An apparatus for measuring the change in the electric charge of a fog droplet group in air

Abstract

The present invention provides a device for measuring the change in the charge quantity of a droplet swarm in air, which comprises an electrostatic nozzle, a motion module, a charge-mass collection module and a charge measurement module, and also includes an electrostatic nozzle fixing component, a speed measurement module and an electromagnetic shielding module. The motion module is used to adjust the distance between the charge-mass collection module and the charge measurement module and the electrostatic nozzle; the charge-mass collection module includes a metal baffle for collecting charged droplets and a droplet container for receiving the droplet swarm. The surface of the metal baffle is smooth and coated with a conductive superhydrophobic material, which can enable the droplet swarm to quickly slide down through a liquid flowmeter into the droplet container. The charge measurement module is used to measure the charge quantity released after the charged droplet swarm contacts the metal baffle. The device of the present invention uses the charge collection module to discretely and periodically measure the droplet swarm, and obtains the change rule of the charge quantity of the droplet swarm during the movement process.

Description

Technical Field

[0001] The present invention belongs to the field of charge measurement, and particularly relates to a device for measuring the change in the electric charge of a droplet swarm in the air. Background Art

[0002] As an environmentally friendly spraying technology, electrostatic spraying technology plays an important role in the field of plant protection. The charge amount of a droplet swarm is an important indicator to verify the effectiveness of electrostatic spraying. When the droplet swarm flies a certain distance in the air after passing through the charging element, due to the presence of ions and free electrons in the air, the charge amount of the droplet swarm decreases, but there is still a lack of measurement equipment for the decreasing law.

[0003] There are mainly two problems in measuring the change in the charge amount of a droplet swarm during movement. First, it is difficult to directly measure the charge change of the droplet swarm. Second, the instruments using indirect measurement methods are expensive and difficult to measure droplets with larger particle sizes. The existing methods and equipment in related technologies include: Faraday cup method, mesh target method, electrical mobility analyzer, and single-particle aerosol relaxation time analyzer. Summary of the Invention

[0004] Aiming at the technical problem of measuring the change in the charge amount during the flight of a droplet swarm, the present invention provides a measuring device composed of standard and inexpensive equipment, which can be used to measure the change in the electric charge of a droplet swarm in the air.

[0005] The technical solution of the present invention is as follows:

[0006] A device for measuring the change in the electric charge of a droplet swarm after flying different distances in the air, characterized by comprising an electrostatic spray head, a motion module, a charge-mass collection module, and a charge measurement module;

[0007] The motion module is used to adjust the distance between the charge-mass collection module and the charge measurement module and the electrostatic spray head. The charge-mass collection module and the charge measurement module are fixedly connected to the slider of the motion module and can move left and right along the guide rail following the slider;

[0008] In a possible implementation manner, the motion module includes: a clamping assembly, a slider, a guide rail, and a slider fixing element;

[0009] The slider and the guide rail are used to adjust the distance between the charge-mass collection module and the charge measurement module and the electrostatic spray head, and manually move the slider to the next specified distance during the next measurement. The specified distance is determined by the distance between the metal baffle of the charge-mass collection module and the electrostatic spray head;

[0010] The guide rail is provided with a scale for precisely adjusting the distance between the charge-mass collection module and the electrostatic spray head;

[0011] A clamping component is provided on the slider. The clamping component is used to clamp the charge-mass collection module and the charge measurement module. The slider is manually adjusted to drive the movement of the clamping component, the charge-mass collection module, and the charge measurement module. Among them, the material of the clamping component is an insulating material.

[0012] The slider fixing element is used to fix the slider after determining the distance between the charge-mass collection module and the electrostatic spray head, so that the charge-mass collection module and the electrostatic spray head maintain a fixed spacing.

[0013] The charge-mass collection module includes a metal baffle for collecting charged droplets, a droplet group diversion tube for diverting the droplet group to a droplet container, and a droplet container for receiving the droplet group. The surface of the metal baffle is smooth and coated with a conductive superhydrophobic material, which can make the droplet group quickly slide down into the droplet container through the droplet group diversion tube;

[0014] The charge measurement module includes a calculation and analysis device and a current measurement device, and uses a 'Z-shaped' cantilever beam as a bracket to connect to the slider. The calculation and analysis device and the current measurement device are fixed at one end of the 'Z-shaped' cantilever beam, and the other end of the 'Z-shaped' cantilever beam is fixedly connected to the slider.

