CN117889926A - Flow measurement method and device, flowmeter and storage medium - Google Patents
Flow measurement method and device, flowmeter and storage medium Download PDFInfo
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Abstract
The invention relates to the technical field of flow measurement, and discloses a flow measurement method and device, a flowmeter and a storage medium, wherein the flow measurement method comprises the following steps: the method comprises the steps that a temperature difference detected by a thermal flow detection assembly in a flowmeter is obtained, wherein the flowmeter comprises a fluid channel and a flow detection unit, the fluid channel comprises a main channel flow channel and a bypass flow channel, a target fluid channel is connected with a main channel flow channel pipeline, a throttling assembly is arranged in the main channel flow channel, an inlet of the bypass flow channel is connected with an upstream pipeline of the throttling assembly, an outlet of the bypass flow channel is connected with a downstream pipeline of the throttling assembly, the flow detection unit is positioned in the bypass channel, and the flow detection unit comprises the thermal flow detection assembly and a differential pressure flow detection assembly; acquiring the differential pressure detected by the differential pressure flow detection assembly; and determining a flow rate of the target fluid channel based on the temperature differential, the pressure differential, and the physical property parameters of the fluid medium in the target fluid channel. Thereby, flow measurement is achieved.
Description
Technical Field
The present invention relates to the field of flow measurement technologies, and in particular, to a flow measurement method and apparatus, a flowmeter, and a storage medium.
Background
Two common flow detection types exist in the existing flow measurement method, namely a thermal flow measurement method and a differential pressure flow measurement method.
The thermal flow measurement method is a technique for directly measuring the mass flow of a fluid based on the heat exchange relationship between the fluid and a sensor heat source, and the output result thereof is related to the mass flow of a measured medium and the physical properties of the medium. The measurement principle of the thermal flow measurement method determines that the thermal flow measurement method can have larger deviation in the application occasion with larger fluctuation of the medium components.
Differential pressure flow measurement is a measurement technique with complete design, calibration and usage criteria that can calculate flow directly from differential pressure, media conditions and flow-blocking piece geometry generated by a fluid flow-blocking piece installed in a pipeline. Differential pressure flow measurement methods also have high requirements for the stability of the media components, with large deviations due to changes in media density as the fluid composition changes.
Neither the thermal flow measurement method nor the differential pressure flow measurement method is suitable for application scenarios in which the medium composition is unstable.
Disclosure of Invention
The embodiment of the invention provides a flow measurement method and device, a flowmeter and a storage medium, which are applicable to application scenes with unstable medium components.
In a first aspect, an embodiment of the present invention provides a flow measurement method for measuring a flow in a target fluid channel, the flow measurement method including: the method comprises the steps that a temperature difference detected by a thermal flow detection assembly in a flowmeter is obtained, wherein the flowmeter comprises a fluid channel and a flow detection unit, the fluid channel comprises a main channel flow channel and a bypass flow channel, a target fluid channel is connected with a main channel flow channel pipeline, a throttling assembly is arranged in the main channel flow channel, an inlet of the bypass flow channel is connected with an upstream pipeline of the throttling assembly, an outlet of the bypass flow channel is connected with a downstream pipeline of the throttling assembly, the flow detection unit is positioned in the bypass channel, and the flow detection unit comprises the thermal flow detection assembly and a differential pressure flow detection assembly; acquiring the differential pressure detected by the differential pressure flow detection assembly; and determining a flow rate of the target fluid channel based on the temperature differential, the pressure differential, and the physical property parameters of the fluid medium in the target fluid channel.
Optionally, the flow detection unit further comprises a temperature detection component and a pressure detection component, wherein the temperature detection component is used for detecting the temperature in the bypass flow passage, and the pressure detection component is used for detecting the pressure in the bypass flow passage; wherein before determining the flow rate of the target fluid channel based on the temperature difference, the pressure difference, and the physical property parameter of the fluid medium in the target fluid channel, the flow rate measurement method further comprises: acquiring the temperature detected by the temperature detecting part; and acquiring the pressure detected by the pressure detecting means; wherein determining the flow rate of the target fluid channel based on the temperature difference, the pressure difference, and the physical property parameters of the fluid medium in the target fluid channel comprises: and determining the flow of the target fluid channel under the standard working condition based on the temperature, the pressure, the temperature difference, the pressure difference and the physical parameters of the fluid medium in the target fluid channel.
Optionally, determining the flow rate of the target fluid channel based on the temperature difference, the pressure difference, and the physical property parameter of the fluid medium in the target fluid channel includes: determining a current thermal flow and a current differential pressure flow of the target fluid channel, wherein the current thermal flow is determined based on the thermal flow measurement mode in combination with the temperature difference, the pressure difference, and the physical property parameter of the fluid medium in the target fluid channel, and the current differential pressure flow is determined based on the differential pressure flow measurement mode in combination with the temperature difference, the pressure difference, and the physical property parameter of the fluid medium in the target fluid channel; and determining the current thermal type flow or the current differential pressure flow as the actual measured flow of the target fluid channel based on the current thermal type flow and/or the current differential pressure flow and the flow measurement mode determining rule so as to determine the flow of the target fluid channel.
Optionally, determining the current thermal flow or the current differential pressure flow as the actual measured flow of the target fluid channel based on the current thermal flow and/or the current differential pressure flow and the flow measurement mode determination rule includes: determining a comparison flow based on the current thermal flow and/or the current differential pressure flow; based on the comparison flow and the flow measurement mode determination rule, the current thermal flow or the current differential pressure flow is determined as the actual measured flow of the target fluid channel to determine the flow of the target fluid channel.
Optionally, the flow measurement mode determination rule includes: determining the current differential pressure flow as the actual measured flow if any of the following is satisfied: the comparison flow is greater than or equal to a preset flow threshold value, and the comparison flow is greater than or equal to the upper limit of the range of the preset flow threshold value; and/or determining the current thermal flow as the actual measured flow if any of the following is satisfied: the comparison flow is less than a preset flow threshold and the comparison flow is less than or equal to the lower limit of the preset flow threshold range.
Optionally, the physical parameters include thermal conductivity, density, and specific heat capacity.
In a second aspect, an embodiment of the present invention further provides a flow measurement device for measuring a flow in a target fluid channel, the flow measurement device including: a memory; and the processor is used for storing a computer program and realizing the flow measurement method by running the computer program stored in the memory.
In a third aspect, an embodiment of the present invention further provides a storage medium, where a computer program is stored, where the computer program when executed by a processor implements the flow measurement method described above.
In a fourth aspect, an embodiment of the present invention further provides a flow meter, including: the fluid channel comprises a main channel flow channel and a bypass flow channel, the target fluid channel is connected with a main channel flow channel pipeline, a throttling assembly is arranged in the main channel flow channel, an inlet of the bypass flow channel is connected with an upstream pipeline of the throttling assembly, and an outlet of the bypass flow channel is connected with a downstream pipeline of the throttling assembly; the flow detection unit is positioned in the bypass channel and comprises a thermal flow detection assembly, a differential pressure flow detection assembly and a physical property parameter detection component; and the control module is used for executing the flow measurement method.
Optionally, the flow detection unit further includes: the substrate comprises a first gas through hole and a second gas through hole, the bypass channel is divided into a micro-channel and a differential pressure detection cavity by the substrate, the thermal type flow detection component and the differential pressure flow detection component are integrated on two sides of the substrate, the physical property parameter detection component and the differential pressure flow detection component are integrated on the same side of the substrate, the differential pressure flow detection component divides the differential pressure detection cavity into a first differential pressure detection cavity and a second differential pressure detection cavity, fluid media in the micro-channel flow through the thermal type flow detection component, gas in the micro-channel enters the first differential pressure detection cavity through the first gas through hole, and gas in the micro-channel enters the second differential pressure detection cavity through the second gas through hole.
