Low-temperature fluid flow reference device and method based on mass method and volume method mixed measurement

Abstract

The invention relates to the technical field of profound hypothermia measurement, and provides a low-temperature fluid flow reference device and method based on mass method and volume method mixed measurement, and the device comprises a fluid supply module which is used for providing low-temperature fluid; an inlet of the testing pipeline is connected with the fluid supply module, and a detected flowmeter is arranged on the testing pipeline; the low-temperature and constant-temperature module is used for providing a low-temperature and constant-temperature testing environment for the detected flowmeter; the standard receiving tank is communicated with the outlet of the test pipeline; the liquid level meter is arranged in the standard receiving tank, and the liquid level meter is used for measuring the liquid level height change delta h in the test time period delta t; and the weighing unit is arranged at the bottom of the standard receiving tank, and the weighing unit is used for measuring the fluid mass increment delta m of the standard receiving tank in the test time period delta t. According to the invention, synchronous and independent measurement of mass flow and volume flow is realized in a single standard container, real-time cross validation of data is realized, each fault of the device is found in time, and the reliability and confidence of a measurement result are improved.

Description

Technical Field

[0001] This invention relates to the field of cryogenic metrology technology, and in particular to a cryogenic fluid flow rate reference device and method based on a hybrid measurement method of mass and volume. Background Technology

[0002] Liquid helium (LHe), as an important cryogenic refrigerant and strategic resource, is indispensable in cutting-edge technology fields such as superconductivity, quantum computing, aerospace, and high-end medical devices. Accurate and reliable measurement of its flow rate is crucial for ensuring technological safety, commercial fairness, and cost control in the production, storage, transportation, and trade settlement of liquid helium.

[0003] Currently, flow rate calibration reference devices for cryogenic fluids mainly rely on the following two methods: Mass method: This method determines flow rate by measuring the mass of fluid flowing into or out of a standard container over a period of time using a high-precision weighing unit, and is widely recognized as the "gold standard" for accuracy. However, its dynamic weighing mode is susceptible to interference from the additional forces in the connecting pipeline, while the static weighing mode requires complex rapid start-stop and pipeline disconnection mechanisms, making the system complex and difficult to implement continuously. Furthermore, in cryogenic environments, the connection between the standard container and the fixed pipeline generates thermal contraction stress and mechanical additional forces, which, without special decoupling design, can severely interfere with weighing accuracy.

[0004] Volumetric method: This method determines flow rate by measuring the change in liquid volume within a standard container. While relatively simple in structure, its fatal flaw lies in the need for precise knowledge of the liquid helium's density. Liquid helium, a typical quantum fluid, is extremely compressible, and its density is highly sensitive to temperature and pressure; even minute fluctuations can cause significant density changes. Traditional volumetric methods rely on external temperature and pressure sensors to indirectly estimate density, a process that introduces considerable uncertainty and time delay, limiting its potential as a high-precision reference.

[0005] In the existing technology, there is no flow reference device that can integrate different measurement principles, achieve data cross-validation, and directly measure the actual density of liquid helium online in a single device. This results in certain limitations in the reliability and fault diagnosis capabilities of existing devices. Therefore, there is an urgent need to study a new type of liquid helium flow reference device and method. Summary of the Invention

[0006] This invention provides a cryogenic fluid flow rate reference device based on a hybrid measurement of mass and volumetric methods. It addresses the shortcomings of existing technologies, such as the complexity of mass-based systems or their susceptibility to pipeline stress interference, the insufficient accuracy of volumetric methods due to inaccurate density, and the lack of effective online self-calibration methods. The invention provides a novel cryogenic fluid flow rate reference device and method based on a hybrid measurement of mass and volumetric methods.

[0007] This invention provides a cryogenic fluid flow rate reference device based on a hybrid measurement method combining mass and volumetric methods, comprising: Fluid supply module for providing cryogenic fluid; The test pipeline has an inlet connected to the fluid supply module, and the test pipeline is equipped with a flow meter under test; The low-temperature constant temperature module is used to provide a low-temperature constant temperature testing environment for the flow meter under test; A standard receiving container is connected to the outlet of the test pipeline; A level gauge is installed inside the standard receiving tank, and the level gauge is used to measure the test time period Δ. t Change in liquid level height Δ h ; A weighing unit is installed at the bottom of the standard receiving container. The weighing unit is used to measure the weight of the standard receiving container during the test period Δ. t Fluid mass increment Δ m .

[0008] According to the present invention, a cryogenic fluid flow rate reference device based on a hybrid measurement method combining mass and volumetric methods is provided, wherein the fluid supply module includes: A supply tank for storing the cryogenic fluid; A liquid supply pump is provided, the inlet of which is connected to the liquid supply tank via a liquid supply pipeline, and the outlet of which is connected to the test pipeline. A first shut-off valve is provided on the liquid supply pipeline.

