CN112782046A - High-temperature particulate matter particle size spectrum rapid measurement device and method based on multistage differential electromigration - Google Patents
High-temperature particulate matter particle size spectrum rapid measurement device and method based on multistage differential electromigration Download PDFInfo
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Abstract
The invention relates to a device and a method for quickly measuring a particle size spectrum of high-temperature particles based on multi-stage differential electromigration. The device comprises a unipolar ultrafine particle charging module, a multistage differential electric mobility analysis module, a thermal deposition-based ultrafine particle collection module and a micro-current detection module. The multi-stage differential electric mobility analyzer used in the particle size spectrum measuring device provided by the invention is provided with N monodisperse particle outlets, N groups of monodisperse ultrafine particles with different particle sizes can be screened out at the same time, namely under the high pressure of one inner electrode, the scanning time of the high pressure of the inner electrode can be reduced, and the time resolution of the particle size spectrum measurement is improved.
Description
Technical Field
The invention relates to the technical field of particle size spectrum measurement of ultrafine particles discharged by motor vehicles, in particular to a device and a method for quickly measuring a particle size spectrum of high-temperature particles based on multistage differential electromigration.
Background
In the technical field of particle size spectrum measurement of ultrafine particles discharged by motor vehicles, the electric mobility particle size of the ultrafine particles is generally distinguished and measured by utilizing the deflection degree of the ultrafine particles in an electric field. The measurement of the electric mobility and the particle size of the ultrafine particles is mainly divided into two types, namely scanning and non-scanning. Typical instruments based on the scanning mode are smps (scanning mobile Particle sizer), and typical instruments based on the non-scanning mode are eeps (engine outside Particle sizer) and dms (differential mobile Mobility spectrometer). Wherein, SMPS is a DMA (differential Mobility analyzer) and a CPC (condensation Particle counter) which are used in series, the CPC detects the number concentration of the monodisperse ultrafine particles screened out by the DMA, and the high voltage of an internal electrode in the DMA is continuously changed to complete the scanning of the Particle size spectrum; EEPS and other particle size spectrum measuring instruments based on a non-scanning mode have the advantages that the high voltage of electrodes is unchanged in the measuring period, the deflection degree of particles with different electric mobility in an electric field is different, therefore, the particles impact on grounding electrodes at different positions to discharge, EEPS and other instruments measure the current on the electrodes, and the particle size spectrum of ultrafine particles in sample gas to be measured is inverted.
The existing particle size spectrum measuring methods based on scanning mode have some problems, such as traditional SMPS, Chinese patent CN109709006A, particle size grading methods mentioned in Chinese patent CN102500559B, and the like, the used DMA only has one outlet of monodisperse particles, only one group of sample gas containing monodisperse ultrafine particles can be screened out under the high pressure of an inner electrode, the time for measuring one group of particle size spectrum is longer, the time resolution is lower, and the method is not suitable for occasions needing to measure the particle size spectrum quickly. In the particle size spectrum measuring instruments based on the non-scanning mode, such as the EEPS, the number of polar plates for receiving charged particles is limited, the particle size resolution is low, and the EEPS can not improve the particle size resolution by scanning high voltage and increasing the number of the polar plates; secondly, because the adjacent ground electrodes are close to each other, the electric leakage phenomenon exists when the high-humidity gas is measured. In addition, due to the zero drift of the electrometer caused by the high voltage of the inner electrode when the machine is started, the electrometer at the rear end of the receiving polar plate is slow in zero calibration, the preheating time of the instrument is long, and the machine is not suitable for an external field observation experiment.
In some specific situations, such as the research on the transient emission particle size spectrum characteristics of motor vehicles, the particle size spectrum of the ultrafine particles in the sample gas with high temperature and high humidity needs to be measured with higher time resolution and particle size resolution. Therefore, it is necessary to design a device and a method for measuring particle size spectrum of high-temperature particulate matter, which can improve the resolution of measurement time on the premise of ensuring the resolution of particle size.
