A method for fixed-point calibration and precision compensation of a differential pressure flowmeter and related apparatus

Abstract

The application discloses a kind of fixed-point calibration and precision compensation method and related equipment of differential pressure flowmeter, it is related to fluid measurement field, comprising: the differential pressure flowmeter to be calibrated is connected in series with standard flowmeter in same gas path, respectively collect front-end pressure, laminar flow element front and back pressure difference and gas temperature, and establish volume flow calculation model based on the structural parameters of laminar flow element.Under the condition that standard flowmeter output constant flow, at multiple discrete temperature nodes and multiple discrete pressure nodes, flowmeter is fixed-point calibrated, temperature compensation factor and pressure compensation factor are determined respectively, and continuous temperature compensation function and pressure compensation function are constructed by B-spline curve fitting.Constitute compensation volume flow model by substituting the compensation function into volume flow calculation model, and the output of differential pressure flowmeter is modified.The influence of temperature variation and pressure variation on laminar flow element flow characteristics and geometric characteristics can be effectively eliminated.

Description

Technical Field

[0001] This invention relates to the field of fluid measurement, specifically to a method and related equipment for fixed-point calibration and accuracy compensation of a differential pressure flow meter. Background Technology

[0002] Differential pressure flow meters are instruments that measure flow rate based on the pressure difference generated before and after a fluid throttling element. Due to their simple structure, wide applicability to various media, and high reliability, they are widely used in industrial process control, metrology, and laboratory testing. For low-velocity, high-precision measurement applications, laminar flow elements are typically used as throttling components, allowing the fluid to pass through microchannels or multichannel structures in a laminar flow state. This allows the deterministic physical laws of laminar flow to establish a functional relationship between flow rate and pressure difference.

[0003] In an ideal state, the volumetric flow rate of a fluid in a laminar flow element satisfies Poiseuille's law with respect to the pressure difference across it, the channel geometry, and the fluid viscosity. However, in practical applications, laminar flow elements are typically composed of multi-channel, non-circular cross-section microstructures formed from metals or composite materials. Their geometry undergoes thermal expansion, elastic deformation, or microstructural changes under different temperature and pressure conditions, leading to deviations in the effective cross-sectional area of ​​the channel, flow resistance, and flow coefficient. Simultaneously, the viscosity, density, and compressibility of gases or liquids also change significantly with temperature and pressure, causing discrepancies between the flow rate calculated based on the ideal model and the actual flow rate.

[0004] Existing differential pressure laminar flow meters typically correct for the aforementioned errors by introducing temperature or pressure compensation. This can be achieved by modifying the calculation formula based on changes in medium properties, or by performing simple calibration of the instrument at limited operating points and using linear or lookup table methods for compensation. However, these methods usually only correct for a single influencing factor or rely on empirical adjustments at a small number of calibration points. They struggle to simultaneously account for the coupled effects of temperature and pressure changes on the geometric and flow characteristics of laminar flow elements, resulting in significant measurement errors even in wide temperature ranges, wide pressure ranges, or high-precision measurement applications.

[0005] Therefore, how to construct a technical solution that can perform high-precision calibration and compensation of differential pressure flowmeters across the entire operating range, without relying on ideal flow assumptions and considering the actual flow characteristics of laminar flow elements under different temperature and pressure conditions, has become an urgent technical problem to be solved in this field. Summary of the Invention

[0006] The technical problem to be solved by this invention is that in high-precision applications, flow meters are subject to various influences during use, such as temperature changes, impurities in the gas, and changes in the upstream pressure. The purpose is to provide a method and related equipment for fixed-point calibration and accuracy compensation of differential pressure flow meters, which solves the problem of how to achieve convenient calibration of differential pressure flow meters and maintain high accuracy after calibration.

