A measurement system and method for ultra-low flow rates

Abstract

This invention discloses an ultra-low flow rate measurement system and method, which can be widely applied in the field of fluid measurement technology. The invention comprises a signal control unit, a voltage signal generation unit, a current detection unit, a conductivity measurement unit, an electro-adsorption electrode unit, and a data processing unit. The voltage signal generation unit generates a DC voltage to control the electro-adsorption electrode unit to adsorb charged particles in the fluid. The current detection unit collects current data during the electro-adsorption process, and the conductivity measurement unit collects data on the conductivity changes and the time of change between the electrodes during adsorption. The data processing unit then uses the current data, conductivity change data, and change time to calculate the fluid velocity. This allows for the measurement of ultra-low flow rates by utilizing the relationship between charged particles and the conductivity process in the fluid, thus improving the accuracy of ultra-low flow rate measurements.

Description

Technical Field

[0001] This invention relates to the field of fluid measurement technology, and in particular to a measurement system and method for ultra-low flow rates. Background Technology

[0002] In related technologies, ultra-low flow velocity refers to the flow rate of liquids at mm / s or μm / s, which is particularly evident in groundwater environments. Conventional flow meters include ultrasonic Doppler flow meters, radar flow meters, and rotor flow meters. These instruments are generally used for measuring water flow velocity in environments such as rivers, cross-sections, and open channels, and their measurement unit is usually m / s. For ultra-low flow velocities of mm / s or μm / s, they are either practically impossible to measure or have significant errors. Summary of the Invention

[0003] The present invention aims to at least solve one of the technical problems existing in the prior art. To this end, the present invention proposes a measurement system and method for ultra-low flow rates, which can improve the measurement accuracy of ultra-low flow rates.

[0004] On one hand, embodiments of the present invention provide a measurement system for ultra-low flow rates, comprising:

[0005] A signal control unit, wherein the signal control unit is configured to generate a first control signal according to a measurement command;

[0006] A voltage signal generating unit, wherein the voltage signal generating unit is configured to generate a DC voltage according to the first control signal;

[0007] A current detection unit is used to detect current data during the electro-adsorption process;

[0008] An electroadsorption electrode unit includes several electrodes, including a positive electrode and a negative electrode. The positive electrode is connected to the positive output terminal of the voltage signal generating unit, and the negative electrode is connected to the negative output terminal of the voltage signal generating unit. The positive electrode and the negative electrode are used to adsorb charged particles in the fluid according to the DC voltage.

[0009] A conductivity measurement unit is installed in the middle of the plurality of electrodes and is used to measure the conductivity change data and change time between the plurality of electrodes. The conductivity change data is related to the change data of charged particles in the fluid.

[0010] A data processing unit is configured to calculate the flow rate of the fluid based on the current data, the conductivity change data, and the change time.

[0011] In some embodiments, the measuring system further includes a fixing device, which includes a fixing rod and a fixing frame;

[0012] The first end of the fixing rod is connected to the top of the fluid device, and the second end of the fixing rod is connected to the fixing frame;

[0013] The voltage signal generating unit, the current detection unit, the electroadsorption electrode unit, the conductivity measuring unit, and the data processing unit are all fixed on the mounting frame.

[0014] In some embodiments, the plurality of electrodes all comprise metal electrodes.

[0015] In some embodiments, the thickness of the metal electrode ranges from 1 mm to 10 mm, and the diameter ranges from 30 mm to 100 mm.

[0016] In some embodiments, the spacing between the plurality of electrodes in the fluid ranges from 10 mm to 100 mm.

[0017] In some embodiments, the DC voltage ranges from 0.8V to 1.5V.

[0018] In some embodiments, the signal control unit is further configured to generate a second control signal, which is used to control the positive electrode and the negative electrode to short-circuit discharge.

