A small hybrid condensation particle counter and its working method

Abstract

The present invention relates to a small hybrid condensation particle counter and its working method. The condensation particle counter includes a particle adjustment unit, a hot steam saturation unit, a particle and steam mixing unit, a particle growth unit, an optical detection unit, and a signal processing and control unit. After the ultrafine particles to be measured pass through the particle adjustment unit that adjusts the flow rate and reduces the temperature, they are fully mixed with the alcohol vapor flowing into the hot steam saturation unit in the particle and steam mixing unit. Then, they absorb moisture in the particle growth unit and grow to an optically detectable size. The optical detection unit converts the measured particle diameter into a light pulse signal, thereby obtaining the number concentration of the ultrafine particles to be measured. The present invention has the advantages of fast and sufficient mixing of particles and hot steam, and low particle loss. While being able to reduce the size of the equipment and achieve portability, it has good performance in dynamic detection, high flow rate operation, and capturing extremely small particle sizes.

Description

Technical Field

[0001] The present invention relates to the technical field of aerosol particle detection, and in particular to a small hybrid condensation particle counter and a working method thereof. Background Art

[0002] A condensation particle counter (CPC) is a precision instrument used to measure particulate matter concentration in air or gas. It introduces the particles to be measured into a saturated vapor environment, causing a condensation reaction between the particles and the vapor. This enlarges nanoscale particles, which would otherwise be impossible to measure directly, to an optically detectable size. Traditional CPCs are primarily categorized into continuous and hybrid types. Continuous CPCs use thermal diffusion to mix vapor and airflow, resulting in stable operation but a larger size and slower response time. Hybrid CPCs, on the other hand, achieve faster vapor mixing and condensation, improving measurement speed and sensitivity. Their simplified internal structure and improved environmental adaptability make them more suitable for measurement environments with large dynamic changes, effectively expanding their operating range and application areas.

[0003] With the increasing demand for ultrafine particle detection in fields such as air quality monitoring and semiconductor processing, the development of a compact, sensitive, and highly accurate portable CPC has become a key technological advancement. However, existing small CPCs often suffer from insufficient sensitivity and unsatisfactory response speed, limiting their widespread application. Furthermore, in practical applications, CPCs face technical challenges such as high vapor loss and unstable temperature control.

[0004] Based on this, there is an urgent need for a small hybrid condensation particle counter with a simple design, small size, rapid response and adaptability to a variety of environments to meet the needs of industry, environmental monitoring and scientific research for efficient and portable particulate matter detection equipment. Summary of the Invention

[0005] The object of the present invention is to provide a small hybrid condensation particle counter and its working method, which can solve the shortcomings of the existing technology and provide a portable and accurate particle counting solution by optimizing the structural design and working principle.

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

[0007] The present invention includes a small hybrid condensation particle counter, which includes a particle adjustment unit, a hot steam saturation unit, a particle and steam mixing unit, a particle growth unit, an optical detection unit, and a signal processing and control unit.

[0008] The particle regulation unit includes a regulation chamber; a condensation particle counter inlet is provided at the inlet of the regulation chamber. The particle and vapor mixing unit includes a mixing chamber and a vapor diffusion chamber sleeved outside the mixing chamber; the mixing chamber and the vapor diffusion chamber are connected; the inlet of the mixing chamber is connected to the outlet of the regulation chamber. The hot vapor saturation unit includes a saturation chamber and a liquid storage chamber arranged in sequence; a porous ceramic rod is installed through the saturation chamber; one end of the porous ceramic rod is located in the saturation chamber, and the other end extends into the liquid storage chamber; the inlet of the saturation chamber is connected to the inlet of the condensation particle counter, and the outlet of the saturation chamber is connected to the inlet of the vapor diffusion chamber. The particle growth unit includes a growth chamber; the inlet of the growth chamber is connected to the outlet of the mixing chamber. The optical detection unit includes an optical detection chamber; a blue light source, a focusing lens, a receiving lens, an extinguisher and a photomultiplier tube are installed in the optical detection chamber; the entrance of the optical detection chamber is connected to the exit of the growth chamber; the blue light source is used to emit a light beam to illuminate the particles entering the optical detection chamber; the focusing lens is used to focus the light beam emitted by the light source at the position where the particle airflow passes; the receiving lens is used to collect and focus the light scattered by the particles; the extinguisher is used to reduce or eliminate the influence of light not scattered by the particles to avoid interfering with the detection of scattered light; the photomultiplier tube is used to convert the weak light signal into an electrical signal and amplify it significantly, and send the obtained electrical signal to the signal processing and control unit. The signal processing and control unit is used to convert the electrical signal obtained by the optical detection unit into information on the number of particles, particle size distribution and particle concentration, and adjust the temperature and gas flow inside each chamber.

