Traceable calibration device and method for mobile source emission particulate matter quantity analyzer

Abstract

The present invention provides a traceable calibration device and method for a mobile source emission particulate matter quantity analyzer, and relates to the technical field of particulate matter quantity analyzers. The particle generation system in the device is used for different types of aerosol samples, and the solenoid valve system is used to control the quantitative entry of various types of aerosol samples into the particle growth system. The particle growth system is used to charge grade different types of aerosol samples to obtain aerosol samples with two charged particles, aerosol samples with three charged particles, and monodisperse aerosol samples, and to control the growth rate of the monodisperse aerosol samples by temperature to obtain grown particle samples. The particle measurement system is used to measure the grown particle samples to obtain output current and particle quantity and concentration. The present invention solves the problem of low calibration accuracy of mobile source emission particulate matter quantity measuring instruments in the prior art.

Description

Technical Field

[0001] The present invention relates to the technical field of particle quantity analyzers, and in particular to a traceable calibration device and method for a mobile source emission particle quantity analyzer. Background Art

[0002] Automobile exhaust emissions are one of the main sources of PM2.5, so improving the level of vehicle pollutant emission control and reducing the pollution emissions of a single vehicle have become one of the main ways and methods to control atmospheric particulate pollutants. In view of the above reasons, various automobile manufacturers and automobile testing institutions have purchased automobile exhaust particle number concentration measuring instruments (hereinafter referred to as PN measuring instruments) and established corresponding testing capabilities for the evaluation of particle number concentration emission performance of engines and complete vehicles and the evaluation of DPF filtration performance of particle capture systems, etc., to provide technical guidance for the technical upgrade of vehicles and accessories.

[0003] The particle number meter is a relatively complex measurement system, including a condensation particle counter (CPC), a particle sampling probe (PSP), a particle transfer tube (PTT), a sampling pre-classifier (PCF), a volatile particle remover (VPR), etc. It can be divided into two types according to its working mode: bench-top type and portable type. In order to ensure the reliability of the measurement data of the particle number meter, the metrological performance of the particle number meter used is clearly specified in the above two national VI standards, such as: counting efficiency in different particle size ranges, particle concentration attenuation coefficient, measurement linearity, removal efficiency of volatile particles, dilution ratio accuracy, etc. However, due to the lack of corresponding metrological standards in China, the above core metrological performance cannot be calibrated and effectively confirmed.

[0004] At present, the calibration of mobile source emission particle number measuring instruments is completed by comparing the instrument to be calibrated with a standard instrument. The standard instrument is usually a calibrated aerosol electrometer or condensation nucleus particle counter. However, there are the following technical problems in the comparison calibration: 1) The upper limit of the concentration calibration of the standard instrument is usually no more than 20,000 / cm 3, if you want to calibrate the particle number meter in the high concentration range, you need to connect an aerosol diluter at the entrance of the standard instrument to ensure that the measurement results of the standard instrument are within its calibration range. However, due to the introduction of the calibration uncertainty of the aerosol diluter, the uncertainty of the final calibration result increases. 2) It is difficult to produce high-concentration and large-particle aerosol samples by conventional methods, so it is impossible to effectively evaluate the indication error of the particle number concentration meter above 100nm. 3) When using an aerosol electrometer to calibrate the particle number meter, the presence of multi-charged particles in the measured aerosol will affect the calibration results. 4) The mismatch between the flow rate of the standard instrument and the calibrated instrument will lead to deviations in the calibration results. 5) When calibrating the particle number meter, the particle materials used are generally polystyrene, silver, carbon soot, NaCl, etc., and due to the differences in composition, particle size and other characteristics between mobile source exhaust and atmospheric particles, there are certain differences in the calibration results. Summary of the invention

[0005] In order to overcome the deficiencies of the prior art, the purpose of the present invention is to provide a traceable calibration device and method for a mobile source emission particulate matter quantity analyzer, which solves the problem of low calibration accuracy of mobile source emission particulate matter quantity measuring instruments in the prior art.

