CN115356246A - Aerosol electrification measuring device based on thermal deposition principle - Google Patents

Aerosol electrification measuring device based on thermal deposition principle Download PDF

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Publication number
CN115356246A
CN115356246A CN202210891654.2A CN202210891654A CN115356246A CN 115356246 A CN115356246 A CN 115356246A CN 202210891654 A CN202210891654 A CN 202210891654A CN 115356246 A CN115356246 A CN 115356246A
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metal sheet
module
thermal deposition
micro
hot metal
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Inventor
桂华侨
康士鹏
余同柱
杨义新
程寅
魏秀丽
陈大仁
刘建国
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Hefei Institutes of Physical Science of CAS
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Hefei Institutes of Physical Science of CAS
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Priority to CN202210891654.2A priority Critical patent/CN115356246A/en
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N15/00—Investigating characteristics of particles; Investigating permeability, pore-volume, or surface-area of porous materials
    • G01N15/06—Investigating concentration of particle suspensions
    • G01N15/0656—Investigating concentration of particle suspensions using electric, e.g. electrostatic methods or magnetic methods
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N15/00—Investigating characteristics of particles; Investigating permeability, pore-volume, or surface-area of porous materials
    • G01N15/06—Investigating concentration of particle suspensions
    • G01N15/0606—Investigating concentration of particle suspensions by collecting particles on a support
    • G01N15/0618—Investigating concentration of particle suspensions by collecting particles on a support of the filter type
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
    • G01R19/145—Indicating the presence of current or voltage
    • G01R19/15—Indicating the presence of current

Abstract

The invention relates to an aerosol electrification measuring device based on a thermal deposition principle. The thermal deposition module consists of a hot metal sheet, a cold metal sheet, a thermal deposition shell, a ceramic heating sheet, a thermocouple and a water cooling device; the micro-current measuring module consists of an electromagnetic shielding shell, a micro-current measuring circuit board and a spring probe; the sampling module consists of a three-way electromagnetic valve and an ultrafine particulate filter. The function of the thermal deposition module is to collect charged ultrafine particles in high-temperature sampling gas on a cold metal sheet and introduce charges carried by the charged ultrafine particles into the micro-current measurement module; the function of the micro-current measuring module is to measure the total charge of the ultrafine particles collected by the thermal deposition module; the sampling module has the functions of reducing measurement errors caused by zero fluctuation of the micro-current measurement module and improving measurement precision. The invention can realize accurate measurement of the charge quantity of the ultrafine particles in the high-temperature sampling gas.