[0009] As a further improvement of the above technical solution, a first filter and an electronic flow valve are installed on the inlet of the condensation particle counter; the regulating chamber includes a first regulating chamber and a second regulating chamber connected in sequence; the diameter of the first regulating chamber is larger than the diameter of the second regulating chamber; a first refrigeration kit is installed on the outer wall of the regulating chamber; a first heat sink is installed on the first refrigeration kit; a first thermal insulation layer is also installed on the outer wall of the regulating chamber; a connecting pipeline is provided between the first regulating chamber and the second chamber; a differential pressure gauge is provided on the connecting pipeline, and the differential pressure gauge is used to measure the pressure difference between the first regulating chamber and the second regulating chamber to determine the particulate matter airflow flow rate.

[0010] As a further improvement of the above technical solution, a plurality of circular hole channels are provided on the side wall of the mixing chamber for connecting the mixing chamber and the vapor diffusion chamber; a first heating kit is provided on the outer wall of the vapor diffusion chamber; a second thermal insulation layer is also installed on the outer wall of the vapor diffusion chamber; a first thermal insulation ceramic layer is wrapped on the outside of the connection between the entrance of the mixing chamber and the regulating chamber; a hot steam interface is provided on the side wall of the vapor diffusion chamber; a first slope is provided on the inner wall of one end of the mixing chamber close to the regulating chamber, and the angle of the first slope is 45°, which is used to prevent vortexes from being generated when the airflow is mixed.

[0011] As a further improvement of the above technical solution, a second heating kit is installed on the outside of the saturation chamber; the second heating kit is used to heat the porous ceramic rod soaked in alcohol solution to generate alcohol vapor; a liquid injection port is provided on the liquid storage chamber; the inlet of the saturation chamber is connected to the outlet of the electronic flow valve through a pipeline, the inlet of the electronic flow valve is connected to the outlet of the first filter, and the inlet of the first filter is connected to the inlet of the condensation particle counter; the outlet of the saturation chamber is connected to the inlet of the vapor diffusion chamber, that is, the outlet of the saturation chamber is connected to the hot vapor interface on the vapor diffusion chamber; the porous ceramic rod is made of silicon carbide, which is used to adsorb the working fluid in the liquid storage chamber and store the working fluid at one end of the porous ceramic rod located in the saturation chamber to generate hot alcohol vapor; the working fluid is a n-butanol solution.

[0012] As a further improvement of the above technical solution, a second refrigeration kit is provided on the outer wall of the growth chamber; a second heat sink is provided on the outside of the second refrigeration kit; the second refrigeration kit is used to reduce the temperature in the growth chamber; a third insulation layer is also installed on the outer wall of the growth chamber; a second insulation ceramic layer is provided on the outside of the connection between the growth chamber and the mixing chamber; a second slope is provided on the inner wall of one end of the growth chamber close to the optical detection chamber, and the angle of the second slope is 45°, which is used to concentrate the particles on the axis to improve the measurement accuracy of the optical detection unit.

[0013] As a further improvement of the above technical solution, a third heating kit and a third thermal insulation layer are installed on the outer wall of the optical detection chamber; a second filter and an air pump are connected to the outlet of the optical detection chamber; the third heating kit is used to prevent condensation of hot alcohol vapor; the connection between the growth chamber and the optical detection chamber is wrapped with a third thermal insulation ceramic layer on the outside; the first refrigeration kit and the second refrigeration kit both include refrigeration plates and temperature sensors for lowering the temperature of the regulating chamber; the first heating kit, the second heating kit and the third heating kit both include heating plates and temperature sensors; the first heat sink and the second heat sink are used to dissipate heat quickly to ensure the normal operation of the first refrigeration kit and the second refrigeration kit; the first thermal insulation layer, the second thermal insulation layer and the third thermal insulation layer are used to isolate the temperature conduction between each chamber and the outside world; the first filter and the second filter are used to remove particulate matter in the gas path.

[0014] As a further improvement of the above technical solution, the signal processing and control unit includes a signal processing module and a control module; the signal processing module is used to receive the optical signal processed by the photomultiplier tube and convert the optical signal into a particle number concentration; the control module is used to control the operation of each refrigeration kit, heating kit, electronic flow valve, air pump, and differential pressure gauge; the differential pressure gauge, the air pump, the first electronic flow valve, and the second electronic flow valve are used to regulate the flow rate and ratio of the particulate airflow and the vapor airflow.

[0015] As a further improvement of the above technical solution, the first insulating ceramic layer, the second insulating ceramic layer and the third insulating ceramic layer are all made of ceramic material, and each insulating ceramic layer is used to insulate and allow cold particles and hot steam to be fully mixed in an insulated manner; the ceramic material is zirconia.