Optionally, the flow detection unit further includes: a temperature detecting unit for detecting a temperature in the bypass flow path; and a pressure detecting member for detecting a pressure in the bypass flow passage.
Optionally, the main channel is further provided with at least one rectifying component, and at least one of the at least one rectifying component is located upstream of an upstream connection position of the bypass channel and the main channel.
According to the technical scheme, the flow of the target fluid channel is determined by combining the physical parameters of the fluid medium and by means of the temperature difference detected by the thermal flow detection assembly and the pressure difference detected by the differential pressure flow detection assembly, so that flow measurement is realized; in addition, the fluid media with different media components and different physical parameters are considered when measuring the flow, and even if the media components of the fluid media are changed, the flow can be measured, so that the technical scheme provided by the embodiment of the invention can be suitable for application scenes with unstable media components, and the application range is enlarged.
Additional features and advantages of the invention will be set forth in the detailed description which follows.
Drawings
The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification, illustrate the invention and together with the description serve to explain, without limitation, the invention. In the drawings:
FIG. 1 is a flow chart of a flow measurement method according to an embodiment of the present invention;
FIG. 2 is a schematic view of a portion of a flow meter according to another embodiment of the present invention;
FIG. 3 is a schematic view of a portion of a flow meter according to yet another embodiment of the present invention;
FIG. 4 is a schematic view of a portion of a flow meter according to yet another embodiment of the present invention;
FIG. 5 is a schematic cross-sectional view of a flow rate detection unit according to another embodiment of the present invention;
FIG. 6 is a schematic cross-sectional view of a flow rate detection unit according to another embodiment of the present invention;
fig. 7 is a schematic view showing a part of the constitution of a flowmeter according to still another embodiment of the present invention.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
Thermal flow measurement methods are very sensitive to small fluid flow responses. However, in the high flow region, as the mass flow rate increases, the response sensitivity of the sensor's output signal is continually decreasing and tends to saturate. Thus, the thermal flow measurement method is mainly used for medium and low flow or medium and low pressure application occasions. In addition, the measurement principle of the thermal flow measurement method also determines that the thermal flow measurement method can have larger deviation in the application occasion with larger fluctuation of the medium components. The differential pressure flow measuring method has clear principle, simple structure and wide application. In addition, differential pressure flow measurement methods have a relatively narrow measurement range (typically only 3:1 to 4:1).
The thermal flow measurement method and the differential pressure flow measurement method have high requirements on the stability of the medium, and are not applicable to occasions with changeable components and unpredictable components. Aiming at the problem, the embodiment of the invention provides a corresponding technical scheme for solving the problem.
In a first aspect, an embodiment of the present invention provides a flow measurement method.
Fig. 1 is a flow chart of a flow measurement method according to an embodiment of the present invention. As shown in fig. 1, the flow measurement method includes the following. The flow measurement method is used for measuring the flow in the target fluid channel.
In step S10, the temperature difference detected by the thermal flow rate detection assembly in the flow meter is acquired. The flowmeter comprises a fluid channel and a flow detection unit, wherein the fluid channel comprises a main channel flow channel and a bypass flow channel, the target fluid channel is connected with the main channel flow channel through a pipeline, a throttling assembly is arranged in the main channel flow channel, an inlet of the bypass flow channel is connected with an upstream pipeline of the throttling assembly, an outlet of the bypass flow channel is connected with a downstream pipeline of the throttling assembly, the flow detection unit is positioned in the bypass channel, and the flow detection unit comprises a thermal flow detection assembly and a differential pressure flow detection assembly.
Alternatively, in an embodiment of the invention, the thermal flow sensing assembly may be a MEMS thermal distributed flow sensor. The thermal flow detection assembly comprises a heating element and at least 1 pair of temperature measuring elements, wherein the temperature measuring elements are symmetrically distributed relative to the heating element. Alternatively, a constant power or constant current or constant voltage heating is applied to the heating element, and the temperature difference change due to the fluid flow is detected by the upstream and downstream temperature measuring elements.
Alternatively, the temperature of the heating element is controlled to be a fixed difference value relative to the ambient temperature by a constant temperature difference control circuit or a constant temperature control circuit, or the heating element is maintained at a constant temperature, and the temperature difference change caused by fluid flow is detected by temperature measuring elements distributed symmetrically at the upstream and downstream.
In step S11, the differential pressure detected by the differential pressure flow rate detecting assembly is acquired.
In step S12, the flow rate of the target fluid passage is determined based on the temperature difference, the pressure difference, and the physical property parameters of the fluid medium in the target fluid passage. The physical property parameter of the fluid medium may be a physical quantity capable of exhibiting the physical property of the fluid medium. The physical property parameters can be obtained by physical property sensors. Optionally, in an embodiment of the present invention, the physical property parameter may include at least one of: thermal conductivity, density, and specific heat capacity. Alternatively, the density may be an average density. Alternatively, the specific heat capacity may be a constant pressure specific heat capacity.
According to the technical scheme, the flow of the target fluid channel is determined by combining the physical parameters of the fluid medium and by means of the temperature difference detected by the thermal flow detection assembly and the pressure difference detected by the differential pressure flow detection assembly, so that flow measurement is realized; in addition, the fluid media with different media components and different physical parameters are considered when measuring the flow, and even if the media components of the fluid media are changed, the flow can be measured, so that the technical scheme provided by the embodiment of the invention can be suitable for application scenes with unstable media components, and the application range is enlarged. In addition, the technical scheme provided by the embodiment of the invention combines the temperature difference detected by the thermal flow detection assembly and the pressure difference detected by the differential pressure flow detection assembly, namely, combines the thermal flow measurement principle and the differential pressure flow measurement principle, improves the measurement accuracy, expands the measuring range, improves the measurement accuracy and the measurement range, and greatly expands the application range.
Alternatively, in an embodiment of the present invention, the flow rate of the target fluid passage may be determined according to the following.
A current thermal flow and a current differential pressure flow of the target fluid channel are determined, wherein the current thermal flow is determined based on the thermal flow measurement mode in combination with the temperature difference, the pressure difference, and the physical property parameter of the fluid medium in the target fluid channel, and the current differential pressure flow is determined based on the differential pressure flow measurement mode in combination with the temperature difference, the pressure difference, and the physical property parameter of the fluid medium in the target fluid channel. The thermal flow measurement mode is based on a thermal flow measurement method, and flow is calculated by combining the temperature difference detected by the thermal flow detection assembly, the pressure difference detected by the differential pressure flow detection assembly and physical parameters. In addition, the differential pressure flow detection mode is based on a differential pressure type flow measurement method, and the flow is calculated by combining the temperature difference detected by the thermal flow detection component, the pressure difference detected by the differential pressure flow detection component and the physical parameters.
And determining the current thermal type flow or the current differential pressure flow as the actual measured flow of the target fluid channel based on the current thermal type flow and/or the current differential pressure flow and the flow measurement mode determining rule so as to determine the flow of the target fluid channel. Wherein the flow measurement mode determination rule indicates what conditions are met to determine the current differential pressure flow as an actual measured flow and what conditions are met to determine the current differential pressure flow as the actual measured flow.
Optionally, in the embodiment of the present invention, the determining the current thermal flow based on the thermal flow measurement mode and the temperature difference, the pressure difference, and the physical parameter of the fluid medium in the target fluid channel may be determining the current thermal flow based on a thermal flow measurement formula, where the independent variables in the thermal flow measurement formula are the temperature difference, the pressure difference, and the physical parameter, and the dependent variables in the thermal flow measurement formula are the flows.