[0015] The charge measurement module is used to measure the amount of charge released after the charged droplet group contacts the metal baffle. The metal baffle is connected to the current measurement device with the shell grounded through a wire to form a circuit, and the current intensity value I (A) of the circuit is obtained;

[0016] In a possible implementation, the motion module further includes:

[0017] An electrostatic spray head fixing component for fixedly connecting the electrostatic spray head to the guide rail.

[0018] In a possible implementation, the device further includes:

[0019] A speed measurement module for measuring the speed of the droplets reaching the charge-mass collection module;

[0020] In a possible implementation, the device further includes:

[0021] An electromagnetic shielding module for shielding the interference of external electromagnetic fields on the charge measurement module and the wires, and reducing the influence of electromagnetic fields on microcurrents.

[0022] In a possible implementation, the electromagnetic shielding module includes a circuit board shielding component and a shielding wire. The circuit board shielding component is used to shield the interference of external electromagnetic fields on the current measurement device, and the circuit board shielding component is made of a metal material; the shielding wire is used to reduce the electromagnetic interference of the electromagnetic field on the wire, especially the connection between the metal baffle and the current measurement device.

[0023] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. The measurement device of the present invention adopts a discrete method, using charge collection elements to discretely measure the droplet group at regular intervals, and obtaining the change law of the electric charge amount of the droplet group during the movement process. 2. Compared with the commonly used direct measurement method, not only can the charge-to-mass ratio of the droplet group be obtained, but also the electric charge amount of the droplet group at different distances can be measured. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 is the front view of the structural schematic diagram of the charge measurement device;

[0025] Figure 2 is the left view of the structural schematic diagram of the charge measurement device;

[0026] Figure 3 is the connection schematic diagram of the measurement part.

[0027] Figure 4 is the curve graph of the change of the electric charge amount of the droplet group measured by the charge measurement device. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0028] The device of the present invention will be further described below in conjunction with the drawings and specific embodiments.

[0029] As Figure 1-2 shown, a device for measuring the change of the electric charge amount of a droplet group in the air includes an electrostatic nozzle 1, a motion module 200, a charge-mass collection module 100, a charge measurement module 300, and a droplet container 5.

[0030] The charge-mass collection module 100 includes a metal baffle 2 and a droplet group drainage tube 4. The metal baffle 2 is connected to the current measurement device 11 of the charge measurement module 300 through a shielded wire. The charge measurement module 300 can measure the microcurrent flowing through the metal baffle 2. The droplet group drainage tube 4 is adhesively connected to the metal baffle 2. The droplet container 5 is located at the bottom of the metal baffle 2 of the charge-mass collection module 100. The droplet group drainage tube 4 is used to drain the droplet group on the metal baffle 2 into the droplet container 5 and calculate the flow mass per unit time.

[0031] Among them, the shape of the metal baffle 2 can be circular, rectangular, rhombic, etc. The area of the metal baffle 2 needs to be larger than the distribution area of the droplet group to ensure that the metal baffle 2 can collect all the electrostatic droplets. It should be understood that the present disclosure does not specifically limit the size of the metal baffle, as long as the measurement requirements can be ensured.

[0032] Among them, the material of the metal baffle should be conducive to the conduction of current and have a small current loss, such as metals such as copper and aluminum. The present disclosure does not limit this.

[0033] The motion module 200 is used to adjust the distance between the charge-mass collection module 100 and the charge measurement module 300 and the electrostatic nozzle 1, and the motion direction is to move left and right along the guide rail 8.

[0034] The charge measurement module 300 is used to measure the charge released on the metal baffle 2 after the droplet group contacts the metal baffle 2. The microcurrent flows from the metal baffle through the shielded wire through the current measurement device 11 and finally to the ground. In this process, the current measurement device 11 can measure the microcurrent and the calculation and analysis device 10 can calculate the charge quantity. The charge measurement module 300 measures, records and calculates the current conducted by the charge-mass collection module 100.

