CN106442238B - Device for detecting concentration of particles in air - Google Patents

Abstract

The invention discloses a device for detecting the concentration of particles in air, which comprises a heating element (4), an air cavity (5) and a transparent mirror surface (6), wherein a thermophoresis effect exists between the heating element (4) and the transparent mirror surface (6), so that the particles in the air cavity (5) move towards the transparent mirror surface (6) and fall on the transparent mirror surface under the action of the thermophoresis effect; the device also comprises a light-emitting element (3), a data receiving unit (7), a data processing unit (8) and a display unit (9), wherein the light-emitting element (3) emits light to irradiate on the transparent mirror surface (6), a light spot is formed on the data receiving unit (7) by the light part through the transparent mirror surface (6), and the data processing unit (8) processes the light spot to obtain the concentration of particles in the air; the device has novel and simple structure, is easy for large-scale production and utilization, has smaller volume, is convenient to carry, is not limited by regions during measurement, and has accurate detection result.

Description

A device for detecting the concentration of particles in the air

technical field

The present invention relates to the field of air quality detection, in particular to the detection of particle concentration in the air, and in particular, to a device for detecting particle concentration in the air.

Background technique

In recent years, many cities in my country have experienced hazy weather, which makes the air cloudy and reduces visibility. The main cause of hazy weather is particulate pollutants in the atmosphere. The main sources of these particulate pollutants are: compounds emitted from automobile exhaust, fuel A large amount of dust released by combustion, waste discharged in industrial production, various granular substances produced by building materials and other industries. Particulate matter in the atmosphere mainly includes: TSP, PM ₁₀ and PM _2.5 , these particles will endanger human health after being inhaled into the human body.

At present, the methods used to measure the concentration of fine particles in the air are generally gravimetric method, micro vibration balance method, Beta ray method and light scattering method. Several methods have their own advantages and disadvantages. The gravimetric method is more direct, but the operation is cumbersome and the equipment is cumbersome; the micro-oscillating balance method is more reliable, but it is not suitable for measuring the particle concentration in humid areas; the Beta ray method is not affected by particle size and composition , but the measurement value is generally high; the light scattering method is small in size and easy to carry, but the accuracy is low.

Contents of the invention

In order to overcome the above-mentioned problems, the inventors have carried out dedicated research and designed a novel device for detecting the concentration of particles in the air, wherein the device facilitates the thermophoretic effect under the temperature gradient to deposit the particles in the air on the transparent mirror surface , and then irradiate the mirror surface. Due to the existence of particles on the mirror surface, light spots are formed after the light passes through the mirror surface. According to the relationship between the spot area and the particle content, the particle concentration in the air can be obtained, thereby completing the present invention.

One aspect of the present invention provides a device for detecting the concentration of particles in the air, which is embodied in the following aspects:

(1) A device for detecting the concentration of particles in the air, wherein the device includes a housing 1, a heating element 4 and a transparent mirror 6 are arranged in the housing 1, and an air gap between the heating element 4 and the transparent mirror 6 Cavity 5;

(2) The device according to the above (1), wherein the housing 1 is made of heat insulating material, the heat insulating material is glass fiber, asbestos, rock wool, foam plastic or vacuum insulation board, preferably asbestos , foam plastic or vacuum heat insulation board; preferably, black aluminum foil is wrapped on the outside of the heat insulation material for shielding the stray light outside the device, and the housing 1 is in the shape of a straight cylinder, such as a cylindrical straight cylinder, a square straight cylinder or Polygonal straight barrel, preferably cylindrical straight barrel;

(3) The device according to (1) or (2) above, wherein

The heating element 4 is used to generate a temperature gradient in the air cavity 5, thereby imparting thermophoretic force to the particles in the air,

The transparent mirror surface 6 is used to carry particles deposited under the action of thermophoretic force,

Preferably, the heating element 4 and the transparent mirror 6 are respectively against the inner wall of the housing 1;

(4) The device according to any one of (1) to (3) above, wherein,

The aspect ratio of the housing 1 is (3-8):(1-5), preferably (4-6):(2-4), more preferably 5:3; and/or