[0007] This invention is achieved through the following technical solution:

[0008] A method for fixed-point calibration and accuracy compensation of a differential pressure flow meter, comprising:

[0009] The differential pressure flow meter to be calibrated is connected in series with the standard flow meter in the same gas path. A pressure sensor is installed at the front end of the laminar flow element of the differential pressure flow meter, and a differential pressure sensor and a temperature sensor are installed inside the laminar flow element, which are used to collect the front end pressure, the pressure difference before and after the laminar flow element and the gas temperature, respectively.

[0010] A volumetric flow rate calculation model is established based on the aforementioned front-end pressure, front-end pressure difference, and gas temperature. In the volumetric flow rate calculation model, pressure compensation factors and temperature compensation factors are used to compensate for the flow rate calculation.

[0011] Under the condition that the standard flow meter outputs a constant flow rate, measurement data are collected at multiple discrete temperature nodes and the corresponding temperature compensation factor is determined. Under the condition that the pressure compensation factor is set to a preset value, the temperature compensation factor is fitted with a B-spline curve to obtain the temperature compensation function.

[0012] Under a constant temperature condition, measurement data are collected at multiple discrete pressure nodes and the corresponding pressure compensation factors are determined. The pressure compensation function is obtained by fitting the pressure compensation factors with a B-spline curve.

[0013] The temperature compensation function and the pressure compensation function are substituted into the volumetric flow rate calculation model to form a compensated volumetric flow rate calculation model, and the flow rate output by the differential pressure flow meter is corrected based on the compensated volumetric flow rate calculation model.

[0014] Furthermore, the volumetric flow rate calculation model is established based on the structural parameters of the laminar flow element, and a compensated volumetric flow rate is constructed, wherein the compensated volumetric flow rate satisfies:

[0015] ;

[0016] The structural parameters include the length of the laminar flow element. laminar element thickness Flow channel width and number of flow channels ,and The pressure difference across the laminar flow element. Let be the viscosity coefficient of the gas. As a stress compensation factor, This is the temperature compensation factor.

[0017] Furthermore, before making corrections based on the compensated volumetric flow rate calculation model, the gas Reynolds number is calculated based on the structural parameters, the pressure difference before and after the laminar flow element, the gas temperature, and the gas physical property parameters; when the Reynolds number is greater than a preset threshold, it is determined that the current operating condition does not meet the laminar flow state, and the compensated volumetric flow rate calculation model is discarded to output the corresponding flow rate result.

[0018] Furthermore, in both the temperature compensation factor calibration stage and the pressure compensation factor calibration stage, the flow rate is controlled to a preset constant value using the standard flow meter, and corresponding measurement data is obtained under the condition of controlling the change of a single variable. Specifically, in the temperature compensation factor calibration stage, the front-end pressure is kept at a preset pressure state, or the pressure compensation factor is equivalently set to a preset value, and in the pressure compensation factor calibration stage, the gas temperature is kept at a preset temperature.

[0019] Furthermore, the construction of the temperature compensation function includes: controlling the ambient temperature within the range of 0 to 60 degrees Celsius, and setting multiple discrete temperature nodes according to a preset temperature interval; determining a temperature compensation factor at each temperature node, and performing B-spline curve fitting on the temperature compensation factor to obtain the temperature compensation function.

[0020] Furthermore, the construction of the pressure compensation function includes: under constant temperature conditions, setting multiple discrete pressure nodes at preset pressure intervals starting from atmospheric pressure and recording the front-end pressure; determining the pressure compensation factor at each pressure node, and performing B-spline curve fitting on the pressure compensation factor to obtain the pressure compensation function.

[0021] Furthermore, the measurement result of the differential pressure flow meter is converted from volumetric flow rate to mass flow rate and then compared with the standard flow meter for calibration. The mass flow rate satisfies the following:

[0022] ;

[0023] in, The pressure at the front end measured by the pressure sensor. The temperature is the thermodynamic temperature measured by the temperature sensor. Given the current gas compressibility, For standard pressure, The standard thermodynamic temperature is... This represents the standard gas compressibility.

