance, serving as the actuator for controlling the flow of sample gas. The online analyzer 55 can be a precision analytical device such as a gas chromatograph, mass spectrometer, or infrared spectrometer, used to perform quantitative analysis of the components of the gas sample entering it, thereby determining whether the residual medium in the core cavity 12 has been adequately replaced. It should be understood that although the figure shows a single analytical pipeline path, in other embodiments, the analytical pipeline may also include a pretreatment module (such as a filter, dryer or pressure reducing valve), or use a multi-way switching valve to achieve time-sharing detection of multiple sampling points, as long as the gas fed into the online analyzer 55 can meet its injection requirements.

[0036] An analytical pressure sensor 53 is installed on the analytical pipeline. The control unit is communicatively connected to the analytical pressure sensor 53 and the analyzer inlet valve 54, and is configured to close the analyzer inlet valve 54 when the detection value of the analytical pressure sensor 53 exceeds the operating pressure range of the online analyzer 55. The core purpose of this interlocking mechanism is to resolve the contradiction between the drastic pressure fluctuations during cryogenic replacement and the limited pressure resistance of precision analytical instruments. Specifically, the online analyzer 55 typically has a strict injection pressure window. For example, some gas chromatographs require the injection pressure to be stable between 0.1 MPa and 0.3 MPa. Too high a pressure can lead to column overload, detector contamination, or even internal pipeline rupture, while too low a pressure can result in insufficient carrier gas flow, baseline drift, or inability to inject. During cryogenic medium replacement, the pressure within the core cavity 12 fluctuates significantly with the injection of replacement gas, temperature changes, and venting operations. This dynamic pressure environment directly threatens the safe operation of the online analyzer 55. The analytical pressure sensor 53 monitors the pressure of the sample gas entering the instrument in real time. If the pressure exceeds the preset safe operating range (which is pre-set according to the analyzer's technical specifications and stored in the control unit), the control unit immediately sends a shut-off command to the analyzer inlet valve 54, physically cutting off the sample gas flow path. This millisecond-level rapid response effectively isolates abnormal pressure surges, preventing irreversible damage to precision sensors and flow paths, and significantly extending the lifespan of expensive analytical equipment. Simultaneously, this interlocking mechanism indirectly ensures the reliability of analytical data, as only data collected within the normal operating pressure range is reliable. Automatically cutting off sample injection under abnormal conditions avoids false alarms or false negatives caused by pressure instability, making the determination of the replacement endpoint more accurate and reliable.

[0037] As another optional implementation, the definition of the working pressure range is not limited to fixed upper and lower thresholds, but can also be set as a dynamic safety domain associated with temperature or flow rate. For example, in some analytical instruments where pressure sensitivity changes with temperature, the control unit can dynamically adjust the allowable upper pressure limit according to the real-time temperature of the sample gas, thereby achieving more refined adaptive protection. In addition, besides passive overpressure / underpressure shut-off protection, the control unit can also add an electronic pressure reducing valve or back pressure regulating valve upstream of the analyzer inlet valve 54. When the pressure deviates from the target value but has not yet reached the safety boundary, it first attempts to stabilize the pressure at the optimal operating point by adjusting the valve opening, and only triggers the emergency closure of the inlet valve 54 when the adjustment fails or the deviation is too large. This graded control strategy can minimize the analysis interruption caused by short-term pressure fluctuations while ensuring safety, and improve the continuity of the replacement process monitoring. This embodiment, by deeply integrating replacement effect verification with instrument safety protection, not only improves the intelligence level of the device, but also provides dual protection for cryogenic medium switching operations, that is, while ensuring the safety of personnel and equipment, it realizes closed-loop control of replacement quality.