Description

Aerosol electrification measuring device based on thermal deposition principle
Technical Field
The invention relates to the technical field of mobile pollution source ultrafine particle emission detection, in particular to an aerosol charge measurement device based on a thermal deposition principle.
Background
The discharge of ultrafine particles from motor vehicles has become one of the key points for preventing and controlling air pollution. On one hand, the number concentration and the surface area of the ultrafine particles discharged by the motor vehicle are high, the chemical components are complex, and the number concentration and the surface area have important influence on human health, atmospheric visibility, global climate and the like; on the other hand, a large amount of ultrafine particles can absorb moisture and increase under certain atmospheric conditions, and can directly form dust-haze pollution. The accurate measurement of the number concentration of the ultrafine particles discharged by the motor vehicle has important significance for the mechanism research of the combustion process of an engine, the control of atmospheric pollution and the like.
However, at present, complex sampling devices, such as hot dilution, cold dilution, water removal devices and the like, need to be equipped for measuring the number concentration of the ultrafine particulate matters discharged by the motor vehicle, so that the measurement error of the number concentration of the particulate matters is increased, and the portability and the stability of the system are reduced. The main reason for this is that the current particle counting devices, both traditional aerosol electrometers and condensation nuclear particle counters, are difficult to implement high temperature direct measurement. The supersaturation increasing module in the condensation nucleus particle counter strictly controls the temperature of the sampling gas, so that high-temperature direct measurement is difficult to realize; a micro-current measuring circuit in the traditional aerosol electrometer is sensitive to temperature, temperature changes can cause zero fluctuation of the electrometer to cause wrong measuring results, and the performance of key electronic components can be deteriorated or even damaged due to overhigh temperature. Therefore, it is necessary to design an aerosol charge measurement device and method that can directly measure the high-temperature sampled gas without being affected by high temperature.
Disclosure of Invention
The aerosol charge measuring device based on the thermal deposition principle can solve the defects in the prior art and realize accurate measurement of the charge quantity of ultrafine particulate matters in high-temperature sampling gas.
In order to realize the purpose, the invention adopts the following technical scheme:
a thermal deposition principle-based aerosol electrification measuring device comprises a thermal deposition module, a micro-current measuring module and a sampling module, wherein the sampling module is communicated with the thermal deposition module, sampling gas sequentially passes through the sampling module and the thermal deposition module and then leaves the device, and ultrafine particles in the sampling gas are deposited in the thermal deposition module and do not leave the device along with the sampling gas; the gas circuit between the thermal deposition module and the micro-current measuring module is not communicated, but is connected through a copper probe.
Furthermore, the hot deposition module comprises a hot metal sheet, a cold metal sheet, a hot deposition shell, a ceramic heating sheet, a thermocouple and a water cooling device; the hot metal sheet and the cold metal sheet are connected and fixed through PEEK screws, and the distance between the hot metal sheet and the cold metal sheet is limited through a mica gasket; the hot metal sheet and the ceramic heating sheet are connected and fixed through PEEK screws, and the distance between the hot metal sheet and the thermal deposition shell is limited through a mica gasket; the ceramic heating sheet is tightly attached to the hot metal sheet, the thermocouple is inserted into the hot metal sheet, the power of the ceramic heating sheet is modulated through the relay, and PID control is carried out by combining thermocouple temperature measurement feedback; the water cooling device is tightly attached to the thermal deposition shell.
Further, the micro-current measuring module comprises an electromagnetic shielding shell, a micro-current measuring circuit board and a spring probe; the micro-current measuring circuit board is fixed in the electromagnetic shielding shell through screws; the spring probe is welded in the center of the circuit board.
Furthermore, the sampling module consists of a three-way electromagnetic valve and an ultrafine particulate filter; one end of the three-way electromagnetic valve is suspended and is an inlet for charged particles; one end of the filter is connected with the ultrafine particle filter and is a clean air inlet; the other end is connected with a hot metal sheet.
Further, the mica shim thickness between the hot metal sheet and the cold metal sheet is less than or equal to 1.5mm;
the cold metal sheet and the thermal deposition shell are filled and connected through a heat-conducting silica gel sheet, and the thickness of the heat-conducting silica gel sheet is less than or equal to 1mm;