[0009] According to the present invention, a cryogenic fluid flow rate reference device based on a hybrid measurement of mass and volumetric methods further includes a pre-cooling recovery pipeline, wherein the outlet of the test pipeline includes a measurement outlet and a bypass outlet; The measuring outlet is connected to the standard receiving tank, and the bypass outlet is connected to the pre-cooling recovery pipeline; and one of the measuring outlet and the bypass outlet is selectively connected.

[0010] According to the present invention, a cryogenic fluid flow rate reference device based on a hybrid measurement of mass and volumetric methods is provided, wherein a three-way pipe is provided on the test pipeline, the inlet of the three-way pipe is connected to the test pipeline, the two outlets of the three-way pipe form the measurement outlet and the bypass outlet respectively, and the other end of the precooling recovery pipeline is connected to the liquid supply tank.

[0011] According to the present invention, a cryogenic fluid flow rate reference device based on a hybrid measurement of mass and volumetric methods further includes a second shut-off valve and a third shut-off valve. The second shut-off valve is disposed on the precooling recovery pipeline, and the third shut-off valve is disposed between the measurement outlet and the standard receiving tank.

[0012] According to the present invention, a cryogenic fluid flow rate reference device based on a hybrid measurement method combining mass and volumetric methods is provided, wherein the cryogenic isothermal module includes: A low-temperature bath is equipped with a pressure relief valve. The liquid supply tank is connected to the cryogenic bath via a liquid supply pipeline; The fourth shut-off valve is installed on the replenishment pipeline.

[0013] According to the present invention, a cryogenic fluid flow rate reference device based on a hybrid measurement of mass and volume is provided, wherein the standard receiving tank is flexibly connected to the test pipeline.

[0014] According to the present invention, a cryogenic fluid flow rate reference device based on a hybrid measurement of mass and volume is provided, wherein an auxiliary sensor is also provided in the standard receiving tank, the auxiliary sensor being used for auxiliary condition monitoring and traditional density estimation.

[0015] The present invention also provides a cryogenic fluid flow rate reference method, utilizing the cryogenic fluid flow rate reference device based on a hybrid measurement of mass and volumetric methods as described above, comprising: When the cryogenic fluid flows into the standard receiving tank, during the same time period Δ t Within the system, the mass increase Δ measured by the weighing unit is recorded synchronously. m The liquid level rise height Δ measured by the level gauge h ; The mass flow rate is calculated based on the increase in mass, and used as the first standard value. Q m =Δ m / Δ t ; Based on the liquid level change Δ h and the internal cross-sectional area of ​​the calibrated standard receiving tank A ( h Calculate the volume change Δ V Combined with density r The mass flow rate was calculated and used as the second standard value, Δ. V =∫ A ( h )d h , Q v =(Δ V / Δ t)⋅ r ; For mass flow rate ( Q m ) and volumetric flow rate ( Q v A weighted average is then performed to obtain the final, internally validated system baseline flow value. Q final .

[0016] The cryogenic fluid flow rate reference method provided by the present invention further includes: Density is calculated using temperature and pressure. r ; Using synchronously measured Δ m and Δ V The true average density of the cryogenic fluid flowing in during the measurement period can be directly calculated. r real , r real = Δ m / Δ V ; Will r and r real The system compares the values; if the difference is within the allowable uncertainty range, the system's normal measurement process is valid; if the difference exceeds the threshold, the system automatically triggers an alarm to indicate an anomaly.

[0017] This invention provides a cryogenic fluid flow rate benchmark device and method based on a hybrid measurement method combining mass and volumetric methods. A fluid supply module provides cryogenic fluid; the inlet of a test pipeline is connected to the fluid supply module, and a flow meter under test is installed on the test pipeline; a cryogenic constant temperature module provides a cryogenic constant temperature test environment for the flow meter under test; a standard receiving tank is connected to the outlet of the test pipeline; a level gauge is installed inside the standard receiving tank, and the level gauge measures the test period. Δt Changes in liquid level height Dh The weighing unit is located at the bottom of the standard receiving tank and is used to measure the weight of the standard receiving tank during the test period. Δt Increment of fluid mass within Δm It can bring the following beneficial effects: (1) By simultaneously measuring the mass and volume, two independent physical principles, real-time cross-validation of data is achieved. The consistency of the results of the two methods greatly enhances the reliability of the measurement data. Any significant deviation can immediately indicate system faults (such as phase change, leakage, sensor failure, etc.), which is something that devices based on a single measurement principle cannot achieve.