[0006] To achieve the above object, the present invention provides the following solutions:

[0007] A traceable calibration device for a mobile source emission particulate matter quantity analyzer, comprising:

[0008] A particle generation system, a solenoid valve system, a particle production system and a particle measurement system connected in sequence;

[0009] The particle generation system is used for different types of aerosol samples, the solenoid valve system is used to control the quantitative entry of various types of aerosol samples into the particle growth system, the particle growth system is used to charge grade the different types of aerosol samples to obtain aerosol samples with two charged particles, aerosol samples with three charged particles and monodisperse aerosol samples, and determine the concentrations of the three aerosol samples, and control the growth rate of the monodisperse aerosol samples by temperature to obtain the grown particle samples, and the particle measurement system is used to measure the grown particle samples to obtain the output current and the number and concentration of particles; wherein the solenoid valve system is set to 7 solenoid valves, and the different types of aerosol samples include: solid polystyrene aerosol samples, NaCl, Ag solid aerosol samples and carbon smoke aerosol samples.

[0010] Preferably, the particle generation system comprises:

[0011] A pneumatic atomization generator and a diffusion dryer, an evaporation condensation generator, and a soot generator all connected to the solenoid valve system;

[0012] The pneumatic atomization generator is connected to the diffusion dryer;

[0013] The pneumatic atomization generator is used to atomize a suspension containing polystyrene particles into micron-sized droplets, the diffusion dryer is used to evaporate the water phase of the micron-sized droplets to obtain a solid polystyrene aerosol sample, the evaporation condensation generator is used to generate NaCl and Ag solid aerosol samples based on air, and the soot generator is used to generate soot aerosol samples based on air.

[0014] Preferably, the particle growth system comprises:

[0015] An electrostatic neutralizer, a first differential electromigration classifier, a second differential electromigration classifier, a third differential electromigration classifier, a condensation nucleus particle counter, a T-valve, a temperature controller, and a particle grower;

[0016] The electrostatic neutralizer is connected to the solenoid valve system, the electrostatic neutralizer is respectively connected to the first differential electromigration classifier, the second differential electromigration classifier, and the third differential electromigration classifier, the condensation nucleus particle counter is respectively connected to the second differential electromigration classifier, the third differential electromigration classifier and the T-shaped valve, the first differential electromigration classifier is connected to the T-shaped valve, and the particle grower is respectively connected to the T-shaped valve and the temperature controller;

[0017] The electrostatic neutralizer is used to neutralize the charges of the different types of aerosol samples to obtain aerosol samples with electrically neutral charges. The first differential electric migration classifier is used to classify the aerosol samples with electrically neutral charges to obtain monodisperse aerosol samples. The second differential electric migration classifier is used to classify the aerosol samples with electrically neutral charges to obtain aerosol samples with two charged particles. The third differential electric migration classifier is used to classify the aerosol samples with electrically neutral charges to obtain aerosol samples with three charged particles. The condensation nucleus particle counter is used to measure the concentrations of the monodisperse aerosol samples, the aerosol samples with two charged particles, and the aerosol samples with three charged particles. The T-valve is used to control the monodisperse aerosol samples to enter the particle measurement system. The temperature controller is used to control the temperature of the particle grower. The particle grower is used to control the growth rate of the monodisperse aerosol samples according to the temperature.

[0018] Preferably, the particle measurement system comprises:

[0019] Pressure gauge, mixing and sampling tube, particle size spectrometer, aerosol electrometer, particle number meter, constant flow pump, first mass flow meter and second mass flow meter;

[0020] One end of the mixing and sampling tube is respectively connected to the T-shaped valve and the particle grower, the pressure gauge is installed at a first preset position at the front end of the mixing and sampling tube, the particle size spectrometer is arranged at a second preset position at the front end of the mixing and sampling tube, the particle number measuring instrument is arranged at a first preset position at the rear end of the mixing and sampling tube, the aerosol electrometer is arranged at a second preset position at the rear end of the mixing and sampling tube, the first mass flowmeter and the second mass flowmeter are both connected to the constant flow pump, the second mass flowmeter is connected to the other end of the mixing and sampling tube, and the first mass flowmeter is connected to the aerosol electrometer;

[0021] The mixing and sampling tube is used for the monodisperse aerosol sample, the aerosol sample with two charged particles and the aerosol sample with three charged particles. The particle size spectrometer is used to monitor the particle size distribution of the aerosol sample in real time. The pressure gauge is used to monitor the pressure in the mixing and sampling tube. The particle number meter is used to measure the number of particles. The aerosol electrometer is used to measure the output current and particle concentration of charged particles. The constant current pump is used to extract aerosol samples from the mixing and sampling tube and the aerosol electrometer. The first mass flowmeter is used to control the measurement flow of the aerosol electrometer. The second mass flowmeter is used to control the aerosol flow in the mixing and sampling tube.