[0019] In some embodiments, the calculation of the fluid velocity based on the current data, the conductivity change data, and the change time is performed using the following formula:

[0020]

[0021] Where V represents the flow velocity;

[0022] k0 is calculated using the following formula:

[0023]

[0024] This represents a sequence of conductivity values ​​corresponding to a stationary liquid with a flow velocity of 0. This represents the conductivity sequence value corresponding to the moment when electroadsorption stops after the current reaches a constant value or a set value. (S) 1n express and The duration of the sampling interval between them;

[0025] k Q Calculated using the following formula:

[0026]

[0027] This represents the series of conductivity values ​​corresponding to a liquid with a flow rate of Q. This represents the conductivity sequence value corresponding to the moment when electroadsorption stops after the current reaches a constant value or a set value. (S) 1n express and The duration of the sampling interval between them;

[0028] k i Calculated using the following formula:

[0029]

[0030] This represents the conductivity sequence value corresponding to the moment when the conductivity is highest at an unknown flow velocity. This represents the conductivity sequence value corresponding to the moment when electroadsorption stops after the current reaches a constant value or a set value. (S) i express and The sampling interval duration between them.

[0031] On the other hand, embodiments of the present invention provide a method for measuring ultra-low flow rates, the method being applied to the system, the method comprising the following steps:

[0032] Generate the first control signal according to the measurement command;

[0033] A DC voltage is generated based on the first control signal;

[0034] The DC voltage controls the adsorption of charged particles in the fluid by several electrodes.

[0035] Acquire current data of the electro-adsorption process, as well as conductivity change data and change time between the plurality of electrodes;

[0036] The flow rate of the fluid is calculated based on the current data, the conductivity change data, and the change time.

[0037] In some embodiments, the calculation of the fluid velocity based on the current data, the conductivity change data, and the change time is performed using the following formula:

[0038]

[0039] Where V represents the flow velocity;

[0040] k0 is calculated using the following formula:

[0041]

[0042] This represents a sequence of conductivity values ​​corresponding to a stationary liquid with a flow velocity of 0. This represents the conductivity sequence value corresponding to the moment when electroadsorption stops after the current reaches a constant value or a set value. (S) 1n express and The duration of the sampling interval between them;

[0043] k Q Calculated using the following formula:

[0044]

[0045] This represents the series of conductivity values ​​corresponding to a liquid with a flow rate of Q. This represents the conductivity sequence value corresponding to the moment when electroadsorption stops after the current reaches a constant value or a set value. (S) 1n express and The duration of the sampling interval between them;

[0046] k i Calculated using the following formula:

[0047]

[0048] This represents the conductivity sequence value corresponding to the moment when the conductivity is highest at an unknown flow velocity. This represents the conductivity sequence value corresponding to the moment when electroadsorption stops after the current reaches a constant value or a set value. (S) i express and The sampling interval duration between them.

[0049] The ultra-low flow rate measurement system provided in this embodiment of the invention has the following beneficial effects:

[0050] This embodiment sets up a signal control unit, a voltage signal generation unit, a current detection unit, a conductivity measurement unit, an electroadsorption electrode unit, and a data processing unit. The DC voltage generated by the voltage signal generation unit controls the electroadsorption electrode unit to adsorb charged particles in the fluid. The current detection unit collects current data of the electroadsorption process, and the conductivity measurement unit collects conductivity change data and change time between the electrodes during the adsorption process. The data processing unit then uses the current data, conductivity change data, and change time to calculate the flow rate of the fluid. Thus, the measurement process of ultra-low flow can be realized by utilizing the relationship between charged particles in the fluid and the change in the conductivity process, thereby improving the measurement accuracy of ultra-low flow rate.

[0051] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0052] The present invention will be further described below with reference to the accompanying drawings and embodiments, wherein:

[0053] Figure 1 This is a schematic diagram of an ultra-low flow rate measurement system according to an embodiment of the present invention;

[0054] Figure 2 This is a flowchart of a method for measuring ultra-low flow rates according to an embodiment of the present invention. Detailed Implementation

[0055] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0056] In the description of this invention, it should be understood that the orientation descriptions, such as up, down, front, back, left, right, etc., are based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting this invention.