[0018] (2) The present invention can measure the true average density of cryogenic fluids in actual flow and accumulation processes online and directly, eliminating the dependence of traditional volumetric methods on density estimation and the huge uncertainty caused by it, and improving the accuracy of volumetric measurement.

[0019] (3) The present invention integrates the results of the quality method that is directly traced to the quality benchmark and the volume method that has been internally verified, and the final output flow benchmark value has higher confidence and lower system uncertainty.

[0020] (4) The two measurement functions are highly integrated into one core component. Compared with building two independent systems for comparison, the present invention has a more compact structure, lower cost, and simpler operation process.

[0021] (5) The interference of pipeline stress on weighing is eliminated by flexible connection, which solves the core problem of dynamic weighing at deep and low temperatures. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in this 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 this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0023] Figure 1 This is a schematic diagram of the structural principle of the cryogenic fluid flow rate reference device based on a hybrid measurement of mass and volumetric methods provided by the present invention.

[0024] Figure 2 This is a schematic flowchart of the cryogenic fluid flow rate reference method provided by the present invention.

[0025] Figure label: 1. Fluid supply module; 2. Test pipeline; 3. Flow meter under test; 4. Low temperature constant temperature module; 5. Standard receiving tank; 6. Weighing unit; 7. Pre-cooling recovery pipeline; 8. T-connector; 9. Second shut-off valve; 10. Third shut-off valve; 11. Data acquisition and control system; 101. Liquid supply tank; 102. Liquid supply pump; 103. Liquid supply pipeline; 104. First shut-off valve; 401. Cryogenic bath; 402. Pressure relief valve; 403. Liquid replenishment tank; 404. Liquid replenishment pipeline; 405. Fourth shut-off valve. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0027] The following is combined with Figure 1 This invention describes a cryogenic fluid flow rate reference device based on a hybrid measurement method combining mass and volumetric methods, provided by an embodiment of the present invention.

[0028] like Figure 1 As shown, the cryogenic fluid flow rate reference device based on a hybrid measurement of mass and volumetric methods provided in this embodiment of the invention includes a fluid supply module 1, a test pipeline 2, a cryogenic constant temperature module 4, a standard receiving tank 5, a level gauge, a weighing unit, and a data acquisition and processing system 11.

[0029] The system comprises the following components: a fluid supply module 1 provides cryogenic fluid; the inlet of test pipeline 2 is connected to the fluid supply module 1, and the flow meter under test 3 is mounted on test pipeline 2; a cryogenic constant temperature module 4 provides a cryogenic constant temperature testing environment for the flow meter under test 3; and a standard receiving tank 5 is connected to the outlet of test pipeline 2. The standard receiving tank 5 is configured to serve as both a weighing object for the gravimetric method and a standard volume container for the volumetric method. The standard receiving tank 5 is a precision-machined and calibrated deep cryogenic Dewar jar, and its internal geometry has precisely known values ​​under cryogenic conditions.

[0030] The level gauge is installed inside the standard receiving tank 5 and is used to measure the level during the test period. Δt Changes in liquid level height Dh Among them, a superconducting level gauge is preferred to reduce heat consumption and improve reading accuracy. The level gauge is used to measure the changes in the liquid level of the cryogenic fluid in the standard receiving tank 5 in real time and with high precision. Dh .

[0031] Weighing unit 6 is located at the bottom of standard receiving tank 5. Weighing unit 6 is used to measure the weight of standard receiving tank 5 during the test period. Δt Increment of fluid mass within Δm .

[0032] The cryogenic fluid flow rate reference device based on a hybrid measurement method combining mass and volumetric methods provided in this invention firstly enables synchronous measurement. During the flow rate calibration process, when the cryogenic fluid flows into the standard receiving tank, the flow rate is measured simultaneously within the same time period Δ. t Within the system, the mass increase Δ measured by the weighing unit is recorded synchronously. m The liquid level rise height Δ measured by the level gauge h .

[0033] Secondly, it can achieve dual-path flow calculation: Mass flow rate: The mass flow rate is calculated based on the increase in mass and used as the first standard value. Q m =Δ m / Δ t ; Volumetric flow rate: based on liquid level change Δ h and the internal cross-sectional area of ​​the calibrated standard receiving tank A ( h Calculate the volume change Δ V Combined with density r The mass flow rate was calculated and used as the second standard value, Δ. V =∫ A ( h )d h , Q v =(Δ V / Δ t )⋅ r ; For mass flow rate ( Q m ) and volumetric flow rate ( Q v A weighted average is then performed to obtain the final, internally validated system baseline flow value. Q final .

[0034] System baseline flow rate Q final Compare and calibrate the readings with the flow meter under test.