Disclosure of Invention
The invention aims to provide a device and a method for rapidly measuring a particle size spectrum of high-temperature particles based on multi-stage differential electromigration, which can solve the defects in the prior art and realize rapid measurement of the particle size spectrum of the particles discharged by a motor vehicle.
In order to achieve the purpose, the invention adopts the following technical scheme:
the device comprises a unipolar ultrafine particle charging module, a multistage differential electromigration rate analysis module, a thermal deposition-based ultrafine particle collection module and a micro-current detection module;
the unipolar ultrafine particle charging module comprises a charging cavity, and a first sheath gas inlet, a first sample gas inlet and a mixed gas outlet which are formed in the charging cavity; the unipolar ultrafine particle charging module is used for charging polydisperse ultrafine particles, and the charged amounts of the ultrafine particles with different particle sizes are different.
The multi-stage differential electric mobility analysis module comprises a grounding shell, a base arranged at an opening at the lower end of the shell, a high-voltage electrode arranged on the base and extending upwards to the upper part in the cavity of the grounding shell, a sample gas inlet II arranged at the top of the grounding shell in a penetrating way, a sheath gas inlet II arranged on the side wall of the upper end of the grounding shell, a laminar flow device arranged in the grounding shell between the sheath gas inlet II and the bottom of the sample gas inlet II, N sample gas outlets arranged on the side wall of the grounding shell below the sample gas inlet II and a waste gas outlet arranged on the side wall of the lower end of the grounding shell; the second sample gas inlet is connected with the mixed gas outlet; and the N sample gas outlets are used for screening a group of sample gases to be detected containing the polydisperse ultrafine particles into N groups and outputting N groups of sample gases containing the monodisperse ultrafine particles.
The ultrafine particle collection module based on thermal deposition comprises N collectors corresponding to N sample gas outlets one by one; the micro-current measuring module comprises N electrometers which correspond to the N collectors one by one; the collector comprises a semiconductor heating patch, a hot metal sheet, a cold metal sheet and a semiconductor refrigerating patch which are sequentially arranged from top to bottom; the hot metal sheet and the cold metal sheet are enclosed to form a collecting cavity; the semiconductor heating patch is arranged on the top of the hot metal sheet; the semiconductor refrigeration patch is arranged at the bottom of the cold metal sheet; the collecting cavity is provided with a gas inlet and a gas outlet; the cold metal sheet is connected with a triaxial cable, one end of the triaxial cable is connected with the cold metal sheet, and the other end of the triaxial cable is connected with the electrometer; and the mixed gas outlet is connected with a second sample gas inlet, and N sample gas outlets are respectively connected with gas inlets on the collecting cavities of the N collectors. The ultrafine particle collection module based on thermal deposition is used for collecting ultrafine particles in the sample gas.
Furthermore, the mixed gas outlet is communicated with the sample gas inlet through a conductive black adhesive hose, and the N sample gas outlets are respectively connected with the gas inlets on the collecting cavities of the N collectors through a conductive black adhesive hose; the waste gas outlet is connected with the second sheath gas inlet; the waste gas flowing out of the waste gas outlet is filtered by the filter and then pumped into the second sheath gas inlet by the pump to form a relatively closed circulating gas path; the flow of the waste gas outlet is equal to that of the second sheath gas inlet, and the flow of the second sample gas inlet is equal to that of the N sample gas outlets.
Furthermore, the device also comprises a control module, wherein the control module comprises a temperature control module, a high-pressure control module and a gas flow control module.
Furthermore, the unipolar ultrafine particle charging module adopts a diffusion charging device.
Furthermore, the base is made of an insulating material.