On the outer surface of the housing 1 and on one side of the heating element 4, there is a heating element access valve 14 for taking out or putting in the heating element 4; and/or

An air inlet and outlet valve 15 is provided on the outer surface of the housing 1 and on one side of the air cavity 5 for air to enter and exit;

(5) The device according to any one of (1) to (4) above, wherein,

The heating element 4 is a resistance plate; and/or

The surface of the transparent mirror 6 is a rough surface, and/or, apply transparent liquid glue on the surface of the transparent mirror 6, wherein the surface is the side facing the heating element 4;

(6) The device according to any one of the above (1) to (5), wherein a light-emitting element 3 is provided on the side of the heating element 4 facing away from the air cavity 5, and optionally a power supply 2 is also provided, wherein ,

The power supply 2 is used to provide electric energy for the light emitting element 3; and/or

The light-emitting element 3 is used to emit light and irradiate it onto the transparent mirror surface 6 deposited with particles, and light spots are formed after the light passes through the transparent mirror surface 6;

(7) The device according to any one of the above (1) to (6), wherein the mirror surface of the light-emitting element 3 is a concave mirror, which is used to diverge the light to completely cover the transparent mirror surface 6;

(8) According to the device described in any one of the above (1) to (7), a data receiving unit 7, a data processing unit 8 and a display are arranged in sequence on the side of the transparent mirror 6 facing away from the air cavity 5 along the light direction. Unit 9, where,

The data receiving unit 7 is used to sense the area of the light spot, and convert the optical signal into an electrical signal and transmit it to the data processing unit 8;

The data processing unit 8 is used to process the electrical signal transmitted by the data receiving unit 7 to obtain the particle concentration in the air;

(9) The device according to any one of (1) to (8) above, wherein,

The data receiving unit 7 is a photosensitive device, preferably a photodiode, more preferably an avalanche photodiode; and/or

The data processing unit 8 is a data processor, preferably a Qualcomm Snapdragon 600 processor; and/or

The display unit 9 is a display.

Another aspect of the present invention provides a use of the device described in any one of (1) to (9) above for detecting the concentration of particles in the air.

Description of drawings

Fig. 1 shows a schematic structural diagram of the device for detecting particle concentration in air according to the present invention.

Explanation of reference numbers:

1-shell

14- Heating element access valve

15- Air inlet and outlet valves

2- Power

3-Light emitting element

4- Heating element

5- air cavity

6-Transparent mirror

7- Data receiving unit

8- Data processing unit

9-display unit

Detailed ways

The present invention will be described in further detail below by means of the accompanying drawings. Through these descriptions, the features and advantages of the present invention will become more apparent.

Wherein, while various aspects of the embodiments are shown in the drawings, the drawings are not necessarily drawn to scale unless specifically indicated.

The present invention provides a device for detecting particle concentration in the air. The device includes a housing 1, wherein a heating element 4 and a transparent mirror 6 are arranged in the housing 1, and between the heating element 4 and the transparent mirror 6 Between them is an air chamber 5; wherein, the air chamber 5 is used to place or contain air to be detected in particle concentration; the heating element 4 can emit heat to generate thermophoretic force; the transparent mirror 6 is used to carry Particles deposited by thermophoretic forces.

Wherein, the heating element 4 emits heat, so that the temperature on one side of the heating element 4 is significantly higher than the temperature on the side of the transparent mirror 6, therefore, a temperature gradient is formed in the air cavity 5, and a thermophoretic effect is generated, giving particles in the air cavity 5 Thermophoretic force, that is, the particles move from the high temperature area to the low temperature area under the effect of thermophoretic effect (thermophoretic force), that is, from the heating element 4 to the transparent mirror 5, and finally fall on the transparent mirror 5.

In the present invention, the thermophoretic force refers to the force that particles move from a high temperature region to a low temperature region under the thermophoretic effect.

According to a preferred embodiment of the present invention, the heating element 4 is a resistance plate.

In a further preferred embodiment, the resistor plate has its own battery, and when the battery is turned on, the resistor starts to generate heat.

