CN115025690B - Monodisperse ultrafine particle stable generation device and method based on double closed-loop control - Google Patents
Monodisperse ultrafine particle stable generation device and method based on double closed-loop control Download PDFInfo
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- B01F35/7179—Feed mechanisms characterised by the means for feeding the components to the mixer using sprayers, nozzles or jets
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- B01J13/0095—Preparation of aerosols
Abstract
The device comprises an electrospray module and a double closed-loop control system, wherein the electrospray module mainly comprises a microsyringe, a capillary spray needle, a high-voltage polar plate and a soft X-ray neutralizer, and the double closed-loop control system comprises a current acquisition module, an image module, a high-voltage regulation module and a logic operation module. The invention aims at controlling the working current of the electrospray module to be stabilized at a certain set value, the control system can collect and process the working current of the electrospray module and the image of the liquid drop at the tip of the capillary spray needle, the measured value of the current and the image signal are used as feedback quantity of the control system, and the working state of the electrospray module is adjusted through the high-voltage adjusting module after being calculated by the control system so as to adjust the working current of the electrospray module. The generated current is easy to be influenced by external factors, and the device can monitor and maintain the stable operation of the electrospray module so as to stably generate monodisperse ultrafine particles.
Description
Technical Field
The invention relates to the technical field of aerosol science, in particular to a device and a method for generating monodisperse ultrafine particulate matters stably based on double closed loop control.
Background
In the field of aerosol science, monodisperse aerosols with adjustable particle size and composition are generally produced by means of electrospray techniques. On one hand, the method can provide a sample for further researching physical and chemical properties of aerosol with specific particle size and specific components, such as suction type growth characteristic research; on the other hand, high concentration monodisperse aerosol samples are also an important component in the calibration system of aerosol measurement instruments. In addition, electrospray has wide application in fuel atomization, thin film deposition, electrospray ionization mass spectrometry, and drug development.
In general, electrospray operation current stabilization is an indicator of stable electrospray operation and the amount of charge generated on the resulting droplets. The operating current and the operating state of electrospray are determined by many factors, such as the physical properties of the spray solution (i.e., conductivity, surface tension, viscosity, etc.), the rate of spray solution introduction, the spray voltage, the distance between the capillary outlet and the high voltage electrode, etc. In addition to the above factors, the stability of electrospray operation and the amount of particulate matter produced may be affected by unexpected factors such as drift in spray solution conductivity due to temperature, the presence of bubbles in the spray solution, and the like. Therefore, electrospray inevitably undergoes current drift during long-term operation, requiring the addition of closed-loop control over the operating current in the electrospray system. In order to keep stable in long-term operation in the spraying process, the invention introduces a new feedback quantity into the control system, and the shape of the liquid drop at the tip of the capillary spray nozzle is improved to improve the stability of the control system, assist the current control of electrospray and stably generate monodisperse ultrafine particles for a long time.
Disclosure of Invention
The monodisperse ultrafine particle stable generation device based on double closed loop control can solve the technical problems and realize long-term stable generation of monodisperse ultrafine particles.
In order to achieve the above purpose, the present invention adopts the following technical scheme:
the monodisperse ultrafine particle stable generation device based on double closed-loop control comprises an electrospray module and a double closed-loop control system, wherein the double closed-loop control system comprises an electrospray module, a current measurement module, an image acquisition module, a high-voltage module and a logic operation module;
the electrospray module comprises a microsyringe, a spray cavity, a capillary spray needle, an air and carbon dioxide inlet, a high-voltage electrode and a soft X-ray neutralizer; the microsyringe is connected with the capillary spray needle through a 1/32' pipe; the air inlet and the carbon dioxide inlet penetrate through the spray cavity and ensure the air tightness between the air inlet and the spray cavity; the high-voltage electrode is arranged on the surface of the capillary spray needle and is not contacted with the capillary spray needle; the soft X-ray neutralizer is arranged outside the spray cavity;
the current measurement module comprises a current-voltage conversion circuit, a voltage follower and an analog-digital signal converter; the current-voltage conversion circuit comprises a conversion resistor and a filter capacitor, wherein one end of the parallel connection circuit is connected to the capillary spray needle through a lead, and the other end of the parallel connection circuit is grounded; the voltage follower is composed of an operational amplifier, the input end of the voltage follower is connected to the capillary spray needle through a wire, and the output end of the voltage follower is connected to the input end of the analog-digital signal converter through a wire; the output end of the analog-digital signal converter is connected to the logic operation module through a wire;
the image acquisition module comprises a CCD camera-micro lens and programmable array logic; the CCD camera-micro lens is arranged outside the spray cavity, and the digital signal output end of the CCD camera is connected to the programmable array logic through a wire; the programmable array logic is connected to the logic operation module through a serial port line;
the high-voltage module comprises a digital-analog signal converter and a high-voltage source; the input end of the digital-analog signal converter is connected with the logic operation module through a wire, and the output end of the digital-analog signal converter is connected to the input end of the high-voltage source through a wire; the output end of the high-voltage source is connected to the high-voltage electrode through a high-voltage resistant wire.
