CN113155215B - Metering output method and device of thermal gas flowmeter and storage medium - Google Patents
Metering output method and device of thermal gas flowmeter and storage medium Download PDFInfo
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- CN113155215B CN113155215B CN202110467041.1A CN202110467041A CN113155215B CN 113155215 B CN113155215 B CN 113155215B CN 202110467041 A CN202110467041 A CN 202110467041A CN 113155215 B CN113155215 B CN 113155215B
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
- G01F1/00—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow
- G01F1/68—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by using thermal effects
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
- G01P5/00—Measuring speed of fluids, e.g. of air stream; Measuring speed of bodies relative to fluids, e.g. of ship, of aircraft
- G01P5/10—Measuring speed of fluids, e.g. of air stream; Measuring speed of bodies relative to fluids, e.g. of ship, of aircraft by measuring thermal variables
Abstract
The invention discloses a metering output method, a metering output device and a storage medium of a thermal gas flowmeter, wherein the method comprises the following steps of firstly, acquiring a temperature difference function of a measured gas; then, carrying out medium independence processing on the temperature difference function to obtain a corrected temperature difference function; and then, the flow velocity of the measured gas is obtained according to the corrected temperature difference function and a pre-stored corresponding relation table of the temperature difference function and the gas flow velocity, so that the influence of thermodynamic physical properties on the measurement output of the thermal gas flowmeter is eliminated, the measurement output of the thermal gas flowmeter is determined by the gas flow velocity and instrument structure parameters and is unrelated to the thermodynamic physical properties of the measured gas, the gas calibration is not needed, and the safety of the gas calibration process is improved.
Description
Technical Field
The embodiment of the invention relates to the technical field of gas metering, in particular to a metering output method and device of a thermal gas flowmeter and a storage medium.
Background
Thermal gas flow meters are meters that measure gas flow based on the principles of fluid heat transfer. The metering output of the thermal gas flowmeter is generally determined by the gas flow rate, thermodynamic properties and instrument structure parameters, wherein the thermodynamic properties are easily changed under the influence of factors such as the components, the temperature or the pressure of the gas to be measured, and the metering output error of the thermal gas flowmeter is larger.
In order to solve the above problems, in the prior art, for a single gas or a multi-component mixed gas with a fixed composition, a gas conversion coefficient K is usually obtained by using a real gas calibration method to correct an output flow value. However, the method has the disadvantages that the method cannot adapt to a multi-component gas application scene with complicated and changeable gas quality, and when a gas conversion coefficient K obtained by calibrating real gas of a single meter is used for correcting all meters, the requirement on the consistency of products is very high.
Or the online flow correction is realized by implanting a component sensing assembly or an external online chromatographic analysis device in the thermal gas flowmeter. The former establishes a mapping relation between component sensing variables and gas through real flow calibration for a limited number of times, further obtains a real-time measured gas conversion coefficient, and carries out online correction on the flow, but the ergodicity is poor; the flow correction of all instruments in the region is realized by using the representative online gas composition, and the flow correction and the measured gas lack synchronism.
Disclosure of Invention
The invention provides a metering output method, a metering output device and a storage medium of a thermal gas flowmeter, which are used for removing the influence of thermodynamic physical properties of the metering output of the thermal gas flowmeter, further ensuring that the metering output of the thermal gas flowmeter is determined by the gas flow rate and instrument structure parameters and is irrelevant to the thermodynamic physical properties of a measured gas, so that real gas calibration is not needed, and the safety of a gas calibration process is improved.
In order to achieve the above object, a first embodiment of the present invention provides a method for measuring output of a thermal gas flowmeter, including the following steps:
acquiring a temperature difference function of the measured gas;
performing medium independence processing on the temperature difference function to obtain a corrected temperature difference function;
and acquiring the flow rate of the gas to be detected according to the corrected temperature difference function and a pre-stored corresponding relation table of the temperature difference function and the gas flow rate.