Alternatively, in an embodiment of the present invention, the thermal flow measurement formula may be formula 1. Equation 1: wherein Q is Heat of the body A total flow of the target fluid channel based on the thermal flow measurement mode; q (Q) Side by side Is bypass flow; delta T is the temperature difference; lambda (lambda) 0 Thermal conductivity of the reference fluid for the calibration phase; (ρ.C) p ) 0 The heat capacity of the volume of the reference fluid is used for calibration; λ is the thermal conductivity of the actual fluid flowing in the target fluid channel of the actual flow to be measured; ρ.C p Is the volumetric heat capacity of the actual fluid; />The flow split ratio of the bypass flow channel and the main flow channel is set; ΔP is the pressure differential of the actual fluid; (DeltaP) 0 For the calibration phase the reference fluid flow is Q 0 Or temperature difference (DeltaT) 0 Differential pressure corresponding to the time, Q 0 Setting or providing for reference fluid standard means when calibrating for calibration phase Standard flow of (DeltaT) 0 Standard flow Q established for calibration stage standard device 0 The temperature difference detected by the time heating type flow detection assembly. Wherein the flow split ratio->And the flow calibration process is adopted for determining. Further, volumetric heat capacity is the product of density and specific heat capacity for any fluid medium. The calibration phase reference fluid has a volumetric heat capacity (ρ.C p ) 0 The density ρ of the calibration phase reference fluid may be used 0 And constant pressure specific heat capacity C p0 The product is obtained, and the volumetric heat capacity rho.C of the actual fluid p The density ρ and the constant pressure specific heat capacity C of the actual fluid can be used p The product is obtained.
For the bypass flow channel design, the following quantitative relationship exists between the total flow of the target fluid channel and the main flow of the main flow channel and the bypass flow of the bypass flow channel:
wherein Q is Total (S) For total flow, including but not limited to mass flow, volumetric flow, nominal volumetric flow (101 325kpa,20 ℃); q (Q) Side by side Is the flow of the bypass flow channel; q (Q) Main unit The flow is the flow of the main channel;is the flow split ratio of the bypass flow channel and the main flow channel. Wherein the flow split ratio->And the flow calibration process is adopted for determining.
Based on the quantitative relationship, a total flow calculation formula can be obtained:
therefore, under the condition that the calculation formula of the bypass flow is determined, the calculation formula of the total flow can be obtained according to the conversion relation between the total flow and the bypass flow.
Alternatively, in the embodiment of the present invention, equation 1 may be derived based on any one of equations 11 to 14.
Equation 11:wherein Q is 11 For flow rates including, but not limited to, mass flow rate, volumetric flow rate, and standard volumetric flow rate (101 325kpa,20 ℃). Deltat is the temperature difference detected by the thermal flow detection assembly. K (K) 1 The instrument coefficient of the thermal flow detection assembly is determined by a factory calibration stage. A is the coefficient of thermal conductivity between the heating element and the environment in the thermal flow sensing assembly, its thermal conductivity lambda with the fluid medium 1 Coefficient of viscosity mu 1 And the like. Typically the thermal conductivity coefficient a can be approximated by the thermal conductivity coefficient of the fluid medium, ignoring the effect of the viscosity properties. (ρ.C) p ) 1 Is the volumetric heat capacity of the fluid medium, is C p1 And ρ 1 Is a product of (a) and (b). C (C) p1 Is the constant pressure specific heat capacity of the fluid medium. ρ 1 Is the density of the fluid medium (preferably, the operating average density may be used). The flow rate obtained based on the thermal flow detection assembly being related to a portion of the physical properties of the fluid medium, e.g. lambda 1 、ρ 1 And C p1 Etc. Delta T is the temperature difference of a temperature measuring element at the upstream and downstream of a heating element in a constant temperature difference or constant power mode of the heating element in the thermal flow detection assembly, and the temperature difference can be obtained through detection by a Wheatstone bridge.
Alternatively, equation 11 may be applied when the fluid medium is in a medium-low flow rate and laminar flow regime, where the bypass flow in the bypass flow path exhibits an approximately linear relationship with the temperature difference detected by the thermal flow detection assembly.
Equation 12:
wherein Q is 12 Is the flow. Delta T is the thermal flowThe temperature difference detected by the quantity detection component. K (K) 2 、K 3 And K 4 Depending on the geometry of the thermal flow detection assembly, the circuit design, and the gas characteristics. For example, the distance between the temperature measuring element and the heating element, the relative magnitude of the resistance value of the temperature measuring element, and the thermal conductivity lambda of the fluid medium in the thermal flow detection assembly 1 Volumetric heat capacity (ρ.C) p ) 1 And the like. K (K) 5 Is mainly affected by the flow state, such as the Raney number (fluid mass flow rate and viscosity coefficient mu 1 A function of (c) and the like. When the measured flow range is wide and the Reynolds number change is large, the coefficient K 5 Not a fixed value, which changes as the reynolds number changes. The introduction of the viscosity characteristic can further improve the accuracy of the measurement result.
Equation 12 may be applied to exhibit a non-linear relationship between the flow rate detected by the thermal flow detection assembly and the temperature differential. As the flow rate of the fluid increases, the thermal flow detection assembly detects a nonlinear relationship between the flow rate and the temperature difference, and the effect of the viscosity of the fluid is more pronounced, so that the flow detection is more accurate based on the formula 12.
Equation 13:
equation 14:
wherein Q is 13 、Q 14 All refer to flow rates including, but not limited to, mass flow rate, volumetric flow rate, and standard volumetric flow rate. Deltat is the temperature difference detected by the thermal flow detection assembly. P (P) 1 、P 2 、P 3 、a 1 、a 2 、a 3 For thermal flow sensing assembly and flow channel geometry, physical properties of fluid medium (lambda 1 、(ρ·C p ) 1 、μ 1 Etc.) related coefficients. For lambda 1 、(ρ·C p ) 1 、μ 1 For an explanation of (a) reference is made to the above. P (P) 1 、P 2 、P 3 、a 1 、a 2 、a 3 Can be obtained by fitting data.
For the pressure loss generated by the fluid medium passing through the bypass flow passage where the thermal flow detection assembly is located, based on Poiseuille (Poiseuille) equation, the following relationship exists between the volume flow in the bypass flow passage and the pressure difference:
wherein Q is Side v Is the volume flow of fluid in the bypass flow channel; q (Q) Side m Is the mass flow of fluid in the bypass flow channel; Δp is the pressure drop generated by the fluid passing through the bypass flow channel or the differential pressure at the inlet and outlet of the bypass flow channel, in other words, Δp is the differential pressure detected by the differential pressure flow detection assembly; s is the flow cross section of the bypass flow channel, L is the length of the bypass flow channel; μ is the viscosity coefficient of the fluid medium; ρ 1 Is the density of the fluid medium (preferably, the working condition average density is adopted); pi is the circumference ratio coefficient of 3.14.
For known fluid flow channels, the viscosity characteristics of the different fluid media can be characterized by a measured differential pressure of the bypass flow channel. The relationship is as follows: Based on this relationship, a conversion relationship between the viscosity coefficient and the differential pressure can be obtained. Wherein mu 0 Characterization of the viscosity coefficient, μ of the reference fluid during the calibration phase 1 Characterizing the viscosity coefficient of the actual fluid; (DeltaP) 0 For the calibration phase the reference fluid flow is Q 0 Or temperature difference (DeltaT) 0 Differential pressure corresponding to the time, Q 0 Standard flow rate (delta T) set or provided for a reference fluid standard device when calibrating for the calibration phase 0 Standard flow Q established for calibration stage standard device 0 Temperature difference detected by time heating type flow detection assembly。(ΔP) 0 And (DeltaP) 1 Two fluid media (reference fluid and actual fluid) at the same flow rate Q 0 And the corresponding differential pressure.