[0035] Among them, as Figure 1 shown, the charge measurement module 300 includes a calculation and analysis device 10 and a current measurement device 11. The current measurement device 11 is used to measure the current value generated by the charge released by the metal plate 2 in the charge-mass collection module 100 due to intercepting the charged droplet group. The current measurement device 11 can be an instrument with high sensitivity and good accuracy such as an electrometer or a picoammeter. The present disclosure does not limit this. As Figure 3 , the current measurement device 11 is connected to the metal baffle 2 through a shielded wire. The calculation and analysis device 10 is used to calculate the charge quantity according to the current value and the droplet mass flow rate, and can be a storage and control terminal such as a computer or a single-chip microcomputer. The present disclosure does not limit this.

[0036] In this embodiment, after the charge measurement module 300 determines the current conducted by the collected droplets, the charge-to-mass ratio of the droplet group can be calculated according to the following formula (1).

[0037]

[0038] Among them, I is the average value of the current on the charge measurement module 300, μA; L is the average mass flow rate of the liquid captured by the droplet group drainage pipe 4, g / s.

[0039] In this embodiment, relevant settings can be made for the measurement time in advance, which can include setting the start time and end time of determining the charge quantity detection, the start time and end time of the electrostatic nozzle starting to spray, the detection end condition, etc.

[0040] Among them, the way to determine the start time is various. For example, the charge-mass collection module 100 starts the charge quantity detection after capturing the droplet group. Or, a button or control can be set in the device. When the charge-mass collection module 100 detects the droplets and the button or control is triggered, the charge quantity detection starts. Among them, the button can be implemented by hardware set in the device, and the control can be displayed in the corresponding display interface through the software in the device for the user to operate.

[0041] The charge detection end time and the spray end time are diverse. For example, the charge-mass collection module 100 ends the charge quantity detection after the electrostatic spray head 1 finishes spraying. Alternatively, buttons or controls can be set in the device, and when the electrostatic spray head finishes spraying and the buttons or controls are triggered, the charge quantity detection ends.

[0042] The detection end conditions can include: the measurement time of the charge measurement module is greater than the time when the current appears stable, the time for the droplet group collector to collect the liquid is greater than the time that causes a large mass measurement error, etc. In this way, the accuracy of current measurement and the accuracy of the collected liquid mass measurement can be ensured. Those skilled in the art can set the detection end conditions according to actual needs, and the present disclosure does not limit this.

[0043] In a possible implementation manner, the motion module 200 can include a clamping assembly 6, a slider 7, a guide rail 8, and a slider fixing element 9. The slider 7 and the guide rail 8 are used to adjust the distance between the measurement device and the electrostatic spray head 1. By manually adjusting the position of the slider and obtaining the precise required distance through a scale, the distance is determined by the distance between the plane of the metal baffle 2 near the electrostatic spray head side in the charge-mass collection module 100 and the electrostatic spray head 1. The guide rail 8 is provided with a scale for determining the distance between the plane of the metal baffle 2 near the electrostatic spray head side and the electrostatic spray head 1. The clamping assembly 6 is arranged on the slider 7, and the clamping assembly 6 is used to clamp the charge-mass collection module 100. Manually adjust the slider 7 to drive the clamping assembly 6, the charge-mass collection module 100, and the charge measurement module 300 to move. The slider fixing element 9 is used to fix the slider after determining the distance between the charge-mass collection module 100 and the electrostatic spray head 1 to prevent inaccurate distance caused by movement.

[0044] Among them, the slider fixing element 9 can fix the position of the slider through fasteners such as bolts, studs, and screws. The present disclosure does not limit this.

[0045] The clamping assembly 6 can firmly clamp the charge-mass collection module 100. The size of the object that the clamping assembly can clamp matches the size of the charge-mass collection module 100 to ensure that the charge-mass collection module 100 is firmly clamped. Those skilled in the art can set the size of the clamping assembly according to actual needs, and the present disclosure does not limit this here. The material of the clamping assembly is an insulating material to avoid charge leakage on the metal baffle 2 in the charge-mass collection module 100 and ensure the accuracy of charge quantity measurement.

[0046] In a possible implementation manner, the device can further include an electrostatic spray head fixing component 0 for connecting the device with the electrostatic spray head 1 together to prevent relative movement of the electrostatic spray head during measurement from affecting the result of droplet group charge quantity measurement.