According to an embodiment of the present invention, the performing a medium independence process on the temperature difference function, and obtaining the corrected temperature difference function includes:
acquiring thermophysical parameters of the detected gas;
and calculating the thermophysical property parameter and the temperature difference function to obtain a corrected temperature difference function.
According to an embodiment of the present invention, calculating the thermophysical property parameter and the temperature difference function, and obtaining the corrected temperature difference function includes:
and performing division calculation on the thermophysical property parameter and the temperature difference function to obtain a corrected temperature difference function.
According to one embodiment of the invention, the thermophysical parameter is one or a combination of a plurality of parameters of a thermal conductivity parameter, a working condition heat capacity parameter, a thermal diffusivity and a viscosity parameter under the actual working condition of the measured gas in real time.
According to an embodiment of the invention, before obtaining the temperature difference function of the measured gas, the method further comprises:
and acquiring a corresponding relation table of the temperature difference function of the calibration gas and the gas flow rate.
According to an embodiment of the present invention, the obtaining of the corresponding relation table of the temperature difference function of the calibration gas and the gas flow rate includes:
acquiring temperature difference functions of calibration gas at different standard flow rates;
performing medium independence processing on the temperature difference function to obtain corrected temperature difference functions at different standard flow rates;
and acquiring a corresponding relation table of the corrected temperature difference function and different standard flow rates.
According to an embodiment of the present invention, the performing a medium independence process on the temperature difference function, and obtaining the corrected temperature difference function at different standard flow rates includes:
acquiring thermophysical parameters of the calibration gas;
and performing division calculation on the temperature difference function and the thermophysical parameters to obtain corrected temperature difference functions at different standard flow rates.
According to an embodiment of the invention, the different standard flow rates comprise one of a volume flow rate, a mass flow rate or a standard volume flow rate.
In order to achieve the above object, a second embodiment of the present invention provides a metering output device of a thermal gas flowmeter, including:
the temperature difference function acquisition module is used for acquiring a temperature difference function of the measured gas;
the processing module is used for carrying out medium independence processing on the temperature difference function to obtain a corrected temperature difference function;
and the flow rate acquisition module is used for acquiring the flow rate of the gas to be detected according to the corrected temperature difference function and a pre-stored corresponding relation table of the temperature difference function and the gas flow rate.
According to one embodiment of the invention, the processing module comprises:
the thermal physical property parameter acquisition module is used for acquiring the thermal physical property parameter of the measured gas;
and the calculation module is used for calculating the thermophysical property parameter and the temperature difference function to obtain a corrected temperature difference function.
According to one embodiment of the invention, the calculation module is configured to,
and performing division calculation on the thermophysical property parameter and the temperature difference function to obtain a corrected temperature difference function.
According to an embodiment of the present invention, further comprising:
and the corresponding relation table acquisition module is used for acquiring a corresponding relation table of the temperature difference function of the calibration gas and the gas flow rate.
According to an embodiment of the present invention, the correspondence table obtaining module includes:
the calibration temperature difference function acquisition unit is used for acquiring temperature difference functions of calibration gas at different standard flow rates;
the calibration processing unit is used for performing medium independence processing on the temperature difference function to obtain corrected temperature difference functions at different standard flow rates; so as to obtain a corresponding relation table of the corrected temperature difference function and different standard flow rates.
According to an embodiment of the present invention, the calibration processing unit includes:
a calibration thermophysical parameter acquiring unit for acquiring thermophysical parameters of the calibration gas;
and the calibration calculation unit is used for performing division calculation on the temperature difference function and the thermophysical property parameter to obtain the corrected temperature difference function under different standard flow rates.
In order to achieve the above object, a storage medium is further provided in an embodiment of the third aspect of the present invention, where the storage medium stores a computer program, and the computer program is readable, and when executed by a processor, the method for metering and outputting a thermal gas flowmeter as described above is implemented.