When the differential pressure flow detection assembly detects that the differential pressure is a pressure drop generated by the fluid passing through the bypass flow channel where the thermal flow detection assembly is placed, equations 11 through 14 can be expanded as follows:
equation 15: q (Q) 15 ＝f(ΔT，ΔP，λ 1 ，(ρ·C p ) 1 )
Therefore, for the known flow channel design, the heat conductivity, density and constant pressure specific heat capacity of the fluid medium are integrated, and more accurate flow information can be obtained by combining the temperature difference delta T and the pressure difference delta P.
It should be noted that, equation 15 is an equation obtained in the calibration phase, in other words, equation 15 may be updated as equation 16: q (Q) 16 ＝f(ΔT，(ΔP) 0 ，λ 0 ，(ρ·C p ) 0 )。λ 0 Thermal conductivity of the reference fluid for the calibration phase; (DeltaP) 0 For the calibration phase the reference fluid flow is Q 0 Or temperature difference (DeltaT) 0 Differential pressure corresponding to the time, Q 0 Standard flow rate (delta T) set or provided for a reference fluid standard device when calibrating for the calibration phase 0 Standard flow Q established for calibration stage standard device 0 The temperature difference detected by the time heating type flow detection assembly; (ρ.C) p ) 0 For the calibration phase the volumetric heat capacity of the reference fluid. The calibration phase reference fluid has a volumetric heat capacity (ρ.C p ) 0 The density ρ of the calibration phase reference fluid may be used 0 And constant pressure specific heat capacity C p0 The product is obtained.
When the fluid composition changes, relative to the reference fluid in the calibration stage, the physical properties of the actual fluid such as heat conductivity, specific heat capacity, density, viscosity coefficient and the like are changed, and the physical properties of the actual fluid are compared with the physical properties of the reference fluid adopted in the calibration stage through the physical properties parameters such as heat conductivity, density, specific heat capacity and the like, and the differential pressure information obtained by the differential pressure detection assembly is combined, so that the differential change of the actual fluid due to the component change is corrected. Thus, the baseEquation 17 is obtained from equation 16: q (Q) Side by side ＝f(ΔT，(ΔP)/(ΔP) 0 ，λ/λ 0 ，(ρ·C p )/(ρ·C p ) 0 )。
Based on equation 17 andequation 1 is obtained: />
Alternatively, in an embodiment of the present invention,
Where m1, m2 and m3 are parameters determined from a variety of actual gas test experiments.
Obtaining corresponding flow based on a calibration relation (formula 16) between a reference fluid flow Q and the temperature difference DeltaT obtained by detection of the thermal flow detection assembly according to the temperature difference DeltaT signal obtained by detection of the thermal flow detection assembly, and simultaneously obtaining differential pressure DeltaP, thermal conductivity lambda and volumetric heat capacity (ρ.C) by detection of the differential pressure flow detection assembly and the physical property parameter detection assembly p ) And obtaining the real flow of the target fluid channel according to the related information of the fluid medium and the formula 1.
The method comprises the steps of determining the current thermal flow of a target fluid channel based on a formula 1, coupling a thermal flow signal detected by a thermal flow detection assembly with a differential pressure flow signal detected by a differential pressure flow detection assembly, and correcting and calculating the flow obtained by a thermal flow measurement method by utilizing a temperature difference signal, a differential pressure signal and physical parameters to obtain real flow information. If the current thermal flow is determined to be the actual measured flow of the target fluid channel, the flow obtained by the thermal flow measurement method is corrected and calculated based on the differential pressure signal, so that the thermal flow measurement method further increases the consideration of components and is more suitable for application scenes with unstable medium components. In addition, the differential pressure signal is related to viscosity, the flow obtained by the thermal flow measurement method is corrected and calculated based on the differential pressure signal, and the viscosity coefficient is taken into consideration, so that the measurement accuracy is further improved.
Alternatively, in the embodiment of the present invention, the current differential pressure flow is determined based on the differential pressure flow measurement mode in combination with the temperature difference, the differential pressure, and the physical property parameter of the fluid medium in the target fluid channel, and the current differential pressure flow may be determined based on the differential pressure flow measurement formula. The independent variables in the differential pressure flow measurement formula are temperature difference, pressure difference and physical property parameters, and the independent variables in the differential pressure flow measurement formula are flow.
Alternatively, in an embodiment of the present invention, the differential pressure flow measurement formula may be formula 2. Equation 2:
wherein Q is Difference of difference A total flow of the target fluid channel based on the differential pressure flow measurement mode; q (Q) Main unit As main path flow, Q Side by side Is bypass flow; delta T is the temperature difference; lambda (lambda) 0 Thermal conductivity of the reference fluid for the calibration phase; (ρ.C) p ) 0 The heat capacity of the volume of the reference fluid is used for calibration; λ is the thermal conductivity of the actual fluid flowing in the target fluid channel of the actual flow to be measured; ρ.C p Is the volumetric heat capacity of the actual fluid; ΔP is the pressure differential of the actual fluid; (DeltaP) 0 For the calibration phase the reference fluid flow is Q 0 Or temperature difference (DeltaT) 0 Differential pressure corresponding to the time, Q 0 Reference to calibration phaseStandard flow rate (Δt) set or provided by the fluid standard device 0 Standard flow Q established for calibration stage standard device 0 The temperature difference detected by the time heating type flow detection assembly;is the flow split ratio of the bypass flow channel and the main flow channel, wherein the flow split ratio is +.>And the flow calibration process is adopted for determining. Further, volumetric heat capacity is the product of density and specific heat capacity for any fluid medium. The calibration phase reference fluid has a volumetric heat capacity (ρ.C p ) 0 The density ρ of the calibration phase reference fluid may be used 0 And constant pressure specific heat capacity C p0 The product is obtained, and the volumetric heat capacity rho.C of the actual fluid p The density ρ and the constant pressure specific heat capacity C of the actual fluid can be used p The product is obtained.
Alternatively, in an embodiment of the present invention, equation 2 may be derived based on equation 21 or equation 22. Based on the measurement principle of the differential pressure type flow detection component, the formula 21 or the formula 22 can be obtained.
Equation 21:
equation 22:
wherein Q is Principal m Is the mass flow of the fluid in the main channel flow channel; q (Q) Principal v Is the volume flow of the fluid in the main channel flow channel; ΔP is the differential pressure detected by the differential pressure flow detection assembly; ρ 1 Is the density of the fluid medium (preferably, the working condition average density is adopted); k (K) 6 Is the gauge factor associated with the geometry of the throttling assembly.
Specifically, equation 21 and equation 22 have different expressions for different throttle assemblies, respectively. Taking the orifice plate structure as an example, the following quantitative relationship exists between the flow rate of the fluid and the differential pressure between the upstream and downstream of the orifice assembly (i.e. the differential pressure detected by the differential pressure flow detecting assembly), in other words, the formula 21 and the formula 22 may be updated as the formula 210 and the formula 220, respectively.
Equation 210:
equation 220:
then, for equation 210 and equation 220,
wherein Q is Principal m Is the mass flow of the fluid in the main channel flow channel; q (Q) Principal v Is the volume flow of the fluid in the main channel flow channel; c is the outflow coefficient; beta is the diameter ratio of the throttling assembly; epsilon is the expansion coefficient; d is the aperture of the orifice plate; k (K) 2 Is a meter factor related to the geometry of the throttling assembly; ρ 1 Is the density of the fluid medium (preferably, the average density under working conditions is adopted); ΔP is the differential pressure detected by the differential pressure flow sensing assembly.
Alternatively, in an embodiment of the present invention, the throttling assembly may also be a venturi structure.