Furthermore, the material of the spray cavity in the single-capillary needle electrospray module is organic glass.
Further, the logic operation module comprises a singlechip.
Further, the electrospray module further comprises a metal protective shell which is arranged opposite to the soft X-ray neutralizer and used for preventing soft X-rays from leaking.
On the other hand, the invention also comprises a method for generating the stable monodisperse ultrafine particulate matters based on the double closed-loop control system, which is characterized by comprising the following steps of:
when no voltage is applied to the high-voltage electrode, the microsyringe conveys the solution with conductivity into the spray cavity through the capillary spray needle at a set speed, the solution is blown away by air and carbon dioxide to form small liquid drops, and the small liquid drops leave the spray cavity after passing through the soft X-ray irradiation area along with the air flow; the voltage on the high-voltage electrode is controlled by a high-voltage module, and as the voltage on the high-voltage electrode gradually rises to a set range, the solution leaves the capillary needle in a conical jet mode to form charged liquid drops with uniform size; the charged liquid drops enter a soft X-ray irradiation area along with the airflow, the charged quantity is neutralized, the liquid drop solution volatilizes in the flying process, and the residual solute forms electrically neutral monodisperse particles.
Further, the top end of the capillary spray needle and the shape of the liquid drop at the top end are shot by a CCD camera-micro lens, and the image is transmitted to the FPGA in the form of digital signals so as to judge whether conical jet flow is formed or not; if the jet flow is conical, the FPGA calculates the vertex angle of the conical jet flow and then transmits the vertex angle to the logic operation module.
In still another aspect, the invention discloses a method for generating stable monodisperse ultrafine particles based on a double closed-loop control system, which adopts the monodisperse ultrafine particle stable generating device based on double closed-loop control and comprises the following steps:
s1, manually setting air inlet flow of clean air and carbon dioxide, manually setting sample injection flow of solution to be generated, automatically and linearly increasing voltage by a logic operation module, continuously judging whether an electrospray module works in a conical jet mode, stopping high-voltage change to stabilize working current and droplet shape if the electrospray module works in the conical jet mode, setting target current, and entering double closed-loop control to maintain the working current of the electrospray module stable;
s2, the original color RGB image obtained by the image acquisition module contains complete liquid drops; the color RGB image is subjected to monochromatic gray level conversion and binarization treatment to obtain a black-and-white image, and then is subjected to Sobel edge detection algorithm treatment to obtain the capillary nozzle tip-liquid drop contour; the FPGA analyzes the contour shape to judge whether the electrospray module works in a conical jet flow mode, if so, the shape of the liquid drop is quantized through the contour, and the vertex angle of the conical liquid drop is calculated and transmitted to the logic operation module for further calculation;
s3, the logic operation module comprises two input signals: the electrospray working current obtained by the current measurement module and the liquid drop profile obtained by the image acquisition module; the logic operation module comprises an output signal: a voltage regulation command sent to the high-voltage module; the double closed-loop control system realized by the logic operation module changes output voltage by calculating and analyzing two input signals so as to adjust working current of electrospray to target current, thus realizing stable operation of electrospray;
s4, the logic operation module performs difference between the target current and the working current measured value to perform outer loop proportional-integral-derivative operation; the operation result is converted into a droplet shape target, and the droplet shape target is differenced with the droplet shape measurement value to perform inner loop PID operation; the operation result is converted into a voltage regulation instruction and then applied to the high-voltage electrode; after double closed-loop control, the current of the electrospray module is converged to a set value, and monodisperse ultrafine particles are stably generated.