The metering output method, the metering output device and the storage medium of the thermal gas flowmeter are provided according to the embodiment of the invention, and the method comprises the steps of firstly obtaining a temperature difference function of a measured gas; then, carrying out medium independence processing on the temperature difference function to obtain a corrected temperature difference function; and then, according to the corrected temperature difference function and a corresponding relation table of the prestored temperature difference function and the gas flow speed, the flow speed of the measured gas is obtained so as to realize that the metering output of the thermal gas flowmeter is free from the influence of thermodynamic physical properties, and further the metering output of the thermal gas flowmeter is determined by the gas flow speed and instrument structure parameters and is irrelevant to the thermodynamic physical properties of the measured gas, so that real gas calibration is not needed, and the safety of the gas calibration process is improved.
Drawings
Fig. 1 is a flowchart of a metering output method of a thermal gas flowmeter according to an embodiment of the present invention;
fig. 2 is a flowchart of a metering output method of a thermal gas flowmeter according to an embodiment of the present invention;
fig. 3 is a flowchart of a metering output method of a thermal gas flowmeter according to another embodiment of the present invention;
fig. 4 is a flowchart of a metering output method of a thermal gas flowmeter according to still another embodiment of the present invention;
fig. 5 is a flowchart of a metering output method of a thermal gas flowmeter according to still another embodiment of the present invention;
fig. 6 is a flowchart of a metering output method of a thermal gas flowmeter according to another embodiment of the present invention;
FIG. 7 is a block schematic diagram of a metering output device of a thermal gas flow meter according to an embodiment of the present invention;
FIG. 8 is a block schematic diagram of a metering output device of a thermal gas flow meter according to one embodiment of the present invention;
fig. 9 is a block schematic diagram of a metering output device of a thermal gas flow meter according to another embodiment of the present invention;
FIG. 10 is a block schematic diagram of a metering output device of a thermal gas flow meter according to yet another embodiment of the present invention;
FIG. 11 is a block schematic diagram of a metering output device of a thermal gas flow meter in accordance with yet another embodiment of the present invention;
fig. 12 is a block schematic diagram of a storage medium according to an embodiment of the present invention.
Detailed Description
The present invention will be described in further detail with reference to the drawings and examples. It is to be understood that the specific embodiments described herein are merely illustrative of the invention and are not limiting of the invention. It should be further noted that, for the convenience of description, only some of the structures related to the present invention are shown in the drawings, not all of the structures.
Fig. 1 is a flowchart of a metering output method of a thermal gas flowmeter according to an embodiment of the present invention. As shown in fig. 1, the metering output method includes the following steps:
s101, acquiring a temperature difference function of the measured gas;
it should be noted that the temperature difference function U (α, f) of the measured gas can be obtained by a temperature variation signal obtained by the MEMS flow velocity sensor, wherein the temperature variation signal obtained by the MEMS flow velocity sensor carries the thermal physical property parameter α (λ, ρ, C) of the gas in addition to the upstream and downstream temperature difference caused by the measured gas flow velocity f p 8230velocity, 8230velocity) temperature change. The temperature change influenced by the gas thermophysical parameter refers to the temperature change between a near heat source and a far heat source of the gas in a static state, the temperature change of the gas in the static state along with the heating of the heat source can be obtained through the difference of the far and near temperatures of the gas in the static state and the heat source, and the thermophysical parameter of the gas can be obtained according to the temperature change. Thereby, the gas thermophysical parameter alpha (lambda, rho, C) can be obtained p \8230;) the temperature difference function U (alpha, f) of the measured gas is removed, so that the temperature difference function U (alpha, f) of the measured gas is changed into U' (f), namely the temperature change obtained by the MEMS flow velocity sensor is only related to the flow velocity f of the measured gas. Therefore, the flow rate of the gas to be measured can be obtained according to the corresponding relation between the pre-stored temperature difference function and the gas flow rate.
The MEMS (Micro-Electro & Mechanical System) refers to a Micro device or System that can be manufactured in batch, and integrates a Micro mechanism, a Micro sensor, a Micro actuator, a signal processing and controlling circuit, and an interface, a communication and a power supply.