[0024] This invention also provides a system for fixed-point calibration and accuracy compensation of a differential pressure flow meter, used to implement the aforementioned method for fixed-point calibration and accuracy compensation of a differential pressure flow meter, comprising:

[0025] The differential pressure flow meter body includes a laminar flow element, and a pressure sensor, a differential pressure sensor and a temperature sensor are disposed at the front end of the laminar flow element and disposed inside the laminar flow element. The pressure sensor is used to collect the front end pressure, the differential pressure sensor is used to collect the pressure difference before and after the laminar flow element, and the temperature sensor is used to collect the gas temperature.

[0026] The data processing unit is used to establish a volumetric flow rate calculation model based on the front-end pressure, the pressure difference between the front and rear ends, and the gas temperature, and to introduce pressure compensation factors and temperature compensation factors into the volumetric flow rate calculation model to compensate for the flow rate calculation.

[0027] The calibration and modeling unit is used to collect measurement data at multiple discrete temperature nodes to determine the temperature compensation factor under the condition that the standard flow meter outputs a constant flow rate, and to perform B-spline curve fitting on the temperature compensation factor to obtain the temperature compensation function under the condition that the pressure compensation factor is set to a preset value; and to collect measurement data at multiple discrete pressure nodes to determine the pressure compensation factor under a constant temperature condition, and to perform B-spline curve fitting on the pressure compensation factor to obtain the pressure compensation function.

[0028] The compensation output unit is used to substitute the temperature compensation function and the pressure compensation function into the volumetric flow rate calculation model to form a compensated volumetric flow rate calculation model, and to correct and output the flow rate result output by the differential pressure flow meter based on the compensated volumetric flow rate calculation model.

[0029] The present invention also provides an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the fixed-point calibration and accuracy compensation method for the differential pressure flow meter as described above.

[0030] The present invention also provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the fixed-point calibration and accuracy compensation method for the differential pressure flow meter as described above.

[0031] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0032] This invention incorporates the actual flow characteristics of laminar flow elements under different temperature and pressure conditions into the calibration and modeling process, constructing a dual-compensation flow calculation system that simultaneously considers the effects of temperature and pressure, thereby significantly improving the accuracy and stability of flow measurement over a wide range of operating conditions.

[0033] Specifically, this invention adopts a fixed-point calibration method based on a standard flow meter, which obtains temperature compensation factors and pressure compensation factors at multiple discrete temperature nodes and multiple discrete pressure nodes respectively, and forms continuous temperature compensation functions and pressure compensation functions through curve fitting. This makes the compensation model no longer limited to a finite number of calibration points, but can continuously correct measurement deviations under any operating conditions, thereby avoiding the problem of rapid error accumulation when traditional table lookup or linear correction methods change significantly.

[0034] Meanwhile, this invention employs a single-variable isolation calibration strategy during the calibration process of temperature compensation and pressure compensation. That is, the pressure conditions are kept constant during the temperature compensation stage, and the temperature conditions are kept constant during the pressure compensation stage. This effectively separates the coupled effects of temperature and pressure changes on the geometric characteristics and flow resistance of laminar flow elements, thereby improving the physical consistency and fitting reliability of the compensation model.

[0035] Furthermore, by embedding the temperature compensation function and pressure compensation function into the volumetric flow rate calculation model established based on the structural parameters of the laminar flow element, the present invention achieves a systematic correction of the deviation of the ideal laminar flow model under actual working conditions, so that even when the laminar flow element has thermal expansion, elastic deformation or changes in material properties, it can still maintain high measurement accuracy.

[0036] Therefore, this invention can provide stable, repeatable and traceable calibration and compensation capabilities for differential pressure flow meters in wide temperature range, wide pressure range and high-precision applications. Attached Figure Description

[0037] To more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of the present invention and should not be considered as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort. In the drawings:

[0038] Figure 1 This is a flowchart of the fixed-point calibration and accuracy compensation method for the differential pressure flow meter in Example 1;

[0039] Figure 2 This is an experimental structural diagram of the fixed-point calibration and accuracy compensation method for the differential pressure flowmeter in Example 1. Detailed Implementation

[0040] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the embodiments and accompanying drawings. The illustrative embodiments and descriptions of the present invention are only used to explain the present invention and are not intended to limit the present invention.