The invention also comprises a measuring method relating to the device for rapidly measuring the particle size spectrum of the high-temperature particulate matter based on the multistage differential electromigration, and the method comprises the following steps:
(1) the sample gas to be tested containing the polydisperse ultrafine particles enters the charging cavity from the first sample gas inlet, the polydisperse ultrafine particles in the sample gas to be tested are negatively charged in the charging cavity, and the charged polydisperse ultrafine particles flow out of the charging cavity from the mixed gas outlet along with the gas flow and enter the grounding shell through the second sample gas inlet.
(2) After charged polydisperse ultrafine particles enter the grounding shell, the charged polydisperse ultrafine particles are mixed with sheath gas which enters the grounding shell from the sheath gas inlet II and is in a laminar flow state under the action of the laminar flow device, and under the action of electric field force generated by the high-voltage electrode, because of different charge quantities, monodisperse ultrafine particles in the negatively charged polydisperse ultrafine particles are deflected in different directions; under the action of an electric field force, N groups of charged monodisperse ultrafine particles with specific particle sizes flow out from N sample gas outlets respectively and enter a collecting cavity of a corresponding ultrafine particle collecting module based on thermal deposition, and the charged ultrafine particles with the rest particle sizes hit on a grounded shell to discharge or flow out from an exhaust gas outlet; the particle sizes of N groups of charged monodisperse ultrafine particles with specific particle sizes, which flow out from N sample gas outlets respectively, are sequentially increased from the top to the bottom of the multistage differential electric mobility analysis module.
(3) The semiconductor heating paster heats the hot metal sheet, the semiconductor refrigerating paster refrigerates the cold metal sheet, so that the hot metal sheet and the cold metal sheet generate temperature difference, and under the thermal diffusion effect of the hot metal sheet and the cold metal sheet, the charged monodisperse ultrafine particles are deposited on the cold metal sheet of the corresponding ultrafine particle collecting module based on thermal deposition.
(4) The charged monodisperse ultrafine particles are deposited on the cold metal sheet and then discharge to generate current, the current flows into the corresponding electrometer along the three coaxial cables, and the electrometer inverts the number concentration of each monodisperse ultrafine particle according to the measured current value.
(5) Under the same high pressure of the high-voltage electrode, N groups of specific particle diameters (D) are measured by adopting N ultrafine particle collecting modules based on thermal deposition and N electrometers11，D12，……，D1N) Is set as PN11，PN12，……，PN1N(ii) a Changing the voltage of the high voltage electrode to measure N groups of specific particle diameters (D)21，D22，……，D2N) Is set as PN21，PN22，……，PN2NRepeating the steps until the voltage of the high-voltage electrode is changed for the Mth time, namely the voltage of the high-voltage electrode is scanned for the Mth time, and obtaining the N group of specific particle diameters (D)M1，DM2，……，DMN) Number concentration of monodisperse particles PNM1，PNM2，……，PNMN(ii) a After the voltage of the high-voltage electrode is scanned for M times, M multiplied by N number concentration PN is obtained11，PN21，……，PNM1；PN12，PN22，……，PNM2，PN1N，PN2N，……，PNMNThe particle size spectrum of the polydisperse ultrafine particles in the sample gas to be detected is obtained.
Compared with the prior art, the invention has the following beneficial effects:
(1) the multi-stage differential electric mobility analyzer used in the particle size spectrum measuring device is provided with N sample gas outlets as outlets of N groups of charged monodisperse ultrafine particles with specific particle sizes, and can screen N groups of monodisperse ultrafine particles with different particle sizes at the same time, namely under the high pressure of one high-voltage electrode, so that the scanning time of the high voltage of the internal electrode can be reduced, and the time resolution of particle size spectrum measurement can be improved.
(2) The particle size spectrum measuring device provided by the invention is used for measuring the particles to be measured after being led out from the N sample gas outlets of the multistage differential mobility analyzer, the zero drift of a rear-end electrometer cannot be caused by the high-voltage change of the high-voltage electrode, and the particle size resolution can be improved by scanning the voltage of the high-voltage electrode.