According to one embodiment of the invention, the thermophysical parameter α is one or a combination of a plurality of parameters of a thermal conductivity parameter, a working condition heat capacity parameter, a thermal diffusivity and a viscosity parameter under the actual working condition of the gas to be detected through real-time monitoring.
The real-time monitoring of the actual working condition of the measured gas means that the corresponding thermophysical property parameter alpha is obtained at each flow rate when the gas flows at different flow rates (for example, when the mass flow rate is 1g/s,2g/s, etc.).
S102, performing medium independence processing on the temperature difference function U (alpha, f) to obtain a corrected temperature difference function U' (f);
according to an embodiment of the present invention, as shown in fig. 2, the step S102 of performing a medium independence process on the temperature difference function U (α, f) to obtain a corrected temperature difference function U' (f) includes:
s1021, acquiring a thermophysical parameter alpha of the detected gas;
the thermophysical parameter alpha of the gas to be detected can be obtained through the temperature change obtained by the MEMS thermophysical sensor, and the MEMS thermophysical sensor detects the temperature change of a near heat source and a far heat source when the gas is in a static state, so that the thermophysical parameter alpha of the gas to be detected is obtained according to the temperature change.
S1022, the thermophysical parameter α and the temperature difference function U (α, f) are calculated to obtain a corrected temperature difference function U' (f).
According to an embodiment of the present invention, as shown in fig. 3, in S1022, the calculating the thermal property parameter α and the temperature difference function U (α, f) to obtain a corrected temperature difference function U' (f) includes:
s10221, a division calculation is carried out on the thermophysical parameter alpha and the temperature difference function U (alpha, f), and a corrected temperature difference function U' (f) is obtained.
Wherein U' (f) = U (α, f)/α (λ, ρ, C) p ，……)。
And S103, acquiring the flow speed f of the gas to be detected according to the corrected temperature difference function U '(f) and a pre-stored corresponding relation table of the temperature difference function U' (f) and the gas flow speed f.
Based on the method, through the integrated application of the flow velocity sensor and the thermal property sensor, the output of the thermal property sensor is utilized to perform medium independence processing on the output of the flow velocity sensor, so that the influence of gas component change on the flow velocity output is eliminated, the problems that the gas component detection is lack of real-time performance and is limited to specific gas types are solved, and the accuracy and the adaptability of the thermal type gas flow meter in the field of multi-component gas metering are improved.
According to an embodiment of the present invention, as shown in fig. 4, before S101, before obtaining the temperature difference function of the measured gas, the method further includes:
s201, obtaining a corresponding relation table of a temperature difference function of the calibration gas and the gas flow rate.
According to an embodiment of the present invention, as shown in fig. 5, the step S201 of obtaining a corresponding relation table of the temperature difference function of the calibration gas and the gas flow rate includes:
s2011, acquiring temperature difference functions of calibration gases at different standard flow rates;
the different standard flow rates may be different volume flow rates, different standard volume flow rates, or different mass flow rates, and are described below by way of example.
Knowing the mass flow rate of the calibration gas, 1g/s, and acquiring a temperature difference function of the mass flow rate under 1g/s by using a flow rate sensor;
knowing the mass flow rate of the calibration gas, 2g/s, and acquiring a temperature difference function of the mass flow rate under 2g/s by using a flow rate sensor; and analogizing in turn to obtain a plurality of temperature difference functions under different mass flow rates.
S2012, performing medium independence processing on the temperature difference function to obtain corrected temperature difference functions at different standard flow rates; and acquiring a corresponding relation table of the corrected temperature difference function and different standard flow rates.
According to an embodiment of the present invention, as shown in fig. 6, in S2012, the media independence is performed on the temperature difference function, and the obtaining of the corrected temperature difference function at different standard flow rates includes:
s20121, acquiring thermophysical property parameters of the calibration gas;
and acquiring the thermophysical parameters of the calibration gas at the mass flow rate of 1g/s by using a thermophysical sensor. And acquiring the thermophysical parameter of the calibration gas at the mass flow rate of 2g/s by using a thermophysical sensor. And analogizing in turn to obtain the thermophysical parameters of the calibration gas under a plurality of different mass flow rates.