[0016] The present invention also includes a method for operating the small hybrid condensation particle counter, the method comprising the following steps:

[0017] S1. The airflow carrying ultrafine particles enters the particle conditioning unit at a certain flow rate and is divided into two paths. One path is first filtered by the first filter to become a clean airflow, and the clean airflow enters the hot steam saturation unit, and the other path enters the conditioning chamber.

[0018] S2. After the airflow enters the regulating chamber, it forms a cold particulate airflow. The pressure difference between the two parts of the regulating chamber with different pipe diameters is measured using a differential pressure meter. The flow rate of the particulate airflow is determined based on the pressure difference. The flow rate of the airflow entering the particulate matter and steam mixing unit and the hot steam saturation unit is controlled by cooperating with the differential pressure meter and the electronic flow valve.

[0019] S3. Control the operation of the first heating kit and the second heating kit to adjust the temperature of the saturation chamber and the vapor diffusion chamber. At this time, the alcohol solution immersed in the porous ceramic rod turns into alcohol vapor and fills the entire saturation chamber. The alcohol vapor is brought into the vapor diffusion chamber by the clean air flow entering the saturation chamber to form a hot vapor airflow. The hot vapor airflow flows into the mixing chamber through the circular hole channel.

[0020] S4. The cold particulate airflow formed in the conditioning chamber and the hot alcohol vapor airflow formed after being processed in the saturation chamber and the vapor diffusion chamber are adiabatically mixed in the mixing chamber to form a mixed airflow that enters the growth chamber.

[0021] S5. The particles in the mixed airflow absorb moisture and grow in the growth chamber, and are concentrated within the threshold range of the axis of the optical detection chamber before entering the optical detection chamber.

[0022] S6. The blue light source is focused by a focusing lens onto the path of the mixed airflow entering the optical detection chamber. When the particles in the mixed airflow are irradiated by the light beam, light scattering occurs. Particles of different sizes scatter light of different intensities. The scattered light is guided to the photomultiplier tube through the receiving lens. The photomultiplier tube amplifies the received scattered light and converts it into an electrical signal.

[0023] S7. The photomultiplier tube sends the converted electrical signal to the signal processing module, which filters and corrects the received signal to obtain information on the number of particles, particle size distribution, and particle concentration.

[0024] As a further improvement of the above technical solution, the temperature of the adjustment chamber and the growth chamber is stabilized at 5°C, and the temperature of the saturation chamber, the vapor diffusion chamber and the optical detection chamber is stabilized at 50°C.

[0025] Compared with the prior art, the advantages of the present invention are:

[0026] (1) The small hybrid condensation particle counter described in the present invention can achieve efficient capture and detection of extremely small particles (as low as 5nm) through rapid airflow mixing, and shows significant advantages in high flow rate and high sensitivity detection. Under turbulent conditions, the small hybrid condensation particle counter allows the particulate airflow to mix rapidly with the saturated vapor airflow. The mixing and turbulence of the airflow contribute to the rapid mixing and growth of the particles, thereby reducing the volume of the condensation particle counter and the diffusion loss of the particles during the flow process. In real-time on-site monitoring and individual exposure studies, miniaturization and low cost are the key directions for the future development of condensation particle counters. Compared with traditional large laboratory equipment, the small hybrid condensation particle counter described in the present invention can perform rapid and sensitive detection in more scenarios, such as vehicle-mounted / portable environmental monitoring, grid-based point monitoring, etc.

[0027] (2) The hybrid condensation particle counter (CPC) described in the present invention can effectively improve the activation and growth rate of ultrafine particles by enhancing turbulent mixing technology, thereby significantly improving detection efficiency and sensitivity. The design adopted by the present invention enables the hybrid CPC to have a faster response time, lower maintenance requirements, and can operate stably under a wider range of environmental conditions. It is particularly suitable for application scenarios that require real-time monitoring and high sensitivity requirements for small-size particles. Compared with the laminar flow CPC, the hybrid CPC adopted in the present invention is more suitable for measurement environments with large dynamic changes due to its simplified internal structure and improved environmental adaptability, effectively expanding the working range and application field. The design of the hybrid CPC allows operation under a wider range of environmental conditions (such as different temperatures and humidity), enhancing the environmental adaptability and application range of the equipment.

[0028] (3) The hybrid condensation particle counter (CPC) described in the present invention can more effectively mix particles with hot alcohol vapor through turbulent mixing technology, accelerate the activation process of particles, and reduce the efficiency of particle activation, especially for ultrafine particles of a few nanometers. Turbulent mixing can quickly and evenly distribute hot alcohol vapor among the particles, which accelerates the growth rate of particles and enables the device to respond more quickly to changes in particle concentration in the environment. The turbulent design reduces the complexity of the internal structure and reduces the maintenance requirements caused by component blockage, making the device easier to clean and maintain. The hybrid CPC described in the present invention can efficiently detect particles of extremely small particle size, improve the sensitivity and overall efficiency of detection, and can not only quickly and accurately provide particle size distribution and concentration data, which is very important for fields such as environmental monitoring and scientific research, but also can operate stably under a wider range of environmental conditions, providing technical equipment support for various industrial and scientific research environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a structural schematic diagram of the small and medium-sized hybrid condensation particle counter of the present invention.