[0041] Example 1

[0042] A method for fixed-point calibration and accuracy compensation of a differential pressure flow meter, such as Figure 1 As shown, it includes:

[0043] The differential pressure flow meter to be calibrated is connected in series with a standard flow meter in the same gas path. A pressure sensor is installed at the front end of the laminar flow element of the differential pressure flow meter, and a differential pressure sensor and a temperature sensor are installed inside the laminar flow element to collect the front end pressure, the pressure difference before and after the laminar flow element, and the gas temperature, respectively. The pressure sensor, differential pressure sensor, and temperature sensor sample synchronously at a preset sampling period, and a timestamp is added to the sampled data to achieve data alignment. The range and accuracy of each sensor meet the preset measurement accuracy requirements to ensure the reliability of the compensation factor calibration and fitting.

[0044] A volumetric flow rate calculation model is established based on the aforementioned front-end pressure, front-end pressure difference, and gas temperature. In the volumetric flow rate calculation model, pressure compensation factors and temperature compensation factors are used to compensate for the flow rate calculation.

[0045] Under the condition that the standard flow meter outputs a constant flow rate, measurement data are collected at multiple discrete temperature nodes and the corresponding temperature compensation factors are determined. Under the condition that the pressure compensation factor is set to a preset value, the temperature compensation factor is fitted with a B-spline curve to obtain a temperature compensation function. Before collecting measurement data at each node, it is first determined that the system has entered a steady state. The steady state includes: within a preset time window, the fluctuation amplitude of the standard flow meter output flow rate is less than a first threshold, and the fluctuation amplitudes of temperature and front-end pressure are less than a second threshold and a third threshold, respectively. After the steady state is satisfied, the measurement data of that node is recorded.

[0046] Under a constant temperature condition, measurement data are collected at multiple discrete pressure nodes and the corresponding pressure compensation factors are determined. The pressure compensation function is obtained by fitting the pressure compensation factors with a B-spline curve.

[0047] The temperature compensation function and the pressure compensation function are substituted into the volumetric flow rate calculation model to form a compensated volumetric flow rate calculation model, and the flow rate output by the differential pressure flow meter is corrected based on the compensated volumetric flow rate calculation model.

[0048] During the temperature compensation factor calibration stage, the differential pressure flow meter is first placed at different temperature nodes under the condition that the standard flow meter outputs a preset constant flow rate. At each temperature node, the initial value of the volumetric flow rate corresponding to the differential pressure flow meter is calculated based on the front-end pressure, the pressure difference before and after the laminar flow element, and the structural parameters of the laminar flow element. The initial value of the volumetric flow rate is compared with the constant flow rate output by the standard flow meter, and the temperature compensation factor for the corresponding temperature node is determined according to the deviation between the two. This ensures that after introducing the temperature compensation factor, the volumetric flow rate calculated by the differential pressure flow meter is consistent with the output of the standard flow meter or meets the preset error requirements.

[0049] During the calibration phase of the pressure compensation factor, multiple pressure nodes are formed by changing the front-end pressure while maintaining a constant gas temperature. At each pressure node, the initial volumetric flow rate of the differential pressure flow meter is calculated based on the front-end pressure, the pressure difference before and after the laminar flow element, and the structural parameters of the laminar flow element. The initial volumetric flow rate is compared with the constant flow rate output by the standard flow meter, and the pressure compensation factor for the corresponding pressure node is determined based on the deviation between the two. This ensures that after introducing the pressure compensation factor, the volumetric flow rate calculated by the differential pressure flow meter is consistent with the output of the standard flow meter or meets the preset error requirements.

[0050] A continuous compensation function is obtained by fitting a B-spline curve to the set of compensation factors obtained from discrete nodes; cubic B-splines are preferred, and the control point parameters can be determined using the least squares method. After fitting, re-measurements can be performed at several verification temperature and pressure points that were not involved in the fitting, and the flow error before and after correction can be calculated to verify the effectiveness of the compensation model across the entire operating range.