[0038] In one implementation, the analytical pipeline includes a top analytical branch and a bottom analytical branch. The top analytical branch connects to the top of the core cavity 12, and the bottom analytical branch connects to the bottom of the core cavity 12. The top and bottom analytical branches merge and connect to the analyzer inlet valve 54. Specifically, the top analytical branch extends from the highest point of the core cavity 12 or a high position on the side wall near the top, and a top gas analytical valve 51 is connected in series on this branch. The bottom analytical branch extends from the lowest point of the core cavity 12 or a low position on the side wall near the bottom, and a bottom gas analytical valve 52 is connected in series on this branch. These two branches physically merge on their path to the online analyzer 55 via a tee joint or manifold to form a common main pipe section. This main pipe section then passes sequentially through the analytical pressure sensor 53 and the analyzer inlet valve 54 before finally connecting to the detection chamber of the online analyzer 55. It should be understood that although the figure shows a preferred layout for top and bottom sampling, in other embodiments not shown, a central analysis branch or a lateral analysis branch may be added depending on the height-to-diameter ratio or internal structural characteristics of the core cavity 12, or the sampling port may be set in a non-extreme position such as the tangential direction of the end cap, as long as it can cover the key area of ​​fluid flow within the cavity. Furthermore, the top gas analysis valve 51 and the bottom gas analysis valve 52 are preferably low-temperature resistant pneumatic shut-off valves with independent on / off control capabilities, allowing the system to perform simultaneous dual-point mixed sampling or time-sharing single-point independent sampling, thus flexibly adapting to different detection strategy requirements.

[0039] A top gas analysis valve 51 is installed on the top analysis branch, and a bottom gas analysis valve 52 is installed on the bottom analysis branch. The design intention of this dual-point or even multi-point sampling structure is to comprehensively evaluate the distribution of medium components at different heights within the core cavity 12, thereby accurately determining the replacement endpoint. During the cryogenic medium replacement process, due to the piston-like pushing effect driven by density difference, a clear stratified interface should theoretically be formed between the residual medium and the newly injected replacement gas. However, under actual working conditions, due to factors such as cavity geometry, inlet gas velocity fluctuations, or thermal convection disturbances, this interface may tilt, twist, or even undergo local entrainment, resulting in replacement dead zones. If only a single sampling point is used (e.g., sampling only from the top), when the replacement interface has not completely reached the top but the top area is already filled with pure replacement gas, the system may misjudge that the replacement is qualified, while in fact, a large amount of old medium remains at the bottom; conversely, if only sampling is done from the bottom, it may also lead to misjudgment because the bottom has been completely replaced but there are still stagnant gas masses at the top. By simultaneously monitoring the component concentrations at the two extreme positions of the top and bottom, the control unit can construct a longitudinal gradient profile of the purity of the medium within the cavity. The replacement process is only considered truly complete when the analysis results at both the top and bottom reach the preset purity threshold and the difference between them is less than the allowable deviation range. This judgment logic based on spatial distribution information effectively eliminates the detection blind zone caused by uneven flow field, significantly improves the reliability of the replacement endpoint determination, avoids the risk of subsequent media mixing due to false positive results, and also prevents gas waste caused by overly conservative replacement, achieving an optimal balance between safety and economy.

[0040] In one implementation, the displacement filling device based on cryogenic medium property measurement further includes a vacuum chamber 1 and a cryogenic intermediate chamber 11, with the core chamber 12 disposed within the cryogenic intermediate chamber 11, which in turn is disposed within the vacuum chamber 1. Specifically, this three-layer nested structure constitutes a functionally graded protection system from the outside in. The outermost vacuum chamber 1 is typically maintained at... The high-vacuum state, utilizing the extremely low thermal conductivity of the vacuum environment, effectively isolates the external environment from heat radiation and gas convection heat transfer. The intermediate low-temperature cavity 11 serves as a temperature control buffer layer, which can be actively adjusted and maintained at a specific low-temperature background temperature by injecting liquid nitrogen or other refrigerants, further reducing residual heat leakage that penetrates the outer insulation barrier. The innermost core cavity 12 directly contains the low-temperature medium to be tested, occupying the thermodynamic core of this multi-protection system. It should be understood that although the figure shows a coaxial cylindrical nested layout, in other embodiments, each cavity can also adopt a spherical, ellipsoidal, or asymmetrical geometry, as long as it can satisfy the functional hierarchy of insulation, temperature buffering, and medium storage from the outside to the inside.