S20122, performing division calculation on the temperature difference function and the thermophysical parameters to obtain corrected temperature difference functions at different standard flow rates.
And (3) performing division calculation on the thermal property parameter of the calibration gas with the mass flow rate of 1g/s and the temperature difference function of the calibration gas with the mass flow rate of 1g/s, and removing the thermal property parameter in the temperature difference function of the calibration gas, so that the temperature difference function of the calibration gas is only related to the mass flow rate, and further the corresponding relation between a group of corrected temperature difference functions and the mass flow rate is obtained.
Similarly, the thermal property parameter of the calibration gas with the mass flow rate of 2g/s and the temperature difference function of the calibration gas with the mass flow rate of 2g/s are calculated by division, the thermal property parameter in the temperature difference function of the calibration gas is removed, so that the temperature difference function of the calibration gas is only related to the mass flow rate, and the corresponding relation between a group of corrected temperature difference functions and the mass flow rate is further obtained.
And analogizing in turn to obtain the corresponding relation between a plurality of groups of corrected temperature difference functions and the mass flow rate.
The finally obtained corrected temperature difference function is irrelevant to the thermophysical parameters, namely the attribute of the gas, so that the calibration gas can be air or nitrogen, and the safety of the calibration process is improved.
In the same way, the corresponding relation between the plurality of groups of corrected temperature difference functions and the volume flow rate or the corresponding relation between the plurality of groups of corrected temperature difference functions and the standard volume flow rate can be obtained. In actual use, the flow rate can be selected according to the requirement condition for calibration.
According to an embodiment of the invention, the different standard flow rates comprise one of a volume flow rate, a mass flow rate or a standard volume flow rate. Wherein the standard volume is the molar volume.
Based on the method, medium independence processing is carried out on the outputs of the flow velocity sensor and the thermal property sensor, real gas calibration is not needed, and the method can be used for measuring any gas after being calibrated by common media such as air or nitrogen at one time, so that the instrument calibration process is greatly simplified, the engineering implementation cost of the MEMS thermal type gas flowmeter is reduced, and meanwhile, the problem that the gas conversion coefficient obtained by real gas calibration is not unique in the full-range is solved.
Fig. 7 is a block schematic diagram of a metering output device of a thermal gas flowmeter according to an embodiment of the present invention. As shown in fig. 7, the apparatus includes:
a temperature difference function obtaining module 101, configured to obtain a temperature difference function U (α, f) of the measured gas;
a processing module 102, configured to perform media independence processing on the temperature difference function U (α, f), and obtain a corrected temperature difference function U' (f);
and the flow rate obtaining module 103 is configured to obtain the flow rate f of the gas to be measured according to the corrected temperature difference function U '(f) and a corresponding relationship table of the prestored temperature difference function U' (f) and the gas flow rate f.
It should be noted that the temperature difference function U (α, f) of the measured gas can be obtained by a temperature variation signal obtained by the MEMS flow velocity sensor, wherein the temperature variation signal obtained by the MEMS flow velocity sensor carries the thermal physical property parameter α (λ, ρ, C) of the gas in addition to the upstream and downstream temperature difference caused by the measured gas flow velocity f p 8230velocity, 8230velocity) temperature change. The temperature change influenced by the gas thermophysical parameters refers to the temperature change of the gas between a near heat source and a far heat source in a static state, the temperature change of the gas heated by the heat source in the static state can be obtained through the difference of the far and near temperatures of the gas in the static state and the heat source, and the thermophysical parameters of the gas can be obtained according to the temperature change. Thereby, the gas thermophysical parameter alpha (lambda, rho, C) can be obtained p \8230; \ 8230;) the temperature difference function U (alpha, f) of the measured gas is removed, so that the temperature difference function U (alpha, f) of the measured gas is changed into U' (f), namely, the temperature change acquired by the MEMS flow velocity sensor is only related to the flow velocity f of the measured gas. Therefore, the flow rate of the gas to be measured can be obtained according to the corresponding relation between the pre-stored temperature difference function and the gas flow rate.