Wherein, the reason why the heating element 4 has its own battery instead of being connected to a power source is to facilitate the later stage (after particle deposition) to take out or take out the heating element 4 from the device.

According to a preferred embodiment of the present invention, the surface of the transparent mirror 6 is a rough surface, wherein the surface refers to the side facing the heating element 4, that is, the side surface for receiving the deposited particles in the air.

Among them, the purpose of setting the surface as a rough surface is to make the particles adhere better to the transparent mirror surface.

According to another preferred embodiment of the present invention, transparent liquid glue is applied on the surface of the transparent mirror surface 6 .

Among them, the application amount of liquid glue does not need to be too much, just cover it with a thin layer. The purpose of choosing transparent liquid glue is to prevent the light from passing through the transparent mirror surface and affect the spot area when the light is illuminated later. At the same time, the purpose of applying liquid glue is also to make the particles better adhere to the transparent mirror surface.

In the present invention, the treatment of the transparent mirror surface can also be processed at the same time as the rough surface, and the transparent liquid glue is applied on the rough surface.

According to a preferred embodiment of the present invention, a heating element access valve 14 is provided on the outer surface of the housing 1 and on one side of the heating element 4 .

Wherein, the heating element access valve 14 is used to facilitate the removal of the heating element from the device after the particle deposition is completed, so as to carry out the later illumination experiment.

According to a preferred embodiment of the present invention, an air inlet and outlet valve 15 is provided on the outer surface of the housing 1 and on one side of the air chamber 5 .

Wherein, the air inlet and outlet valve 15 is used for detecting the air in the environment to be tested entering the device. For example, to pre-detect the particle concentration in a certain environment, the air inlet and outlet valve 15 of the device is opened, the device is placed in the environment, and the air in the environment enters the device for detection. Preferably, the heating element 4 is put into the device first, and then the air is put into the device.

According to a preferred embodiment of the present invention, a light-emitting element 3 is provided on the side of the heating element 4 facing away from the air cavity 5, and a power supply 2 is optionally also provided; wherein the light-emitting element 3 is used to emit light, and The light is irradiated onto the transparent mirror surface 6 deposited with particles; the power supply 2 is used to provide electric energy for the light emitting element 3 .

Wherein, the power supply is optional. If the light-emitting element 3 is powered by a battery, no power supply 3 is required. If the light-emitting element 3 is not equipped with a battery, an external power supply, that is, a power supply 2 needs to be provided.

In the present invention, first put the heating element 4 into the device, start it, and generate the thermophoretic effect, so that the particles are deposited on the transparent mirror 6, and then the particle mass is calculated, wherein the particle quality is carried out by the deposition area of the particle derived. In the present invention, after the particles are all deposited on the transparent mirror surface, the heating element 4 is taken out, and the light-emitting element 3 is started to irradiate the transparent mirror surface 6. Where there are particles on the mirror surface, the light will not pass through the mirror surface, but if there is no particle Local light passes through to form a spot. Therefore, the area of the spot is directly related to the number of deposited particles. The greater the concentration of particles in the air, the more deposited particles, and the smaller the area of the spot.

According to a preferred embodiment of the present invention, the mirror surface of the light emitting element 3 is a concave mirror, which is used to diverge the light so as to completely cover the transparent mirror surface 6 .

According to a preferred embodiment of the present invention, a data receiving unit 7 , a data processing unit 8 and a display unit 9 are sequentially arranged on the side of the transparent mirror 6 facing away from the air cavity 5 along the light direction.

Wherein, the data receiving unit is arranged on the adjacent side of the transparent mirror 6, and the light is irradiated on the transparent mirror 6, and passes through the transparent mirror 6 and is irradiated on the data receiving unit 7. Because there are particles on the transparent mirror 6, the light cannot All pass through the transparent mirror 6, therefore, a light spot will be formed on the data receiving unit, and the data receiving unit 7 is used to sense the area of the light spot, and convert the optical signal into an electrical signal and transmit it to the data processing unit 8; and the data The processing unit is used to process the electrical signal (ie, spot area) transmitted by the data receiving unit 7, and perform data processing to obtain the particle concentration, and transmit the result to the display for display.