[0035] Furthermore, it can also achieve true density calculation: using synchronously measured Δ m and Δ V The true average density of liquid helium flowing in during the measurement period can be directly calculated. r real . r real = Δ m / Δ V .

[0036] The cryogenic fluid can be liquid helium, or other cryogenic fluids such as liquid hydrogen, liquid nitrogen, liquid oxygen, and liquefied natural gas. The following explanation will mainly use liquid helium as an example.

[0037] The flow meter under test is a measuring instrument that requires accuracy calibration and is installed in the ultra-low temperature isothermal environment created by the cryogenic constant temperature module 4. Different types of cryogenic level gauges can be used, such as capacitive, differential pressure, or more advanced superconducting microwave resonant cavity type, to meet different accuracy and cost requirements.

[0038] This invention achieves real-time cross-validation of data through the simultaneous measurement of two independent physical principles: mass and volume. The consistency between the results of the two methods greatly enhances the reliability of the measurement data. Any significant deviation can immediately indicate system faults (such as phase transitions, leaks, sensor failures, etc.), which is something that devices based on a single measurement principle cannot achieve.

[0039] The data acquisition and control system 11 is used to acquire and record data from the weighing unit 6, the level gauge and the flow meter under test 3 for subsequent flow measurement and calculation.

[0040] Therefore, this invention can measure the true average density online and directly during actual flow and accumulation processes, eliminating the dependence on density estimation in traditional volumetric methods and the resulting uncertainty, thus improving the accuracy of volumetric method measurements.

[0041] This invention integrates the results of a mass method directly traceable to a quality benchmark and an internally validated volumetric method, resulting in a higher confidence level and lower system uncertainty in the final output flow benchmark value. Furthermore, by highly integrating the two measurement functions into a single core component, this invention offers a more compact structure, lower cost, and simplified operation compared to building two separate systems for comparison.

[0042] In a feasible embodiment of the present invention, the fluid supply module 1 includes a supply tank 101, a supply pump 102, a supply pipeline 103, and a first shut-off valve 104. The supply tank 101 is used to store and supply the source container of the cryogenic fluid required for calibration. The inlet of the supply pump 102 is connected to the supply tank 101 via the supply pipeline 103, and the outlet of the supply pump 102 is connected to the test pipeline 2. The supply pump 102 is a device used to pressurize the cryogenic fluid from the supply tank 101, providing power for the flow in the supply pipeline 103. The first shut-off valve 104 is provided on the supply pipeline 103, and the first shut-off valve 104 is used to control the outflow of the cryogenic fluid from the supply tank 101.

[0043] In one feasible embodiment of the present invention, a precooling recovery pipeline 7 is also included, which is used to recover cryogenic fluid.

[0044] The outlet of test pipeline 2 includes a measurement outlet and a bypass outlet; the measurement outlet is connected to the standard receiving tank 5, and the bypass outlet is connected to the pre-cooling recovery pipeline 7; and the measurement outlet and the bypass outlet are selectively connected.

[0045] Before the formal start of the flow calibration, the test system is pre-cooled. The first shut-off valve 104 and the liquid supply pump 102 are opened, and the cryogenic fluid is slowly introduced into the entire pipeline system and the standard receiving tank 5 to completely cool it to 4.2 K. This eliminates the heat in the container and pipeline and prevents the liquid helium flowing in after the calibration starts from undergoing violent vaporization (i.e., phase change) due to heat absorption, thereby ensuring that the measured fluid is a pure liquid phase.

[0046] In a feasible embodiment of the present invention, a three-way pipe 8 is provided on the test pipeline 2. The inlet of the three-way pipe 8 is connected to the test pipeline 2, and the two outlets of the three-way pipe 8 form a measurement outlet and a bypass outlet, respectively. The other end of the pre-cooling recovery pipeline 7 is connected to the liquid supply tank 101.

[0047] In a feasible embodiment of the present invention, a second shut-off valve 9 and a third shut-off valve 10 are further included. The second shut-off valve 9 is disposed on the precooling recovery pipeline 7, and the third shut-off valve 10 is disposed between the measuring outlet and the standard receiving tank 5. The second shut-off valve 9 and the third shut-off valve 10 are installed after the flow meter under test 3 to control the time when the cryogenic fluid flows into the standard receiving tank 5.

[0048] Among them, the second shut-off valve 9 and the third shut-off valve 10 are controlled by a reversing device to precisely control the start and end times of liquid helium flowing into the standard receiving tank 5 or the bypass pipeline, so as to ensure accurate measurement; the fluid flows into the three-way pipe 8 after passing through the flow meter under test 3. One end of the three-way pipe 8 is connected to the pre-cooling recovery pipeline 7, and the other end is connected to the standard receiving tank 5.