The MEMS (Micro-Electro & Mechanical System) refers to a Micro device or System that can be manufactured in batch, and integrates a Micro mechanism, a Micro sensor, a Micro actuator, a signal processing and controlling circuit, and an interface, a communication and a power supply.
According to one embodiment of the invention, as shown in fig. 8, the processing module 102 includes:
a thermophysical parameter acquisition module 1021 for acquiring thermophysical parameter alpha of the measured gas;
the thermophysical parameter alpha of the gas to be detected can be obtained through the temperature change obtained by the MEMS thermophysical sensor, and the MEMS thermophysical sensor detects the temperature change of a near heat source and a far heat source when the gas is in a static state, so that the thermophysical parameter alpha of the gas to be detected can be obtained according to the temperature change.
The calculating module 1022 calculates the thermal property parameter α and the temperature difference function U (α, f) to obtain a corrected temperature difference function U' (f).
According to one embodiment of the invention, the calculation module 1022 is configured to,
and (4) performing division calculation on the thermophysical parameter alpha and the temperature difference function U (alpha, f) to obtain a corrected temperature difference function U' (f).
Wherein U' (f) = U (α, f)/α (λ, ρ, C) p ，……)。
Based on the method, through the integrated application of the flow velocity sensor and the thermal property sensor, the output of the thermal property sensor is utilized to perform medium independence processing on the output of the flow velocity sensor, so that the influence of gas component change on the flow velocity output is eliminated, the problems that the gas component detection is lack of real-time performance and is limited to specific gas types are solved, and the accuracy and the adaptability of the thermal type gas flowmeter in the field of multi-component gas metering are improved.
According to an embodiment of the present invention, as shown in fig. 9, the apparatus further includes:
the correspondence table obtaining module 201 is configured to obtain a correspondence table between a temperature difference function of the calibration gas and a gas flow rate.
According to an embodiment of the present invention, as shown in fig. 10, the correspondence table obtaining module 201 includes:
a calibrated temperature difference function obtaining unit 2011, configured to obtain temperature difference functions of calibration gas at different standard flow rates;
the different standard flow rates may be different volume flow rates, different standard volume flow rates, or different mass flow rates, and are described below by way of example.
Knowing the mass flow rate of the calibration gas, 1g/s, and acquiring a temperature difference function of the mass flow rate under 1g/s by using a flow rate sensor;
knowing the mass flow rate of the calibration gas, 2g/s, and acquiring a temperature difference function of the mass flow rate under 2g/s by using a flow rate sensor; and analogizing in turn to obtain a plurality of temperature difference functions under different mass flow rates.
The calibration processing unit 2012 is configured to perform media independence processing on the temperature difference function to obtain a corrected temperature difference function at different standard flow rates; so as to obtain a corresponding relation table of the corrected temperature difference function and different standard flow rates.
According to an embodiment of the present invention, as shown in fig. 11, the calibration processing unit 2012 includes:
a calibration thermophysical parameter acquiring unit 20121, configured to acquire a thermophysical parameter of a calibration gas;
and acquiring the thermophysical parameter of the calibration gas at the mass flow rate of 1g/s by using a thermophysical sensor. And acquiring the thermophysical parameter of the calibration gas at the mass flow rate of 2g/s by using a thermophysical sensor. And analogizing in turn to obtain the thermophysical parameters of the calibration gas under a plurality of different mass flow rates.
And the calibration calculation unit 20122 is used for performing division calculation on the temperature difference function and the thermophysical property parameters to obtain the corrected temperature difference function under different standard flow rates.
And performing division calculation on the thermophysical property parameter of the calibration gas with the mass flow rate of 1g/s and the temperature difference function of the calibration gas with the mass flow rate of 1g/s, and eliminating the thermophysical property parameter in the temperature difference function of the calibration gas, so that the temperature difference function of the calibration gas is only related to the mass flow rate, and further acquiring a group of corrected corresponding relations between the temperature difference function and the mass flow rate.