[0047] The fixed position of the electrostatic nozzle can be, for example, Figure 1 as shown, on the same horizontal line as the center of the charge-mass collection module 100. In this way, a large amount of the to-be-measured droplet group can be ensured to deposit on the charge-mass collection module 100. The fixing component of the electrostatic nozzle can also be higher than the center of the charge-mass collection module. In this way, the mass loss caused by the gravity of the droplets can be reduced, and the amount of collected droplets can be increased. Those skilled in the art can set the relative position between the electrostatic nozzle and the charge-mass collection module 100 according to actual needs to ensure that the droplets can deposit on the metal baffle 2. The present disclosure does not limit this.

[0048] The slider fixing element 9 can connect the charge-mass collection module 100 to the guide rail through detachable connection methods such as threaded connection, key connection, and pin connection. The present disclosure does not limit this.

[0049] In a possible implementation manner, as Figure 1 shown, the device may further include a speed measurement module 3. The speed measurement module 3 is installed above the droplet group diversion tube 4 through a bayonet for measuring the movement speed of the droplet group.

[0050] In this implementation manner, the speed measurement module 3 can measure in a point measurement manner, such as a hot wire anemometer, a laser Doppler velocimeter, a phase Doppler particle analyzer, etc. The present disclosure does not limit this.

[0051] In this embodiment, the charge measurement module 300 can further calculate the change in the droplet charge according to the change in the charge-to-mass ratio λ. Assuming that the charge-to-mass ratio of the droplet group remains unchanged at a certain distance, the velocity-distance curve of the droplet movement is obtained according to the distance between the charge-mass collection module 100 and the electrostatic nozzle 1 and the velocity of the droplet reaching the charge-mass collection module, and the time-distance curve of the droplet movement is obtained through integral conversion. According to the charge measurement data of different spacings between the charge-mass collection module 100 and the electrostatic nozzle 1 and the droplet movement time, the law of charge change is obtained.

[0052] In a possible implementation manner, the device may further include an electromagnetic shielding module for shielding the external electromagnetic field to avoid interference with the measurement results.

[0053] In a possible implementation manner, the electromagnetic shielding module may include a circuit board shielding component and a shielding wire for shielding the interference of the external electromagnetic field on the measurement and calculation circuits.

[0054] In this implementation manner, the circuit board shielding component can be an instrument with good shielding performance and simplicity and convenience, such as a shielding box or a shielding cover. No specific limitation is made here. The material of the circuit board shielding component can be a metal material, such as metals like iron and aluminum. No specific limitation is made here.

[0055] In a possible implementation, the electromagnetic shielding module may further include shielded wires for shielding the interference of external electromagnetic fields on the transmission of microcurrents by wires.

[0056] In this implementation, the shielded wires may be an outer shielding layer and an inner shielding layer on the inner core of the wire, which can avoid the influence of the external electromagnetic environment on the microcurrent.

[0057] Application Example

[0058] The following presents an application example according to the embodiments of the present disclosure in combination with an exemplary application scenario to facilitate the understanding of the measurement of the change in the amount of electric charge using the charge measurement device. Those skilled in the art should understand that the following application examples are merely for the purpose of facilitating the understanding of the embodiments of the present disclosure and should not be regarded as a limitation on the embodiments of the present disclosure.

[0059] The environmental temperature of this experiment is 18°C, the humidity is 60%, the charge-mass collection module uses aluminum as the material of the metal baffle, the shape is a rectangular plate, the size is 600mm×400mm×2mm, and the medium of the spray system is distilled water. The process of the experiment based on the charge amount change measurement device provided by the present disclosure is as follows:

[0060] Install the sector electrostatic spray head (80-01) on the electrostatic spray head fixing component; the installation height of the electrostatic spray head is at the same height as the center of the metal baffle and the electrostatic spray head faces the plane of the metal baffle, the test spray pressure is 0.3MPa, and the output voltage of the high-voltage electrostatic generator is 6kV; before the test starts, manually adjust the slider to the specified position and fix it with the slider fixing element. The specified positions include different distances (0.3, 0.5, 0.7, 0.9, 1.0, 1.3, 1.6, 2.0, 2.4, 2.8, 3.2, and 3.6m) between the metal baffle of the charge-mass collection module and the electrostatic spray head; after the system starts working, when the charge-mass collection module detects a microcurrent, stop after continuing for 30s; read the current value measured by the current measurement device, weigh the mass of the liquid in the droplet container, and calculate the average charge-to-mass ratio.