the mica pad thickness between the hot metal sheet and the thermal deposition casing is greater than or equal to 0.5mm.
Further, the temperature of the hot metal sheet is controlled to be a certain value between 100 ℃ and 200 ℃ through a ceramic heating sheet and a thermocouple; and ice water with the temperature of 0 ℃ is introduced into the water cooling device at a fixed flow rate.
Further, the thermal deposition module is coaxial with the micro-current measuring module and is connected and fixed through an internal thread below the thermal deposition module and an external thread above the micro-current measuring module.
Further, the total length of the spring probe in the micro-current measuring module is longer than the distance from the micro-current measuring circuit board to the cold metal sheet.
Furthermore, a three-way electromagnetic valve in the sampling module is connected with the hot metal sheet by adopting a heat-resistant conductive material pipeline, and the total length of the pipeline is not more than 10cm; the three-way electromagnetic valve is connected with the ultrafine particle filter by adopting a pipeline made of heat-resistant conductive material, and the total length of the pipeline is not more than 10cm.
On the other hand, the invention also discloses an aerosol charged-electricity measuring method based on the thermal deposition principle, and the aerosol charged-electricity measuring device based on the thermal deposition principle comprises the following steps:
(1) Connecting an electrified particulate matter inlet of the three-way electromagnetic valve with sampling gas, and setting the working state of the three-way electromagnetic valve to be 0; connecting a sampling gas outlet on the thermal deposition shell with an external gas pump, and setting the flow at a certain value of 0.4L/min-1L/min;
(2) Keeping ice water at 0 ℃ and introducing the ice water into the water cooling device; keeping the micro-current measuring module to measure the current at the frequency of 10 Hz; starting temperature control of the hot metal sheet, and heating and stabilizing the hot metal sheet at a preset temperature value;
(3) Stopping heating after the temperature of the hot metal sheet is stable and the zero point of the micro-current measuring module is stable, and naturally radiating the heat of the hot metal sheet; carrying out the steps (4) to (6) within 0 to 3X seconds;
(4) Within 0-X seconds after the step (3), the three-way electromagnetic valve is connected with the ultrafine particulate filter, and the current measured by the micro-current measuring module is zero at the moment; record the effective "Current-time", forming a set, denoted O 1 And the working state of the three-way electromagnetic valve is set to 1;
(5) Within X-2X seconds after the step (3), the sampled gas enters the thermal deposition module through the three-way electromagnetic valve, deposits on the cold metal sheet under the action of a thermal surge effect and loses charges to form current; recording effective current value-time to form a set, recording the set as Q, and setting the working state of the three-way electromagnetic valve as 0;
(6) Within 2X-3X seconds after the step (3), the three-way electromagnetic valve is connected with the ultrafine particulate filter, and the current measured by the micro-current measuring module is zero at the moment; record the effective "Current-time", forming a set, denoted O 2 ；
(7) According to O 1 And O 2 Fitting the inner points with a quadratic function to obtain a zero point curve L of the micro-current measuring module 0 (ii) a According to Q-L 0 Obtaining a current measured value after the zero point is removed;
(8) Repeating the steps (2) to (7), and measuring the charge quantity of the ultrafine particles in the sampled gas at a set time frequency
According to the technical scheme, the aerosol charge measurement device based on the thermal deposition principle has the following beneficial effects:
compared with the prior art, the invention has the following beneficial effects:
(1) The aerosol electrification measuring device based on the thermal deposition principle structurally separates a particulate matter collecting area from a micro-current measuring area, so that the high temperature in the collecting area does not influence a micro-current measuring circuit board any more, and the measurement of the electrification amount of ultrafine particulate matters in high-temperature sampling gas is realized.
(2) The aerosol charge measurement device based on the thermal deposition principle can collect particles on a cold metal sheet while measuring the charge quantity of ultrafine particles, and the collected particles can be used for further physicochemical property analysis.
(3) According to the aerosol charged quantity measuring method based on the thermal deposition principle, the zero point curve of the electrometer can be calculated in actual measurement through operation of the sampling module, and measurement errors caused by zero point fluctuation are reduced.
Drawings
FIG. 1 is a schematic diagram of an aerosol charge measurement device according to the present invention based on the principle of thermal deposition;