Among them, the deposition area of particles on the transparent mirror surface is directly related to the area of the spot, wherein, the particle deposition area is equal to the area of the transparent mirror minus the spot area, that is: S _particles = S _lens - S _spot , that is, the larger the spot area, the deposition Fewer particles means a lower concentration of particles in the air, and vice versa. Since the mass of particles deposited by particles has a certain functional relationship with the spot area, the data processing unit 8 can obtain the mass m of the deposited particles according to the electrical signal (spot area), and then divide the mass m by the volume of the air cavity 5 to obtain the air The mass concentration of the particles.

It should be noted that the concentration of particles in the air is not particularly high after all, so when the particles in the air cavity are deposited on the transparent lens during the test, there will not be too much amount, and there will be no repeated superposition of particles.

According to a preferred embodiment of the present invention, the data receiving unit 7 is a photosensitive device.

In a further preferred embodiment, the data receiving unit 7 is a photodiode.

In a further preferred embodiment, the data receiving unit 7 is an avalanche photodiode.

Wherein, the data receiving unit 7 should have photosensitive performance, sense transmitted light, and have the ability to convert optical signals into electrical signals. The avalanche photodiode is a P-N junction photodiode, in which the avalanche multiplication effect of carriers is used to amplify photoelectric signals to improve detection sensitivity.

According to a preferred embodiment of the present invention, the data processing unit is a data processor.

In a further preferred embodiment, the data processing unit is a Qualcomm Snapdragon 600 processor.

According to a preferred embodiment of the present invention, the display unit 9 is a display for displaying the detection result, that is, the concentration of particles in the air, preferably the mass concentration.

In a further preferred embodiment, the display unit 9 is a liquid crystal display.

According to a preferred embodiment of the present invention, the housing 1 is made of heat insulating material to ensure that the temperature inside the housing 1 remains constant and is not affected by the ambient temperature outside the housing.

In a further preferred embodiment, the heat insulating material is glass fiber, asbestos, rock wool, foamed plastic or vacuum insulation board, preferably asbestos, foamed plastic or vacuum insulation board.

In a further preferred embodiment, black aluminum foil is wrapped on the outside of the heat insulating material for shielding stray light outside the device.

Among them, in order to ensure that the thermophoretic effect inside the shell is not affected by the external environment temperature, the heat insulation performance of the shell should be ensured, and the purpose of setting the black aluminum foil is to prevent the light from the external environment from affecting the processing of the spot area in the device.

According to a preferred embodiment of the present invention, the housing 1 is in the shape of a straight cylinder.

In a further preferred embodiment, the housing 1 is cylindrical, square or polygonal.

In a further preferred embodiment, the housing 1 is cylindrical and straight.

Among them, the purpose of setting the housing 1 into a straight cylindrical shape is as follows: first, to ensure that the movement of the particles to the transparent mirror 6 is not hindered under the thermophoretic force; 6 covered. If not, the following phenomena will occur: one, when the inner diameter of the housing 1 increases first and then decreases according to the temperature gradient direction (illumination direction), the particles move under the thermophoretic force, and the movement space gradually decreases, which will inevitably cause its movement to be hindered. It is even possible to partially fall on the reduced wall, and cannot fall on the transparent mirror surface, so that the detection is seen less than the actual value; two, when the internal diameter of the housing 1 is small and then large according to the temperature gradient direction (illumination direction), The space inside the shell is small and then large, and the light starts from the smaller end, which will inevitably cause no light to pass through around the larger end, but there may be particles deposited around it, which will affect the final structure. Make the detection seen less than the actual value. Therefore, the casing 1 needs to be arranged in a straight cylindrical shape, so that the deposition process of particles and the transmission process of light are not hindered.

According to a preferred embodiment of the present invention, the edges of the heating element 4 , the transparent mirror 6 , and the data receiving unit 7 respectively abut against the inner wall of the housing 1 , that is, they are all the same size as the inside of the housing.

