Measurement method and measurement equipment for sub-micron aerosol particle size charged quantity

Abstract

The invention discloses a method and equipment for measuring the charged quantity of sub-micron aerosol according to particle sizes. According to the invention, the number of the aerosols with the set particle size in the first mode which does not pass through the neutralizer and the number of the aerosols with the set particle size in the first mode which passes through the neutralizer are combined with the probability distribution that the aerosol with each particle size carries one charge after passing through the neutralizer; the probability distribution that the sub-micron aerosol has a charge in the environment is obtained; according to the invention, the charged characteristic of the aerosol with different particle sizes in the range of 140-700nm is measured, the charged characteristic of the sub-micron aerosol with different particle sizes in the atmospheric environment is measured with high time resolution, the measured particle size of the charged characteristic of the atmospheric aerosol is broadened, and the measured time resolution is improved to 5 minutes; and the physical and chemical process of the atmospheric aerosol can be better understood.

Description

Technical Field

[0001] The present invention relates to aerosol particle size charge measurement technology, and in particular to a method for measuring the charge of sub-micron aerosol particles by particle size and a measuring device thereof. Background Art

[0002] Aerosols (ions) are universally charged in the atmosphere. When charged, aerosols significantly influence the formation of new particles in the atmosphere, increase their stability in the environment, reduce their volatility, and accelerate their particle size growth. Therefore, accurately measuring the charge characteristics of ambient atmospheric aerosols is crucial for understanding the atmospheric chemistry and physical processes of atmospheric aerosols. Currently, the primary instrument for measuring aerosol charge properties is the air ion particle size spectrometer developed at the University of Tartu, Estonia, which can measure the size-specific charge characteristics of aerosols in the 1 to 40 nm range. However, the average particle size of aerosols that contributes most to the number of atmospheric aerosols is between 100 nm and 200 nm, while the average particle size that contributes most to the mass of atmospheric aerosols is between 500 nm and 700 nm. Currently, there are no methods or equipment to measure the size-specific charge characteristics of aerosols in the 100 to 700 nm range, significantly limiting our understanding of the physical and chemical processes of atmospheric aerosols. Summary of the Invention

[0003] In response to the above problems in the prior art, the present invention proposes a method and device for measuring the charge of sub-micron aerosol particles by size, which can achieve high time resolution measurement of the charge characteristics of sub-micron aerosol particles by size in the atmospheric environment.

[0004] One purpose of the present invention is to provide a method for measuring the charge of sub-micron aerosol particles by particle size.

[0005] The method for measuring the charge amount of submicron aerosol by particle size of the present invention comprises the following steps:

[0006] 1) Device connection:

[0007] The neutralizer is connected to the input end of the electric mobility particle size analyzer through a pipeline through a pipeline switching device; the output end of the electric mobility particle size analyzer is connected to the optical particle counter; the pipeline switching device is connected to a computer, and the pipeline switching device is controlled by the computer to control the flow path of the aerosol;

[0008] 2) Measure the number of aerosols with the particle size set in the first mode without passing through the combiner:

[0009] a) Using a computer to control the pipeline switching device, the aerosol to be measured is directly input into the electric mobility particle size analyzer without passing through the neutralizer;

[0010] b) setting the passing particle size of the electric mobility particle size analyzer so that the aerosol passing through the electric mobility particle size analyzer has the set particle size Dp and remains in the electric mobility particle size analyzer for the set time;

[0011] c) transmitting the aerosol of the set particle size to an optical counter; the optical counter records in real time the frequency distribution of the optical scattering intensity of the aerosol that does not pass through the neutralizer at each particle size set by the electric mobility particle size analyzer in step 2) b);

[0012] d) Based on the frequency distribution of the optical scattering intensity of the aerosol that does not pass through the neutralizer measured in step 2) c), record the number of aerosols with the particle size Dp set in the first mode that does not pass through the neutralizer

[0013] e) Increase the number of particle size steps between 140nm and 700nm, and repeat steps b) to d) at the set time interval to obtain the number of aerosols with the particle size Dp set in the first mode that do not pass through the neutralizer.