The double closed-loop control system disclosed by the invention aims to control the working current of the electrospray module to be stabilized at a certain set value (the current stabilization is a main sign that the electrospray module stably generates monodisperse ultrafine particles). The control system can acquire and process the working current of the electrospray module and the image of the liquid drop at the tip of the capillary spray nozzle, takes the current measured value and the image signal as the feedback quantity of the control system, and adjusts the working state of the electrospray module through the high-voltage adjusting module after being calculated by the control system so as to adjust the working current of the electrospray module. In long-time operation, the generated current is easily interfered by external factors such as air pressure and temperature, and the device can monitor and maintain the stable operation of the electrospray module so as to stably generate monodisperse ultrafine particles.
Compared with the prior art, the invention has the following beneficial effects:
(1) The double closed-loop control system provided by the invention realizes control of the electrospray working current, and solves the problem that the current is easy to change in long-time operation of electrospray so as to influence the quality of generated particles.
(2) The double closed-loop control system introduces a new feedback quantity: the capillary spray tip solution shape. In the high-frequency voltage change, the control system disclosed by the invention takes the shape of the capillary nozzle tip solution with good open-loop characteristics as a control target, so that the stability of the control system is improved.
(3) The monodisperse particle generation method can realize automatic starting of an electrospray system, automatic adjustment of a conical jet flow mode and automatic control of working current, and simplifies the operation of the electrospray system.
Drawings
FIG. 1 is a schematic diagram of a particle generating apparatus and its control system according to the present invention;
FIG. 2 is a schematic view of a capillary needle tip and a conical jet enlarged;
FIG. 3 is a control system block diagram;
FIG. 4 is a start-up flow of a monodisperse ultra-fine particle generating apparatus;
wherein: A. single capillary needle electrospray module, B, current measurement module, C, image acquisition module, D, high voltage module, E, logic operation module, F, capillary needle tip, G, droplet shape schematic diagram, 1, microsyringe, 2, spray cavity, 3, capillary needle, 4, air inlet, 5, carbon dioxide inlet, 6, high voltage electrode, 7, soft X-ray neutralizer, 8, metal protective shell, 9, converting resistor, 10, filter capacitor, 11, voltage follower, 12, analog-digital signal converter, 13, CCD camera-microscope (. Times.300), 14, programmable array logic (FPGA), 15, digital-analog signal converter, 16, high voltage source, 17, singlechip (STM 32F103RCT 6).
Detailed Description
For the purpose of making the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is apparent that the described embodiments are some embodiments of the present invention, but not all embodiments of the present invention.
As shown in fig. 1, the monodisperse ultrafine particulate matter stability generating device based on double closed-loop control in this embodiment includes a single capillary needle electrospray module a, a current measuring module B, an image acquisition module C, a high-voltage module D, and a logic operation module E;
the single capillary needle electrospray module A comprises a microsyringe 1, a spray cavity 2, a capillary needle 3, an air inlet 4, a carbon dioxide inlet 5, a high-voltage electrode 6, a soft X-ray neutralizer 7 and a metal protective shell 8; the microsyringe is connected with the capillary needle 3 through a 1/32' pipe; the capillary spray needle 3 penetrates through the spray cavity 2 and ensures air tightness between the capillary spray needle and the spray cavity 2; the air inlet 4 and the carbon dioxide inlet 5 penetrate through the spray cavity 2 and ensure the air tightness between the spray cavity 2 and the air inlet; the high-voltage electrode 6 is arranged opposite to the capillary needle 3 and is not contacted with the capillary needle 3; the soft X-ray neutralizer 7 is arranged outside the spray cavity 2; a metal protective shell 8 is arranged opposite to the soft X-ray neutralizer 7;