[0022] A traceable calibration method for a mobile source emission particulate matter quantity analyzer, the method comprising:

[0023] Turn on the aerosol electrometer and particle number analyzer and adjust the flow rates to keep them consistent;

[0024] Respectively setting the first differential electromigration classifier, the second differential electromigration classifier, and the third differential electromigration classifier to the corresponding first preset particle size, second preset particle size, third preset particle size, first preset voltage size, second preset voltage size, and third preset voltage size, and keeping the sheath gas flow rate and the aerosol flow rate consistent;

[0025] Control the opening and closing of the corresponding electromagnetic valves in the electromagnetic valve system, respectively use the evaporation condensation generator, the pneumatic atomization generator and the soot generator to obtain solid polystyrene aerosol samples, NaCl, Ag solid aerosol samples and soot aerosol samples and transmit them to the first differential electromigration classifier, the second differential electromigration classifier and the third differential electromigration classifier to obtain aerosol samples with different charge states;

[0026] Using a condensation nucleus particle counter to measure the concentrations of the aerosol samples in different charge states respectively and obtain a particle fraction set according to the concentrations, so as to correct the measurement results of the aerosol electrometer;

[0027] According to the T-shaped valve, the aerosol sample passing through the first differential electric migration classifier enters the mixing and sampling tube, and the flow rate and pressure of the mixing and sampling tube are controlled by a mass flow controller and dilution air;

[0028] According to the measured values, average values ​​and efficiency formula of the aerosol electrometer and the particle number analyzer, the particle counting efficiency of different types of aerosol samples is obtained.

[0029] Preferably, the efficiency formula is expressed as:

[0030] ;

[0031] in, is the particle counting efficiency of the calibrated particle number analyzer; is the average value of the measurement results of the calibrated particle number analyzer, pieces / cm 3 ; is the average value of the measurement results of the aerosol electrometer, pieces / cm 3 ; is the particle counting efficiency of the aerosol electrometer, a dimensionless quantity; Carried in aerosol particles p The fraction of charged particles, a dimensionless quantity; It is the number of positive and negative charges carried by the particles, a dimensionless quantity.

[0032] The present invention discloses the following technical effects:

[0033] The present invention provides a traceable calibration device and method for a mobile source emission particulate matter quantity analyzer, the device comprising: a particle generation system, an electromagnetic valve system, a particle generation system and a particle measurement system connected in sequence; the particle generation system is used for different types of aerosol samples, the electromagnetic valve system is used to control various types of aerosol samples to quantitatively enter the particle growth system, the particle growth system is used to charge grade the different types of aerosol samples to obtain aerosol samples with two charged particles, aerosol samples with three charged particles and a monodisperse aerosol sample, and control the growth rate of the monodisperse aerosol sample by temperature to obtain grown particle samples, the particle measurement system is used to measure the grown particle samples to obtain output current and particle quantity and concentration; wherein the electromagnetic valve system is set to 7 electromagnetic valves, and the different types of aerosol samples include: solid polystyrene aerosol samples, NaCl, Ag solid aerosol samples and carbon smoke aerosol samples. The present invention can calibrate the counting efficiency of the particle number concentration measuring instrument in the range of (10-200) nm. Since the method can produce typical aerosol samples of different materials such as polystyrene, NaCl, Ag, and carbon smoke, the influence of aerosol samples of different materials on the particle counting efficiency of the particle number measuring instrument can be effectively evaluated. At the same time, the evaporation condensation generation technology is combined with the particle grower to effectively produce high concentration (106 / cm 3 ), monodisperse aerosol samples with large particle size (200nm); the measurement standard used is an aerosol electrometer with adjustable flow rate, built-in flow calibration curve, multiple charge correction factors, and flow correction factor, which can output current and particle number concentration within a large range (106 / cm 3 ) accurately measures particle number concentration with results traceable to SI units. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0035] Figure 1 A schematic structural diagram of a traceable calibration device for a mobile source emission particulate matter quantity analyzer provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0036] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0037] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0038] like Figure 1 As shown, the present invention provides a traceable calibration device for a mobile source emission particulate matter quantity analyzer, comprising:

[0039] A particle generation system, a solenoid valve system, a particle production system and a particle measurement system connected in sequence;

[0040] The particle generation system is used for different types of aerosol samples, the solenoid valve system is used to control the quantitative entry of various types of aerosol samples into the particle growth system, the particle growth system is used to charge grade the different types of aerosol samples to obtain aerosol samples with two charged particles, aerosol samples with three charged particles and monodisperse aerosol samples, and control the growth rate of the monodisperse aerosol samples by temperature to obtain grown particle samples, and the particle measurement system is used to measure the grown particle samples to obtain output current and particle number and concentration; wherein the solenoid valve system is set to 7 solenoid valves, and the different types of aerosol samples include: solid polystyrene aerosol samples, NaCl, Ag solid aerosol samples and carbon smoke aerosol samples.