[0014] 3) Measure the number of aerosols of the particle size set in the first mode passing through the combiner:

[0015] a) Using a computer to control the pipeline switching device, the aerosol to be measured first passes through the neutralizer and then is input into the electric mobility particle size analyzer;

[0016] b) The aerosol to be measured passes through a neutralizer, which can change the charge distribution of the aerosol and obtain the probability distribution of each aerosol particle size carrying a charge after passing through the neutralizer;

[0017] c) The aerosol output from the combiner is input to an electric mobility particle size analyzer. By setting the passing particle size of the electric mobility particle size analyzer, the aerosol passing through the electric mobility particle size analyzer has a set particle size Dp and remains in the electric mobility particle size analyzer for a set time;

[0018] d) transmitting the aerosol of the set particle size to an optical counter; the optical counter records in real time the frequency distribution of the optical scattering intensity of the aerosol passing through the neutralizer at each particle size set by the electric mobility particle size analyzer in step c) of step 3);

[0019] e) Based on the frequency distribution of the optical scattering intensity of the aerosol passing through the neutralizer measured in step 3) (d), record the number of aerosols with a set particle size Dp in the first mode passing through the neutralizer.

[0020] f) Increase the number of particle size steps between 140nm and 700nm and repeat the steps at the set time intervals.

[0021] 3) c) ~ e), get the number of aerosols with the particle size Dp set in the first mode of the neutralizer

[0022]

[0023] 4) For a given particle size Dp, the probability distribution of an aerosol carrying a charge in the environment is:

[0024]

[0025] in, The probability distribution of an aerosol of a set particle size carrying a charge after passing through the neutralizer is obtained from step 3) b).

[0026] Wherein, in step 1), the pipeline switching device adopts a first three-way solenoid valve and a second three-way solenoid valve; wherein, the aerosol to be measured is connected to the first port of the first three-way solenoid valve through a pipeline, and the second port of the first three-way solenoid valve is connected to the input end of the combiner through a pipeline; the output end of the combiner is connected to the second port of the second three-way solenoid valve through a pipeline; the third port of the first three-way solenoid valve is connected to the first port of the second three-way solenoid valve through a pipeline; the third port of the second three-way solenoid valve is connected to the input end of the electric mobility particle size analyzer through a pipeline; the first three-way solenoid valve and the second three-way solenoid valve are respectively connected to a computer.

[0027] In step 2) a), the second port of the first three-way solenoid valve and the second port of the second three-way solenoid valve are closed by computer control, and the first port and the third port of the first three-way solenoid valve and the first port and the third port of the second three-way solenoid valve are opened, and the aerosol to be measured is directly input into the electric mobility particle size analyzer without passing through the neutralizer.

[0028] In step 2) b), the particle size is set to 140 to 700 nm; and the duration is set to 5 to 10 seconds.

[0029] In step 2) d), the time interval is set to 5 to 10 seconds, which is consistent with the continuous time set in step 2) b). The time interval does not affect the measurement results and effects, but only changes the time resolution of the data. The smaller the time interval, the higher the time resolution of the data. However, if the time interval is less than 5 seconds, the uncertainty increases, so the minimum time is 5 seconds; the set particle size step number is 5 to 10 nm.

[0030] In step 3) a), the third port of the first three-way solenoid valve and the first port of the second three-way solenoid valve are closed by computer control, and the first port and the second port of the first three-way solenoid valve and the second port and the third port of the second three-way solenoid valve are opened, so that the aerosol to be measured first passes through the neutralizer and then is input into the electric mobility particle size analyzer.

[0031] In step c) of step 3), the duration set is consistent with the duration set in step b) of step 2).

[0032] In step 3) f), the set time interval is consistent with the duration set in step 3) c).

[0033] Another object of the present invention is to provide a device for measuring the charge of sub-micron aerosol particles by particle size.