[0049] During the flow calibration process, the opening of the first shut-off valve 104 is adjusted to keep the flow rate at the target value. At the same time, the reversing device controls the third shut-off valve 10 to close and the second shut-off valve 9 to open. The cryogenic fluid flows into the recovery pipeline after passing through the flow meter under test 3. This state is maintained for a period of time until the system flow rate, temperature and pressure are completely stable.

[0050] The data acquisition and control system 11 issues a command, and the commutator controls the third shut-off valve 10 to open instantaneously, while the second shut-off valve 9 closes instantaneously, switching the stable liquid helium flow into the standard receiving tank 5. Simultaneously, the data acquisition and control system 11 records this moment as... t 0, and begin synchronously recording and storing the mass from weighing unit 6 at a high frequency (e.g., 10 Hz). m ( t ), Height of the level gauge h ( t ) and the internal liquid temperature of standard receiving tank 5 T ( t and pressure P ( t Real-time data. Record initial quality. m 0 and initial liquid level h 0.

[0051] Among them, the second shut-off valve 9 and the third shut-off valve 10 adopt fast-response pneumatic valves with a switching time of less than 100ms, and are combined with a precision timing system to reduce the time measurement error introduced by the reversing process.

[0052] Liquid helium continuously flows into the standard receiving tank 5 until the preset measurement time or cumulative amount is reached. Then, the data acquisition and control system 11 issues a termination command, the commutator controls the third shut-off valve 10 to close instantaneously, and the second shut-off valve 9 to open instantaneously, switching the liquid helium flow back to the pre-cooling recovery pipeline 7. The data acquisition and control system 11 records this time as... t 1. Stop the data acquisition cycle. Record the final quality. m 1 and final liquid level h 1.

[0053] Further data processing is performed to obtain the final traffic baseline value: (1) Calculate the cumulative amount Time period: Δ t = t 1- t 0 Cumulative mass: Δ m = m 1- m 0 Cumulative volume: using a pre-calibrated volume function V ( h ) Calculate, Δ V = V ( h 1) - V ( h 0) (2) Calculate the flow rate using the mass method (main measurement value): This value is directly derived from the weighing results, with the shortest traceability chain, and serves as the primary baseline flow value. Q mass =Δ m / Δ t (3) Online verification and true density calculation (core innovation step): a) Online true density calculation: Using the simultaneously measured cumulative mass and volume, the true average density of the liquid helium flowing in during this measurement process is directly calculated. r real . r real =Δ m / Δ V .

[0054] b) Deduced density based on state: based on temperature during the measurement period. T ( tand pressure P ( t (average) T avg and P avg The theoretically calculated density was obtained by querying an internationally standardized physical property database. r state .

[0055] (4) Cross-validate and output the final baseline flow rate. Compare r real and r state If | r real - r state | / r state If the value exceeds the preset threshold (e.g., 0.1%), the system will automatically alarm, indicating that the measurement may be invalid. Possible reasons include phase transition, sensor failure, or external interference.

[0056] If | r real - r state | / r state If the value is less than the preset minimum threshold, it proves that the flowing liquid helium is a pure single-phase fluid; the weighing unit, level gauge, temperature and pressure sensors are all working properly; and the entire measurement process is valid.

[0057] At this point, the mass flow method can be used. Q mass Volumetric flow rate Q v ( The final flow rate baseline value is output by fusing the data using an uncertainty-weighted average method. Q final The specific calculation formula is shown below: in, Q mass The flow rate is expressed as mass flow, in kg / s. Q v The flow rate is expressed as volumetric flow, in kg / s. u mass For the uncertainty of flow measurement by mass method, u v The uncertainty of flow rate measurement by volumetric method.

[0058] Through the above-described embodiments, the present invention not only provides a high-precision liquid helium flow rate reference value, but more importantly, it establishes an internally self-consistent verification system, improving the reliability and automation level of flow meter calibration.

[0059] In a feasible embodiment of the present invention, the low-temperature constant temperature module 4 includes a low-temperature bath 401, a liquid supply tank 403, and a fourth shut-off valve 405.

[0060] The low-temperature bath 401 contains a low-temperature fluid, providing a low-temperature isothermal testing environment for the flow meter 3 under test, thus preventing fluid vaporization from affecting the flow measurement.

[0061] A pressure relief valve 402 is provided on it. The pressure relief valve 402 is located on the upper part of the low temperature bath. As the liquid inside the low temperature bath will gradually vaporize during the test, when there is too much gas in its internal space, the pressure relief valve 402 will automatically open to discharge the gas contained inside.