(3) The ultrafine particle collection module based on thermal deposition in the particle size spectrum measurement device can measure the charge quantity of ultrafine particles in high-temperature sample gas under the condition of collecting ultrafine particles to be measured. The existing static Faraday cup can not measure the charge quantity of particles in high-temperature sample gas, and the dynamic Faraday cup can not collect the particles. The cold metal sheet in the ultrafine particle collection module based on thermal deposition protects the rear-end electrometer from high temperature, so that high-temperature sample gas can be directly measured, and the collected particles can be further applied to other experiments.
Drawings
FIG. 1 is a schematic view of the structure of a measuring apparatus according to the present invention;
FIG. 2 is a schematic diagram of the motion trajectory of particles in a multi-stage differential electro-mobility analysis module;
FIG. 3 is a schematic diagram of a particle size spectrum of polydispersed ultrafine particles in a sample gas to be measured.
Wherein:
q, unipolar ultrafine particle charging module, T, ultrafine particle collecting module based on thermal deposition, A, a microcurrent measuring module, 11, a first sample gas inlet, 12, a first sheath gas inlet, 13, a mixed gas outlet, 14, a second sample gas inlet, 15, a 1 st sample gas outlet, 16, a 2 nd sample gas outlet, 17, an N th sample gas outlet, 18, a gas inlet, 19, a gas outlet, 20, a laminar flow device, 21, a second sheath gas inlet, 22, a waste gas outlet, 23, a high-voltage electrode, 24, a grounding shell, 25, a semiconductor heating patch, 26, a hot metal sheet, 27, a semiconductor refrigerating patch, 28, a cold metal sheet, 29 and a three-coaxial cable.
Detailed Description
The invention is further described below with reference to the accompanying drawings:
the device for rapidly measuring the particle size spectrum of the high-temperature particulate matter based on multi-stage differential electromigration shown in fig. 1 comprises a unipolar ultrafine particulate matter charging module Q, a multi-stage differential electromigration rate analysis module, a ultrafine particulate matter collection module T based on thermal deposition and a micro-current detection module A.
The unipolar ultrafine particle charged module Q comprises a charged cavity, a first sheath gas inlet 12, a first sample gas inlet 11 and a mixed gas outlet 13, wherein the first sheath gas inlet 12, the first sample gas inlet 11 and the mixed gas outlet 13 are formed in the charged cavity, and the first sheath gas inlet 11 is used for introducing sheath gas into the charged cavity. The sheath gas is clean air and has the function of ensuring higher charge efficiency. The unipolar ultrafine particle charging module Q is used for charging polydisperse ultrafine particles, and the charged amounts of the ultrafine particles with different particle sizes are different.
Multistage difference electric mobility analysis module includes ground connection shell 24, install the base at 24 lower extreme openings part of ground connection shell, install on the base and upwards stretch into the high voltage electrode 23 to the interior top of 24 cavity of ground connection shell, run through and install two 14 of sample gas entry at 24 tops of ground connection shell, install two 21 of sheath gas entry on 24 upper end lateral walls of ground connection shell, install laminar flow ware 20 in the ground connection shell 24 between two 21 of sheath gas entry and two 14 bottoms of sample gas entry, set up N sample gas export 19 on the 24 lateral walls of ground connection shell below two 14 of sample gas entry and set up the exhaust outlet 22 on the lateral wall of 24 lower extreme of ground connection shell. The second sample gas inlet 14 is connected with the mixed gas outlet 13. In fig. 1, the N sample gas outlets are a first stage sample gas outlet 15 and a second stage sample gas outlet 16 … …, and an nth stage sample gas outlet 17. And the N sample gas outlets 19 are used for screening a group of sample gases to be detected containing the polydisperse ultrafine particles into N groups, and respectively outputting the N groups of sample gases containing the monodisperse ultrafine particles. The positions of the N sample gas outlets 19 are determined by L in fig. 2, i.e., the moving distance of the charged particles in the vertical direction.