Among them, the purpose of the heating element 4 and the transparent mirror 6 having the same size as the inside of the housing is to ensure that the particles will not flow to other areas after entering the air cavity 5, but are accurately blocked between the heating element 4 and the transparent mirror 6 The reason why the data receiving unit 7 is the same size as the inside of the housing is that it needs to be exactly the same size as the transparent mirror 6, so as to receive all the light spots and ensure that the area of the light spots is accurate, while the transparent mirror 6 and the housing The inside of the same size, therefore, the data receiving unit 7 is also the same size as the inside of the housing.

According to a preferred embodiment of the present invention, the aspect ratio of the housing is (3-8):(1-5), preferably (4-6):(2-4), more preferably 5: 3.

Among them, if the aspect ratio of the housing is too small, it means that the distance from the heating element to the transparent mirror is too short, and the temperature of the heating element will gradually affect the temperature of the transparent mirror, so that the temperature of the entire air cavity rises, and the temperature difference is relatively small. Small, the thermophoretic effect is not obvious. If the aspect ratio of the shell is too large, the thermophoretic effect cannot reach the transparent mirror surface, that is, it is difficult for particles to flow to the transparent mirror surface, or the time required for thermophoretic precipitation is too long, so a reasonable aspect ratio is required .

The present invention also provides a kind of method utilizing above-mentioned device to detect particle concentration in the air on the other hand, proceed as follows:

Step 1, generate a thermophoretic effect, so that the particles are deposited on the transparent mirror surface 6;

Step 2, turn on the light-emitting element 3 to irradiate the transparent mirror 6, so that a light spot is generated on the data receiving unit 7;

Step 3. Data processing is performed by the data processing unit 8, and the processing result is transmitted to the display unit 9 for display to obtain the particle concentration in the air.

According to a preferred embodiment of the present invention, the step 1 includes the following sub-steps:

Step 1-1, put the heating element 4 into the device, and close the heating element access valve 14;

Step 1-2, open the air inlet and outlet valve 15 to fill the air cavity 5 with the air to be tested, and then close the air inlet and outlet valve 15;

Steps 1-3, turning on the heating element 4 to generate a thermophoretic effect, so that the particles are deposited on the transparent mirror surface 6 .

According to a preferred embodiment of the present invention, after step 1 and before step 2, the heating element 4 is taken out, and the heating element access valve 14 is closed.

Wherein, the heating element 4 needs to be taken out before lighting, otherwise the heating element 4 will resist the light emitted by the light emitting element 3 .

According to a preferred embodiment of the present invention, step 3 includes the following sub-steps:

Step 3-1, the data processing unit 8 receives the electrical signal transmitted by the data receiving unit 7, and obtains the spot area through processing;

Step 3-2, according to the functional relationship between the spot area and the particle mass, the particle mass is obtained;

Step 3-3: Divide the particle mass by the volume of the air cavity 5 to obtain the particle concentration in the air.

In the present invention, there is a certain relationship between the area of the light spot and the quality of the particles, the larger the area of the light spot is, the more the quality of the particles is, and the smaller the area of the light spot is, the less the quality of the particles is. The specific functional relationship between the two can be obtained through experimental verification: carry out experiments according to the above-mentioned steps 1-3 to obtain the spot area, then take out the transparent mirror 6, and weigh the mass of particles on it (preferably, set it on the transparent mirror. A layer of transparent plastic film, weigh the film and the deposited particles together, and then subtract the weight of the film, which is the weight of the particles), then obtain the particle mass corresponding to the spot area, repeat the experiment to get a series of spot area and particle weight Quality data, and then fit, get the functional relationship between the spot area and particle quality. The functional relationship is imported into the data processing unit, and can be directly applied in practical applications.

The beneficial effects that the present invention has include:

(1) The device provided by the present invention has a novel and simple structure, and is suitable for large-scale production and application;

(2) The device provided by the present invention can detect the concentration of small particles with a particle diameter less than 2.5 μm in the air;

(3) The device provided by the present invention is small in size, easy to carry, free from geographical restrictions during measurement, and the detection result is accurate.