[0034] The device for measuring the charge quantity of sub-micron aerosol by particle size of the present invention comprises: a pipeline switching device, a neutralizer, an electric mobility particle size analyzer, an optical particle counter, and a computer; wherein the neutralizer is connected to the input end of the electric mobility particle size analyzer via a pipeline through the pipeline switching device; the output end of the electric mobility particle size analyzer is connected to the optical particle counter; the pipeline switching device is connected to the computer, and the pipeline switching device is controlled by the computer to control the flow path of the aerosol;

[0035] When measuring the number of aerosols of a particle size set in the first mode without passing through the neutralizer, the computer controls the aerosol to be measured to be input into the electric mobility particle size analyzer and the optical particle counter in sequence without passing through the neutralizer, thereby obtaining the number of aerosols of all particle sizes set in the first mode without passing through the neutralizer; when measuring the number of aerosols of a particle size set in the first mode without passing through the neutralizer, the computer controls the pipeline switching device to make the aerosol to be measured pass through the neutralizer first, thereby changing the charge distribution of the aerosol, thereby obtaining the number of each aerosol. The probability distribution of aerosols of a certain particle size carrying a charge after passing through the neutralizer is then input into the electric mobility particle size analyzer and the optical particle counter in sequence to obtain the number of aerosols of the particle size set in the first mode that all pass through the neutralizer; based on the number of aerosols of the particle size set in the first mode that does not pass through the neutralizer and the number of aerosols of the particle size set in the first mode that passes through the neutralizer, combined with the probability distribution of aerosols of the particle size carrying a charge after passing through the neutralizer, the probability distribution of aerosols of the set particle size carrying a charge in the environment is obtained.

[0036] The pipeline switching device adopts a first three-way solenoid valve and a second three-way solenoid valve; wherein, the aerosol to be measured is connected to the first port of the first three-way solenoid valve through a pipeline, and the second port of the first three-way solenoid valve is connected to the input end of the combiner through a pipeline; the output end of the combiner is connected to the second port of the second three-way solenoid valve through a pipeline; the third port of the first three-way solenoid valve is connected to the first port of the second three-way solenoid valve through a pipeline; the third port of the second three-way solenoid valve is connected to the input end of the electric mobility particle size analyzer through a pipeline; the first three-way solenoid valve and the second three-way solenoid valve are respectively connected to a computer.

[0037] Advantages of the present invention:

[0038] The present invention uses the number of aerosols with a particle size set in the first mode that does not pass through the neutralizer and the number of aerosols with a particle size set in the first mode that passes through the neutralizer, combined with the probability distribution of aerosols of each particle size carrying a charge after passing through the neutralizer, to obtain the probability distribution of sub-micron aerosol particle sizes carrying a charge in the environment; the present invention measures the charge characteristics of aerosol particle sizes in the range of 140 to 700 nm, achieves high-time-resolution measurement of the charge characteristics of sub-micron aerosol particle sizes in the atmospheric environment, broadens the measurement particle size of the charge characteristics of atmospheric aerosols and increases the time resolution of the measurement to 5 minutes, which can help to better understand the physical and chemical processes of atmospheric aerosols. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 Schematic diagram of an embodiment of a device for measuring the charge amount of sub-micron aerosol particles by size according to the present invention;

[0040] Figure 2 FIG1 is a frequency distribution diagram of the optical scattering intensity of aerosol that does not pass through a neutralizer, obtained according to an embodiment of the method for measuring the charge amount of sub-micron aerosol by particle size of the present invention. DETAILED DESCRIPTION

[0041] The present invention will be further described below through specific embodiments in conjunction with the accompanying drawings.