the current measurement module B comprises a current-voltage conversion circuit (composed of a conversion resistor 9 and a filter capacitor 10), a voltage follower 11 and an analog-digital signal converter 12; the current-voltage conversion circuit comprises a conversion resistor 9 and a filter capacitor 10, wherein one end of the parallel connection is connected to the capillary needle 3 through a lead, and the other end of the parallel connection is grounded; the voltage follower 11 is composed of an operational amplifier, the input end of the voltage follower 11 is connected to the capillary needle 3 through a wire, and the output end is connected to the input end of the analog-digital signal converter 12 through a wire; the output end of the analog-digital signal converter 12 is connected to the logic operation module E through a wire;
the image acquisition module C comprises a CCD camera-micro lens (multiplied by 300) 13 and a programmable array logic (FPGA) 14; a CCD camera-micro lens (x 300) 13 is arranged outside the spray cavity 2, and the digital signal output of the CCD camera 13 is connected to an FPGA (14) through a wire; the FPGA (14) is connected to the logic operation module E through a serial port line;
the high voltage module D comprises a digital-analog signal converter 15 and a high voltage source 16; the input end of the digital-analog signal converter 15 is connected with the logic operation module E through a wire, and the output end is connected with the input end of the high-voltage source 16 through a wire; the output end of the high voltage source 16 is connected to the high voltage electrode 6 through a high voltage resistant wire;
the logic operation module is composed of a single chip microcomputer (STM 32F103RCT 6) 17;
in the monodisperse ultrafine particle stable generation device based on double closed loop control, when no voltage is applied to a high-voltage electrode 6, a solution (containing solute) with certain conductivity is conveyed into a spray cavity 2 through a capillary needle 3 at a certain speed by a microsyringe 1, and the solution is blown away by air and carbon dioxide (introduced by 4 and 5) to form small liquid drops, and then leaves the spray cavity 2 after passing through a soft X-ray irradiation area (provided by 7) along with air flow; the voltage on the high-voltage electrode 6 is controlled by the high-voltage module D, and as the voltage on the high-voltage electrode 6 is gradually increased to a certain range, the solution leaves the capillary needle 3 in a conical jet mode to form charged liquid drops with uniform size; the charged liquid drops enter a soft X-ray irradiation area (provided by 7) along with the air flow, then the charged quantity is neutralized, the liquid drop solution volatilizes in the flying process, and the residual solute forms electrically neutral monodisperse particles;
the monodisperse ultrafine particulate matter stable generating device based on double closed loop control is characterized in that the top end of a capillary spray needle 3 and the shape of liquid drops at the top end are shot by a CCD camera-micro lens (x 300) 13, and an image is transmitted to an FPGA (14) in a digital signal form to judge whether conical jet flow is formed or not; if the jet flow is conical, the FPGA (14) calculates the vertex angle of the conical jet flow and then transmits the vertex angle to the logic operation module E;
the capillary needle 3 of the monodisperse ultrafine particulate matter stable generating device based on double closed-loop control is connected to the current measuring module B through a lead; the current signal is converted into a voltage signal after passing through a current-voltage conversion circuit (composed of 9 and 10); in order to prevent the leakage current from affecting the measurement accuracy, the voltage signal is converted by the voltage follower 11 and then enters the analog-digital signal converter 12; the analog-to-digital signal converter 12 transmits the current value converted into the digital signal to the logic operation module E;
the logic operation module E of the monodisperse ultrafine particulate matter stable generation device based on double closed loop control sends a command to the high-voltage module D to be a digital signal; the instruction is converted into an analog signal by a digital-analog signal converter 15 and then transmitted to a high voltage source 16, and the high voltage source 16 supplies high voltage to the high voltage electrode 6;
the material of the spray cavity 2 in the single capillary needle electrospray module A of the single-dispersion ultra-fine particulate matter stable generation device based on double closed-loop control is organic glass; the function of the metallic protective shell 8 mounted opposite the soft X-rays 7 is to prevent soft X-rays from leaking;