In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "upper", "inner" and "outer" are based on the orientation or positional relationship in the working state of the present invention, and are only for the convenience of describing the present invention. The invention and the simplified description do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore should not be construed as limiting the present invention.

The present invention has been described above in conjunction with preferred embodiments, but these embodiments are only exemplary and serve as illustrations only. On this basis, various replacements and improvements can be made to the present invention, all of which fall within the protection scope of the present invention.

Claims (10)

1. A device for detecting the concentration of particles in air, which is characterized by comprising a shell (1), wherein a heating element (4) and a transparent mirror surface (6) are arranged in the shell (1), and an air cavity (5) is arranged between the heating element (4) and the transparent mirror surface (6);

the heating element (4) is used for generating a temperature gradient in the air cavity (5) so as to endow particles in the air with thermophoresis force;

the transparent mirror (6) is used for bearing particles deposited under the action of thermophoresis force;

the heating element (4) and the transparent mirror surface (6) are respectively propped against the inner wall of the shell (1);

a light-emitting element (3) and a power supply (2) are arranged on one side of the heating element (4) which is away from the air cavity (5),

the power supply (2) is used for providing electric energy for the light-emitting element (3);

the light-emitting element (3) is used for emitting light and irradiating the light on the transparent mirror surface (6) deposited with the particles, and the light passes through the transparent mirror surface (6) to form light spots;

a data receiving unit (7), a data processing unit (8) and a display unit (9) are sequentially arranged on one side of the transparent mirror surface (6) which is away from the air cavity (5) along the light direction,

the data receiving unit (7) is used for sensing the area of the light spot and converting the optical signal into an electric signal to be transmitted to the data processing unit (8);

the data processing unit (8) is used for processing the electric signals transmitted by the data receiving unit (7) to obtain the concentration of particles in the air.

2. The device according to claim 1, characterized in that the housing (1) is made of a heat insulating material, which is fiberglass, asbestos, rock wool, foam or vacuum insulation panels;

and the outer side of the heat insulating material is wrapped with black aluminum foil for shielding stray light outside the device, and the shell (1) is in a straight cylinder shape.

3. The apparatus of claim 2, wherein the device comprises a plurality of sensors,

the heat insulating material is asbestos, foamed plastic or a vacuum heat insulating board;

the shell (1) is a cylindrical straight cylinder, a square straight cylinder or a polygonal straight cylinder.

4. The apparatus of claim 1, wherein the device comprises a plurality of sensors,

the length-diameter ratio of the shell (1) is (3-8) (1-5); and/or

A heating element taking-out and placing-in opening valve (14) is arranged on the outer surface of the shell (1) and positioned on one side of the heating element (4) and is used for taking out or placing in the heating element (4); and/or

The air cavity (5) is used for placing air with the concentration of particles to be detected.

5. The apparatus of claim 4, wherein the device comprises a plurality of sensors,

the length-diameter ratio of the shell (1) is (4-6): (2-4); and/or

An air inlet and outlet valve (15) is arranged on the outer surface of the shell (1) and positioned on one side of the air cavity (5) for air to enter and exit.

6. The apparatus of claim 1, wherein the device comprises a plurality of sensors,

the heating element (4) is a resistance flat plate; and/or

The surface of the transparent mirror surface (6) is a rough surface and/or,

and (3) coating transparent liquid glue on the surface of the transparent mirror surface (6), wherein the surface is one surface facing the heating element (4).

7. The device according to one of claims 1 to 6, characterized in that the mirror surface of the light-emitting element (3) is a concave mirror for diverging the light rays to completely cover the transparent mirror surface (6).

8. The device according to any one of claims 1 to 6, wherein,

the data receiving unit (7) is a photosensitive device; and/or

The data processing unit (8) is a data processor; and/or

The display unit (9) is a display.

9. The apparatus of claim 8, wherein the device comprises a plurality of sensors,

the data receiving unit (7) is an avalanche photodiode; and/or

The data processing unit (8) is a high-pass cell 600 processor.

10. Use of a device according to one of claims 1 to 9 for detecting the concentration of particles in air.

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