[0041] In terms of material configuration, the core cavity 12 is made of copper, while the vacuum cavity 1 and the cryogenic intermediate cavity 11 are made of stainless steel. This differentiated material combination is carefully designed based on the different roles each cavity plays in the thermodynamic system. Specifically, the core cavity 12 is made of copper (such as oxygen-free copper T2 or TU1), mainly utilizing the extremely high thermal conductivity of copper at low temperatures (reaching hundreds of W / (m·K) at 2K). This high thermal conductivity allows the walls of the core cavity 12 to quickly reach thermal equilibrium with the internal medium, eliminating temperature hysteresis between the walls and the fluid, and ensuring a highly uniform temperature field and rapid response within the cavity. This is crucial for property measurements and real-time density calculations during the displacement process, which rely on precise temperature control. In contrast, the vacuum cavity 1 and the cryogenic intermediate cavity 11 are made of stainless steel (preferably 316L austenitic stainless steel), which balances structural strength, low-temperature toughness, and relatively low thermal conductivity. Stainless steel maintains good mechanical properties even at low temperatures, sufficient to withstand atmospheric pressure, vacuum pressure differences, and the pressure load of the internal refrigerant. Simultaneously, its thermal conductivity is far lower than that of copper, forming an additional thermal barrier that helps reduce heat transfer to the core area along the supporting structure or connecting flanges. Furthermore, 316L stainless steel possesses excellent corrosion resistance and weldability, facilitating the fabrication of complex vacuum container structures and ensuring long-term sealing reliability.

[0042] This embodiment significantly improves the thermal stability of the device under extreme low-temperature conditions through the synergistic design of the aforementioned structure and materials. In actual operation, even if the external ambient temperature fluctuates or the vacuum level slightly degrades, the combination of multi-layer cavities and heterogeneous materials can act like a "thermal filter," gradually attenuating thermal disturbances and ensuring that the medium within the core cavity 12 remains in a controlled and uniform low-temperature environment. This not only ensures that the intake switching logic based on real-time density can obtain accurate state parameter inputs but also avoids medium flash evaporation caused by local overheating or structural fatigue caused by temperature difference stress. As another optional implementation, the material of the core cavity 12 is not limited to copper; high-purity aluminum, copper-aluminum alloys, or other metal materials with excellent low-temperature thermal conductivity can be selected depending on the specific medium type and measurement accuracy requirements. Similarly, the vacuum cavity 1 and the low-temperature intermediate cavity 11 can also use other structural materials suitable for cryogenic environments, such as titanium alloys and nickel-based alloys, as long as they can meet the insulation, pressure-bearing, and temperature control requirements of the corresponding level.

[0043] This embodiment provides a displacement filling method based on cryogenic medium property measurement. This method is applied to the displacement filling device based on cryogenic medium property measurement as described in any of the preceding embodiments. Unlike the aforementioned device embodiments, which focus on hardware architecture and connectivity, this embodiment explains how to achieve efficient and safe medium displacement through dynamic control logic from the perspective of timing execution and data processing. The core of this method lies in abandoning the traditional displacement strategy based on standard state density or fixed patterns, and instead adopting an adaptive intake control process based on real-time operating condition perception. Specifically, the method includes the following steps: Step S1: Acquire the real-time state parameters of the residual medium within the core cavity 12. Specifically, this step is the data sensing foundation for the entire replacement control logic. Before or at any point during the replacement operation, the system, through sensing components integrated inside the core cavity 12 or on associated pipelines, collects in-situ physical quantities characterizing the current thermodynamic state of the residual medium. Here, "real-time state parameters" do not refer to a fixed standard value or historical empirical value, but rather to instantaneous data directly measured at the current moment under the current pressure and temperature conditions. For example, state parameters may include the absolute pressure value and multiple temperature values ​​within the core cavity 12, or in some embodiments, auxiliary parameters such as liquid level and sound velocity. Through this in-situ real-time sensing, the system can capture minute state drifts of the cryogenic medium caused by environmental heat leakage, throttling effects, or phase changes, thereby providing high-fidelity input data for subsequent density calculations. This fundamentally overcomes the shortcomings of traditional methods that rely on standard state parameters and produce significant deviations under cryogenic variable operating conditions.