the outline is obtained after the capillary needle tip and the liquid drop shot by a CCD camera-microscope (x 300) 13 are processed by an FPGA (14), the schematic diagram is shown in figure 2, F is the schematic diagram of the capillary needle tip, G is the schematic diagram of the liquid drop shape, and P point is defined as the point with the largest value of the liquid drop abscissa (x-axis coordinate) without losing generality; taking a plurality of points along the P point to the positive direction and the reverse direction of the y axis respectively, and fitting a straight line according to a least square method respectively to obtain l 1 :y＝k 1 x+b 1 And l 2 :y＝k 2 x+b 2 The method comprises the steps of carrying out a first treatment on the surface of the Then two straight lines l 1 And l 2 Is included by an angle alpha= -arctank 1 +arctank 2 Wherein k is 1 And k 2 Respectively straight line l 1 And l 2 Slope of b 1 And b 2 Respectively straight line l 1 And l 2 Is defined by the intercept of (2); the least square method for fitting the straight line specifically comprises the following steps: set fitting point set as%x i ,y i ) Wherein i=1, 2,3, …, n; order the
Then the fit line is y=kx+b; let mean square error->
If the mean square error MSE is larger than a certain preset threshold value, judging that the electrospray system does not reach a conical jet flow state through the FPGA (14); if the mean square error MSE is not greater than a certain preset threshold value, judging that the electrospray system works in a conical jet flow state through the FPGA (14), and transmitting alpha into a logic operation module E to perform the next operation;
the control system used in the logic operation module is shown in fig. 3, and the control system comprises two closed loop circuits, namely a main loop (outer loop) with PID1 and an auxiliary control loop (formed by G(s) in the broken line box of fig. 3); the goal of the control system is to keep the spray current constant; in electrospray systems, after the droplets form a cone-shaped jet, the positive correlation between the apex angle α and the voltage on the high-voltage electrode is α=h 1 (V), wherein V is the voltage on the high voltage electrode; similarly, there is a positive correlation i=h between the operating current of electrospray and the voltage on the high voltage electrode 2 (V), positive correlation h 1 And h 2 Has been verified in the past literature; it can thus be obtained that there is a positive correlation i=h between the cone jet apex angle and the operating current 3 (alpha); will h 3 The Laplace transformation is carried out to be converted into a complex frequency domain, and G is obtained 2 (s) mixing h 1 The Laplace transformation is carried out to be converted into a complex frequency domain, and G is obtained 1 (s); from the above analysis, the high-pressure conversion determined by the outer loop control loop is G 1 (s) converting into a droplet shape objective function, the droplet shape output function being G 2 (s) converting into a working current output function to complete variable connection of inner loop control and outer loop control; the input of the outer loop of the control system is an objective function of the operating current of the electrospray system,the output is the actual value of the working current, the outer loop carries out PID1 operation at a lower frequency (1 Hz) (so as to avoid the current fluctuation caused by voltage change from being mistakenly regarded as a current output value), and the PID1 obtains the operation result and then transmits the operation result into G(s); the input (target value) of the auxiliary control loop is the output of PID1, the auxiliary control loop performs the operation of PID2 at a higher frequency (30 Hz), the shape of the control cone droplet (characterized by the apex angle α) converges on the input of the auxiliary control loop, according to i=h 3 It is clear that the operating current can be considered to be stable as long as the droplet shape (the cone-shaped droplet apex angle α) is maintained stable for a short period of time;
the automatic start-up flow of the system is shown in fig. 4; in the flow chart, except that manual operation is needed in the first step of setting the air inlet flow of clean air and carbon dioxide and setting the sample injection flow of solution to be generated, other operations can be automatically completed by a logic operation module E; after the air, carbon dioxide and sample introduction flow are set, the working voltage of the electrospray system is linearly increased by a logic operation module E, and whether the electrospray system works in a conical jet flow mode is judged in real time by an image shot by a CCD camera-micro lens (multiplied by 300) 13 and the method; once the electrospray is operated in the cone-jet mode, the voltage is stopped and the droplet shape is waited for, the operating current stabilizes, and the target current of the dual closed-loop control system is set according thereto, and the closed-loop control is entered to converge the electrospray operating current to the target value.