wherein: 1. the device comprises a hot metal sheet, a cold metal sheet, a hot deposition shell, a cold electromagnetic shielding shell, a micro-current measuring circuit board, a spring probe, a ceramic heating sheet, a thermocouple, a water cooling device, a three-way electromagnetic valve, a sampling gas inlet of the three-way electromagnetic valve, a gas outlet of the three-way electromagnetic valve, a clean gas inlet of the three-way electromagnetic valve, a superfine particulate filter and a gas outlet of the three-way electromagnetic valve, wherein the hot metal sheet is 2;
FIG. 2 is an algorithm diagram of the aerosol charge measurement method based on the principle of thermal deposition in the present invention;
wherein: 0. x, 2X and 3X are time, A, a measurement zero time interval, B, a conversion time interval after the sampling gas inlet is connected, C, an effective measurement time interval, D, a conversion time interval after the clean gas inlet is connected, and E, a measurement zero time interval.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention.
The aerosol electric charge measuring device based on the thermal deposition principle as shown in fig. 1 comprises a thermal deposition module, a micro-current measuring module and a sampling module;
the sampling module is communicated with the thermal deposition module, the sampling gas sequentially passes through the sampling module and the thermal deposition module and then leaves the device, and ultrafine particles in the sampling gas are deposited in the thermal deposition module and do not leave the device along with the sampling gas. The gas circuit between the thermal deposition module and the micro-current measuring module is not communicated, but is connected through a copper probe (electric conduction) so as to release charges carried on the surface of the particles through the copper probe after the particles are deposited in the thermal deposition module, and the micro-current measuring module measures the discharge current.
The following is a detailed description:
the hot deposition module consists of a hot metal sheet 1, a cold metal sheet 2, a hot deposition shell 3, a ceramic heating sheet 7, a thermocouple 8 and a water cooling device 9; the hot metal sheet 1 and the cold metal sheet 2 are connected and fixed through PEEK screws, and the distance between the hot metal sheet 1 and the cold metal sheet 2 is limited through a mica gasket; the hot metal sheet 1 and the ceramic heating sheet 7 are connected and fixed through PEEK screws, and the distance between the hot metal sheet 1 and the heat deposition shell 3 is limited through a mica gasket; the ceramic heating plate 7 is tightly attached to the hot metal sheet 1, the thermocouple is inserted into the hot metal sheet 8, the power of the ceramic heating plate 7 is modulated through the relay, and PID control is carried out by combining temperature measurement feedback of the thermocouple 8; the water cooling device 9 is tightly attached to the thermal deposition shell 3;
the micro-current measuring module consists of an electromagnetic shielding shell 4, a micro-current measuring circuit board 5 and a spring probe 6; the micro-current measuring circuit board 5 is fixed in the electromagnetic shielding shell 4 through screws; the spring probe is welded 6 in the right center of the micro-current measuring circuit board 5;
the sampling module consists of a three-way electromagnetic valve 10 and an ultrafine particulate filter 11; a 10.1 port of the three-way electromagnetic valve is suspended and is an inlet for charged particles; the 10.3 port is connected with the ultrafine particle filter and is a clean air inlet; 10.2 the port is connected with a hot metal sheet;
in particular, the mica shim thickness between the hot metal sheet 1 and the cold metal sheet 2 is not greater than 1.5mm, and too large a spacing reduces the deposition efficiency, resulting in a measurement that is less so that a maximum of 1.5mm is defined herein.
Specifically, the cold metal sheet 2 and the thermal deposition shell 3 are filled and connected through a heat-conducting silica gel sheet, and the thickness of the heat-conducting silica gel sheet is not more than 1mm; the larger the thickness of the heat-conducting silicon sheet is, the poorer the refrigeration effect of the water cooling device on the cold metal sheet is, so that the temperature difference between the cold metal sheet and the hot metal sheet cannot be opened, the deposition efficiency of particulate matters is reduced, and finally the measurement result is smaller. Therefore, the thickness of the heat conduction silica gel sheet is limited to be not more than 1mm so as to ensure the refrigeration effect of the water cooling device.
Specifically, the thickness of the mica gasket between the hot metal sheet 1 and the thermal deposition shell 3 is not less than 0.5mm, and the larger the thickness of the mica gasket is, the poorer the heat transfer effect is, so that the influence of the heating metal sheet on the temperature of the cold metal sheet is reduced, and the temperature difference between the hot metal sheet and the cold metal sheet is ensured.
Specifically, the temperature of the hot metal sheet 1 is controlled to be a certain value between 100 ℃ and 200 ℃ through a ceramic heating sheet 7 and a thermocouple 8; ice water with the temperature of 0 ℃ is introduced into the water cooling device 9 at a fixed flow rate; the temperature of the sampling gas is kept above 100 ℃, and the water vapor in the sampling gas is prevented from condensing. The upper limit of 200 ℃ is to prevent excessive temperatures from affecting the proper operation of the microcurrent measurement module.