[0030] Figure 2 It is a schematic diagram of the supersaturation distribution simulation of the small and medium-sized hybrid condensation particle counter of the present invention.

[0031] Figure 3 This is a distribution diagram of the supersaturation of the small and medium-sized hybrid condensation particle counter on the Z-axis center line.

[0032] Figure 4 It is a schematic diagram of the supersaturation distribution simulation of the small and medium-sized hybrid condensation particle counter of the present invention.

[0033] in:

[0034] 1. Airway tube wall, 2. First cooling kit, 3. First heat sink, 4. Electronic flow valve, 5. Insulating ceramic, 6. First thermal insulation layer, 7. First heating kit, 8. Porous ceramic rod, 9. Liquid injection port, 10. Liquid storage chamber, 11. Hot vapor interface, 12. Vapor diffusion chamber, 13. Optical detection chamber, 14. De-optical device, 15. Receiving lens, 16. First filter, 17. Air pump, 18. Photomultiplier tube, 19. Focusing lens, 20. Blue light source, 21. Growth chamber, 22. Mixing chamber, 23. Adjustment chamber, 24. Differential pressure gauge, 25. Condensation particle counter inlet, 26. Signal processing and control unit, 27. Signal processing module, 28. Control module, 29. Particle adjustment unit, 30. Hot vapor saturation unit, 31. Particle and vapor mixing unit, 32. Particle growth unit, 33. Optical detection unit, 34. Saturation chamber. DETAILED DESCRIPTION

[0035] The present invention will be further described below with reference to the accompanying drawings:

[0036] like Figure 1 A small hybrid condensation particle counter is shown, which includes: a particle adjustment unit 29, a hot vapor saturation unit 30, a particle and vapor mixing unit 31, a particle growth unit 32, an optical detection unit 33 and a signal processing and control unit 26.

[0037] Specifically, the particle control unit 29 includes a control chamber 23; a condensation particle counter inlet 25 is provided at one end of the control chamber 23; a first filter 16 and an electronic flow valve 4 are installed on the condensation particle counter inlet 25; the control chamber 23 can be divided into two parts with different pipe diameters, including a first control chamber and a second control chamber that are connected in sequence; the diameter of the first control chamber is larger than the diameter of the second control chamber; a first cooling kit 2 is installed on the outer wall of the control chamber 23; a first heat sink 3 is installed on the first cooling kit 2; a first thermal insulation layer is also installed on the outer wall of the control chamber 23; a connecting pipe is provided between the first and second control chambers; a differential pressure gauge 24 is installed on the connecting pipe, and the differential pressure gauge 24 is used to measure the pressure difference between the first and second control chambers to determine the particulate matter airflow rate. The first cooling kit 2 includes a cooling fin and a temperature sensor to reduce the temperature of the control chamber.

[0038] As a further improvement of the above technical solution, the first heat sink 3 is used to quickly dissipate heat to ensure the normal operation of the refrigeration kit 2; the first insulation layer, the second insulation layer and the third insulation layer are used to isolate the temperature conduction between each chamber and the outside world; the first filter 16 is used to remove particulate matter in the air path.

[0039] As a further improvement to the above technical solution, the particle and steam mixing unit 31 comprises a mixing chamber 22 and an annular vapor diffusion chamber 12 positioned outside the mixing chamber 22. The annular vapor diffusion chamber is designed to allow the hot alcohol vapor to mix relatively evenly with the cold particle airflow from all sides. The mixing chamber 22 is connected to the vapor diffusion chamber 12. The sidewalls of the mixing chamber 22 are provided with multiple circular channels connecting the mixing chamber 22 and the vapor diffusion chamber 12. These multiple circular channels are designed to increase the velocity of the hot alcohol vapor before it meets the cold particles, enhancing turbulent mixing and promoting the growth of ultrafine particles. A first heating element is installed on the outer wall of the vapor diffusion chamber 12, along with a second thermal insulation layer. The inlet of the mixing chamber 22 is connected to the outlet of the conditioning chamber 23, and the junction between the two is wrapped with a first thermally insulating ceramic layer 5. A hot vapor port 11 is provided on the sidewall of the vapor diffusion chamber 12.