[0062] Liquid supply tank 403 is connected to cryogenic bath 401 via supply line 404. A fourth shut-off valve 405 is installed on supply line 404. Liquid supply tank 403 contains cryogenic liquid and is installed above cryogenic bath 401 (or maintains a slight positive pressure). When the liquid level inside cryogenic bath 401 falls below a certain height (50%), the liquid self-supply system automatically starts, driven by gravity or pressure difference, and the liquid in liquid supply tank 403 flows into cryogenic bath 401 through the fourth shut-off valve 405.

[0063] In a feasible embodiment of the present invention, the standard receiving tank 5 is flexibly connected to the test pipeline 2, which can eliminate the influence of the external connection pipeline on the weighing accuracy. The liquid inlet of the standard receiving tank 5 can be connected to the external pipeline through a highly flexible corrugated pipe or a non-contact gas seal structure to achieve mechanical decoupling.

[0064] In a feasible embodiment of the present invention, an auxiliary sensor is also provided in the standard receiving tank 5. The auxiliary sensor is used to assist in state monitoring and traditional density calculation. The auxiliary sensor includes a liquid temperature sensor and a pressure sensor, which can detect and measure the liquid temperature and pressure in real time.

[0065] like Figure 2 As shown, a second aspect of the present invention provides a method for reference of cryogenic fluid flow rate, utilizing the cryogenic fluid flow rate reference device based on a hybrid measurement of mass and volumetric methods described above, comprising: S1. When cryogenic fluid flows into the standard receiving tank, during the same time period Δ t Within the system, the mass increase Δ measured by the weighing unit is recorded synchronously. m The liquid level rise height Δ measured by the level gauge h ; S2. Calculate the mass flow rate based on the increase in mass, and use it as the first standard value. Q m =Δ m / Δ t ; S3, based on the liquid level change Δ h and the internal cross-sectional area of ​​the calibrated standard receiving tank A ( h Calculate the volume change Δ V Combined with density r The mass flow rate was calculated and used as the second standard value, Δ. V =∫ A ( h )d h , Q v =(Δ V / Δ t )⋅ r ; S4, regarding the mass flow rate ( Q m ) and volumetric flow rate ( Q v A weighted average is then performed to obtain the final, internally validated system baseline flow value. Q final .

[0066] According to the cryogenic fluid flow rate reference method provided by the present invention, before step S3, the method further includes: Density is calculated using temperature and pressure. r ; Using synchronously measured Δ m and Δ V The true average density of the cryogenic fluid flowing in during the measurement period can be directly calculated. r real , r real = Δ m / Δ V ; Will r and r real If the difference is within the allowable uncertainty range, the system is normal and the measurement process is valid. In this case, the flow rate can be obtained by weighted averaging of the mass flow rate and the volumetric flow rate to obtain the final, internally validated system reference flow rate value. Q final If the difference exceeds the threshold, the system will automatically trigger an alarm to indicate an abnormality, which may indicate a phase change or sensor malfunction.

[0067] In other embodiments provided by the invention, in addition to performing an uncertainty-weighted average based on the real-time uncertainties of the two measurement methods under different operating conditions, a simple arithmetic average can also be used to obtain measurement results more quickly.

[0068] In the description of the embodiments of the present invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of the present invention according to the specific circumstances.

[0069] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "method," "specific method," or "some methods," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or method is included in at least one embodiment or method of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or method. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or methods. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or methods described in this specification, as well as the features of different embodiments or methods.

[0070] 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 cryogenic fluid flow rate reference device based on a hybrid measurement method combining mass and volumetric methods, characterized in that, The application relates to a low-temperature fluid flow reference device based on a mixed measurement of mass method and volume method. The application relates to a low-temperature fluid flow reference device based on a mixed measurement of mass method and volume method. The application relates to a low-temperature fluid flow reference device based on a mixed measurement of mass method and volume method. The application relates to a low-temperature fluid flow reference device based on a mixed measurement of mass method and volume method. The application relates to a low-temperature fluid flow reference device based on a mixed measurement of mass method and volume method. a liquid level gauge is provided in the standard receiving tank (5), the liquid level gauge being used to measure the change in liquid level height Δ t in the test period Δt h ; a weighing unit (6) arranged at the bottom of the standard receiving tank (5), the weighing unit (6) being used to measure the fluid mass increment Δm t in the standard receiving tank (5) in a test time period Δt m .

2. The cryogenic fluid flow reference device based on a hybrid of mass and volumetric methods of claim 1, wherein, The application relates to a low-temperature fluid flow reference device based on a mixed measurement of mass method and volume method. The application relates to a low-temperature fluid flow reference device based on a mixed measurement of mass method and volume method. The application relates to a low-temperature fluid flow reference device based on a mixed measurement of mass method and volume method.