[0042] The method for measuring the charge of sub-micron aerosol particles by particle size in this embodiment includes the following steps:

[0043] 1) Device connection, such as Figure 1 As shown:

[0044] The aerosol to be measured is connected to the first port of a first three-way solenoid valve through a pipe, and the second port of the first three-way solenoid valve is connected to the input end of a combiner through a pipe; the output end of the combiner is connected to the second port of a second three-way solenoid valve through a pipe; the third port of the first three-way solenoid valve is connected to the first port of the second three-way solenoid valve through a pipe; the third port of the second three-way solenoid valve is connected to the input end of an electric mobility particle size analyzer through a pipe; the output end of the electric mobility particle size analyzer is connected to an optical particle counter; the first and second three-way solenoid valves are respectively connected to a computer, and the first and second three-way solenoid valves are controlled by the computer to control the flow path of the aerosol;

[0045] 2) Measure the number of aerosols with the particle size set in the first mode without passing through the combiner:

[0046] a) by computer control, closing the second port of the first three-way solenoid valve and the second port of the second three-way solenoid valve, and opening the first port and the third port of the first three-way solenoid valve and the first port and the third port of the second three-way solenoid valve, so that the aerosol passes through Figure 1 In the short-dashed line pipeline, the aerosol to be measured is directly input into the electric mobility particle size analyzer without passing through the neutralizer;

[0047] b) By setting the passing particle size of the electric mobility particle size analyzer, the aerosol passing through is the set particle size

[0048] Dp, and lasts for 5s in the electric mobility particle size analyzer;

[0049] c) The aerosol of the set particle size is transmitted to the optical counter; the optical counter records in real time the frequency distribution of the optical scattering intensity of the aerosol that does not pass through the neutralizer at each particle size set by the electric mobility particle size analyzer in step 2) b); wherein the frequency distribution of the aerosol of the set particle size that does not pass through the neutralizer is measured as follows Figure 2 As shown in the figure, only by obtaining the frequency distribution of the optical scattering intensity of the aerosol can the number of aerosols with the particle size Dp set in the first mode be obtained; wherein multiple modes may appear in the optical scattering intensity, which are the scattering intensities of aerosols with 1 charge, 2 charges, and 3 charges from left to right respectively;

[0050] d) Based on the frequency distribution of the optical scattering intensity of the aerosol that does not pass through the neutralizer measured in step 2) c), record the number of aerosols with the particle size Dp set in the first mode that does not pass through the neutralizer

[0051] e) Between 140 nm and 700 nm, increase the particle size by 10 nm, and repeat steps b) to d) at a set time interval of 5 seconds to obtain the number of aerosols with the particle size Dp set in the first mode that do not pass through the neutralizer. Where Dp = 140, 150, 160 ... 700 nm, the required time is 290 seconds. The other 10 seconds are used to set the passing particle size of the electric mobility particle size analyzer to 140 nm as equipment preparation time.

[0052] 3) Measure the number of aerosols of the particle size set in the first mode passing through the combiner:

[0053] a) By computer control, the third port of the first three-way solenoid valve and the first port of the second three-way solenoid valve are closed, and the first port and the second port of the first three-way solenoid valve and the second port and the third port of the second three-way solenoid valve are opened, so that the aerosol to be measured is Figure 1 The middle long dashed line pipeline first passes through the combiner and then inputs into the electric mobility particle size analyzer;

[0054] b) The aerosol to be measured passes through a neutralizer, which can change the probability distribution of the aerosol's charge, obtaining the probability distribution of each aerosol particle size carrying a charge after passing through the neutralizer;

[0055] c) The aerosol output from the combiner is input to the electric mobility particle size analyzer. By setting the passing particle size of the electric mobility particle size analyzer, the aerosol passing through the electric mobility particle size analyzer is set to the particle size Dp, and the aerosol is continuously in the electric mobility particle size analyzer for 5 seconds;

[0056] d) transmitting the aerosol of the set particle size to an optical counter; the optical counter records in real time the frequency distribution of the optical scattering intensity of the aerosol passing through the neutralizer at each particle size set by the electric mobility particle size analyzer in step c) of step 3);

[0057] e) Based on the frequency distribution of the optical scattering intensity of the aerosol passing through the neutralizer measured in step 3) (d), record the number of aerosols with a set particle size Dp in the first mode passing through the neutralizer.

[0058] f) Between 140 nm and 700 nm, increase the particle size by 10 nm, and repeat steps c) to e) of step 3) at a set time interval of 5 s to obtain the number of aerosols with the set particle size Dp in the first mode passing through the neutralizer.