[0057] In the description of this invention, "several" means one or more, "multiple" means two or more, "greater than," "less than," and "exceeding" are understood to exclude the stated number, while "above," "below," and "within" are understood to include the stated number. The use of "first" and "second" in the description is merely for distinguishing technical features and should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features, or implicitly indicating the order of the indicated technical features.

[0058] In the description of this invention, unless otherwise explicitly defined, terms such as "set up," "install," and "connect" should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in this invention in conjunction with the specific content of the technical solution.

[0059] In the description of this invention, the terms "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0060] Reference Figure 1 This invention provides an ultra-low flow rate measurement system, including a signal control unit, a voltage signal generation unit 110, a current detection unit 120, an electroadsorption electrode unit, a conductivity measurement unit 140, and a data processing unit 150. In this embodiment, the signal control unit can be a microcontroller, a mobile terminal, or a server, etc., which can receive test commands input by the target object and generate a first control signal according to the measurement commands. Specifically, the signal control unit can be wirelessly connected to each functional module. A voltage signal generating unit is used to generate a DC voltage according to a first control signal; an electroadsorption electrode unit includes several electrodes, including a positive electrode 131 and a negative electrode 132. The positive electrode is connected to the positive output terminal of the voltage signal generating unit, and the negative electrode is connected to the negative output terminal of the voltage signal generating unit. The positive and negative electrodes are used to adsorb charged particles in the fluid according to the DC voltage; a current detection unit is used to detect the current data of the electroadsorption process; a conductivity measuring unit is installed in the middle of the several electrodes to measure the conductivity change data and change time between the several electrodes. The conductivity change data is related to the change data of charged particles in the fluid; a data processing unit is used to calculate the flow rate of the fluid based on the current data, conductivity change data, and change time.

[0061] In this embodiment, the voltage signal generating unit converts DC power to the required electrode operating voltage using the DC-DC step-down principle and outputs it. The output voltage range can be controlled and adjusted by the signal control unit, ensuring an output DC voltage between 0.8V and 1.5V. In this embodiment, the positive terminal of the voltage signal generating unit is connected to the positive electroadsorption electrode, and the negative terminal is connected to the negative electroadsorption electrode. It is understood that the electroadsorption electrode unit can consist of several electrodes, which are paired to form positive and negative electroadsorption electrodes. Specifically, all electrodes can be metal electrodes. The thickness of the metal electrodes can range from 1mm to 10mm, and the diameter can range from 30mm to 100mm. During the test, the spacing between the electrodes in the tested fluid can range from 10mm to 100mm. During the test, the electrodes need to be placed in the tested fluid. When the electrodes are working, the voltage applied across them creates an electrostatic field between them. Influenced by this field, positively charged ions in the water attract and are adsorbed towards the negative electrode, while negatively charged ions attract and are adsorbed towards the positive electrode. Over time, more and more ions are adsorbed at the electrodes, increasing the conductivity. The conductivity of the liquid between the electroadsorption electrodes is typically several times, or even tens of times, higher than that of the liquid surrounding the electrodes. Therefore, this embodiment includes a conductivity measurement unit. This conductivity measurement unit is installed between two circular metal electrodes; one unit is used. If there are multiple pairs of electroadsorption electrodes, they are installed according to the number of pairs. Each pair of electroadsorption electrodes is equipped with a conductivity sensor. The conductivity sensor installed between the electroadsorption electrodes measures the conductivity of the liquid between them. When the electroadsorption electrodes are energized, charged particles in the liquid attract and are adsorbed towards the electrodes due to electrostatic adsorption. The more charged particles there are, the higher the conductivity.

[0062] In this embodiment, the operating current of the electrode is related to the number of charged particles in the fluid. Therefore, this embodiment uses a current detection unit to detect current changes during the electroadsorption process, and judges the adsorption strength and adsorption status by the operating current of the electroadsorption electrode. The larger the current, the stronger the adsorption effect, and the more conductive ions are adsorbed on the water surface of the electrode; the smaller the current, the weaker the adsorption, and the fewer conductive ions are adsorbed on the electrode surface. The change in current varies with the electrode's operating time.