The ultrafine particle collecting module T based on thermal deposition comprises N collectors corresponding to N sample gas outlets one by one; the micro-current measuring module A comprises N electrometers which correspond to the N collectors one by one; the collector comprises a semiconductor heating patch 25, a hot metal sheet 26, a cold metal sheet 28 and a semiconductor refrigerating patch 27 which are sequentially arranged from top to bottom; wherein, the semiconductor heating patch 25 is used for controlling the temperature of the hot metal sheet 26; a semiconductor cooling patch 27 for controlling the temperature of the cold metal sheet 28. The hot metal sheet 26 is used to provide the energy required for the thermal movement of the particles. The cold metal sheet 28 is used for collecting particles and electric charges carried by the particles. The hot metal sheet 26 and the cold metal sheet 28 enclose a collecting chamber. The semiconductor heating patch 25 is mounted on top of a heat metal sheet 26. The semiconductor cooling patch 27 is mounted on the bottom of a cold metal plate 28. The collection cavity is provided with a gas inlet 18 and a gas outlet 19. The cold metal sheet 28 is connected with a triaxial cable 29, one end of the triaxial cable 29 is connected with the cold metal sheet 28, and the other end is connected with the electrometer. The mixed gas outlet 13 is connected with the second sample gas inlet 14, and the N sample gas outlets 19 are respectively connected with the gas inlets 18 on the collecting cavities of the N collectors. The ultrafine particle collecting module T based on thermal deposition is used for collecting ultrafine particles in the sample gas.
Furthermore, the mixed gas outlet 13 is communicated with the second sample gas inlet 14 through a conductive black adhesive hose, and the N sample gas outlets 19 are respectively connected with the gas inlets 18 on the collecting cavities of the N collectors through a conductive black adhesive hose. The waste gas outlet 22 is connected with the second sheath gas inlet 21; the waste gas flowing out from the waste gas outlet 22 is filtered by the filter and then pumped into the second sheath gas inlet 21 by the pump to form a relatively closed circulating gas path. The flow of the waste gas outlet is equal to that of the second sheath gas inlet, and the flow of the second sample gas inlet is equal to that of the N sample gas outlets.
Furthermore, the device also comprises a control module, wherein the control module comprises a temperature control module, a high-pressure control module and a gas flow control module.
Furthermore, the unipolar ultrafine particle charging module Q adopts a diffusion charging device.
Furthermore, the base is made of an insulating material.
The moving trajectory model of the charged particles in the multi-stage differential electrical mobility analysis module is shown in fig. 2, the charged particles are negatively charged particles flowing out of the unipolar ultrafine particle charging module, a particle inlet represents a second sample gas inlet, a particle outlet represents one of N sample gas outlets, and the high voltage of the internal electrode represents the voltage of the high-voltage electrode. In the model, the airflow state is laminar flow, and the laminar flow state is ensured by sheath gas introduced from the sheath gas inlet II and the laminar flow device.
The design principle of the motion trail model is as follows:
wherein v iseRepresenting the velocity of particle movement in the electric field, ZPRepresenting the electrical mobility of the particles, E representing the electric field strength, n representing the charged number of the particles, E representing the elementary charge, CcDenotes the slip flow correction factor, kn denotes the Knudsen number, eta denotes the gas viscosity, dpIndicates the particle diameter. α, β, γ are constants. λ represents the mean free path of the gas molecule.
Denotes the particle diameter dpC is a constant, x is a constant determined by the charge performance, typically x ≈ 1.
I.e. in the device, dpEnlargement → ZPDecrease → veAnd decreases. Assuming that the moving distance of the particles in the horizontal direction is W and the moving distance in the vertical direction is L, t is W/ve，L＝t·v0Is obtained by
veDecreasing → L increasing, then, in case the particle enters the multi-stage differential electro-mobility analyzer from the same inlet and the air flow is laminar, the moving distance of the particle in the vertical direction increases with the increase of the particle size, and in the theoretical model, the particle size is in one-to-one correspondence with the moving distance in the vertical direction, and the size of the particle size can be inverted from the known L. Therefore, under the action of the high-voltage electrode with the same voltage value, N groups of monodisperse particles with different particle sizes can be obtained from N outlets of the multistage differential electric mobility analysis module.