[0041] Further, the particle generation system comprises:

[0042] A pneumatic atomization generator and a diffusion dryer, an evaporation condensation generator, and a soot generator all connected to the solenoid valve system;

[0043] The pneumatic atomization generator is connected to the diffusion dryer;

[0044] The pneumatic atomization generator is used to atomize a suspension containing polystyrene particles into micron-sized droplets, the diffusion dryer is used to evaporate the water phase of the micron-sized droplets to obtain a solid polystyrene aerosol sample, the evaporation condensation generator is used to generate NaCl and Ag solid aerosol samples based on air, and the soot generator is used to generate soot aerosol samples based on air.

[0045] Specifically, the particle generation system is mainly composed of a pneumatic atomizer and a diffusion dryer, an evaporation condensation generator, a soot generator, etc., wherein the pneumatic atomizer is used to atomize the suspension containing polystyrene particles into micron-sized droplets, and the water phase in the liquid evaporates under the action of the diffusion dryer, thereby obtaining a solid polystyrene aerosol sample. The evaporation condensation generator is used to produce NaCl and Ag solid aerosol samples. The soot generator is used to produce soot aerosol samples. The solenoid valves 1-6 are switched by a computer so that different materials enter the subsequent aerosols into the particle classification and growth, particle mixing and measurement systems at the back end. For example: by opening solenoid valves 4 and 7 and closing solenoid valves 3, 5, and 6, only polystyrene aerosol can enter the back-end system, and at the same time, solenoid valves 1 and 2 are opened so that other aerosol samples are emptied after filtering. By opening solenoid valves 5 and 7 and closing solenoid valves 2, 4, and 6, only NaCl (or Ag) aerosol can enter the back-end system. At the same time, solenoid valves 1 and 3 are opened to allow other aerosol samples to be exhausted after filtration. By opening solenoid valves 6 and 7 and closing solenoid valves 1, 4, and 5, only carbon smoke aerosol can enter the back-end system. At the same time, solenoid valves 2 and 3 are opened to allow other aerosol samples to be exhausted after filtration. In the evaporation condensation generation technology, powder samples such as NaCl and Ag are placed in a heating furnace. By adjusting the heating temperature, clean air flow, etc., the particle size and concentration of the aerosol sample are adjusted to produce a particle size of (10~120) nm and a concentration of not less than 108 / cm 3 NaCl and Ag aerosol samples. In the soot generation technology, the particle size and concentration of the soot aerosol sample are adjusted by adjusting the flow of combustion gas, combustion-supporting gas, etc. By adjusting the switch and flow of the solenoid valve 7, the aerosol sample can flow into the electrostatic neutralizer quantitatively, and the excess aerosol sample is filtered and discharged. In the pneumatic atomization generation technology, the particle size and concentration of the aerosol sample can be adjusted by controlling the clean air pressure and selecting polystyrene standard particles of different particle sizes, and a dry polystyrene aerosol sample is obtained after passing through a diffusion dryer.

[0046] Furthermore, the particle growth system comprises:

[0047] An electrostatic neutralizer, a first differential electromigration classifier, a second differential electromigration classifier, a third differential electromigration classifier, a condensation nucleus particle counter, a T-valve, a temperature controller, and a particle grower;

[0048] The electrostatic neutralizer is connected to the solenoid valve system, the electrostatic neutralizer is respectively connected to the first differential electromigration classifier, the second differential electromigration classifier, and the third differential electromigration classifier, the condensation nucleus particle counter is respectively connected to the second differential electromigration classifier, the third differential electromigration classifier and the T-shaped valve, the first differential electromigration classifier is connected to the T-shaped valve, and the particle grower is respectively connected to the T-shaped valve and the temperature controller;

[0049] The electrostatic neutralizer is used to neutralize the charges of the different types of aerosol samples to obtain aerosol samples with electrically neutral charges. The first differential electric migration classifier is used to classify the aerosol samples with electrically neutral charges to obtain monodisperse aerosol samples. The second differential electric migration classifier is used to classify the aerosol samples with electrically neutral charges to obtain aerosol samples with two charged particles. The third differential electric migration classifier is used to classify the aerosol samples with electrically neutral charges to obtain aerosol samples with three charged particles. The condensation nucleus particle counter is used to measure the concentrations of the monodisperse aerosol samples, the aerosol samples with two charged particles, and the aerosol samples with three charged particles. The T-valve is used to control the monodisperse aerosol samples to enter the particle measurement system. The temperature controller is used to control the temperature of the particle grower. The particle grower is used to control the growth rate of the monodisperse aerosol samples according to the temperature.