[0059] 4) For a given particle size Dp, the probability distribution P of an aerosol with a charge in the environment isDp for:

[0060]

[0061] in, The probability distribution of an aerosol of a set particle size carrying a charge after passing through the neutralizer is obtained from step 3) b).

[0062] Finally, it should be noted that the purpose of disclosing the embodiments is to facilitate a further understanding of the present invention. However, those skilled in the art will appreciate that various substitutions and modifications are possible without departing from the spirit and scope of the present invention and the appended claims. Therefore, the present invention should not be limited to the contents disclosed in the embodiments; the scope of protection claimed by the present invention shall be determined by the scope defined in the claims.

Claims

1. A method for measuring the charge of sub-micron aerosol by particle size, characterized in that: The measuring method comprises the following steps: 1) Device connection: The neutralizer is connected to the input end of the electric mobility particle size analyzer through a pipeline through a pipeline switching device; the output end of the electric mobility particle size analyzer is connected to the optical particle counter; the pipeline switching device is connected to a computer, and the pipeline switching device is controlled by the computer to control the flow path of the aerosol; 2) Measure the number of aerosols of the particle size set in the first mode without passing through the combiner: a) Controlling the pipeline switching device by a computer so that the aerosol to be measured is directly input into the electric mobility particle size analyzer without passing through the neutralizer; b) setting the passing particle size of the electric mobility particle size analyzer so that the aerosol passing through the electric mobility particle size analyzer has a set particle size Dp and remains in the electric mobility particle size analyzer for a set time; c) The aerosol of the set particle size is transmitted to the optical counter; the optical counter records in real time in step 2) b), Frequency distribution of optical scattering intensity of aerosol without neutralizer for each particle size set by the electric mobility particle size analyzer; d) Based on the frequency distribution of the optical scattering intensity of the aerosol that does not pass through the neutralizer measured in step 2) c), record the number N of aerosols with a set particle size Dp in the first mode that does not pass through the neutralizer D 1 p ; e) Increase the number of particle size steps between 140 nm and 700 nm, and repeat steps b) to d) at the set time interval to obtain the number N of aerosols with the set particle size Dp in the first mode that does not pass through the neutralizer. D 1 p ; 3) Measure the number of aerosols of the particle size set in the first mode passing through the neutralizer: a) Controlling the pipeline switching device by computer, the aerosol to be measured first passes through the neutralizer and then is input into the electric mobility particle size analyzer; b) The aerosol to be measured passes through a neutralizer, which can change the charge distribution of the aerosol and obtain the probability distribution of each particle size of the aerosol carrying a charge after passing through the neutralizer; c) The aerosol output from the combiner is input to the electric mobility particle size analyzer, and the aerosol passing through the electric mobility particle size analyzer is set to a set particle size Dp by setting the passing particle size of the electric mobility particle size analyzer, and is kept in the electric mobility particle size analyzer for a set time; d) The aerosol of the set particle size is transmitted to the optical counter; the optical counter records in real time in step 3) c), Frequency distribution of the optical scattering intensity of the aerosol passing through the neutralizer for each particle size set by the electric mobility particle size analyzer; e) According to the frequency distribution of the optical scattering intensity of the aerosol passing through the neutralizer measured in step 3) (d), record the number of aerosols with a set particle size Dp in the first mode passing through the neutralizer f) Increase the number of particle size steps between 140nm and 700nm, and repeat step 3) c) to e) at the set time interval to obtain the number of aerosols with the set particle size Dp in the first mode passing through the neutralizer. 4) For a set particle size Dp, the probability distribution of an aerosol carrying a charge in the environment is: in, The probability distribution of an aerosol of a set particle size carrying a charge after passing through the neutralizer is obtained from step 3) b).