The invention also comprises a measuring method relating to the device for rapidly measuring the particle size spectrum of the high-temperature particulate matter based on the multistage differential electromigration, and the method comprises the following steps:
(1) the sample gas to be tested containing the polydisperse ultrafine particles enters the charging cavity from the first sample gas inlet, the polydisperse ultrafine particles in the sample gas to be tested are negatively charged in the charging cavity, and the charged polydisperse ultrafine particles flow out of the charging cavity from the mixed gas outlet along with the gas flow and enter the grounding shell through the second sample gas inlet.
(2) After charged polydisperse ultrafine particles enter the grounding shell, the charged polydisperse ultrafine particles are mixed with sheath gas which enters the grounding shell from the sheath gas inlet II and is in a laminar flow state under the action of the laminar flow device, and under the action of electric field force generated by the high-voltage electrode, because of different charge quantities, monodisperse ultrafine particles in the negatively charged polydisperse ultrafine particles are deflected in different directions; under the action of an electric field force, N groups of charged monodisperse ultrafine particles with specific particle sizes flow out from N sample gas outlets respectively and enter a collecting cavity of a corresponding ultrafine particle collecting module based on thermal deposition, and the charged ultrafine particles with the rest particle sizes hit on a grounded shell to discharge or flow out from an exhaust gas outlet; the particle sizes of N groups of charged monodisperse ultrafine particles with specific particle sizes, which flow out from N sample gas outlets respectively, are sequentially increased from the top to the bottom of the multistage differential electric mobility analysis module.
(3) The semiconductor heating paster heats the hot metal sheet, the semiconductor refrigerating paster refrigerates the cold metal sheet, so that the hot metal sheet and the cold metal sheet generate temperature difference, and under the thermal diffusion effect of the hot metal sheet and the cold metal sheet, the charged monodisperse ultrafine particles are deposited on the cold metal sheet of the corresponding ultrafine particle collecting module based on thermal deposition.
(4) The charged monodisperse ultrafine particles are deposited on the cold metal sheet and then discharge to generate current, the current flows into the corresponding electrometer along the three coaxial cables, and the electrometer inverts the number concentration of each monodisperse ultrafine particle according to the measured current value.
(5) Under the same high pressure of a high-voltage electrode, N ultrafine particle collecting modules based on thermal deposition are adopted andn electrometers to measure N groups of specific particle diameters (D)11，D12，……，D1N) Is set as PN11，PN12，……，PN1N(ii) a Changing the voltage of the high voltage electrode to measure N groups of specific particle diameters (D)21，D22，……，D2N) Is set as PN21，PN22，……，PN2NRepeating the steps until the voltage of the high-voltage electrode is changed for the Mth time, namely the voltage of the high-voltage electrode is scanned for the Mth time, and obtaining the N group of specific particle diameters (D)M1，DM2，……，DMN) Number concentration of monodisperse particles PNM1，PNM2，……，PNMN(ii) a After the voltage of the high-voltage electrode is scanned for M times, M multiplied by N number concentration PN is obtained11，PN21，……，PNM1；PN12，PN22，……，PNM2，PN1N，PN2N，……，PNMNI.e. the particle size spectrum of the polydisperse ultrafine particles in the sample gas to be detected as shown in fig. 3. D11，D12，……，D1N，D21，D22，……，D2N，DM1，DM2，……，DMNIndicating different particle sizes.