[0040] As a further improvement to the above technical solution, the hot vapor saturation unit 30 comprises a saturation chamber 34 and a liquid storage chamber 10, arranged in sequence. A porous ceramic rod 8 is installed through the saturation chamber 34. One end of the porous ceramic rod 8 is located in the saturation chamber 34, and the other end extends into the liquid storage chamber 10. This design prevents alcohol solution from flowing into the mixing chamber when the instrument is inverted or tilted. A second heating assembly is installed outside the saturation chamber 34. This second heating assembly is used to heat the porous ceramic rod 8, which is soaked in alcohol solution, to generate alcohol vapor. A liquid inlet 9 is provided in the liquid storage chamber 10. The inlet of the saturation chamber 34 is connected to the outlet of the electronic flow valve 4 via a pipeline. The inlet of the electronic flow valve 4 is connected to the outlet of the first filter 16, and the inlet of the first filter 16 is connected to the inlet 25 of the condensation particle counter. The outlet of the saturation chamber 34 is connected to the inlet of the vapor diffusion chamber 12, that is, the outlet of the saturation chamber 34 is connected to the hot vapor port 11 on the vapor diffusion chamber 12.

[0041] As a further improvement of the above technical solution, the porous ceramic rod 8 is made of silicon carbide, which is used to adsorb the working fluid in the liquid storage chamber 10 and store the working fluid at one end of the porous ceramic rod 8 located in the saturation chamber to generate hot alcohol vapor; the working fluid is a n-butanol solution.

[0042] As a further improvement of the above technical solution, the mixing chamber 22 is provided with a slope near the regulating chamber 23 with an angle of 45°, which is used to prevent vortexes from being generated when the airflow is mixed.

[0043] As a further improvement of the above technical solution, the first heating kit, the second heating kit and the third heating kit all include heating plates and temperature sensors.

[0044] As a further improvement to the above technical solution, the particle growth unit 32 includes a growth chamber 21; a second cooling assembly is installed on the outer wall of the growth chamber 21; a second heat sink is installed on the outer side of the second cooling assembly; and the second cooling assembly is used to reduce the temperature within the growth chamber 21. A third thermal insulation layer is also installed on the outer wall of the growth chamber 21. The inlet of the growth chamber 21 is connected to the outlet of the mixing chamber 22, and a second thermal insulation ceramic layer is installed on the outer side of the connection between the growth chamber 21 and the mixing chamber 22.

[0045] As a further improvement of the above technical solution, the growth chamber 21 is provided with a slope near the optical detection chamber 13 with a slope angle of 45°, which concentrates the particles on the axis to improve the measurement accuracy of the optical detection unit 33.

[0046] As a further improvement to the above technical solution, the optical detection unit 33 includes an optical detection chamber 13; a third heating kit and a third thermal insulation layer are installed on the outer wall of the optical detection chamber 13; a blue light source 20, a focusing lens 19, a receiving lens 15, a de-optical device 14, and a photomultiplier tube 18 are installed within the optical detection chamber 13; the inlet of the optical detection chamber 13 is connected to the outlet of the growth chamber 21, and the outlet of the optical detection chamber 13 is connected to a second filter 35 and an air pump 17. The third heating kit is used to prevent condensation of hot alcohol vapor. The connection between the growth chamber 21 and the optical detection chamber 13 is wrapped with a third thermal insulation ceramic layer.

[0047] As a further improvement of the above technical solution, the blue light source 20 is used to emit a light beam to illuminate the particulate matter entering the optical detection chamber 13; the focusing lens 19 is used to focus the light beam emitted by the light source 20 at the position where the particulate matter airflow passes; the receiving lens 15 is used to collect and focus the light scattered by the particulate matter; the de-optical device 14 is used to reduce or eliminate the influence of direct light (transmitted light) that is not scattered by the particles, so as to avoid interference with the detection of scattered light; the photomultiplier tube 18 is used to convert the weak light signal into an electrical signal and significantly amplify it to facilitate subsequent signal processing.

[0048] As a further improvement of the above technical solution, the differential pressure gauge 24, the air pump 17 and the electronic flow valve 4 are used to regulate the flow rate and ratio of the particulate airflow and the steam airflow.

[0049] As a further improvement to the above technical solution, the signal processing and control unit 26 is used to convert the optical signal from the optical detection unit 33 into a particle number concentration and control the normal operation of the cooling kit and heating kit, electronic flow valve, and air pump 17 on the outer side of each cavity wall. The signal processing and control unit 26 includes a signal processing module 27 and a control module 28. The signal processing module 27 is used to receive the optical signal processed by the photomultiplier tube 18 and convert the optical signal into a particle number concentration. The control module 28 is used to control the operation of each cooling kit, heating kit, electronic flow valve, air pump, and differential pressure gauge.

[0050] As a further improvement of the above technical solution, the first insulating ceramic layer, the second insulating ceramic layer and the third insulating ceramic layer are all made of ceramic material, and each insulating ceramic layer is used to insulate and allow cold particles and hot steam to be fully mixed in an insulated manner; the ceramic material is zirconia.