When the fluid composition changes, the density of the fluid changes, and accurate measurement results cannot be obtained only by detecting the obtained differential pressure and temperature and pressure compensation correction through the differential pressure flow detection assembly.
According to the above analysis for the thermal flow measurement mode, when the fluid composition changes, the flow rate and the pressure difference corresponding to the same temperature difference change due to the change of the physical property of the fluid, wherein the change can be corrected by introducing the physical property parameter.
Based on the above equation 17, it can be obtained that when the reference fluid in the calibration phase flows in the bypass flow channel: q (Q) Side, 0 ＝f(ΔT，(ΔP) 0 /(ΔP) 0 ，λ 0 /λ 0 ，(ρ·C p ) 0 /(ρ·C p ) 0 )。
Based on the above equation 17, it can be obtained that when the other actual fluid than the reference fluid in the calibration phase flows in the bypass flow passage: q (Q) Side by side ＝f(ΔT，(ΔP)/(ΔP) 0 ，λ/λ 0 ，(ρ·C p )/(ρ·C p ) 0 )。
Based on the above formula 21 or formula 22, when the reference fluid in the calibration phase flows in the main channel flow channel: q (Q) Main, 0 ＝g((ΔP) 0 ，ρ 0 )。
Based on the above formula 21 or formula 22, when the main flow channel is flowing other actual fluid than the reference fluid in the calibration phase: q (Q) Main unit ＝g(ΔP，ρ)
According to the bypass flow sensor flow dividing principle, the main flow and the bypass flow are in proportion, and then:
thus, equation 23 is obtained:wherein Q is Side by side ＝f(ΔT，(ΔP)/(ΔP) 0 ，λ/λ 0 ，(ρ·C p )/(ρ·C p ) 0 )；Q Side, 0 ＝f(ΔT，(ΔP) 0 /(ΔP) 0 ，λ 0 /λ 0 ，(ρ·C p ) 0 /(ρ·C p ) 0 )。
Based on equation 23 andequation 2 is obtained: />
The current differential pressure flow of the target fluid channel is determined based on the formula 2, the thermal type flow signal detected by the thermal type flow detection assembly and the differential pressure flow signal detected by the differential pressure flow detection assembly are coupled, and the differential pressure flow obtained by the differential pressure flow measurement method is corrected and calculated by utilizing the differential pressure signal, the differential pressure signal and the physical property parameter, so that the real flow information is obtained. If the current differential pressure flow is determined as the actual measured flow of the target fluid channel, the flow obtained by the differential pressure flow measurement method is corrected and calculated based on the temperature difference signal, and the factor sensitive to the components in the thermal flow measurement is introduced, so that the differential pressure flow measurement method further increases the consideration of the components, and is more suitable for application scenes in which the medium components are unstable.
Thus, the change of the main channel due to the component change is corrected, and the secondary correction of the change of the density rho of the fluid medium is not needed.
Alternatively, in the embodiment of the present invention, the thermal conductivity and the specific heat capacity are detected by the physical property parameter detecting means. Specifically, the physical property parameter detection component detects the thermal conductivity and the specific heat capacity by using a transient thermal impulse response method based on the thermal flow detection component. Alternatively, the physical property parameter detecting means may be a physical property sensor.
Alternatively, in an embodiment of the present invention, determining the actual measured flow of the target fluid channel based on the current thermal flow and/or the current differential pressure flow and the flow measurement mode determination rules may include the following.
The comparison flow rate is determined based on the current thermal flow rate and/or the current differential pressure flow rate. For example, the current thermal flow is determined as the comparison flow. Alternatively, the current differential pressure flow is determined as the comparison flow. Alternatively, the comparison flow rate is determined by calculating the current thermal flow rate and the current differential pressure flow rate. For example, the comparison flow rate is determined by averaging the current thermal flow rate and the current differential pressure flow rate. Alternatively, the comparison flow rate may be determined by performing other calculations on the current thermal flow rate and the current differential pressure flow rate. Based on the comparison flow and the flow measurement mode determination rule, the current thermal flow or the current differential pressure flow is determined as the actual measured flow of the target fluid channel to determine the flow of the target fluid channel.
Alternatively, in an embodiment of the present invention, the flow measurement mode determination rule may include the following. Under the condition that the comparison flow is greater than or equal to a preset flow threshold, determining the current differential pressure flow as the actual measurement flow; and/or determining the current thermal flow as the actual measured flow in case the compared flow is smaller than the preset flow threshold. Alternatively, in the embodiment of the present invention, the preset flow rate threshold may be set empirically.
Optionally, in an embodiment of the present invention, the preset flow threshold is a flow value such that a flow rate change rate in the differential pressure flow measurement mode and a flow rate change rate in the thermal flow measurement mode are equal. Specifically, the preset flow threshold may be determined according to the following.
Calculating a derivative f' (Δt) =dq of the bypass flow in the thermal flow measurement mode Side by side D (Δt) and a derivative function g' (Δp) =dq of the main flow in the differential pressure flow measurement mode Main unit D (ΔP). So that f '(Δt) =g' (Δp), an appropriate critical flow switching value Q is determined s ，Q s Is a preset flow threshold. Wherein,
alternatively, in an embodiment of the present invention, the flow measurement mode determination rule may include the following. Under the condition that the comparison flow is greater than or equal to the upper limit of the preset flow threshold range, determining the current differential pressure flow as the actual measurement flow; and/or determining the current thermal flow as the actual measured flow in the case that the comparative flow is less than the lower limit of the preset flow threshold range. Alternatively, in the embodiment of the present invention, the preset flow threshold range may be set empirically.
Alternatively, in an embodiment of the present invention, the preset flow threshold range may be determined according to the following. Based on the method, the preset flow threshold Q is determined s . The preset flow threshold range is [ Q ] s -δ，Q s +δ]. Delta is a positive integer and can be empirically set.
And comparing the comparison flow with the upper limit and the lower limit of a preset flow threshold or a preset flow threshold range, and dividing the target fluid channel into a medium flow mode and a small flow mode or a large flow mode. When the comparison flow is smaller than a preset flow threshold or smaller than or equal to the lower limit of a preset flow threshold range, the target fluid channel is in a medium-small flow mode, and at the moment, the current thermal flow is determined to be the actual measurement flow by adopting a thermal flow measurement mode, so that the target fluid channel has high micro flow sensitivity; when the comparison flow is greater than or equal to a preset flow threshold or greater than or equal to the upper limit of a preset flow threshold range, the target fluid channel is in a large flow mode, and at the moment, the current differential pressure flow is determined to be the actual measurement flow by adopting a differential pressure type flow detection mode, so that the speed sensitivity can be ensured, and the measurement range and the measurement precision can be greatly improved. The thermal flow measurement mode is more suitable for a medium and small flow mode, and has higher sensitivity in the medium and small flow mode; the differential pressure flow measurement mode is more suitable for a high flow mode, and has higher sensitivity in the high flow mode. Therefore, whether the target fluid channel is in a medium-small flow mode or a large flow mode is determined based on comparison of the flow and the preset flow threshold or the upper limit and the lower limit of the preset flow threshold range, and a proper measurement mode is selected, so that the sensitivity of flow measurement can be ensured, and the measurement accuracy is improved.
Optionally, in the embodiment of the present invention, to ensure continuity of flow switching, the flow measurement results in the two flow measurement modes are synchronously output to preset a flow threshold range [ Q ] s -δ，Q s +δ]Switching of the flow measurement mode is performed on the basis of the above.
The current output result Q (equivalent to the comparative flow described in the embodiment of the invention) is the flow data obtained in the thermal flow measurement mode, and Q is more than or equal to Q s When +deltaSwitching the output result to flow data in the differential pressure flow measurement mode:
the current output Q (corresponding to the comparative flow described in the embodiments of the present invention) is the flow data in the differential pressure flow measurement mode, and Q.ltoreq.Q s When the output structure is switched to flow data in the thermal flow measurement mode, then:
alternatively, in an embodiment of the present invention, the flow rate of the target fluid channel under the standard working condition may be detected.