[0063] It is understandable that, such as Figure 1As shown, the measurement system of this embodiment uses a fixing device to fix each detection component. Specifically, the fixing device includes a fixing rod 161 and a fixing frame 162; the first end of the fixing rod 161 is connected to the top of the fluid device 170, and the second end of the fixing rod 161 is connected to the fixing frame 162; the voltage signal generation unit, current detection unit, electroadsorption electrode unit, conductivity measurement unit, and data processing unit are all fixed on the fixing frame. After fixing each functional component, the system can be tested and calibrated before actual testing is performed. During the test, when the electrode adsorbs charged particles to saturation, the signal control unit of this embodiment will also generate a second control signal to control the positive electrode and the negative electrode to short-circuit and discharge, thereby realizing the automatic detachment of charged particles adsorbed on the electrode surface. The data processing unit analyzes the relationship between the changes in the working current and conductivity of the electroadsorption electrode and the diffusion of charged particles in the liquid through processes such as adsorption, saturation, power-off, and discharge, based on the collected working current and conductivity data. When a liquid is still, charged particles in the water are generally suspended and stationary, and the change in conductivity is small. When a liquid is flowing, charged particles in the liquid are active and will spread rapidly with the flow velocity of the liquid, resulting in a larger change in the measured conductivity value. The current liquid flow velocity can be calculated by measuring the change in conductivity in the liquid.

[0064] Specifically, in the testing process of this embodiment, after the hardware device is installed, it is necessary to calculate the coefficient of change of time and conductivity. This can be achieved by testing the ion adsorption function of the electroadsorption electrode in water with a fixed flow rate, while simultaneously monitoring the changes in the electrode's operating current, conductivity, and time. Once the operating current and conductivity reach preset or saturated values, the electrode power supply unit is disconnected, and the positive and negative electrodes are short-circuited to achieve discharge, allowing the ions adsorbed on the electrode surface to automatically detach. The detachment process data is acquired in real time by a conductivity sensor installed between the electrodes. The detachment time is related to the liquid flow rate; the higher the flow rate, the faster the detachment, and vice versa. The coefficient of change of time and conductivity is then calculated.

[0065] In this embodiment, the coefficient of variation is set to 0 before testing. During the test, the coefficient of variation is first calculated when the fluid velocity is 0. Specifically, the conductivity sequence values ​​corresponding to the static fluid when the fluid velocity is 0 are obtained. Then, obtain the conductivity sequence values ​​corresponding to the moment when the current reaches a constant value or a set value and the electroadsorption operation stops when the fluid flow rate is 0 during the test. And obtain the sampling interval S between these two conductivity sequence values. 1n Then, the coefficient of variation k0 when the fluid velocity is 0 is calculated using formula (1):

[0066]

[0067] Next, the coefficient of variation when the fluid velocity is a preset value Q is calculated. Specifically, the conductivity sequence values ​​corresponding to a stationary fluid with a fluid velocity of 0 are obtained. Then, obtain the conductivity sequence values ​​corresponding to the moment when the current reaches a constant value or a set value and the electroadsorption operation stops after the fluid flow rate is Q during the test. And obtain the sampling interval S between these two conductivity sequence values. 2n Then, the coefficient of variation k when the fluid velocity is Q is calculated using formula (2). Q :

[0068]

[0069] After calculating the coefficients of change k0 and k Q These two coefficients of variation are then applied to the measurement process of actual fluids. Specifically, the conductivity sequence values ​​corresponding to the moment when the conductivity of the tested fluid is at its highest under unknown flow velocity conditions are first obtained. Then, the conductivity sequence value corresponding to the moment when the current of the tested fluid reaches a constant value or a set value and the electroadsorption operation stops is obtained. And obtain the sampling interval S between these two conductivity sequence values. i Then, the coefficient of variation k of the tested fluid is calculated using formula (3). i :