Similarly, the thermal property parameter of the calibration gas with the mass flow rate of 2g/s and the temperature difference function of the calibration gas with the mass flow rate of 2g/s are calculated by division, the thermal property parameter in the temperature difference function of the calibration gas is removed, so that the temperature difference function of the calibration gas is only related to the mass flow rate, and the corresponding relation between a group of corrected temperature difference functions and the mass flow rate is further obtained.
And analogizing in turn to obtain the corresponding relation between the plurality of groups of corrected temperature difference functions and the mass flow rate.
The finally obtained corrected temperature difference function is irrelevant to the thermophysical parameters, namely the attribute of the gas, so that the calibration gas can be air or nitrogen, and the safety of the calibration process is improved.
In the same way, the corresponding relation between the plurality of groups of corrected temperature difference functions and the volume flow rate or the corresponding relation between the plurality of groups of corrected temperature difference functions and the standard volume flow rate can be obtained. In actual use, the flow rate can be selected according to the requirement condition for calibration.
Based on the method, medium independence processing is carried out on the outputs of the flow velocity sensor and the thermal property sensor, real gas calibration is not needed, and the method can be used for measuring any gas after being calibrated by common media such as air or nitrogen at one time, so that the instrument calibration process is greatly simplified, the engineering implementation cost of the MEMS thermal type gas flowmeter is reduced, and meanwhile, the problem that the gas conversion coefficient obtained by real gas calibration is not unique in the full-range is solved.
Fig. 12 is a block schematic diagram of a storage medium according to an embodiment of the present invention. As shown in fig. 12, a storage medium 301 has stored thereon a computer program, which is readable by a computer and which, when executed by a processor 302, implements a metering output method of a thermal gas flowmeter as before.
Therefore, the flow velocity sensor and the thermal physical property sensor are integrated in the thermal gas flowmeter, the output of the thermal physical property sensor is used for performing medium independence processing on the output of the flow velocity sensor, the quantitative relation between the flow of the measured medium and the output of the medium independence sensor is obtained through calibration, the flow of the measured medium is directly output in the measuring process, and the limitation of gas component detection on a specific detection method and device is solved and avoided. A 'medium independence calibration curve' (namely the corresponding relation between the flow speed and the corrected temperature difference function) is built in the MEMS thermal type gas flowmeter, and the gas conversion coefficient is not required to be obtained through real-flow calibration so as to carry out secondary conversion correction on the flow.
According to the embodiment of the invention, the conventional gas conversion coefficient correction flow scheme in the multi-component gas correction method of the MEMS thermal gas flowmeter is improved into thermophysical online tracking compensation, and the improved flowmeter does not need to perform real gas calibration again to obtain a gas conversion coefficient, so that the calibration process is greatly simplified, the problem that the full-range detection precision cannot be ensured by fixing the gas conversion coefficient is solved, and the measurement precision and the environmental adaptability of the thermal gas flowmeter in the multi-component gas field are improved.
The MEMS thermophysical property sensor is used for tracking the physical property change of the gas to be detected due to components or environmental factors (temperature and pressure) in real time, the specific components and the environmental state of the gas to be detected do not need to be acquired after improvement, the method and the device are not limited to a specific detection method and a specific detection device for gas component detection, the dependence on real gas calibration is reduced, and the popularization and the application of the thermal gas flowmeter in the field of multi-component mixed gas are promoted.
In summary, according to the metering output method, the metering output device, and the storage medium of the thermal gas flowmeter provided by the embodiments of the present invention, the method includes first obtaining a temperature difference function of a measured gas; then, carrying out medium independence processing on the temperature difference function to obtain a corrected temperature difference function; and then, the flow velocity of the measured gas is obtained according to the corrected temperature difference function and a pre-stored corresponding relation table of the temperature difference function and the gas flow velocity, so that the influence of thermodynamic physical properties on the measurement output of the thermal gas flowmeter is eliminated, the measurement output of the thermal gas flowmeter is determined by the gas flow velocity and instrument structure parameters and is unrelated to the thermodynamic physical properties of the measured gas, the gas calibration is not needed, and the safety of the gas calibration process is improved.