Optionally, the flow detection unit further comprises a temperature detection component and a pressure detection component. The temperature detecting part is used for detecting the temperature in the bypass flow passage, and the pressure detecting part is used for detecting the pressure in the bypass flow passage. The flow measurement method further includes the following before determining the flow of the target fluid channel based on the temperature difference, the pressure difference, and the physical property parameter of the fluid medium in the target fluid channel. The temperature detected by the temperature detecting means is acquired. The pressure detected by the pressure detecting means is acquired. The flow rate of the target fluid channel is determined based on the acquired temperature and the acquired pressure, and the determined flow rate of the target fluid channel is the flow rate under the standard working condition. Specifically, determining the flow rate of the target fluid channel based on the temperature difference, the pressure difference, and physical parameters of the fluid medium in the target fluid channel includes: and determining the flow of the target fluid channel under the standard working condition based on the temperature, the pressure, the temperature difference, the pressure difference and the physical parameters of the fluid medium in the target fluid channel.
Optionally, for thermal flow measurement mode, temperature and pressure corrections are used primarily for correction of specific heat capacity to obtain volumetric flow under specific standard conditions:
wherein (ρC) p ) std The volume heat capacity is the volume heat capacity under the standard working condition; (ρ.C) p ) Is the volumetric heat capacity under the operating condition; (ρ.C) p ) 0 The volumetric heat capacity (generally referred to as air) of the reference fluid for the calibration phase; p is the operating pressure, i.e. the pressure detected by the pressure detecting means; t is the operating temperature, i.e., the temperature detected by the temperature detecting means; p (P) Label (C) Operating pressure at standard operating conditions (101.325 kPa); t (T) Label (C) Is the working temperature (20 ℃) under the standard working condition.
Alternatively, for the differential pressure flow measurement mode, when the obtained flow is the volume flow under the operating condition, the volume flow under different operating conditions, such as the standard operating condition (101 325kpa,20 ℃), can be converted by using the temperature and pressure obtained by the detection.
Wherein Q is v,std The volume flow is the volume flow under the standard working condition; q (Q) Difference of difference Is the volume flow under the operating condition; p is the operating pressure, i.e. the pressure detected by the pressure detecting means; t is the operating temperature, i.e., the temperature detected by the temperature detecting means; p (P) Label (C) Operating pressure at standard operating conditions (101.325 kPa); t (T) Label (C) Is the working temperature (20 ℃) under the standard working condition.
In a second aspect, an embodiment of the present invention further provides a flow measurement device. The flow rate measuring device includes: memory and a processor. The memory is used for storing a computer program. The processor is configured to implement the flow measurement method described in the above embodiment by executing a computer program stored in the memory.
In a third aspect, an embodiment of the present invention further provides a storage medium, where a computer program is stored, where the computer program, when executed by a processor, implements the flow measurement method described in the foregoing embodiment.
In a fourth aspect, embodiments of the present invention also provide a flow meter. The flow meter includes a fluid channel, a flow detection unit, and a control module. The control module is configured to perform the flow measurement method described in the above embodiments.
Fig. 2 is a schematic view of a portion of a flow meter according to another embodiment of the present invention. The fluid passage includes a main passage 10 and a bypass passage 11. The main flow path 10 includes a main flow path pipe body. The bypass flow passage 11 includes a bypass flow passage pipe body. As shown in fig. 3, the bypass flow path 11 and the main flow path 10 are connected by a bypass communication pipe 110.
The target fluid channel is connected with a main channel 10 through a pipeline, and a throttling component 101 is arranged in the main channel 10. The inlet of the bypass flow passage 11 is connected to an upstream line of the throttle assembly 101, and the outlet of the bypass flow passage 11 is connected to a downstream line of the throttle assembly 101. Specifically, as shown in fig. 4, the inlet of the bypass flow passage 11 is connected to the upstream of the throttle unit 101 through the bypass communication pipe 110, and the outlet of the bypass flow passage 11 is connected to the downstream of the throttle unit 101 through the bypass communication pipe 110.
Alternatively, in the embodiment of the present invention, the relative pressure difference between the upstream inlet section and the downstream outlet pipe of the bypass communication pipe 110 is small, that is, the pressure difference is negligible with respect to the inside of the bypass flow passage 11. Equivalent diameter d of bypass communication pipe 110 pipe Far greater than the equivalent diameter d of the bypass flow passage 11 channel . Preferably d pipe ≥2d channel . The consistency of the differential pressure between the main channel flow channel 10 and the bypass flow channel 11 is ensured.
The flow detection unit is located in the bypass flow channel 11. Alternatively, the fluid in the bypass flow passage 11 is in a laminar flow state.
The flow rate detection unit includes a thermal flow rate detection module 20, a differential pressure flow rate detection module 21, and a physical property parameter detection member (not shown in fig. 2). A temperature differential signal may be derived based on the thermal flow sensing assembly 20. The differential pressure signal before and after the differential pressure flow rate detection module 21 can be obtained based on the differential pressure flow rate detection module 21. The physical property parameter detecting means can detect a physical property parameter.
Optionally, in the embodiment of the present invention, the thermal flow detection assembly 20 and the differential pressure flow detection assembly 21 are connected in parallel, the inlet of the flow channel where the thermal flow detection assembly 20 is located is communicated with the inlet of the flow channel where the differential pressure flow detection assembly 21 is located, and the outlet of the flow channel where the thermal flow detection assembly 20 is located is communicated with the outlet of the flow channel where the differential pressure flow detection assembly 21 is located. In fig. 2, solid arrows indicate the flow direction of the fluid medium, and broken arrows indicate the flow direction of the gas.
Alternatively, in an embodiment of the present invention, the thermal flow sensing assembly 20 may be a thermal flow sensor. Preferably, the thermal flow sensing assembly 20 may be a MEMS thermal flow sensor.
Alternatively, in an embodiment of the present invention, differential pressure flow sensing assembly 21 may be a differential pressure flow sensor. Preferably, differential pressure flow sensing assembly 21 may be a static differential pressure sensor (no airflow in the pressure sensing chamber). Preferably, differential pressure flow sensing assembly 21 may be a thin film differential pressure sensor.
Optionally, in an embodiment of the present invention, a rectifying component 102 may also be disposed in the main channel 10. The number of rectifying components 102 may be as appropriate. However, in the case where the flow straightening assemblies 102 are provided, at least one flow straightening assembly 102 is located upstream of the position where the bypass flow passage 11 is connected upstream of the main flow passage 10. As shown in fig. 4, the main flow channel 10 includes two rectifying components 102 therein, wherein one rectifying component 102 is located upstream of the junction of the bypass flow channel 11 and the main flow channel 10, and one rectifying component 102 is located downstream of the junction of the flow channel 11 and the main flow channel 10. Wherein in embodiments of the present invention, upstream and downstream may be dependent on the direction of flow of the fluid medium.
The flow straightener 102 is a conventional flow regulator for regulating the uniformity of the fluid velocity entering the main flow path 10. Alternatively, in embodiments of the present invention, the fairing assembly 102 may be a perforated plate, grid plate, screen, or the like.
The throttling assembly 101 is used to create a fluid pressure differential in the flow direction. Alternatively, in embodiments of the present invention, the throttling assembly 101 may be a standard orifice plate, a perforated plate, a laminar flow member, a grating plate, a screen, or the like.