2. The measuring method according to claim 1, characterized in that: In step 1), the pipeline switching device adopts a first three-way solenoid valve and a second three-way solenoid valve; wherein, the aerosol to be measured is connected to the first port of the first three-way solenoid valve through a pipeline, and the second port of the first three-way solenoid valve is connected to the input end of the combiner through a pipeline; the output end of the combiner is connected to the second port of the second three-way solenoid valve through a pipeline; the third port of the first three-way solenoid valve is connected to the first port of the second three-way solenoid valve through a pipeline; the third port of the second three-way solenoid valve is connected to the input end of the electric mobility particle size analyzer through a pipeline; the first three-way solenoid valve and the second three-way solenoid valve are respectively connected to a computer.

3. The measuring method according to claim 2, characterized in that: In step 2) a), by computer control, the second port of the first three-way solenoid valve and the second port of the second three-way solenoid valve are closed, and the first port and the third port of the first three-way solenoid valve and the first port and the third port of the second three-way solenoid valve are opened, and the aerosol to be measured is directly input into the electric mobility particle size analyzer without passing through the neutralizer.

4. The measuring method according to claim 1, characterized in that: In step 2) b), the particle size is set to 140 to 700 nm.

5. The measuring method according to claim 1, characterized in that: In step 2) b), the duration is set to 5 to 10 seconds.

6. The measuring method according to claim 1, characterized in that: In step 2) d), the time interval is set to 5 to 10 seconds.

7. The measuring method according to claim 1, characterized in that: In step 2) d), the particle size step number is set to 5 to 10 nm.

8. The measuring method according to claim 2, characterized in that: In step 3) a), by computer control, the third port of the first three-way solenoid valve and the first port of the second three-way solenoid valve are closed, and the first port and the second port of the first three-way solenoid valve and the second port and the third port of the second three-way solenoid valve are opened, so that the aerosol to be measured first passes through the neutralizer and then is input into the electric mobility particle size analyzer.

9. A device for measuring the charge of sub-micron aerosol by particle size, characterized in that: The measuring device comprises: a pipeline switching device, a neutralizer, an electric mobility particle size analyzer, an optical particle counter and a computer; wherein the neutralizer is connected to the input end of the electric mobility particle size analyzer through a pipeline via the pipeline switching device; the output end of the electric mobility particle size analyzer is connected to the optical particle counter; the pipeline switching device is connected to the computer, and the pipeline switching device is controlled by the computer to control the flow path of the aerosol; When measuring the number of aerosols of a particle size set in the first mode without passing through the neutralizer, the aerosol to be measured is input into the electric mobility particle size analyzer and the optical particle counter in sequence without passing through the neutralizer through computer control, so as to obtain the number of aerosols of the particle size set in the first mode without passing through the neutralizer; when measuring the number of aerosols of a particle size set in the first mode without passing through the neutralizer, the pipeline switching device is controlled by the computer so that the aerosol to be measured first passes through the neutralizer, changes the charge distribution of the aerosol, and obtains each The probability distribution of aerosols of a certain particle size carrying a charge after passing through the neutralizer is then input into the electric mobility particle size analyzer and the optical particle counter in sequence to obtain the number of aerosols of the particle size set in the first mode that passes through the neutralizer; based on the number of aerosols of the particle size set in the first mode that does not pass through the neutralizer and the number of aerosols of the particle size set in the first mode that passes through the neutralizer, combined with the probability distribution of aerosols of a certain particle size carrying a charge after passing through the neutralizer, the probability distribution of aerosols of the set particle size carrying a charge in the environment is obtained.

10. The measuring device according to claim 9, characterized in that The pipeline switching device adopts a first three-way solenoid valve and a second three-way solenoid valve; wherein, the aerosol to be measured is connected to the first port of the first three-way solenoid valve through a pipeline, and the second port of the first three-way solenoid valve is connected to the input end of the combiner through a pipeline; the output end of the combiner is connected to the second port of the second three-way solenoid valve through a pipeline; the third port of the first three-way solenoid valve is connected to the first port of the second three-way solenoid valve through a pipeline; the third port of the second three-way solenoid valve is connected to the input end of the electric mobility particle size analyzer through a pipeline; the first three-way solenoid valve and the second three-way solenoid valve are respectively connected to a computer.

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