It is to be noted that the foregoing is only illustrative of the preferred embodiments of the present invention and the technical principles employed. It will be understood by those skilled in the art that the present invention is not limited to the particular embodiments described herein, but is capable of various obvious changes, rearrangements and substitutions as will now become apparent to those skilled in the art without departing from the scope of the invention. Therefore, although the present invention has been described in some detail by the above embodiments, the invention is not limited to the above embodiments, and may include other equivalent embodiments without departing from the spirit of the invention, and the scope of the invention is determined by the scope of the appended claims.
Claims (9)
1. A metering output method of a thermal gas flowmeter is characterized by comprising the following steps:
acquiring a temperature difference function of the measured gas;
performing medium independence processing on the temperature difference function to obtain a corrected temperature difference function;
acquiring the flow rate of the gas to be measured according to the corrected temperature difference function and a pre-stored corresponding relation table of the temperature difference function and the gas flow rate;
performing medium independence processing on the temperature difference function, wherein acquiring the corrected temperature difference function comprises:
acquiring thermophysical parameters of the detected gas;
and calculating the thermophysical property parameter and the temperature difference function to obtain a corrected temperature difference function.
2. The metering output method of a thermal gas flowmeter according to claim 1,
calculating the thermophysical property parameter and the temperature difference function, and acquiring a corrected temperature difference function comprises the following steps:
and performing division calculation on the thermophysical property parameter and the temperature difference function to obtain a corrected temperature difference function.
3. The method for metering output of the thermal gas flowmeter according to claim 1 or 2, wherein the thermophysical parameter is one or a combination of a plurality of parameters selected from a thermal conductivity parameter, a working condition heat capacity parameter, a thermal diffusivity and a viscosity parameter under real-time monitoring of the actual working condition of the measured gas.
4. The method for metering output of a thermal gas flowmeter according to claim 1, further comprising, before obtaining the temperature difference function of the measured gas:
and acquiring a corresponding relation table of the temperature difference function of the calibration gas and the gas flow rate.
5. The metering output method of the thermal gas flowmeter as claimed in claim 4, wherein obtaining the correspondence table of the temperature difference function of the calibration gas and the gas flow rate comprises:
acquiring temperature difference functions of calibration gas at different standard flow rates;
performing medium independence processing on the temperature difference function to obtain corrected temperature difference functions at different standard flow rates;
and acquiring a corresponding relation table of the corrected temperature difference function and different standard flow rates.
6. The metering output method of the thermal gas flowmeter according to claim 5, wherein the performing the media independence processing on the temperature difference function, and obtaining the corrected temperature difference function at different standard flow rates comprises:
acquiring thermophysical parameters of the calibration gas;
and performing division calculation on the temperature difference function and the thermophysical property parameter to obtain corrected temperature difference functions at different standard flow rates.
7. The method of metering output of a thermal gas flow meter according to claim 5, wherein the different standard flow rates comprise one of a volumetric flow rate, a mass flow rate, or a standard volumetric flow rate.
8. A metering output device of a thermal gas flowmeter, comprising:
the temperature difference function acquisition module is used for acquiring a temperature difference function of the measured gas;
the processing module is used for carrying out medium independence processing on the temperature difference function to obtain a corrected temperature difference function;
the flow rate obtaining module is used for obtaining the flow rate of the gas to be measured according to the corrected temperature difference function and a pre-stored corresponding relation table of the temperature difference function and the gas flow rate;
the processing module comprises:
the thermophysical parameter acquisition module is used for acquiring thermophysical parameters of the detected gas;
and the calculation module is used for calculating the thermophysical property parameter and the temperature difference function to obtain a corrected temperature difference function.
9. A storage medium having a computer program stored thereon, the computer program being readable, wherein the program, when executed by a processor, implements the method of metering output of a thermal gas flow meter according to any one of claims 1 to 7.
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