[0061] While the charge measurement module is performing the measurement, the speed measurement module measures and records the droplet movement speed; each measurement value is stored in the hard disk of the calculation and analysis device.

[0062] Subsequently, the change in the amount of electric charge of the droplets in the air is obtained according to the correspondence between the distance between the electrostatic spray head and the charge-mass collection module, the speed of the droplets reaching the charge-mass collection module, and the charge-to-mass ratio measured by the charge measurement module. It should be noted that when conducting the experiment again, the charge carried by the metal baffle needs to be completely released.

[0063] Figure 4It shows the variation of the electric charge with the distance (velocity × time) measured at different droplet movement velocities and movement times according to the embodiments of the present disclosure. The attenuation curves of the electric charge at different droplet group velocities are obtained. This provides assistance for further improving the droplet charging performance and designing excellent electrostatic nozzles.

[0064] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be within the protection scope of the present invention.

Claims

1. A device for measuring the change in the electric charge of a droplet group in air, characterized in that It includes an electrostatic spray head, a motion module, a charge-mass collection module, and a charge measurement module; The motion module is used to adjust the distance between the charge-mass collection module and the charge measurement module and the electrostatic spray head; The charge-mass collection module includes a metal baffle for collecting charged droplets, a droplet group diversion tube for diverting the droplet group to a droplet container, and a droplet container for receiving the droplet group; The surface of the metal baffle is smooth and coated with a conductive superhydrophobic material, which can enable the droplet group to quickly slide down through the droplet group diversion tube into the droplet container; The charge measurement module includes a calculation and analysis device and a current measurement device, and uses a 'Z-shaped' cantilever beam as a bracket to be connected to the motion module; the calculation and analysis device and the current measurement device are fixed at one end of the 'Z-shaped' cantilever beam, and the other end of the 'Z-shaped' cantilever beam is fixedly connected to the slider; The charge measurement module is used to measure the amount of charge released after the charged droplet group contacts the metal baffle. The metal baffle is connected to the current measurement device with the shell grounded through a wire to form a circuit, and the current intensity value I (A) of the circuit is obtained.

2. The device for measuring the change in the electric charge of a droplet swarm in air according to claim 1, wherein The motion module includes a clamping assembly, a slider, a guide rail, and a slider fixing element; The slider and the guide rail are used to adjust the distance between the charge-mass collection module and the charge measurement module and the electrostatic spray head, and manually move the slider to the next specified distance during the next measurement. The specified distance is determined by the distance between the metal baffle of the charge-mass collection module and the electrostatic spray head; The guide rail is provided with a scale for precisely adjusting the distance between the charge-mass collection module and the electrostatic spray head; The slider is provided with a clamping assembly. The clamping assembly is used to clamp the charge-mass collection module and the charge measurement module, and manually adjust the slider to drive the movement of the clamping assembly, the charge-mass collection module, and the charge measurement module. Among them, the material of the clamping assembly is an insulating material; The slider fixing element is used to fix the slider after determining the distance between the charge-mass collection module and the electrostatic spray head, so that the charge-mass collection module and the electrostatic spray head maintain a fixed distance.

3. The device according to claim 2, characterized in that The motion module further includes an electrostatic spray head fixing component for fixedly connecting the electrostatic spray head and the guide rail together.

4. The device according to claim 1, characterized in that, The device further includes a speed measurement module, which is installed above the droplet group diversion tube through a bayonet for measuring the speed of the droplets reaching the charge-mass collection module.

5. The device according to claim 1, wherein The device further includes an electromagnetic shielding module for shielding the interference of external electromagnetic fields on the charge measurement module and the wires, and reducing the influence of the electromagnetic field on the microcurrent.

6. The device according to claim 5, wherein The electromagnetic shielding module includes a circuit board shielding component and a shielding wire. The circuit board shielding component is used to shield the interference of external electromagnetic fields on the current measurement device, and the circuit board shielding component is made of a metal material; the shielding wire is used to reduce the electromagnetic interference of the electromagnetic field on the wires, especially the connection between the metal baffle and the current measurement device.

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