[0051] In this embodiment, before correction based on the compensated volumetric flow rate calculation model, the gas Reynolds number is calculated based on the structural parameters, the pressure difference before and after the laminar flow element, the gas temperature, and the gas physical property parameters; when the Reynolds number is greater than a preset threshold, it is determined that the current operating condition does not meet the laminar flow state, and the compensated volumetric flow rate calculation model is discarded to output the corresponding flow rate result.

[0052] The laminar flow element is composed of multiple rectangular microchannels connected in parallel, and the gas flows in a laminar manner within each microchannel. For a single microchannel with a width of... Thickness is , length is The rectangular flow channel, under laminar flow conditions, has a volumetric flow rate of... Pressure difference across the channel and gas dynamic viscosity The flow relationship between them satisfies the following equation for the rectangular channel Poisson's flow:

[0053]

[0054] When the laminar flow element contains n parallel flow channels, the total volumetric flow rate is:

[0055]

[0056] Among them, coefficient 12 is the viscous drag coefficient of laminar Poisson flow in rectangular microchannels.

[0057] To ensure the validity of the above laminar flow model, the flow state needs to be determined. In this embodiment, the flow state is determined based on the Reynolds number, which is calculated as follows:

[0058]

[0059] Where ρ is the gas density. The average flow velocity within the channel. For gas dynamic viscosity, The hydraulic diameter of the rectangular flow channel. satisfy:

[0060]

[0061] when Much larger At that time, the hydraulic diameter can be approximated as:

[0062]

[0063] In this embodiment, when the calculated Reynolds number exceeds a preset threshold, the flow state is considered to deviate from the laminar flow model, and the volumetric flow rate model based on Poiseuille flow is not used for flow output.

[0064] In this embodiment, since the gas density, dynamic viscosity, and geometric dimensions of the laminar flow elements all change under different temperature and pressure conditions, the ideal laminar flow model described above will exhibit systematic deviations under actual operating conditions. Therefore, this embodiment introduces temperature and pressure compensation factors based on the Poiseuille flow rate model to obtain a compensated volumetric flow rate model. The volumetric flow rate calculation model is established based on the structural parameters of the laminar flow elements and constructs a compensated volumetric flow rate, which satisfies the following:

[0065]

[0066] The structural parameters include the length of the laminar flow element. laminar element thickness Flow channel width and number of flow channels ,and The pressure difference across the laminar flow element. Let be the viscosity coefficient of the gas. As a stress compensation factor, This is the temperature compensation factor.

[0067] like Figure 2 As shown, a high-precision differential pressure mass flow meter is used as the standard flow meter for calibration and control. The outlet of the gas source is connected in series to the gas input terminal of the standard flow meter, and the gas output terminal of the standard flow meter is connected in series to the gas input terminal of the experimental meter. The experimental meter is placed in a constant temperature chamber. The experimental meter is a differential pressure flow meter containing laminar flow elements. The gas is controlled to a specific flow rate under standard conditions using the standard flow meter, and the flow rate is measured under different pressure and temperature conditions using the experimental meter. The measurement result of the differential pressure flow meter is converted from volumetric flow rate to mass flow rate using a computing device and then compared with the standard flow meter for calibration. The mass flow rate satisfies the following:

[0068] ;

[0069] in, The pressure at the front end measured by the pressure sensor. The temperature is the thermodynamic temperature measured by the temperature sensor. Given the current gas compressibility, For standard pressure, The standard thermodynamic temperature is... This represents the standard gas compressibility.

[0070] In this embodiment, during the calibration stages of the temperature compensation factor and the pressure compensation factor, the flow rate is controlled to a preset constant value using the standard flow meter, and corresponding measurement data is acquired under the condition of controlling the change of a single variable. Specifically, during the calibration stage of the temperature compensation factor, the upstream pressure is maintained at a preset pressure state, or equivalently, the pressure compensation factor is set to a preset value; during the calibration stage of the pressure compensation factor, the gas temperature is maintained at a preset temperature.