The prior instrument SMPS can achieve the highest particle size resolution, and the particle size resolution depends on the high-pressure precision; the ELPI can achieve the highest time resolution within 1 s; however, SMPS scan a spectrum with high particle size resolution over 100s, ELPI has only 14 channels. The choice between the two resolutions is often left out of the other during the measurement. The invention solves the problem of slow scanning speed of the traditional SMPS, improves the measuring speed by N times, shortens the scanning time of the traditional DMA by N times, wherein N is not less than 10, and can improve the time resolution of the SMPS by one order of magnitude if N is 10. Compared with DMS and EEPS, the invention adopts a mode of scanning high-voltage electrode voltage, and can improve the resolution of the measured particle size. When EEPS and DMS are used in an external field experiment, the back-end induced current is caused by adding high voltage of an inner electrode when the EEPS and the DMS are started up, so that the zero point of the electrometer is unstable, and the zero calibration needs a long time.
The above-mentioned embodiments are merely illustrative of the preferred embodiments of the present invention, and do not limit the scope of the present invention, and various modifications and improvements of the technical solution of the present invention by those skilled in the art should fall within the protection scope defined by the claims of the present invention without departing from the spirit of the present invention.
Claims (6)
1. High temperature particulate matter particle size spectrum quick measuring device based on multistage difference electromigration, its characterized in that: the device comprises a unipolar ultrafine particle charging module, a multi-stage differential electric mobility analysis module, a thermal deposition-based ultrafine particle collection module and a micro-current detection module;
the unipolar ultrafine particle charging module comprises a charging cavity, and a first sheath gas inlet, a first sample gas inlet and a mixed gas outlet which are formed in the charging cavity;
the multi-stage differential electric mobility analysis module comprises a grounding shell, a base arranged at an opening at the lower end of the shell, a high-voltage electrode arranged on the base and extending upwards to the upper part in the cavity of the grounding shell, a sample gas inlet II arranged at the top of the grounding shell in a penetrating way, a sheath gas inlet II arranged on the side wall of the upper end of the grounding shell, a laminar flow device arranged in the grounding shell between the sheath gas inlet II and the bottom of the sample gas inlet II, N sample gas outlets arranged on the side wall of the grounding shell below the sample gas inlet II and a waste gas outlet arranged on the side wall of the lower end of the grounding shell; the second sample gas inlet is connected with the mixed gas outlet;
the ultrafine particle collection module based on thermal deposition comprises N collectors corresponding to N sample gas outlets one by one; the micro-current measuring module comprises N electrometers which correspond to the N collectors one by one; the collector comprises a semiconductor heating patch, a hot metal sheet, a cold metal sheet and a semiconductor refrigerating patch which are sequentially arranged from top to bottom; the hot metal sheet and the cold metal sheet are enclosed to form a collecting cavity; the semiconductor heating patch is arranged on the top of the hot metal sheet; the semiconductor refrigeration patch is arranged at the bottom of the cold metal sheet; the collecting cavity is provided with a gas inlet and a gas outlet; the cold metal sheet is connected with a triaxial cable, one end of the triaxial cable is connected with the cold metal sheet, and the other end of the triaxial cable is connected with the electrometer; and the mixed gas outlet is connected with a second sample gas inlet, and N sample gas outlets are respectively connected with gas inlets on the collecting cavities of the N collectors.
2. The device for rapidly measuring the particle size spectrum of the high-temperature particles based on the multi-stage differential electromigration according to claim 1, wherein: the mixed gas outlet is communicated with the sample gas inlet through a conductive black adhesive hose, and the N sample gas outlets are respectively connected with the gas inlets on the collecting cavities of the N collectors through a conductive black adhesive hose; the waste gas outlet is connected with the second sheath gas inlet; the waste gas flowing out of the waste gas outlet is filtered by the filter and then pumped into the second sheath gas inlet by the pump to form a relatively closed circulating gas path; the flow of the waste gas outlet is equal to that of the second sheath gas inlet, and the flow of the second sample gas inlet is equal to that of the N sample gas outlets.