3. The cryogenic fluid flow reference device based on a hybrid of mass and volumetric methods of claim 2, wherein, The application relates to a low-temperature fluid flow reference device based on a mixed measurement of mass method and volume method. The application relates to a low-temperature fluid flow reference device based on a mixed measurement of mass method and volume method.

4. The cryogenic fluid flow reference device based on a hybrid of mass and volumetric methods of claim 3, wherein, The application relates to a low-temperature fluid flow reference device based on a mixed measurement of mass method and volume method.

5. Cryogenic fluid flow reference device based on a hybrid mass and volumetric method of measurement according to claim 3 or 4, characterized in that, The application relates to a low-temperature fluid flow reference device based on a mixed measurement of mass method and volume method.

6. A primary low temperature fluid flow device based on a combination of mass and volumetric methods according to any one of claims 1 to 4, wherein, The application relates to a low-temperature fluid flow reference device based on a mixed measurement of mass method and volume method. The application relates to a low-temperature fluid flow reference device based on a mixed measurement of mass method and volume method. The application relates to a low-temperature fluid flow reference device based on a mixed measurement of mass method and volume method. The application relates to a low-temperature fluid flow reference device based on a mixed measurement of mass method and volume method.

7. A primary low temperature fluid flow device based on a combination of mass and volumetric methods according to any one of claims 1 to 4, wherein, The application relates to a low-temperature fluid flow reference device based on a mixed measurement of mass method and volume method.

8. A primary low temperature fluid flow device based on a combination of mass and volumetric methods according to any one of claims 1 to 4, wherein, The application relates to a low-temperature fluid flow reference device based on a mixed measurement of mass method and volume method.

9. A method of cryogenic fluid flow calibration, comprising: The application relates to a low-temperature fluid flow reference device based on a mixed measurement of mass method and volume method. When the cryogenic fluid flows into the standard receiving tank (5), at the same time interval Δ t , the mass increase Δ m measured by the weighing unit (6) and the liquid level rise Δ h measured by the liquid level gauge are recorded simultaneously. The mass flow rate is calculated based on the mass increase amount as a first standard value, Q m = Δ m / Δ t ; According to the liquid level change Δ h and the calibrated internal cross-sectional area of the standard receiving tank (5) A ( h ) the volume change Δ V is calculated The application relates to a low-temperature fluid flow reference device based on a mixed measurement of mass method and volume method. , in combination with the density V the mass flow is calculated as a second standard value, Δ A =∫ h ( h )d Q , v =(Δ V / Δ t )⋅ The application relates to a low-temperature fluid flow reference device based on a mixed measurement of mass method and volume method. ; For mass flow rate ( Q m ) and volumetric flow rate ( Q v A weighted average is then performed to obtain the final, internally validated system baseline flow value. Q final .