[0044] Step S2 determines the actual density of the residual medium based on real-time state parameters. Specifically, this step is a crucial computational step in converting physically sensed data into fluid property parameters. Because the density of a cryogenic medium has a highly nonlinear functional relationship with its temperature and pressure, especially near the critical region or saturation line, even small fluctuations in state can lead to drastic changes in density. Therefore, after receiving the real-time state parameters obtained in step S1, the control unit maps them to the actual density value under the current operating conditions using a preset property model. As one implementation method, this determination process can be achieved by querying a preset high-precision property database and performing interpolation calculations, or by calling a state equation suitable for the target medium (such as the Peng-Robinson equation or the BWR equation) for real-time solution. Regardless of the specific algorithm used, the "actual density" output in this step is a dynamically updated variable that accurately reflects the true inertial mass distribution characteristics of the residual medium within the core cavity 12 at the current instant, providing a unique and reliable benchmark for determining its relative weight relationship with the replacement gas.

[0045] Step S3 involves comparing the relative density of the actual medium with the density of the replacement gas. Based on the comparison result, the control unit opens either the first or second replacement gas inlet channel to inject replacement gas into the core cavity 12 for replacement. Specifically, this step is a decision-making and execution step based on the difference in physical properties to reconstruct the flow field. The control unit compares the actual density of the residual medium determined in step S2 with the density of the replacement gas under the current operating conditions (this value can be a preset constant or a dynamic value calculated in real time in the same way). When it is determined that the density of the replacement gas is less than the actual density of the residual medium, it means that the injected gas is relatively light. At this time, the control unit automatically selects to open the first replacement gas inlet channel located at the high position, so that the light gas enters gently from the top and forms a piston-like pushing interface from top to bottom using the principle of buoyancy stability. Conversely, when it is determined that the density of the replacement gas is greater than or equal to the actual density of the residual medium, it means that the injected gas is heavier or equivalent. The control unit then automatically switches to the second replacement gas inlet channel located at the low position, so that the heavy gas is injected from the bottom, lifting and replacing the medium above from bottom to top. It should be understood that "control activation" here is a dynamic logical judgment and signal output process, which is essentially to match the optimal intake topology in real time based on the sign of the density difference.

[0046] The replacement filling method provided in this embodiment achieves complete self-adaptation of the replacement strategy to complex cryogenic conditions by constructing a closed-loop time-sequential control logic of "state perception-density calculation-channel decision". Compared with existing technologies, this method does not rely on manual experience judgment or fixed operating procedures, but instead allows the control logic to be directly anchored to the real-time physical properties of the fluid. This data-driven dynamic switching mechanism ensures that a stable density stratification interface is always maintained between the replacement gas and the residual medium under any temperature and pressure combination, minimizing turbulent mixing and vortex entrainment. Thus, while ensuring thorough replacement, it significantly reduces the safety risks caused by medium mixing and the ineffective consumption of replacement gas, improving the standardization level and operational efficiency of cryogenic medium switching operations.

[0047] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0048] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A displacement filling device based on cryogenic medium property measurement, characterized in that, include: The core cavity is used to contain the cryogenic medium to be tested; The first replacement air intake channel is located in the high area of ​​the core cavity; The second replacement air intake channel is located in the lower part of the core cavity; The status monitoring component is configured to acquire real-time status parameters of the residual medium within the core cavity; The control unit is communicatively connected to the first replacement intake channel, the second replacement intake channel, and the status monitoring component. The control unit is configured to: determine the actual density of the residual medium based on real-time state parameters, and control the opening of the first or second replacement gas inlet channel according to the relative magnitude of the actual density and the replacement gas density, so as to inject replacement gas into the core cavity.