[0070]

[0071] The coefficient of change k corresponding to the tested fluid is calculated. i Then, the flow velocity V of the tested fluid at the current time point can be calculated using formula (4):

[0072]

[0073] In summary, the embodiments of this application can use the DC voltage generated by the voltage signal generating unit to control the electro-adsorption electrode unit to adsorb charged particles in the fluid, and collect the current data of the electro-adsorption process through the current detection unit, and collect the conductivity change data and change time between the electrodes during the adsorption process through the conductivity measurement unit. Then, the data processing unit uses the current data, conductivity change data and change time to calculate the flow rate of the fluid. Thus, the measurement process of ultra-low flow can be realized by utilizing the relationship between the charged particles in the fluid and the change of the conductivity process, thereby improving the measurement accuracy of ultra-low flow rate.

[0074] Reference Figure 2 As shown, this embodiment of the invention provides a method for measuring ultra-low flow rates. Figure 2 The method shown is applied to Figure 1The system shown. Specifically, the method of this embodiment includes, but is not limited to, the following steps:

[0075] Step S210: Generate a first control signal according to the measurement command;

[0076] Step S220: Generate a DC voltage according to the first control signal;

[0077] Step S230: Control several electrodes to adsorb charged particles in the fluid according to the DC voltage;

[0078] Step S240: Obtain current data of the electroadsorption process, as well as conductivity change data and change time between several electrodes;

[0079] Step S250: Calculate the flow rate of the fluid based on the current data, conductivity change data, and change time.

[0080] In this embodiment, the flow rate can be calculated using formula (4):

[0081]

[0082] Where V represents the flow velocity;

[0083] In formula (4), k0 is calculated using formula (1):

[0084]

[0085] In formula (1), This represents a sequence of conductivity values ​​corresponding to a stationary liquid with a flow velocity of 0. This represents the conductivity sequence value corresponding to the moment when electroadsorption stops after the current reaches a constant value or a set value. (S) 1n express and The duration of the sampling interval between them;

[0086] In formula (4), k Q Calculated using formula (2):

[0087]

[0088] In formula (2), This represents the series of conductivity values ​​corresponding to a liquid with a flow rate of Q. This represents the conductivity sequence value corresponding to the moment when electroadsorption stops after the current reaches a constant value or a set value. (S) 1n express and The duration of the sampling interval between them;

[0089] In formula (4), k i Calculated using formula (3):

[0090]

[0091] In formula (3), This represents the conductivity sequence value corresponding to the moment when the conductivity is highest at an unknown flow velocity. This represents the conductivity sequence value corresponding to the moment when electroadsorption stops after the current reaches a constant value or a set value. (S) i express and The sampling interval duration between them.

[0092] The content of the system embodiments of the present invention is applicable to the method embodiments. The specific functions implemented by the method embodiments are the same as those of the above system embodiments, and the beneficial effects achieved are also the same as those achieved by the above system.

[0093] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments, and various changes can be made within the scope of knowledge possessed by those skilled in the art without departing from the spirit of the present invention. Furthermore, the embodiments of the present invention and the features thereof can be combined with each other unless otherwise specified.

Claims

1. A measurement system for ultra-low flow rates, characterized in that, include: A signal control unit, wherein the signal control unit is configured to generate a first control signal according to a measurement command; A voltage signal generating unit, wherein the voltage signal generating unit is configured to generate a DC voltage according to the first control signal; A current detection unit is used to detect current data during the electro-adsorption process; An electroadsorption electrode unit includes several electrodes, including a positive electrode and a negative electrode. The positive electrode is connected to the positive output terminal of the voltage signal generating unit, and the negative electrode is connected to the negative output terminal of the voltage signal generating unit. The positive electrode and the negative electrode are used to adsorb charged particles in the fluid according to the DC voltage. A conductivity measurement unit is installed in the middle of the plurality of electrodes and is used to measure the conductivity change data and change time between the plurality of electrodes. The conductivity change data is related to the change data of charged particles in the fluid. A data processing unit is configured to calculate the flow rate of the fluid based on the current data, the conductivity change data, and the change time.