[0050] Specifically, the particle classification and growth system (particle growth system) mainly includes an electrostatic neutralizer, a differential electromigration classifier, a particle grower, a controller, etc., wherein the electrostatic neutralizer is used to neutralize the charge of the aerosol sample so that the sample is electrically neutral as a whole. Differential electromigration classifier 1 (first differential electromigration classifier) ​​is used to classify the sample according to the different electromobility of the charged particles in the electric field to obtain a monodisperse aerosol sample. Differential electromigration classifiers 2 (second differential electromigration classifier) ​​and 3 (third differential electromigration classifier) ​​classify the particles with 2 and 3 charges in the aerosol sample by setting the voltage. The particle grower contains a saturation chamber and a condensation chamber. When the monodisperse aerosol sample passes through the saturation chamber and enters the condensation chamber with a large amount of saturated steam, due to the decrease in temperature, the saturated steam will condense on the surface of the monodisperse aerosol sample, thereby causing the solid particles to grow. Since the selected working medium (carnauba wax) is solid at room temperature, the grown solid particles are solid particles. And by adjusting the temperature ratio of the condensation chamber and the saturation chamber, controllable growth of the aerosol sample can be achieved.

[0051] Furthermore, the particle measurement system comprises:

[0052] Pressure gauge, mixing and sampling tube, particle size spectrometer, aerosol electrometer, particle number meter, constant flow pump, first mass flow meter and second mass flow meter;

[0053] One end of the mixing and sampling tube is respectively connected to the T-shaped valve and the particle grower, the pressure gauge is installed at a first preset position at the front end of the mixing and sampling tube, the particle size spectrometer is arranged at a second preset position at the front end of the mixing and sampling tube, the particle number measuring instrument is arranged at a first preset position at the rear end of the mixing and sampling tube, the aerosol electrometer is arranged at a second preset position at the rear end of the mixing and sampling tube, the first mass flowmeter and the second mass flowmeter are both connected to the constant flow pump, the second mass flowmeter is connected to the other end of the mixing and sampling tube, and the first mass flowmeter is connected to the aerosol electrometer;

[0054] The mixing and sampling tube is used for the monodisperse aerosol sample, the aerosol sample with two charged particles and the aerosol sample with three charged particles. The particle size spectrometer is used to monitor the particle size distribution of the aerosol sample in real time. The pressure gauge is used to monitor the pressure in the mixing and sampling tube. The particle number meter is used to measure the number of particles. The aerosol electrometer is used to measure the output current and particle concentration of charged particles. The constant current pump is used to extract aerosol samples from the mixing and sampling tube and the aerosol electrometer. The first mass flowmeter is used to control the measurement flow of the aerosol electrometer. The second mass flowmeter is used to control the aerosol flow in the mixing and sampling tube.

[0055] Specifically, the particle mixing and measurement system mainly includes a mixing and sampling tube, a particle size spectrometer, an aerosol electrometer, a calibrated particle number meter, a constant flow pump, a mass flow controller, etc. Among them, the mixing and sampling tube is used to dilute and mix the generated aerosol samples. The front section of the mixing and sampling tube is a turbulent mixing zone for particle samples and dilution gas, and the rear end is a sampling zone, which can simultaneously realize the difference-free sampling and comparative measurement of 6 instruments. The particle size spectrometer is used to monitor the particle size distribution of the aerosol sample in real time, and the pressure gauge is used to monitor the pressure in the mixing and sampling tube, so as to realize the correction of the sampling flow of the aerosol electrometer and the particle number meter. The aerosol electrometer is a standard measuring instrument, and its measurement flow is continuously adjustable in the range of 0.3~5L / min through a mass flowmeter and a constant flow pump, and can output two measurement results: current and particle number concentration. Among them, the current measurement result is corrected by the built-in calibration curve, and the particle number concentration measurement result is corrected by multiple charges and flow. The calibrated particle number meter is an instrument for measuring the number of particles emitted from mobile sources.