3. The device for rapidly measuring the particle size spectrum of the high-temperature particles based on the multi-stage differential electromigration according to claim 1, wherein: the device also comprises a control module, wherein the control module comprises a temperature control module, a high-pressure control module and a gas flow control module.
4. The device for rapidly measuring the particle size spectrum of the high-temperature particles based on the multi-stage differential electromigration according to claim 1, wherein: the unipolar ultrafine particle charging module adopts a diffusion charging device.
5. The device for rapidly measuring the particle size spectrum of the high-temperature particles based on the multi-stage differential electromigration according to claim 1, wherein: the base is made of insulating materials.
6. The method for measuring the high-temperature particle size spectrum rapid measurement device based on the multi-stage differential electromigration according to any one of the claims 1 to 5, wherein: the method comprises the following steps:
(1) the sample gas to be detected containing the polydisperse ultrafine particles enters the charging cavity from the first sample gas inlet, the polydisperse ultrafine particles in the sample gas to be detected are negatively charged in the charging cavity, and the charged polydisperse ultrafine particles flow out of the charging cavity from the mixed gas outlet along with the gas flow and enter the grounding shell through the second sample gas inlet;
(2) after charged polydisperse ultrafine particles enter the grounding shell, the charged polydisperse ultrafine particles are mixed with sheath gas which enters the grounding shell from the sheath gas inlet II and is in a laminar flow state under the action of the laminar flow device, and under the action of electric field force generated by the high-voltage electrode, because of different charge quantities, monodisperse ultrafine particles in the negatively charged polydisperse ultrafine particles are deflected in different directions; under the action of an electric field force, N groups of charged monodisperse ultrafine particles with specific particle sizes flow out from N sample gas outlets respectively and enter a collecting cavity of a corresponding ultrafine particle collecting module based on thermal deposition, and the charged ultrafine particles with the rest particle sizes hit on a grounded shell to discharge or flow out from an exhaust gas outlet; the particle sizes of N groups of charged monodisperse ultrafine particles with specific particle sizes, which respectively flow out of N sample gas outlets, are sequentially increased from the top to the bottom of the multistage differential electric mobility analysis module;
(3) the semiconductor heating patch heats the hot metal sheet, the semiconductor refrigerating patch refrigerates the cold metal sheet to enable the hot metal sheet and the cold metal sheet to generate temperature difference, and under the thermal diffusion action of the hot metal sheet and the cold metal sheet, the charged monodisperse ultrafine particles are deposited on the cold metal sheet of the corresponding ultrafine particle collecting module based on thermal deposition;
(4) the charged monodisperse ultrafine particles are deposited on the cold metal sheet and then discharge to generate current, the current flows into a corresponding electrometer along the three coaxial cables, and the electrometer inverts the number concentration of each monodisperse ultrafine particle according to the measured current value;
(5) under the same high pressure of the high-voltage electrode, N ultrafine particle collecting modules based on thermal deposition and N ultrafine particle collecting modules based on thermal deposition are adoptedElectrometer, measuring N groups of specific particle diameters (D)11，D12，……，D1N) Is set as PN11，PN12，……，PN1N(ii) a Changing the voltage of the high voltage electrode to measure N groups of specific particle diameters (D)21，D22，……，D2N) Is set as PN21，PN22，……，PN2NRepeating the steps until the voltage of the high-voltage electrode is changed for the Mth time, namely the voltage of the high-voltage electrode is scanned for the Mth time, and obtaining the N group of specific particle diameters (D)M1，DM2，……，DMN) Number concentration of monodisperse particles PNM1，PNM2，……，PNMN(ii) a After the voltage of the high-voltage electrode is scanned for M times, M multiplied by N number concentration PN is obtained11，PN21，……，PNM1；PN12，PN22，……，PNM2，PN1N，PN2N，……，PNMNThe particle size spectrum of the polydisperse ultrafine particles in the sample gas to be detected is obtained.
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