Specifically, the thermal deposition module is coaxial with the micro-current measuring module and is connected and fixed through internal threads below the thermal deposition module and external threads above the micro-current measuring module.
Specifically, the total length of the spring probe 6 in the micro-current measuring module is slightly longer than the distance from the micro-current measuring circuit board 5 to the cold metal sheet 2; the purpose is in order to guarantee that the metal spring probe is compressed and the atress when accomplishing the installation, can reduce the influence that vibrations brought like this, improves measurement accuracy.
Specifically, a three-way electromagnetic valve 10 in the sampling module is connected with a hot metal sheet 1 through a heat-resistant conductive material pipeline, and the total length of the pipeline is not more than 10cm; the conduit length is defined to reduce the overall loss of particulate matter in the conduit. The three-way electromagnetic valve 10 is connected with the ultrafine particle filter 11 by adopting a heat-resistant conductive pipeline, and the total length of the pipeline is not more than 10cm;
specifically, the three-way solenoid valve 10 has two working states, where "state 0" is to connect 10.2 to port 10.3 and disconnect 10.1; "state 1" is to put the 10.2 port in communication with the 10.1 port and to disconnect the 10.3 port;
the embodiment of the invention also relates to a method for the electric quantity measuring device, which comprises the following steps:
(1) Connecting a port 10.1 of an electrified particulate matter inlet of the three-way electromagnetic valve 10 with sampling gas, and setting the working state of the three-way electromagnetic valve 10 to be 'state 0'; connecting a sampling gas outlet on the thermal deposition shell 3 with an external gas pump, and setting the flow at a certain value of 0.4L/min-1L/min;
(2) Keeping ice water at 0 ℃ and introducing the ice water into the water cooling device 9; keeping the micro-current measuring module to measure current at the frequency of 10 Hz; starting temperature control of the hot metal sheet 1, and heating and stabilizing the hot metal sheet at a preset temperature value;
(3) After the temperature of the hot metal sheet 1 is stable and the zero point of the micro-current measuring module is stable, stopping heating, and naturally radiating the hot metal sheet 1; carrying out the steps (4) to (6) within 0 to 3X seconds;
(4) As shown in fig. 2, within 0-X seconds after step (3), the current measured by the micro-current measuring module is at zero point when the three-way solenoid valve 10 is connected to the ultrafine particulate filter 11; all the "current values-times" in the recording interval A form a set, denoted as O 1 And the working state of the three-way electromagnetic valve 10 is set to "state 1";
(5) As shown in fig. 2, within X-2X seconds after step (3), the sampled gas enters the thermal deposition module through the three-way solenoid valve 10, deposits on the cold metal sheet 2 under the action of the thermal surge effect and loses charges to form a current; the interval B is a conversion time interval, data is abandoned, the current value-time in all the intervals C is recorded to form a set and recorded as Q, and the working state of the three-way electromagnetic valve is set to be 0;
(6) As shown in fig. 2, within 2X to 3X seconds after step (3), the interval D is a conversion time interval, data is discarded, and for the interval E, the three-way electromagnetic valve 10 is switched on the ultrafine particulate filter 11, and the current measured by the microcurrent measurement module is at zero point at this time; all "Current-time" values within recording interval E "Form a set, denoted as O 2 ；
(7) According to O 1 And O 2 Fitting the inner points with a quadratic function to obtain a zero point curve L of the micro-current measuring module 0 (ii) a According to Q-L 0 Obtaining a current measured value after the zero point is removed;
(8) And (5) repeating the steps (2) to (7), and measuring the charge quantity of the ultrafine particles in the sampled gas at a certain time frequency.
In conclusion, the invention has the following beneficial effects:
(1) The aerosol electrification measuring device based on the thermal deposition principle structurally separates a particulate matter collecting area from a micro-current measuring area, so that the high temperature in the collecting area does not influence a micro-current measuring circuit board any more, and the measurement of the electrification amount of ultrafine particulate matters in high-temperature sampling gas is realized.
(2) The aerosol charge measuring device based on the thermal deposition principle can collect particles on a cold metal sheet while measuring the charge quantity of ultrafine particles, and the collected particles can be used for further physicochemical property analysis.
(3) According to the aerosol charged quantity measuring method based on the thermal deposition principle, the zero point curve of the electrometer can be calculated in actual measurement through operation of the sampling module, and measurement errors caused by zero point fluctuation are reduced.
The above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it should be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.