Specifically, the embodiment of the invention discloses a monodisperse ultrafine particle stable generation method based on a double closed-loop control system, which adopts the monodisperse ultrafine particle stable generation device based on the double closed-loop control and comprises the following steps:
s1, manually setting air inlet flow of clean air and carbon dioxide, manually setting sample injection flow of solution to be generated, automatically and linearly increasing voltage by a logic operation module, continuously judging whether an electrospray module works in a conical jet mode, stopping high-voltage change to stabilize working current and droplet shape if the electrospray module works in the conical jet mode, setting target current, and entering double closed-loop control to maintain the working current of the electrospray module stable;
s2, the original color RGB image obtained by the image acquisition module contains complete liquid drops; the color RGB image is subjected to monochromatic gray level conversion and binarization treatment to obtain a black-and-white image, and then is subjected to Sobel edge detection algorithm treatment to obtain the capillary nozzle tip-liquid drop contour; the FPGA analyzes the contour shape to judge whether the electrospray module works in a conical jet flow mode, if so, the shape of the liquid drop is quantized through the contour, and the vertex angle of the conical liquid drop is calculated and transmitted to the logic operation module for further calculation;
s3, the logic operation module comprises two input signals: the electrospray working current obtained by the current measurement module and the liquid drop profile obtained by the image acquisition module; the logic operation module comprises an output signal: a voltage regulation command sent to the high-voltage module; the double closed-loop control system realized by the logic operation module changes output voltage by calculating and analyzing two input signals so as to adjust working current of electrospray to target current, thus realizing stable operation of electrospray;
s4, the logic operation module performs difference between the target current and the working current measured value to perform outer loop proportional-integral-derivative operation; the operation result is converted into a droplet shape target, and the droplet shape target is differenced with the droplet shape measurement value to perform inner loop PID operation; the operation result is converted into a voltage regulation instruction and then applied to the high-voltage electrode; after double closed-loop control, the current of the electrospray module is converged to a set value, and monodisperse ultrafine particles are stably generated.
In summary, the dual closed-loop control system according to the embodiments of the present invention aims to control the working current of the electrospray module to be stabilized at a certain set value (the current stabilization is a main sign that the electrospray module stably generates monodisperse ultrafine particles). The control system can acquire and process the working current of the electrospray module and the image of the liquid drop at the tip of the capillary spray nozzle, takes the current measured value and the image signal as the feedback quantity of the control system, and adjusts the working state of the electrospray module through the high-voltage adjusting module after being calculated by the control system so as to adjust the working current of the electrospray module. In long-time operation, the generated current is easily interfered by external factors such as air pressure and temperature, and the device can monitor and maintain the stable operation of the electrospray module so as to stably generate monodisperse ultrafine particles.
In yet another aspect, the invention also discloses a computer readable storage medium storing a computer program which, when executed by a processor, causes the processor to perform the steps of any of the methods described above.
In yet another aspect, the invention also discloses a computer device comprising a memory and a processor, the memory storing a computer program which, when executed by the processor, causes the processor to perform the steps of any of the methods described above.
In yet another embodiment provided herein, there is also provided a computer program product containing instructions which, when run on a computer, cause the computer to perform the steps of any of the methods of the above embodiments.
It may be understood that the system provided by the embodiment of the present invention corresponds to the method provided by the embodiment of the present invention, and explanation, examples and beneficial effects of the related content may refer to corresponding parts in the above method.
Those skilled in the art will appreciate that all or part of the processes in the methods of the above embodiments may be implemented by a computer program for instructing relevant hardware, where the program may be stored in a non-volatile computer readable storage medium, and where the program, when executed, may include processes in the embodiments of the methods described above. Any reference to memory, storage, database, or other medium used in the various 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 embodiments are only for illustrating the technical solution of the present invention, and are not limiting; although the invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit and scope of the technical solutions of the embodiments of the present invention.