[0056] This embodiment also provides a traceable calibration method for a mobile source emission particulate matter quantity analyzer, the method comprising:

[0057] Turn on the aerosol electrometer and particle number analyzer and adjust the flow rates to keep them consistent;

[0058] Respectively setting the first differential electromigration classifier, the second differential electromigration classifier, and the third differential electromigration classifier to the corresponding first preset particle size, second preset particle size, third preset particle size, first preset voltage size, second preset voltage size, and third preset voltage size, and keeping the sheath gas flow rate and the aerosol flow rate consistent;

[0059] Control the opening and closing of the corresponding electromagnetic valves in the electromagnetic valve system, respectively use the evaporation condensation generator, the pneumatic atomization generator and the soot generator to obtain solid polystyrene aerosol samples, NaCl, Ag solid aerosol samples and soot aerosol samples and transmit them to the first differential electromigration classifier, the second differential electromigration classifier and the third differential electromigration classifier to obtain aerosol samples with different charge states;

[0060] Using a condensation nucleus particle counter to measure the concentrations of the aerosol samples in different charge states respectively and obtain a particle fraction set according to the concentrations, so as to correct the measurement results of the aerosol electrometer;

[0061] According to the T-shaped valve, the aerosol sample passing through the first differential electric migration classifier enters the mixing and sampling tube, and the flow rate and pressure of the mixing and sampling tube are controlled by the second mass flow meter and the dilution air;

[0062] According to the measured values, average values ​​and efficiency formula of the aerosol electrometer and the particle number analyzer, the particle counting efficiency of different types of aerosol samples is obtained.

[0063] Specifically, the calibration method of the particle counting efficiency of the particle number analyzer includes the following steps (taking the counting efficiency of 100nm and 200nm as an example):

[0064] Step 1: Turn on the aerosol electrometer and particle number analyzer and adjust their measuring flow rates to be consistent. Allow them to stabilize for at least 2 hours.

[0065] Step 2: Set the particle size of the differential electromigration classifier 1 to 100 nm (corresponding to a voltage of U ), and then set the voltage of differential electromigration classifier 2 and 3 to 2 U and 3 U， The classification particle sizes are made to be 146 nm and 195 nm respectively, and the sheath gas flow rate and aerosol flow rate of the differential electromigration classifiers 1, 2 and 3 should be kept consistent.

[0066] Step 3: Open solenoid valve 2 and place NaCl solid particles in the evaporation condensation generator. Set the temperature of the evaporation condensation generator tube furnace to (700±20)℃ and the carrier gas flow rate to (2~10)L / min.

[0067] Step 4: Open the solenoid valve 3, drop the 100 nm polystyrene suspension into the liquid storage bottle of the pneumatic atomizer, introduce compressed air into the pneumatic atomizer and adjust the atomization pressure.

[0068] Step 5: Open the solenoid valve 1, introduce the combustion gas (propane) and the combustion-supporting gas (air) into the soot generator, turn on the electronic igniter to allow the combustion gas to burn stably and generate soot aerosol particles quantitatively.

[0069] Step 6: Close the solenoid valve 2 and open the solenoid valve 5, so that the NaCl aerosol sample passes through the aerosol splitter and enters the differential electromigration classifiers 1, 2 and 3 respectively, and generates a monodisperse aerosol sample with a positive charge.

[0070] Step 7: Use a condensation nucleus particle counter to measure the particle concentrations of differential electromigration classifiers 1, 2, and 3, respectively, and record them as , , The computer calculates the fraction of particles carrying one, two, and three charges in the 100 nm aerosol sample according to the following formula.

[0071]

[0072]

[0073]

[0074]

[0075]

[0076] Where:

[0077] is the particle counting efficiency of the condensation nucleus particle counter, a dimensionless quantity; , is the particle number concentration of monodisperse aerosol samples with a particle size of 146 nm and 1 or 2 positive charges on the surface, particles / cm 3 ; , is the charge probability of a particle with a diameter of 146 nm and one or two positive charges on the surface, , is the particle number concentration of monodisperse aerosol samples with a particle size of 195 nm and 1 and 3 positive charges on the surface, respectively, particles / cm 3 ; , It is the fraction of particles with a diameter of 146nm and 1 or 3 positive charges on the surface.

[0078] Step 8: Switch the T-shaped valve to allow the aerosol sample classified by the differential electromigration classifier 1 to enter the mixing and sampling tube.

[0079] Step 9: Control the flow rate of the mass flow controller within the range of (1~5) L / min, and introduce dilution air so that the pressure indication value is within the range of (-30-0) kPa.