Alternatively, in the embodiment of the present invention, regarding the geometric design of the bypass flow passage 11, a laminar flow pattern design is preferable. The Reynolds number Re of the medium flow in the full flow measurement range is less than or equal to 2300 through laminar flow type design. That is to say,wherein u is max Is the maximum flow rate allowed for the thermal flow detection assembly 20. D is the diameter of the bypass flow passage, and the equivalent diameter is taken when the flow passage is not a circular pipe flow passage.
Thereby the processing time of the product is reduced,the diameter of the bypass flow passage can be designed according to the physical property and the flow measurement range of the fluid.
In the case of a rectangular flow-through cross-section,that is to say,where μ is the viscosity coefficient of the fluid medium, ρ is the density of the fluid medium, L is the height of the rectangular bypass flow cross section, and W is the width of the rectangular bypass flow cross section.
Alternatively, where the thermal flow sensing assembly 20 is a MEMS thermal flow sensor, the aspect ratio L/W of the flow interface is greater than or equal to 2. The height L and the width W of the flow section of the bypass flow channel can be solved by combining the above.
Fig. 5 is a schematic cross-sectional structure of a flow rate detection unit according to still another embodiment of the present invention.
As shown in fig. 5, the flow detection unit is located in the bypass flow channel. The flow rate detection means includes a thermal flow rate detection unit 20, a differential pressure flow rate detection unit 21, a substrate 22, and a physical property parameter detection member 23. The substrate 22 includes a first gas via 220 and a second gas via 221. The substrate 22 separates the bypass channels into a microchannel 110 and a differential pressure sensing chamber. Thermal flow sensing assembly 20 and differential pressure flow sensing assembly 21 are integrated on both sides of substrate 22. The physical property parameter detecting member 23 and the differential pressure flow rate detecting unit 21 are integrated on the same side of the substrate 22. Differential pressure flow sensing assembly 21 separates the differential pressure sensing chambers into a first differential pressure sensing chamber 1110 and a second differential pressure sensing chamber 1111. The fluid medium in the micro flow channel 111 flows through the thermal flow rate detection assembly 20, and the gas in the micro flow channel 111 enters the first differential pressure detection chamber 1110 through the first gas through hole 220, and the gas in the micro flow channel 111 enters the second differential pressure detection chamber 1111 through the second gas through hole 221.
Alternatively, in an embodiment of the present invention, the control module may be integrated on the substrate 22.
In the bypass flow channel, the upstream detection hole of the differential pressure flow detection assembly 21 is connected with the upstream of the micro flow channel 111 contacted by the thermal flow detection assembly 20, and the downstream detection hole of the differential pressure flow detection assembly 21 is connected with the downstream of the micro flow channel 111 contacted by the thermal flow detection assembly 20, so that the influence of the local pressure loss of the inlet section and the outlet section of the flow channel on the linear pressure change rule is minimized.
Alternatively, in the embodiment of the present invention, the flow areas of the first gas through-hole 220 and the second gas through-hole 221 are not lower than the equivalent diameter d of the bypass communication pipe 110 pipe The first gas through-hole 220 and the second gas through-hole 221 are prevented from being throttled to affect the measurement result of the differential pressure flow detection assembly 21. Preferably, first differential pressure sensing chamber 1110 and second differential pressure sensing chamber 1111 are symmetrically designed with respect to differential pressure flow sensing assembly 21.
Alternatively, in the embodiment of the present invention, as illustrated in fig. 5, the flow rate detecting unit may further include a temperature detecting part 24 and a pressure detecting part 25. The temperature detecting part 24 and the pressure detecting part 25 are integrated on the substrate 22. The temperature detecting member 24 is for detecting the temperature in the bypass flow passage. Specifically, temperature sensing component 24 senses the temperature within first differential pressure sensing chamber 1110. Alternatively, the temperature detecting member 24 is a temperature sensor. The pressure detecting member 25 is for detecting the pressure in the bypass flow passage. Specifically, the pressure detecting member 25 detects the pressure inside the first differential pressure detecting chamber 1110. Alternatively, the pressure detecting member 24 is a pressure sensor.
Fig. 6 is a schematic cross-sectional structure of a flow rate detection unit according to still another embodiment of the present invention. The flow rate detection unit shown in fig. 6 differs from the flow rate detection unit shown in fig. 5 only in that the flow rate detection unit shown in fig. 6 further includes a first bypass-cut micro valve 26 and a first bypass-cut micro valve 27. The first bypass cut-off micro valve 26 and the first bypass cut-off micro valve 27 are located downstream of the thermal flow rate detection assembly 20 on both sides of the second gas through hole 221. The first bypass-cut-off micro valve 26 and the first bypass-cut-off micro valve 27 are located downstream of the thermal flow detection assembly 20, and can avoid the influence of flow field interference caused by mismatch of the micro valve channels and the bypass flow channels on flow measurement.
The bypass flow path structure activation state and the zero point correction of the thermal flow rate detection assembly 20 and the differential pressure flow rate detection assembly 21 are achieved by the open states of the first bypass cut-off micro valve 26 and the first bypass cut-off micro valve 27.
When the first bypass cut-off micro valve 26 is closed and the first bypass cut-off micro valve 27 is opened, no medium flows in the bypass flow passage, and the bypass flow passage can be used for zero point correction of the components such as the thermal flow detection component 20 and the physical property parameter detection component 23 so as to eliminate the influence of the change of the operating condition or the difference of the fluid medium on the zero point. Similarly, in this case, the flow meter may be switched to the differential pressure flow rate detection mode in which no bypass flow path flows, that is, the bypass flow rate is not required to be considered
The situation can be used for solving the problems of partial or complete blockage of the bypass flow passage, metering failure of the thermal flow detection assembly caused by pollution or faults in the long-term operation process and other application occasions, and can be used for solving the flow measurement problem in the period that the thermal flow detection assembly cannot work normally.
When the first bypass cut-off micro valve 26 is opened and the first bypass cut-off micro valve 27 is closed, no medium flows in the bypass flow passage, and the differential pressure detection chamber and the upstream and downstream communication holes (the first gas through hole 220 and the second gas through hole 221) of the micro flow passage 111 are in a short-circuited state, which can be used for zero point correction of the differential pressure flow rate detection module 21.
Alternatively, in an embodiment of the present invention, the first bypass-cut micro valve 26 and the first bypass-cut micro valve 27 may also be located upstream of the thermal flow detection assembly 20, on either side of the first gas through-hole 220. When the first bypass-cut micro valve 26 and the first bypass-cut micro valve 27 are located upstream of the thermal flow rate detection assembly 20, the on-off state is just opposite to that when the first bypass-cut micro valve 26 and the first bypass-cut micro valve 27 are located downstream of the thermal flow rate detection assembly 20.
Optionally, in an embodiment of the present invention, the flow detection unit further includes: the flow measurement module described in the above embodiments is integrated on a substrate.
Fig. 7 is a schematic view showing a part of the constitution of a flowmeter according to still another embodiment of the present invention. As shown in fig. 7, the flowmeter includes a differential pressure flow rate detection module, a thermal flow rate sensor, and the like. Further, the flowmeter may include an integrated chip module composed of a differential pressure flow detection assembly, a thermal flow sensor, and the like. The integrated chip module comprises a sensor integrated unit, an MEMS micro-valve system, a conditioning and amplifying module, an A/D conversion module, a digital processing and communication module and the like. The sensor integration unit comprises a thermal flow sensor, a physical property sensor, a temperature sensor, a pressure sensor and a differential pressure flow detection component. The MEMS micro-valve system includes the first bypass-cut micro-valve and the first bypass-cut micro-valve described in the above embodiments. The conditioning amplification module amplifies the signal received from the sensor integrated unit and then transmits the signal to the a/D conversion module. The A/D conversion module converts the received signal into a digital signal. The digital processing and communication module receives the signal transmitted by the a/D conversion module, processes the signal based on the flow measurement method described in the above embodiment to obtain flow, and may transmit the obtained flow.