Claims (5)
1. The stable generation method of the monodisperse ultrafine particles based on double closed-loop control comprises an electrospray module and a double closed-loop control system, wherein the double closed-loop control system comprises the electrospray module, a current measurement module, an image acquisition module, a high-voltage module and a logic operation module; the method is characterized in that:
the electrospray module comprises a microsyringe, a spray cavity, a capillary spray needle, an air and carbon dioxide inlet, a high-voltage electrode and a soft X-ray neutralizer; the microsyringe is connected with the capillary spray needle through a 1/32' pipe; the air inlet and the carbon dioxide inlet penetrate through the spray cavity and ensure the air tightness between the air inlet and the spray cavity; the high-voltage electrode is arranged on the surface of the capillary spray needle and is not contacted with the capillary spray needle; the soft X-ray neutralizer is arranged outside the spray cavity;
the current measurement module comprises a current-voltage conversion circuit, a voltage follower and an analog-digital signal converter; the current-voltage conversion circuit comprises a conversion resistor and a filter capacitor, wherein one end of the parallel connection circuit is connected to the capillary spray needle through a lead, and the other end of the parallel connection circuit is grounded; the voltage follower is composed of an operational amplifier, the input end of the voltage follower is connected to the capillary spray needle through a wire, and the output end of the voltage follower is connected to the input end of the analog-digital signal converter through a wire; the output end of the analog-digital signal converter is connected to the logic operation module through a wire;
the image acquisition module comprises a CCD camera-micro lens and programmable array logic; the CCD camera-micro lens is arranged outside the spray cavity, and the digital signal output end of the CCD camera is connected to the programmable array logic through a wire; the programmable array logic is connected to the logic operation module through a serial port line;
the high-voltage module comprises a digital-analog signal converter and a high-voltage source; the input end of the digital-analog signal converter is connected with the logic operation module through a wire, and the output end of the digital-analog signal converter is connected to the input end of the high-voltage source through a wire; the output end of the high-voltage source is connected to the high-voltage electrode through a high-voltage-resistant wire;
the generation method of the monodisperse ultrafine particulate matter stable generation device based on double closed-loop control comprises the following steps:
s1, manually setting air inlet flow of clean air and carbon dioxide, manually setting sample injection flow of solution to be generated, automatically and linearly increasing voltage by a logic operation module, continuously judging whether an electrospray module works in a conical jet mode, stopping high-voltage change to stabilize working current and droplet shape if the electrospray module works in the conical jet mode, setting target current, and entering double closed-loop control to maintain the working current of the electrospray module stable;
s2, the original color RGB image obtained by the image acquisition module contains complete liquid drops; the color RGB image is subjected to monochromatic gray level conversion and binarization treatment to obtain a black-and-white image, and then is subjected to Sobel edge detection algorithm treatment to obtain the capillary nozzle tip-liquid drop contour; the FPGA analyzes the contour shape to judge whether the electrospray module works in a conical jet flow mode, if so, the shape of the liquid drop is quantized through the contour, and the vertex angle of the conical liquid drop is calculated and transmitted to the logic operation module for further calculation;
s3, the logic operation module comprises two input signals: the electrospray working current obtained by the current measurement module and the liquid drop profile obtained by the image acquisition module; the logic operation module comprises an output signal: a voltage regulation command sent to the high-voltage module; the double closed-loop control system realized by the logic operation module changes output voltage by calculating and analyzing two input signals so as to adjust working current of electrospray to target current, thus realizing stable operation of electrospray;
s4, the logic operation module performs difference between the target current and the working current measured value to perform outer loop proportional-integral-derivative operation; the operation result is converted into a droplet shape target, and the droplet shape target is differenced with the droplet shape measurement value to perform inner loop PID operation; the operation result is converted into a voltage regulation instruction and then applied to the high-voltage electrode; after double closed-loop control, the current of the electrospray module is converged to a set value, and monodisperse ultrafine particles are stably generated.