[0080] Step 10: Record the measured values ​​and average values ​​of the aerosol electrometer and the particle number analyzer, and calculate the particle counting efficiency of the particle number analyzer for the 100 nm polystyrene sample according to formula (6).

[0081] (6)

[0082] is the particle counting efficiency of the calibrated particle number analyzer; is the average value of the measurement results of the calibrated particle number analyzer, pieces / cm 3 ; is the average value of the measurement results of the aerosol electrometer, pieces / cm 3 ; is the particle counting efficiency of the aerosol electrometer, a dimensionless quantity; Carried in aerosol particles p The fraction of charged particles, a dimensionless quantity; It is the number of positive and negative charges carried by the particles, a dimensionless quantity.

[0083] Step 11: Close solenoid valves 3 and 5, and open solenoid valves 2 and 4, so that the polystyrene aerosol sample passes through the aerosol splitter and enters the differential electromigration classifiers 1, 2, and 3 respectively, and generates a monodisperse aerosol sample with a positive charge. Then repeat steps 7 to 10 to obtain the particle counting efficiency of the particle number analyzer for the 100nm polystyrene sample.

[0084] Step 12: Close solenoid valves 1 and 5, and open solenoid valves 2 and 6, so that the soot aerosol sample passes through the aerosol splitter and enters the differential electromigration classifiers 1, 2, and 3 respectively, and generates a monodisperse aerosol sample with a positive charge. Then repeat steps 7 to 10 to obtain the particle counting efficiency of the particle number analyzer for the 100nm soot sample.

[0085] Step 13: When calibrating the counting efficiency of the particle number analyzer for a 200nm aerosol sample, first repeat steps 1 to 7, then switch the T-valve so that the aerosol sample classified by the differential electromigration classifier 1 enters the particle grower, and adjust the temperature of the saturation chamber and the condensation chamber in the particle grower to (100-300)℃ and (10-50)℃, respectively, so that the working medium in the grower condenses on the particle surface and grows to 200nm. The particle size of the grown particle sample is monitored using a particle size spectrometer. Repeat steps 9-10 to obtain the particle counting efficiency of the particle number analyzer for a 200nm sample.

[0086] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0087] The principles and implementation methods of the present invention are described in this article using specific examples. The description of the above embodiments is only used to help understand the method and core idea of ​​the present invention. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A traceable calibration device for a mobile source emission particulate matter quantity analyzer, characterized in that: include: A particle generation system, a solenoid valve system, a particle growth system and a particle measurement system connected in sequence; The particle generation system is used for different types of aerosol samples, the solenoid valve system is used to control the quantitative entry of various types of aerosol samples into the particle growth system, the particle growth system is used to charge grade the different types of aerosol samples to obtain monodisperse aerosol samples, aerosol samples with two charged particles, and aerosol samples with three charged particles, and determine the concentrations of the three aerosol samples, and control the growth rate of the monodisperse aerosol sample by temperature to obtain the grown particle sample, and the particle measurement system is used to measure the grown particle sample to obtain the output current and the particle number concentration; wherein the solenoid valve system is set to 7 solenoid valves, and the different types of aerosol samples include: solid polystyrene aerosol samples, NaCl, Ag solid aerosol samples and carbon smoke aerosol samples; The particle generation system comprises: A pneumatic atomization generator and a diffusion dryer, an evaporation condensation generator, and a soot generator all connected to the solenoid valve system; The pneumatic atomization generator is connected to the diffusion dryer; The pneumatic atomization generator is used to atomize the suspension containing polystyrene particles into micron-sized droplets, the diffusion dryer is used to evaporate the water phase of the micron-sized droplets to obtain a solid polystyrene aerosol sample, the evaporation condensation generator is used to generate NaCl and Ag solid aerosol samples according to air, and the soot generator is used to generate a soot aerosol sample according to air; The particle growth system comprises: An electrostatic neutralizer, a first differential electromigration classifier, a second differential electromigration classifier, a third differential electromigration classifier, a condensation nucleus particle counter, a T-valve, a temperature controller, and a particle grower; The electrostatic neutralizer is connected to the solenoid valve system, the electrostatic neutralizer is respectively connected to the first differential electromigration classifier, the second differential electromigration classifier, and the third differential electromigration classifier, the condensation nucleus particle counter is respectively connected to the second differential electromigration classifier, the third differential electromigration classifier and the T-shaped valve, the first differential electromigration classifier is connected to the T-shaped valve, and the particle grower is respectively connected to the T-shaped valve and the temperature controller; The electrostatic neutralizer is used to neutralize the charges of the different types of aerosol samples to obtain aerosol samples with electrically neutral charges. The first differential electric migration classifier is used to classify the aerosol samples with electrically neutral charges to obtain monodisperse aerosol samples. The second differential electric migration classifier is used to classify the aerosol samples with electrically neutral charges to obtain aerosol samples with two charged particles. The third differential electric migration classifier is used to classify the aerosol samples with electrically neutral charges to obtain aerosol samples with three charged particles. The condensation nucleus particle counter is used to measure the concentrations of the monodisperse aerosol samples, the aerosol samples with two charged particles, and the aerosol samples with three charged particles. The T-valve is used to control the monodisperse aerosol samples to enter the particle measurement system. The temperature controller is used to control the temperature of the particle grower. The particle grower is used to control the growth rate of the monodisperse aerosol samples according to the temperature.