[0051] The present invention also includes a method for operating the small hybrid condensation particle counter, the method comprising the following steps:

[0052] S1. The airflow carrying ultrafine particles enters the particle adjustment unit 29 at a certain flow rate and is divided into two paths. One path first passes through the first filter 16 and the electronic flow valve 4 and then becomes a clean airflow and enters the hot steam saturation unit 30. The other path directly enters the adjustment chamber 23.

[0053] S2 and the differential pressure gauge 24 measure the pressure difference between two sections of different diameters in the regulating chamber 23 to determine the particle airflow velocity. This, in conjunction with the first and second electronic flow valves 4 and 3, controls the flow rates of the airflow entering the particle and steam mixing unit 31 and the hot steam saturation unit 30. The air pump 17 at the end of the condensation particle counter draws an overall flow rate of 0.3 L / min. The differential pressure gauge 24, the first and second electronic flow valves 4 and 3, monitor and control the flow ratio of the airflow entering the regulating chamber 23 and the airflow entering the saturation chamber 34.

[0054] S3. Control the operation of the heating kit on the outside of the saturated chamber wall and the annular vapor diffusion chamber wall so that the temperature of the saturated chamber 34 and the annular vapor diffusion chamber 12 is maintained at 50°C. At this time, the alcohol solution immersed in the porous ceramic rod 8 turns into alcohol vapor and fills the entire saturated chamber 34, and is brought into the annular vapor diffusion chamber 12 by the clean air flow. Finally, the hot vapor air flow passes through the circular through hole between the annular vapor diffusion chamber 12 and the mixing chamber 22 and quickly flows into the mixing chamber 22.

[0055] S4: The cold particulate flow passing through conditioning chamber 23 is adiabatically mixed with the hot alcohol vapor flow passing through saturation chamber 34 and vapor diffusion chamber 12 in mixing chamber 22, forming a mixed flow that enters growth chamber 21. The refrigeration kit 2 outside the conditioning chamber wall is controlled to maintain a temperature of 5°C for the particles entering mixing chamber 22. The direction of the particulate flow is perpendicular to the direction of the hot vapor flow entering mixing chamber 22 from all sides, and the two are adiabatically mixed in mixing chamber 22.

[0056] S5. The particles in the mixed airflow absorb moisture and grow in the growth chamber, concentrating near the axis before entering the optical detection chamber. Specifically, the mixed airflow enters the growth chamber 21 (temperature 5°C), where the hot vapor in the mixed airflow condenses onto the surface of the particles, allowing the particles in the mixed airflow to complete their moisture absorption and growth. Finally, the mixed airflow is concentrated near the axis before entering the optical detection chamber 13.

[0057] S6. In the optical detection chamber 13, particles scatter as they pass through the light beam. The photomultiplier tube 18 amplifies the received scattered light and converts it into an electrical signal. Specifically, a blue light source 20 is focused onto the path of the mixed airflow entering the optical detection chamber 13 via a focusing lens 19. Particles in the mixed airflow scatter light as they pass through the light beam, and particles of different sizes scatter light of varying intensities. The scattered light is guided through the receiving lens 15 to the photomultiplier tube 18, which amplifies the received scattered light and converts it into an electrical signal. The intensity of the signal is proportional to the intensity of the scattered light, and thus related to the size and number of the particles.

[0058] S7. The signal processing module 27 filters and corrects the received signal, and finally obtains information such as the number of particles, particle size distribution, and particle concentration.

[0059] As a further improvement of the above technical solution, the temperature of the adjustment chamber 23 and the growth chamber 21 is stabilized at 5°C, and the temperature of the saturation chamber 34, the vapor diffusion chamber 12 and the optical detection chamber 13 is stabilized at 50°C.

[0060] Figure 2 This is a schematic diagram of the supersaturation distribution simulation of the small and medium-sized hybrid condensation particle counter of the present invention. Figure 2 It can be seen that the cold particles and the hot alcohol vapor are fully mixed in the mixing chamber 22, and the supersaturation of the alcohol vapor in the mixing chamber 22 and the growth chamber 21 exceeds 1, indicating that the ultrafine particles can condense and grow. Figure 3 This is the distribution diagram of the supersaturation of the small and medium-sized hybrid condensation particle counter on the Z axis center line. Figure 3 It can be seen that the supersaturation is close to 2 at the junction of the mixing chamber 22 and the regulating chamber 23, indicating that the particles can condense and grow faster here.

[0061] Figure 4 This is a schematic diagram of the supersaturation distribution simulation of the small and medium-sized hybrid condensation particle counter of the present invention. Figure 4 It can be seen that the activated particle size at the junction of the mixing chamber 22 and the regulating chamber 23 can be as low as 5 nm. The activated particle size is the minimum particle size at which ultrafine particles can condense and grow.

[0062] The above-described embodiments are merely descriptions of preferred implementations of the present invention and are not intended to limit the scope of the present invention. Without departing from the spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should fall within the scope of protection determined by the claims of the present invention.