2. The ultra-low flow rate measurement system according to claim 1, characterized in that, The measurement system also includes a fixing device, which includes a fixing rod and a fixing frame; The first end of the fixing rod is connected to the top of the fluid device, and the second end of the fixing rod is connected to the fixing frame; The voltage signal generating unit, the current detection unit, the electroadsorption electrode unit, the conductivity measuring unit, and the data processing unit are all fixed on the mounting frame.

3. The ultra-low flow rate measurement system according to claim 1, characterized in that, All of the electrodes include metal electrodes.

4. The ultra-low flow rate measurement system according to claim 3, characterized in that, The thickness of the metal electrode ranges from 1mm to 10mm, and the diameter ranges from 30mm to 100mm.

5. The ultra-low flow rate measurement system according to claim 3, characterized in that, The spacing between the electrodes in the fluid ranges from 10mm to 100mm.

6. The ultra-low flow rate measurement system according to claim 1, characterized in that, The range of the DC voltage includes 0.8V-1.5V.

7. The ultra-low flow rate measurement system according to claim 1, characterized in that, The signal control unit is also used to generate a second control signal, which is used to control the positive electrode and the negative electrode to short-circuit discharge.

8. The measurement system for ultra-low flow rates according to claim 1, characterized in that, The flow velocity of the fluid is calculated based on the current data, the conductivity change data, and the change time using the following formula: Where V represents the flow velocity; k0 is calculated using the following formula: This represents a sequence of conductivity values ​​for a stationary liquid with a flow velocity of 0. This represents the conductivity sequence value corresponding to the moment when electroadsorption stops after the current reaches a constant value or a set value. (S) 1n express and The duration of the sampling interval between them; k Q Calculated using the following formula: This represents the series of conductivity values ​​corresponding to a liquid with a flow rate of Q. This represents the conductivity sequence value corresponding to the moment when electroadsorption stops after the current reaches a constant value or a set value. (S) 1n express and The duration of the sampling interval between them; k i Calculated using the following formula: This represents the conductivity sequence value corresponding to the moment when the conductivity is highest at an unknown flow velocity. This represents the conductivity sequence value corresponding to the moment when electroadsorption stops after the current reaches a constant value or a set value. (S) i express and The sampling interval duration between them.

9. A method for measuring ultra-low flow rates, characterized in that, The method is applied to the system according to any one of claims 1-8, and the method includes the following steps: The first control signal is generated according to the measurement command; A DC voltage is generated based on the first control signal; The DC voltage controls the adsorption of charged particles in the fluid by several electrodes. Acquire current data of the electro-adsorption process, as well as conductivity change data and change time between the plurality of electrodes; The flow rate of the fluid is calculated based on the current data, the conductivity change data, and the change time.

10. The method for measuring ultra-low flow rates according to claim 9, characterized in that, The flow velocity of the fluid is calculated based on the current data, the conductivity change data, and the change time using the following formula: Where V represents the flow velocity; k0 is calculated using the following formula: This represents a sequence of conductivity values ​​for a stationary liquid with a flow velocity of 0. This represents the conductivity sequence value corresponding to the moment when electroadsorption stops after the current reaches a constant value or a set value. (S) 1n express and The duration of the sampling interval between them; k Q Calculated using the following formula: This represents the series of conductivity values ​​corresponding to a liquid with a flow rate of Q. This represents the conductivity sequence value corresponding to the moment when electroadsorption stops after the current reaches a constant value or a set value. (S) 1n express and The duration of the sampling interval between them; k i Calculated using the following formula: This represents the conductivity sequence value corresponding to the moment when the conductivity is highest at an unknown flow velocity. This represents the conductivity sequence value corresponding to the moment when electroadsorption stops after the current reaches a constant value or a set value. (S) i express and The sampling interval duration between them.

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