2. The apparatus according to claim 1, characterized in that, The condition monitoring components include temperature sensors and pressure sensors; The control unit is configured to determine the actual density based on temperature data collected by a temperature sensor and pressure data collected by a pressure sensor. When the density of the replacement gas is less than the actual density, the first replacement intake channel is opened. When the density of the replacement gas is greater than or equal to the actual density, the second replacement intake channel is opened.

3. The apparatus according to claim 2, characterized in that, The control unit is configured to calculate the actual density based on temperature and pressure data by querying a preset physical property database or calling the equation of state. The first replacement air intake channel is equipped with a first air intake valve, and the second replacement air intake channel is equipped with a second air intake valve. The control unit controls the opening and closing of the first air intake valve or the second air intake valve to realize the opening of the first replacement air intake channel or the second replacement air intake channel.

4. The apparatus according to claim 2, characterized in that, It also includes a media recovery pipeline, which is connected to the core cavity and is equipped with a recovery status monitoring component and a recovery control valve. The control unit is communicatively connected to the recycling status monitoring component and the recycling control valve, and is configured to close the recycling control valve when the recycling status parameters detected by the recycling status monitoring component exceed a preset safety threshold.

5. The apparatus according to claim 4, characterized in that, The medium recovery pipeline includes a gas recovery branch, which is equipped with a cryogenic gas valve, a heat exchanger, a gas pressure sensor, and a gas temperature sensor in sequence. The recovery control valves include cryogenic gas valves, and the recovery status monitoring components include gas pressure sensors and gas temperature sensors; The control unit is configured to close the cryogenic gas valve when the gas pressure sensor detects a value greater than a preset pressure threshold or the gas temperature sensor detects a value less than a preset temperature threshold.

6. The apparatus according to claim 4, characterized in that, The medium recovery pipeline includes a medium recovery branch, which is equipped with a medium pressure sensor, a medium temperature sensor, and a cryogenic medium valve. The recovery control valves include cryogenic medium valves, and the recovery status monitoring components include medium pressure sensors and medium temperature sensors; The control unit is configured to close the cryogenic medium valve when the detected value of the medium pressure sensor is greater than a preset pressure threshold or the detected value of the medium temperature sensor is greater than a preset medium temperature threshold.

7. The apparatus according to claim 2, characterized in that, It also includes an online analysis component, which includes an analysis pipeline, an analyzer inlet valve, and an online analyzer. One end of the analysis pipeline is connected to the core cavity, and the other end is connected to the online analyzer through the analyzer inlet valve. An analytical pressure sensor is installed on the analytical pipeline. The control unit is communicatively connected to the analytical pressure sensor and the analyzer inlet valve and is configured to close the analyzer inlet valve when the detected value of the analytical pressure sensor exceeds the working pressure range of the online analyzer.

8. The apparatus according to claim 7, characterized in that, The analytical pipeline includes a top analytical branch and a bottom analytical branch. The top analytical branch connects to the top of the core cavity, and the bottom analytical branch connects to the bottom of the core cavity. The top analytical branch and the bottom analytical branch merge and connect to the analyzer inlet valve. The top analysis branch is equipped with a top gas analysis valve, and the bottom analysis branch is equipped with a bottom gas analysis valve.

9. The apparatus according to claim 1, characterized in that, It also includes a vacuum chamber and a low-temperature intermediate chamber, with the core chamber located inside the low-temperature intermediate chamber and the low-temperature intermediate chamber located inside the vacuum chamber; The core cavity is made of copper, while the vacuum cavity and low-temperature intermediate cavity are made of stainless steel.

10. A displacement filling method based on cryogenic medium property measurement, characterized in that, The apparatus used in any one of claims 1-9 comprises: Obtain real-time status parameters of the residual medium within the core cavity; The actual density of the residual medium is determined based on real-time state parameters. By comparing the relative density of the actual density with that of the replacement gas, the first or second replacement gas inlet channel is opened based on the comparison result to inject replacement gas into the core cavity for replacement.

Images