Claims

1. A small hybrid condensation particle counter, characterized in that: The condensation particle counter comprises: a particle adjustment unit (29), a hot steam saturation unit (30), a particle and steam mixing unit (31), a particle growth unit (32), an optical detection unit (33), and a signal processing and control unit (26); The particle regulation unit (29) comprises a regulation chamber (23); a condensation particle counter inlet (25) is provided at the inlet of the regulation chamber (23); The particle and steam mixing unit (31) comprises a mixing chamber (22) and a steam diffusion chamber (12) sleeved outside the mixing chamber (22); the mixing chamber (22) and the steam diffusion chamber (12) are connected; the inlet of the mixing chamber (22) is connected to the outlet of the regulating chamber (23); The hot vapor saturation unit (30) includes a saturation chamber (34) and a liquid storage chamber (10) arranged in sequence; a porous ceramic rod (8) is installed through the saturation chamber (34); one end of the porous ceramic rod (8) is located in the saturation chamber (34), and the other end extends into the liquid storage chamber (10); the inlet of the saturation chamber (34) is connected to the inlet of the condensation particle counter (25), and the outlet of the saturation chamber (34) is connected to the inlet of the vapor diffusion chamber (12); The particle growth unit (32) comprises a growth chamber (21); an inlet of the growth chamber (21) is connected to an outlet of the mixing chamber (22); The optical detection unit (33) includes an optical detection chamber (13); a blue light source (20), a focusing lens (19), a receiving lens (15), a de-optical device (14) and a photomultiplier tube (18) are installed in the optical detection chamber (13); the entrance of the optical detection chamber (13) is connected to the exit of the growth chamber (21); the blue light source (20) is used to emit a light beam to illuminate the particles entering the optical detection chamber (13); the focusing lens (19) is used to focus the light beam emitted by the light source (20) at a position where the particle airflow passes; the receiving lens (15) is used to collect and focus light scattered by the particles; the de-optical device (14) is used to reduce or eliminate the influence of light not scattered by the particles to avoid interference with the detection of scattered light; the photomultiplier tube (18) is used to convert a weak light signal into an electrical signal and amplify it significantly, and send the obtained electrical signal to the signal processing and control unit (26); The signal processing and control unit (26) is used to convert the electrical signal obtained by the optical detection unit (33) into information on the number of particles, particle size distribution, and particle concentration, and to adjust the temperature and gas flow inside each chamber.

2. The small hybrid condensation particle counter according to claim 1, characterized in that: A first filter (16) and an electronic flow valve (4) are installed on the inlet (25) of the condensation particle counter; the regulating chamber (23) includes a first regulating chamber and a second regulating chamber that are connected in sequence; the diameter of the first regulating chamber is larger than the diameter of the second regulating chamber; a first refrigeration kit (2) is installed on the outer wall of the regulating chamber (23); a first heat sink (3) is installed on the first refrigeration kit (2); a first thermal insulation layer is also installed on the outer wall of the regulating chamber (23); a connecting pipeline is provided between the first regulating chamber and the second chamber; a differential pressure gauge (24) is provided on the connecting pipeline, and the differential pressure gauge (24) is used to measure the pressure difference between the first regulating chamber and the second regulating chamber to determine the particulate matter airflow flow rate.

3. The small hybrid condensation particle counter according to claim 2, characterized in that: A plurality of circular hole channels are provided on the side wall of the mixing chamber (22) for connecting the mixing chamber (22) and the vapor diffusion chamber (12); a first heating kit is provided on the outer wall of the vapor diffusion chamber (12); a second thermal insulation layer is also installed on the outer wall of the vapor diffusion chamber (12); a first thermal insulation ceramic layer (5) is wrapped on the outer side of the connection between the inlet of the mixing chamber (22) and the regulating chamber (23); a hot vapor interface (11) is provided on the side wall of the vapor diffusion chamber (12); a first slope is provided on the inner side wall of one end of the mixing chamber (22) close to the regulating chamber (23), and the angle of the first slope is 45 degrees, which is used to prevent vortexes from being generated when the air flows are mixed.

4. The small hybrid condensation particle counter according to claim 3, characterized in that: A second heating kit is installed on the outside of the saturation chamber (34); the second heating kit is used to heat the porous ceramic rod (8) soaked in alcohol solution to generate alcohol vapor; a liquid injection port (9) is opened on the liquid storage chamber (10); the inlet of the saturation chamber (34) is connected to the outlet of the electronic flow valve (4) through a pipeline, the inlet of the electronic flow valve (4) is connected to the outlet of the first filter (16), and the inlet of the first filter (16) is connected to the inlet (25) of the condensation particle counter; the outlet of the saturation chamber (34) is connected to the inlet of the vapor diffusion chamber (12), that is, the outlet of the saturation chamber (34) is connected to the hot vapor interface (11) on the vapor diffusion chamber (12); the material of the porous ceramic rod (8) is silicon carbide, and is used to adsorb the working fluid in the liquid storage chamber (10), and store the working fluid at one end of the porous ceramic rod (8) located in the saturation chamber (34) to generate hot alcohol vapor; the working fluid is a n-butanol solution.