[0071] The construction of the temperature compensation function includes: controlling the ambient temperature within the range of 0 to 60 degrees Celsius, and setting multiple discrete temperature nodes at preset temperature intervals; determining the temperature compensation factor at each temperature node, and performing B-spline curve fitting on the temperature compensation factor to obtain the temperature compensation function. Specifically, the temperature of the constant temperature chamber is controlled between 0 and 60 degrees Celsius, with each 3 degrees Celsius as a node, and the pressure compensation factor C(T) is set to 1. This yields t1, t2, t3...tn; the front-end standard flow meter is controlled to a specific flow rate, and under each temperature condition, the temperature compensation factors D(t1), D(t2), D(t3)...D(tn) are obtained based on the flow rate value controlled by the experimental meter. The corresponding experimental data B-spline curves are then fitted with the temperature compensation factor curve.

[0072] The construction of the pressure compensation function includes: under constant temperature conditions, setting multiple discrete pressure nodes at preset pressure intervals starting from atmospheric pressure and recording the upstream pressure; determining the pressure compensation factor at each pressure node, and performing B-spline curve fitting on the pressure compensation factor to obtain the pressure compensation function. The temperature compensation factor after curve fitting is substituted into the volumetric flow rate formula. Under constant temperature conditions, starting from atmospheric pressure, the upstream pressure value is recorded every 0.05 MPa (it is recommended to record to 2 MPa). The upstream standard flow meter is controlled to a specific flow rate. When an undesirable deviation is found in the experimental flow rate, the current upstream pressure value is recorded. This yields p1, p2, p3…pn; the pressure compensation factors C(p1), C(p2), C(p3)…C(pn) are obtained based on the flow rate controlled by the experimental meter. The corresponding experimental data are used to perform curve fitting of the pressure compensation factor on the experimental B-spline curve.

[0073] This invention incorporates a standard flowmeter into the calibration process of a differential pressure flowmeter. It performs point-to-point calibration of the actual flow characteristics of the laminar flow element at multiple temperature and pressure nodes, and constructs temperature and pressure compensation functions respectively. This allows the flow calculation model of the differential pressure flowmeter to accurately reflect the physical changes of the laminar flow element under different operating conditions. By embedding the compensation functions into the volumetric flow rate calculation model based on the structural parameters of the laminar flow element, this invention achieves a systematic correction of measurement deviations caused by temperature and pressure changes, thereby maintaining high flow measurement accuracy and stability over a wide temperature and pressure range.

[0074] Compared with traditional differential pressure flow meters that rely solely on ideal models or simple empirical corrections, the fixed-point calibration and accuracy compensation method provided by this invention has stronger adaptability to operating conditions and higher repeatability, and can effectively solve the error problems caused by thermal expansion, elastic deformation and changes in medium properties of laminar flow elements.

[0075] Example 2

[0076] A system for fixed-point calibration and accuracy compensation of a differential pressure flow meter, used to implement the fixed-point calibration and accuracy compensation method for the differential pressure flow meter as described in Example 1, comprising:

[0077] The differential pressure flow meter body includes a laminar flow element, and a pressure sensor, a differential pressure sensor and a temperature sensor are disposed at the front end of the laminar flow element and disposed inside the laminar flow element. The pressure sensor is used to collect the front end pressure, the differential pressure sensor is used to collect the pressure difference before and after the laminar flow element, and the temperature sensor is used to collect the gas temperature.

[0078] The data processing unit is used to establish a volumetric flow rate calculation model based on the front-end pressure, the pressure difference between the front and rear ends, and the gas temperature, and to introduce pressure compensation factors and temperature compensation factors into the volumetric flow rate calculation model to compensate for the flow rate calculation.