In a fifth aspect, embodiments of the present invention also provide a computer program product comprising computer program instructions which, when executed by a processor, cause the processor to perform the steps of the flow measurement method described in the above embodiments.
A computer program product may include program code for performing operations of embodiments of the present description in any combination of one or more programming languages, including an object oriented programming language such as Java, c++ or the like and conventional procedural programming languages, such as the "C" programming language or similar programming languages. The program code may execute entirely on the user's computing device, partly on the user's device, as a stand-alone software package, partly on the user's computing device, partly on a remote computing device, or entirely on the remote computing device or server.
Those skilled in the art will appreciate that implementing all or part of the above described methods may be accomplished by way of a computer program stored on a non-transitory computer readable storage medium, which when executed, may comprise the steps of the embodiments of the methods described above. Any reference to memory, storage, database, or other medium used in the embodiments provided herein may include non-volatile and/or volatile memory. The nonvolatile memory can include Read Only Memory (ROM), programmable ROM (PROM), electrically Programmable ROM (EPROM), electrically Erasable Programmable ROM (EEPROM), or flash memory. Volatile memory can include Random Access Memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in a variety of forms such as Static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double Data Rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous Link DRAM (SLDRAM), memory bus direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM), among others.
The technical features of the above embodiments may be arbitrarily combined, and all possible combinations of the technical features in the above embodiments are not described for brevity of description, however, as long as there is no contradiction between the combinations of the technical features, they should be considered as the scope of the description.
The above examples only represent a few embodiments of the present specification, which are described in more detail and are not to be construed as limiting the scope of the invention. It should be noted that it will be apparent to those skilled in the art that several variations and modifications can be made without departing from the spirit of the present description, which is within the scope of the present description. Accordingly, the protection scope of the patent should be determined by the appended claims.
Claims (10)
1. A flow measurement method for measuring a flow in a target fluid passage, the flow measurement method comprising:
the method comprises the steps that a temperature difference detected by a thermal flow detection assembly in a flowmeter is obtained, wherein the flowmeter comprises a fluid channel and a flow detection unit, the fluid channel comprises a main channel flow channel and a bypass flow channel, the target fluid channel is connected with the main channel flow channel through a pipeline, a throttling assembly is arranged in the main channel flow channel, an inlet of the bypass flow channel is connected with an upstream pipeline of the throttling assembly, an outlet of the bypass flow channel is connected with a downstream pipeline of the throttling assembly, the flow detection unit is positioned in the bypass channel, and the flow detection unit comprises the thermal flow detection assembly and a differential pressure flow detection assembly;
Acquiring the differential pressure detected by the differential pressure flow detection assembly; and
determining a flow rate of the target fluid channel based on the temperature differential, the pressure differential, and a physical property parameter of the fluid medium in the target fluid channel.
2. The flow rate measurement method according to claim 1, wherein the flow rate detection unit further includes a temperature detection means for detecting a temperature in the bypass flow passage and a pressure detection means for detecting a pressure in the bypass flow passage;
wherein prior to said determining a flow rate of said target fluid channel based on said temperature differential, said pressure differential, and physical properties parameters of a fluid medium in said target fluid channel, said flow rate measurement method further comprises:
acquiring the temperature detected by the temperature detecting component; and
acquiring the pressure detected by the pressure detecting part;
wherein the determining the flow rate of the target fluid channel based on the temperature difference, the pressure difference, and the physical property parameter of the fluid medium in the target fluid channel comprises:
and determining the flow rate of the target fluid channel under the standard working condition based on the temperature, the pressure, the temperature difference, the pressure difference and the physical property parameters of the fluid medium in the target fluid channel.
3. The flow measurement method of claim 1, wherein the determining the flow of the target fluid channel based on the temperature differential, the pressure differential, and physical parameters of the fluid medium in the target fluid channel comprises:
determining a current thermal flow and a current differential pressure flow of the target fluid channel, wherein the current thermal flow is determined based on a thermal flow measurement mode in combination with the temperature difference, the pressure difference, and a physical property parameter of the fluid medium in the target fluid channel, and the current differential pressure flow is determined based on a differential pressure flow measurement mode in combination with the temperature difference, the pressure difference, and the physical property parameter of the fluid medium in the target fluid channel;
and determining that the current thermal flow or the current differential pressure flow is the actual measured flow of the target fluid channel based on the current thermal flow and/or the current differential pressure flow and a flow measurement mode determination rule so as to determine the flow of the target fluid channel.
4. A flow measurement method according to claim 3, wherein determining that the current thermal flow or the current differential pressure flow is the actual measured flow of the target fluid passage based on the current thermal flow and/or the current differential pressure flow and a flow measurement pattern determination rule comprises:
Determining a comparison flow based on the current thermal flow and/or the current differential pressure flow;
and determining that the current thermal flow or the current differential pressure flow is the actual measured flow of the target fluid channel based on the comparison flow and the flow measurement mode determination rule to determine the flow of the target fluid channel.
5. The flow measurement method of claim 4, wherein the flow measurement mode determination rule comprises:
determining the current differential pressure flow as the actual measured flow if any of the following is satisfied: the comparison flow is greater than or equal to a preset flow threshold value, and the comparison flow is greater than or equal to the upper limit of a preset flow threshold value range; and/or
Determining the current thermal flow as the actual measured flow if any of the following is satisfied: the comparison flow is smaller than the preset flow threshold value, and the comparison flow is smaller than or equal to the lower limit of the preset flow threshold value range.
6. The flow measurement method of claim 1, wherein the physical parameters include thermal conductivity, density, and specific heat capacity.
7. A flow measurement device for measuring flow in a target fluid passage, the flow measurement device comprising:
A memory;
a processor for storing a computer program for implementing the flow measurement method of any one of claims 1-6 by running the computer program stored in the memory.
8. A storage medium having stored thereon a computer program which, when executed by a processor, implements the flow measurement method according to any of claims 1-6.
9. A flow meter, the flow meter comprising:
the fluid channel comprises a main channel flow channel and a bypass flow channel, the target fluid channel is connected with a main channel flow channel pipeline, a throttling assembly is arranged in the main channel flow channel, an inlet of the bypass flow channel is connected with an upstream pipeline of the throttling assembly, and an outlet of the bypass flow channel is connected with a downstream pipeline of the throttling assembly; and
the flow detection unit is positioned in the bypass channel and comprises a thermal flow detection assembly, a differential pressure flow detection assembly and a physical property parameter detection component;
a control module for performing the flow measurement method of any one of claims 1-6.
10. The flowmeter of claim 9, wherein said flow detection unit further comprises:
the substrate comprises a first gas through hole and a second gas through hole, the bypass channel is divided into a micro-channel and a differential pressure detection cavity by the substrate, the thermal type flow detection component and the differential pressure flow detection component are integrated on two sides of the substrate, the physical property parameter detection component and the differential pressure flow detection component are integrated on the same side of the substrate, the differential pressure flow detection component divides the differential pressure detection cavity into a first differential pressure detection cavity and a second differential pressure detection cavity, a fluid medium in the micro-channel flows through the thermal type flow detection component, gas in the micro-channel enters the first differential pressure detection cavity through the first gas through hole, and gas in the micro-channel enters the second differential pressure detection cavity through the second gas through hole;
preferably, the flow rate detection unit further includes: a temperature detecting unit configured to detect a temperature in the bypass flow passage; and a pressure detecting means for detecting a pressure in the bypass flow passage;
preferably, the main channel is further internally provided with at least one rectifying component, and at least one of the at least one rectifying component is positioned at the upstream of the upstream connection position of the bypass channel and the main channel.
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