Claims (10)

1. The utility model provides an aerosol electrification measuring device based on thermal deposition principle, includes thermal deposition module, little current measurement module and sampling module, its characterized in that:
the sampling module is communicated with the thermal deposition module, the sampling gas sequentially passes through the sampling module and the thermal deposition module and then leaves the device, and ultrafine particles in the sampling gas are deposited in the thermal deposition module and do not leave the device along with the sampling gas; the gas circuit between the thermal deposition module and the micro-current measuring module is not communicated, but is connected through a copper probe.
2. A device for measuring the charge of an aerosol according to claim 1 based on the principle of thermal deposition, comprising: the thermal deposition module comprises a hot metal sheet, a cold metal sheet, a thermal deposition shell, a ceramic heating sheet, a thermocouple and a water cooling device; the hot metal sheet and the cold metal sheet are connected and fixed through PEEK screws, and the distance between the hot metal sheet and the cold metal sheet is limited through a mica gasket; the hot metal sheet and the ceramic heating sheet are connected and fixed through PEEK screws, and the distance between the hot metal sheet and the thermal deposition shell is limited through a mica gasket; the ceramic heating sheet is tightly attached to the hot metal sheet, the thermocouple is inserted into the hot metal sheet, the power of the ceramic heating sheet is modulated through the relay, and PID control is carried out by combining thermocouple temperature measurement feedback; the water cooling device is tightly attached to the thermal deposition shell.
3. The apparatus according to claim 1, wherein the apparatus comprises: the micro-current measuring module comprises an electromagnetic shielding shell, a micro-current measuring circuit board and a spring probe; the micro-current measuring circuit board is fixed in the electromagnetic shielding shell through screws; the spring probe is welded in the center of the circuit board.
4. A device for measuring the charge of an aerosol according to claim 1 based on the principle of thermal deposition, comprising: the sampling module consists of a three-way electromagnetic valve and an ultrafine particulate filter; one end of the three-way electromagnetic valve is suspended and is an inlet for charged particles; one end of the filter is connected with the ultrafine particle filter and is a clean air inlet; the other end is connected with the hot metal sheet.
5. The apparatus according to claim 1, wherein the apparatus comprises: the thickness of the mica gasket between the hot metal sheet and the cold metal sheet is less than or equal to 1.5mm;
the cold metal sheet and the thermal deposition shell are filled and connected through a heat-conducting silica gel sheet, and the thickness of the heat-conducting silica gel sheet is less than or equal to 1mm;
the mica pad thickness between the hot metal sheet and the thermal deposition housing is greater than or equal to 0.5mm.
6. The apparatus according to claim 1, wherein the apparatus comprises: the temperature of the hot metal sheet is controlled to be a certain value between 100 and 200 ℃ through a ceramic heating sheet and a thermocouple; and ice water with the temperature of 0 ℃ is introduced into the water cooling device at a fixed flow rate.
7. A device for measuring the charge of an aerosol according to claim 1 based on the principle of thermal deposition, comprising: the thermal deposition module is coaxial with the micro-current measuring module and is connected and fixed through internal threads below the thermal deposition module and external threads above the micro-current measuring module.
8. The apparatus according to claim 1, wherein the apparatus comprises: the total length of the spring probe in the micro-current measuring module is longer than the distance from the micro-current measuring circuit board to the cold metal sheet.
9. The apparatus according to claim 1, wherein the apparatus comprises: the three-way electromagnetic valve in the sampling module is connected with the hot metal sheet by adopting a pipeline made of heat-resistant conductive material, and the total length of the pipeline is not more than 10cm; the three-way electromagnetic valve and the ultrafine particle filter are connected by adopting a heat-resistant conductive material pipeline, and the total length of the pipeline is not more than 10cm.
10. A method for measuring the amount of charged aerosol based on the principle of thermal deposition, which comprises using the apparatus for measuring the amount of charged aerosol based on the principle of thermal deposition as claimed in any one of claims 1 to 9, wherein: the method comprises the following steps:
(1) Connecting an electrified particulate matter inlet of the three-way electromagnetic valve with sampling gas, and setting the working state of the three-way electromagnetic valve to be 0; connecting a sampling gas outlet on the thermal deposition shell with an external gas pump, and setting the flow at a certain value of 0.4L/min-1L/min;
(2) Keeping ice water at 0 ℃ and introducing the ice water into the water cooling device; keeping the micro-current measuring module to measure the current at the frequency of 10 Hz; starting temperature control of the hot metal sheet, and heating and stabilizing the hot metal sheet at a preset temperature value;
(3) Stopping heating after the temperature of the hot metal sheet is stable and the zero point of the micro-current measuring module is stable, and naturally radiating the heat of the hot metal sheet; carrying out the steps (4) to (6) within 0 to 3X seconds;
(4) Within 0-X seconds after the step (3), the three-way electromagnetic valve is connected with the ultrafine particle filter, and the current measured by the micro-current measuring module is zero at the moment; record the effective "Current-time", forming a set, denoted O 1 And the working state of the three-way electromagnetic valve is set to 1;
(5) Within X-2X seconds after the step (3), the sampled gas enters a thermal deposition module through a three-way electromagnetic valve, deposits on a cold metal sheet under the action of a thermal surge effect and loses charges to form current; recording effective current value-time to form a set, recording the set as Q, and setting the working state of the three-way electromagnetic valve as 0;
(6) Within 2X-3X seconds after the step (3), the three-way electromagnetic valve is connected with the ultrafine particle filter, and the current measured by the micro-current measuring module is zero at the moment; record the effective "Current-time", forming a set, denoted O 2 ；
(7) According to O 1 And O 2 Fitting the inner points with a quadratic function to obtain a zero point curve L of the micro-current measuring module 0 (ii) a According to Q-L 0 Obtaining a current measured value after the zero point is removed;
(8) And (5) repeating the steps (2) to (7), and measuring the charge quantity of the ultrafine particles in the sampled gas at a set time frequency.
CN202210891654.2A 2022-07-27 2022-07-27 Aerosol electrification measuring device based on thermal deposition principle Pending CN115356246A (en)

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CN202210891654.2A CN115356246A (en) 2022-07-27 2022-07-27 Aerosol electrification measuring device based on thermal deposition principle

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Application Number Priority Date Filing Date Title
CN202210891654.2A CN115356246A (en) 2022-07-27 2022-07-27 Aerosol electrification measuring device based on thermal deposition principle

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Publication Number Publication Date
CN115356246A true CN115356246A (en) 2022-11-18

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