[0079] The calibration and modeling unit is used to collect measurement data at multiple discrete temperature nodes to determine the temperature compensation factor under the condition that the standard flow meter outputs a constant flow rate, and to perform B-spline curve fitting on the temperature compensation factor to obtain the temperature compensation function under the condition that the pressure compensation factor is set to a preset value; and to collect measurement data at multiple discrete pressure nodes to determine the pressure compensation factor under a constant temperature condition, and to perform B-spline curve fitting on the pressure compensation factor to obtain the pressure compensation function.

[0080] The compensation output unit is used to substitute the temperature compensation function and the pressure compensation function into the volumetric flow rate calculation model to form a compensated volumetric flow rate calculation model, and to correct and output the flow rate result output by the differential pressure flow meter based on the compensated volumetric flow rate calculation model.

[0081] Example 3

[0082] An electronic device includes a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the program, it implements the point calibration and accuracy compensation method for a differential pressure flow meter as described in Example 1.

[0083] Example 4

[0084] A computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the point calibration and accuracy compensation method for a differential pressure flowmeter as described in Example 1.

[0085] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0086] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, as well as combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0087] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0088] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0089] Those skilled in the art will understand that all or part of the steps in the above facts and methods can be implemented by a program instructing related hardware. The program or the program described therein can be stored in a computer-readable storage medium. When the program is executed, it includes the following steps: at this time, the corresponding method steps are introduced. The storage medium can be ROM / RAM, magnetic disk, optical disk, etc.

[0090] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for fixed-point calibration and accuracy compensation of a differential pressure flow meter, characterized in that, include: The differential pressure flow meter to be calibrated is connected in series with the standard flow meter in the same gas path. A pressure sensor is installed at the front end of the laminar flow element of the differential pressure flow meter, and a differential pressure sensor and a temperature sensor are installed inside the laminar flow element, which are used to collect the front end pressure, the pressure difference before and after the laminar flow element and the gas temperature, respectively. Based on the aforementioned front-end pressure, front-end pressure difference, and gas temperature, a volumetric flow rate calculation model based on Poiseuille flow is established by combining the structural parameters of the laminar flow element. In the volumetric flow rate calculation model, pressure compensation factor and temperature compensation factor are used to compensate for the flow rate calculation. Calculate the gas Reynolds number and determine the flow state based on the Reynolds number. When the flow state deviates from the laminar flow model, the volumetric flow rate calculation model is not used to calculate the flow rate. Under the condition that the standard flow meter outputs a constant flow rate, measurement data are collected at multiple discrete temperature nodes and the corresponding temperature compensation factor is determined. Under the condition that the pressure compensation factor is set to a preset value, the temperature compensation factor is fitted with a B-spline curve to obtain the temperature compensation function. Under a constant temperature condition, measurement data are collected at multiple discrete pressure nodes and the corresponding pressure compensation factors are determined. The pressure compensation function is obtained by fitting the pressure compensation factors with a B-spline curve. The temperature compensation function and the pressure compensation function are substituted into the volumetric flow rate calculation model to form a compensated volumetric flow rate calculation model, and the flow rate output by the differential pressure flow meter is corrected based on the compensated volumetric flow rate calculation model.

2. The method for fixed-point calibration and accuracy compensation of a differential pressure flowmeter according to claim 1, characterized in that, The volumetric flow rate calculation model is established based on the structural parameters of the laminar flow element, and a compensated volumetric flow rate is constructed, which satisfies the following: ； The structural parameters include the length of the laminar flow element. laminar element thickness Flow channel width and number of flow channels ,and The pressure difference across the laminar flow element. Let be the viscosity coefficient of the gas. As a stress compensation factor, This is the temperature compensation factor.

3. The method for fixed-point calibration and accuracy compensation of a differential pressure flowmeter according to claim 2, characterized in that, Before making corrections based on the compensated volumetric flow rate calculation model, the gas Reynolds number is calculated based on the structural parameters, the pressure difference before and after the laminar flow element, the gas temperature, and the gas physical property parameters. When the Reynolds number is greater than a preset threshold, it is determined that the current operating condition does not meet the laminar flow state, and the corresponding flow result is output by discarding the compensated volumetric flow rate calculation model.