2. The device for generating the stable monodisperse ultrafine particulate matters based on double closed-loop control is used for realizing the method for generating the stable monodisperse ultrafine particulate matters based on double closed-loop control, and is characterized in that:
the system comprises an electrospray module and a double closed-loop control system, wherein the double closed-loop control system comprises an electrospray module, a current measurement module, an image acquisition module, a high-voltage module and a logic operation module; the method is characterized in that:
the electrospray module comprises a microsyringe, a spray cavity, a capillary spray needle, an air and carbon dioxide inlet, a high-voltage electrode and a soft X-ray neutralizer; the microsyringe is connected with the capillary spray needle through a 1/32' pipe; the air inlet and the carbon dioxide inlet penetrate through the spray cavity and ensure the air tightness between the air inlet and the spray cavity; the high-voltage electrode is arranged on the surface of the capillary spray needle and is not contacted with the capillary spray needle; the soft X-ray neutralizer is arranged outside the spray cavity;
the current measurement module comprises a current-voltage conversion circuit, a voltage follower and an analog-digital signal converter; the current-voltage conversion circuit comprises a conversion resistor and a filter capacitor, wherein one end of the parallel connection circuit is connected to the capillary spray needle through a lead, and the other end of the parallel connection circuit is grounded; the voltage follower is composed of an operational amplifier, the input end of the voltage follower is connected to the capillary spray needle through a wire, and the output end of the voltage follower is connected to the input end of the analog-digital signal converter through a wire; the output end of the analog-digital signal converter is connected to the logic operation module through a wire;
the image acquisition module comprises a CCD camera-micro lens and programmable array logic; the CCD camera-micro lens is arranged outside the spray cavity, and the digital signal output end of the CCD camera is connected to the programmable array logic through a wire; the programmable array logic is connected to the logic operation module through a serial port line;
the high-voltage module comprises a digital-analog signal converter and a high-voltage source; the input end of the digital-analog signal converter is connected with the logic operation module through a wire, and the output end of the digital-analog signal converter is connected to the input end of the high-voltage source through a wire; the output end of the high-voltage source is connected to the high-voltage electrode through a high-voltage resistant wire.
3. The monodisperse ultrafine particulate stabilization generating device based on double closed loop control according to claim 2, wherein: the material of the spray cavity in the single capillary needle electrospray module is organic glass.
4. The monodisperse ultrafine particulate stabilization generating device based on double closed loop control according to claim 2, wherein: the logic operation module comprises a singlechip.
5. The monodisperse ultrafine particulate stabilization generating device based on double closed loop control according to claim 2, wherein: the electrospray module further comprises a metal protective shell which is arranged opposite to the soft X-ray neutralizer and used for preventing soft X-rays from leaking.
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| CN202210461153.0A CN115025690B (en) | 2022-04-28 | 2022-04-28 | Monodisperse ultrafine particle stable generation device and method based on double closed-loop control |
| PCT/CN2023/091093 WO2023208099A1 (en) | 2022-04-28 | 2023-04-27 | Double closed loop control-based monodisperse ultrafine particulate matter stable generation apparatus and method |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| US5873523A (en) * | 1996-02-29 | 1999-02-23 | Yale University | Electrospray employing corona-assisted cone-jet mode |
| EP1297895A4 (en) * | 2000-06-29 | 2003-04-02 | Anest Iwata Corp | Electrostatic painting device |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| DE02744176T1 (en) * | 2001-05-24 | 2005-01-13 | New Objective, Inc., Woburn | METHOD AND DEVICE FOR ELECTROSPRAY WITH FEEDBACK CONTROL |
| US20050072915A1 (en) * | 2003-10-07 | 2005-04-07 | Biospect Inc. | Methods and apparatus for self-optimization of electrospray ionization devices |
| GB0524979D0 (en) * | 2005-12-07 | 2006-01-18 | Queen Mary & Westfield College | An electrospray device and a method of electrospraying |
| US9195156B2 (en) * | 2013-02-25 | 2015-11-24 | Ricoh Company, Ltd. | Particulate material production method, and particulate material production apparatus |
| CN103586154B (en) * | 2013-10-29 | 2015-10-21 | 华中科技大学 | Electrospray device, electron spray is utilized to prepare method and the solar cell of solar cell anti-reflection layer |
| CN103933901B (en) * | 2014-04-23 | 2015-08-19 | 清华大学 | 1 ~ 3nm monodisperse aerosol generation systems |
| US9925547B2 (en) * | 2014-08-26 | 2018-03-27 | Tsi, Incorporated | Electrospray with soft X-ray neutralizer |
| WO2018042256A2 (en) * | 2016-08-31 | 2018-03-08 | Avectas Limited | Adaptive electrospray device |
| CN115025690B (en) * | 2022-04-28 | 2023-05-30 | 中国科学院合肥物质科学研究院 | Monodisperse ultrafine particle stable generation device and method based on double closed-loop control |
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Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5873523A (en) * | 1996-02-29 | 1999-02-23 | Yale University | Electrospray employing corona-assisted cone-jet mode |
| EP1297895A4 (en) * | 2000-06-29 | 2003-04-02 | Anest Iwata Corp | Electrostatic painting device |
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