10. The method of claim 9, wherein, The application relates to a low-temperature fluid flow reference device based on a mixed measurement of mass method and volume method. Density is calculated from temperature and pressure The application relates to a low-temperature fluid flow reference device based on a mixed measurement of mass method and volume method. ; The true average density of the cryogenic fluid flowing into the cryogenic fluid tank during the measurement period is directly calculated from the synchronous measurements of Δ m and Δ V , The application relates to a low-temperature fluid flow reference device based on a mixed measurement of mass method and volume method. real , The application relates to a low-temperature fluid flow reference device based on a mixed measurement of mass method and volume method. real = Δ m / Δ V ; Will The application relates to a low-temperature fluid flow reference device based on a mixed measurement of mass method and volume method. and The application relates to a low-temperature fluid flow reference device based on a mixed measurement of mass method and volume method. The application relates to a low-temperature fluid flow reference device based on a mixed measurement of mass method and volume method. The application relates to a low-temperature fluid flow reference device based on a mixed measurement of mass method and volume method. The application relates to a low-temperature fluid flow reference device based on a mixed measurement of mass method and volume method. The application relates to a low-temperature fluid flow reference device based on a mixed measurement of mass method and volume method. The application relates to a low-temperature fluid flow reference device based on a mixed measurement of mass method and volume method. The application relates to a low-temperature fluid flow reference device based on a mixed measurement of mass method and volume method. The application relates to a low-temperature fluid flow reference device based on a mixed measurement of mass method and volume method. The application relates to a low-temperature fluid flow reference device based on a mixed measurement of mass method and volume method. The application relates to a low-temperature fluid flow reference device based on a mixed measurement of mass method and volume method. The application relates to a low-temperature fluid flow reference device based on a mixed measurement of mass method and volume method. The application relates to a low-temperature fluid flow reference device based on a mixed measurement of mass method and volume method. The application relates to a low-temperature fluid flow reference device based on a mixed measurement of mass method and volume method. The application relates to a low-temperature fluid flow reference device based on a mixed measurement of mass method and volume method. The application relates to a low-temperature fluid flow reference device based on a mixed measurement of mass method and volume method. The application relates to a low-temperature fluid flow reference device based on a mixed measurement of mass method and volume method. The application relates to a low-temperature fluid flow reference device based on a mixed measurement of mass method and volume method. The application relates to a low-temperature fluid flow reference device based on a mixed measurement of mass method and volume method. The application relates to a low-temperature fluid flow reference device based on a mixed measurement of mass method and volume method. The application relates to a low-temperature fluid flow reference device based on a mixed measurement of mass method and volume method. The application relates to a low-temperature fluid flow reference device based on a mixed measurement of mass method and volume method. The application relates to a low-temperature fluid flow reference device based on a mixed measurement of mass method and volume method. The application relates to a low-temperature fluid flow reference device based on a mixed measurement of mass method and volume method. The application relates to a low-temperature fluid flow reference device based on a mixed measurement of mass method and volume method. The application relates to a low-temperature fluid flow reference device based on a mixed measurement of mass method and volume method. The application relates to a low-temperature fluid flow reference device based on a mixed measurement of mass method and volume method. The application relates to a low-temperature fluid flow reference device based on a mixed measurement of mass method and volume method. The application relates to a low-temperature fluid flow reference device based on a mixed measurement of mass method and volume method. The application relates to a low-temperature fluid flow reference device based on a mixed measurement of mass method and volume method. The application relates to a low-temperature fluid flow reference device based on a mixed measurement of mass method and volume method. The application relates to a low-temperature fluid flow reference device based on a mixed measurement of mass method and volume method. The application relates to a low-temperature fluid flow reference device based on a mixed measurement of mass method and volume method. The application relates to a low-temperature fluid flow reference device based on a mixed measurement of mass method and volume method. The application relates to a low-temperature fluid flow reference device based on a mixed measurement of mass method and volume method. The application relates to a low-temperature fluid flow reference device based on a mixed measurement of mass method and volume method. The application relates to a low-temperature fluid flow reference device based on a mixed measurement of mass method and volume method. The application relates to a low-temperature fluid flow reference device based on a mixed measurement of mass method and volume method. The application relates to a low-temperature fluid flow reference device based on a mixed measurement of mass method and volume method. The application relates to a low-temperature fluid flow reference device based on a mixed measurement of mass method and volume method. The application relates to a low-temperature fluid flow reference device based on a mixed measurement of mass method and volume method. The application relates to a low-temperature fluid flow reference device based on a mixed measurement of mass method and volume method. The application relates to a low-temperature fluid flow reference device based on a mixed measurement of mass method and volume method. The application relates to a low-temperature fluid flow reference device based on a mixed measurement of mass method and volume method. The application relates to a low-temperature fluid flow reference device based on a mixed measurement of mass method and volume method. The application relates to a low-temperature fluid flow reference device based on a mixed measurement of mass method and volume method. The application relates to a low-temperature fluid flow reference device based on a mixed measurement of mass method and volume method. The application relates to a low-temperature fluid flow reference device based on a mixed measurement of mass method and volume method. The application relates to a low-temperature fluid flow reference device based on a mixed measurement of mass method and volume method. The application relates to a low-temperature fluid flow reference device based on a mixed measurement of mass method and volume method. The application relates to a low-temperature fluid flow reference device based on a mixed measurement of mass method and volume method. The application relates to a low-temperature fluid flow reference device based on a mixed measurement of mass method and volume method. The application relates to a low-temperature fluid flow reference device based on a mixed measurement of mass method and volume method. The application relates to a low-temperature fluid flow reference device based on a mixed measurement of mass method and volume method. The application relates to a low-temperature fluid flow reference device based on a mixed measurement of mass method and volume method. The application relates to a low-temperature fluid flow reference device based on a mixed measurement of mass method and volume method. The application relates to a low-temperature fluid flow reference device based on a mixed measurement of mass method and volume method. The application relates to a low-temperature fluid flow reference device based on a mixed measurement of mass method and volume method. The application relates to a low-temperature fluid flow reference device based on a mixed measurement of mass method and volume method. The application relates to a low-temperature fluid flow reference device based on a mixed measurement of mass method and volume method. The application relates to a low-temperature real The system compares the values; if the difference is within the allowable uncertainty range, the system's normal measurement process is valid; if the difference exceeds the threshold, the system automatically triggers an alarm to indicate an anomaly.

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