4. The method for fixed-point calibration and accuracy compensation of a differential pressure flowmeter according to claim 1, characterized in that, In both the temperature compensation factor calibration stage and the pressure compensation factor calibration stage, the flow rate is controlled to a preset constant value by the standard flow meter, and corresponding measurement data is obtained under the condition of controlling the change of a single variable. Specifically, in the temperature compensation factor calibration stage, the front-end pressure is kept at a preset pressure state, or the pressure compensation factor is equivalently set to a preset value, and in the pressure compensation factor calibration stage, the gas temperature is kept at a preset temperature.

5. The method for fixed-point calibration and accuracy compensation of a differential pressure flowmeter according to claim 4, characterized in that, The construction of the temperature compensation function includes: controlling the ambient temperature within the range of 0 to 60 degrees Celsius, and setting multiple discrete temperature nodes according to a preset temperature interval; determining the temperature compensation factor at each temperature node, and performing B-spline curve fitting on the temperature compensation factor to obtain the temperature compensation function.

6. The method for fixed-point calibration and accuracy compensation of a differential pressure flowmeter according to claim 4, characterized in that, The construction of the pressure compensation function includes: under constant temperature conditions, setting multiple discrete pressure nodes at preset pressure intervals starting from atmospheric pressure and recording the front-end pressure; determining the pressure compensation factor at each pressure node, and performing B-spline curve fitting on the pressure compensation factor to obtain the pressure compensation function.

7. The method for fixed-point calibration and accuracy compensation of a differential pressure flowmeter according to claim 1, characterized in that, The measurement result of the differential pressure flow meter, after being converted from volumetric flow rate to mass flow rate, is compared with the standard flow meter for calibration. The mass flow rate satisfies the following: ； in, The pressure at the front end measured by the pressure sensor. The temperature is the thermodynamic temperature measured by the temperature sensor. Given the current gas compressibility, For standard pressure, The standard thermodynamic temperature is... This represents the standard gas compressibility.

8. A system for fixed-point calibration and accuracy compensation of a differential pressure flow meter, characterized in that, A method for implementing the fixed-point calibration and accuracy compensation of a differential pressure flowmeter as described in any one of claims 1 to 7, comprising: The differential pressure flow meter body includes a laminar flow element, and a pressure sensor, a differential pressure sensor and a temperature sensor are disposed at the front end of the laminar flow element and disposed inside the laminar flow element. The pressure sensor is used to collect the front end pressure, the differential pressure sensor is used to collect the pressure difference before and after the laminar flow element, and the temperature sensor is used to collect the gas temperature. The data processing unit is used to establish a volumetric flow rate calculation model based on the front-end pressure, the pressure difference between the front and rear ends, and the gas temperature, and to introduce pressure compensation factors and temperature compensation factors into the volumetric flow rate calculation model to compensate for the flow rate calculation. The calibration and modeling unit is used to collect measurement data at multiple discrete temperature nodes to determine the temperature compensation factor under the condition that the standard flow meter outputs a constant flow rate, and to perform B-spline curve fitting on the temperature compensation factor to obtain the temperature compensation function under the condition that the pressure compensation factor is set to a preset value; and to collect measurement data at multiple discrete pressure nodes to determine the pressure compensation factor under a constant temperature condition, and to perform B-spline curve fitting on the pressure compensation factor to obtain the pressure compensation function. The compensation output unit is used to substitute the temperature compensation function and the pressure compensation function into the volumetric flow rate calculation model to form a compensated volumetric flow rate calculation model, and to correct and output the flow rate result output by the differential pressure flow meter based on the compensated volumetric flow rate calculation model.

9. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the program, it implements the fixed-point calibration and accuracy compensation method for the differential pressure flow meter as described in any one of claims 1 to 7.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that, When executed by the processor, the program implements the point calibration and accuracy compensation method for the differential pressure flowmeter as described in any one of claims 1 to 7.

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