2. The traceable calibration device for a mobile source emission particulate matter quantity analyzer according to claim 1, characterized in that: The particle measurement system comprises: Pressure gauge, mixing and sampling tube, particle size spectrometer, aerosol electrometer, particle number meter, constant flow pump, first mass flow meter and second mass flow meter; One end of the mixing and sampling tube is respectively connected to the T-shaped valve and the particle grower, the pressure gauge is installed at a first preset position at the front end of the mixing and sampling tube, the particle size spectrometer is arranged at a second preset position at the front end of the mixing and sampling tube, the particle number measuring instrument is arranged at a first preset position at the rear end of the mixing and sampling tube, the aerosol electrometer is arranged at a second preset position at the rear end of the mixing and sampling tube, the first mass flowmeter and the second mass flowmeter are both connected to the constant flow pump, the second mass flowmeter is connected to the other end of the mixing and sampling tube, and the first mass flowmeter is connected to the aerosol electrometer; The mixing and sampling tube is used for the monodisperse aerosol sample, the aerosol sample with two charged particles and the aerosol sample with three charged particles. The particle size spectrometer is used to monitor the particle size distribution of the aerosol sample in real time. The pressure gauge is used to monitor the pressure in the mixing and sampling tube. The particle number meter is used to measure the number of particles. The aerosol electrometer is used to measure the output current and particle concentration of charged particles. The constant current pump is used to extract aerosol samples from the mixing and sampling tube and the aerosol electrometer. The first mass flowmeter is used to control the measurement flow of the aerosol electrometer. The second mass flowmeter is used to control the aerosol flow in the mixing and sampling tube.

3. A traceable calibration method for a mobile source emission particulate matter quantity analyzer, applied to the device described in any one of claims 1-2, characterized in that: The method comprises: Turn on the aerosol electrometer and particle number analyzer and adjust the flow rates to keep them consistent; Respectively setting the first differential electromigration classifier, the second differential electromigration classifier, and the third differential electromigration classifier to the corresponding first preset particle size, second preset particle size, third preset particle size, first preset voltage size, second preset voltage size, and third preset voltage size, and keeping the sheath gas flow rate and the aerosol flow rate consistent; Control the opening and closing of the corresponding electromagnetic valves in the electromagnetic valve system, respectively use the evaporation condensation generator, the pneumatic atomization generator and the soot generator to obtain solid polystyrene aerosol samples, NaCl, Ag solid aerosol samples and soot aerosol samples and transmit them to the first differential electromigration classifier, the second differential electromigration classifier and the third differential electromigration classifier to obtain aerosol samples with different charge states; Using a condensation nucleus particle counter to measure the concentrations of the aerosol samples in different charge states respectively and obtain a particle fraction set according to the concentrations, so as to correct the measurement results of the aerosol electrometer; According to the T-shaped valve, the aerosol sample passing through the first differential electric migration classifier enters the mixing and sampling tube, and the flow rate and pressure of the mixing and sampling tube are controlled by the second mass flow meter and the dilution air; According to the measured values, average values ​​and efficiency formula of the aerosol electrometer and the particle number analyzer, the particle counting efficiency of different types of aerosol samples is obtained.

4. The traceable calibration method of a mobile source emission particulate matter quantity analyzer according to claim 3 is characterized in that: The expression of the efficiency formula is: ； in, is the particle counting efficiency of the calibrated particle number analyzer; is the average value of the measurement results of the calibrated particle number analyzer; is the average value of the measurement results of the aerosol electrometer; is the particle counting efficiency of the aerosol electrometer; Carried in aerosol particles p The fraction of particles with a charge; is the number of positive and negative charges carried by the particle, and n is a natural number.

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