5. The small hybrid condensation particle counter according to claim 4, characterized in that: A second cooling kit is provided on the outer wall of the growth chamber (21); a second heat sink is provided on the outer side of the second cooling kit; the second cooling kit is used to reduce the temperature in the growth chamber (21); a third heat insulation layer is also installed on the outer wall of the growth chamber (21); a second heat insulating ceramic layer is provided on the outer side of the connection between the growth chamber (21) and the mixing chamber (22); a second slope is provided on the inner wall of one end of the growth chamber (21) close to the optical detection chamber (13), and the angle of the second slope is 45 degrees, which is used to concentrate the particles on the axis to improve the measurement accuracy of the optical detection unit (33).

6. The small hybrid condensation particle counter according to claim 5, characterized in that: A third heating kit and a third thermal insulation layer are installed on the outer wall of the optical detection chamber (13); a second filter (35) and an air pump (17) are connected to the outlet of the optical detection chamber (13); the third heating kit is used to prevent condensation of hot alcohol vapor; the outer side of the connection between the growth chamber (21) and the optical detection chamber (13) is wrapped with a third thermal insulation ceramic layer; the first refrigeration kit (2) and the second refrigeration kit each include a refrigeration plate and a temperature sensor for reducing the temperature of the regulating chamber; the first heating kit, the second heating kit and the third heating kit each include a heating plate and a temperature sensor; the first heat sink and the second heat sink are used to quickly dissipate heat to ensure the normal operation of the first refrigeration kit (2) and the second refrigeration kit; the first thermal insulation layer, the second thermal insulation layer and the third thermal insulation layer are used to isolate the temperature conduction between each chamber and the outside world; the first filter (16) and the second filter (35) are used to remove particulate matter in the gas path.

7. The small hybrid condensation particle counter according to claim 6, characterized in that: The signal processing and control unit (26) includes a signal processing module (27) and a control module (28); the signal processing module (27) is used to receive the optical signal processed by the photomultiplier tube (18) and convert the optical signal into a particle number concentration; the control module (28) is used to control the operation of each refrigeration kit, heating kit, electronic flow valve, air pump, and differential pressure gauge; the differential pressure gauge (24), the air pump (17), the first electronic flow valve (4), and the second electronic flow valve are used to regulate the flow rate and ratio of the particle airflow and the vapor airflow.

8. The small hybrid condensation particle counter according to claim 7, characterized in that: The first insulating ceramic layer, the second insulating ceramic layer and the third insulating ceramic layer are all made of ceramic material. Each insulating ceramic layer is used for heat insulation and sufficient thermal insulation mixing of cold particles and hot steam. The ceramic material is zirconia.

9. The operating method of the small hybrid condensation particle counter according to claim 8, characterized in that: The method comprises the following steps: S1. The airflow carrying ultrafine particles enters the particle conditioning unit (29) at a certain flow rate and is then divided into two paths. One path is first filtered by the first filter (16) to become a clean airflow, which then enters the hot steam saturation unit (30). The other path enters the conditioning chamber (23). S2, after the airflow enters the regulating chamber (23), a cold particulate airflow is formed. The pressure difference between two parts of the regulating chamber (23) with different pipe diameters is measured using a differential pressure meter (24). The flow rate of the particulate airflow is determined based on the pressure difference. The flow rate of the airflow entering the particulate and steam mixing unit (31) and the hot steam saturation unit (30) is controlled by cooperating with the differential pressure meter (24) and the first electronic flow valve (4) and the second electronic flow valve; S3, controlling the operation of the first heating kit and the second heating kit to adjust the temperature of the saturation chamber (34) and the vapor diffusion chamber (12), at which time the alcohol solution immersed in the porous ceramic rod (8) turns into alcohol vapor and fills the entire saturation chamber (34), and the alcohol vapor is carried by the clean air flow entering the saturation chamber (34) into the vapor diffusion chamber (12) to form a hot vapor air flow, and the hot vapor air flow flows into the mixing chamber (22) through the circular hole channel; S4, the cold particulate airflow formed in the conditioning chamber (23) and the hot alcohol vapor airflow formed after being processed in the saturation chamber (34) and the vapor diffusion chamber (12) are adiabatically mixed in the mixing chamber (22) to form a mixed airflow that enters the growth chamber (21); S5. The particles in the mixed airflow absorb moisture and grow in the growth chamber (21), and are concentrated within a threshold range of the axis of the optical detection chamber (13) before entering the optical detection chamber (13); S6, the blue light source (20) is focused on the path of the mixed airflow entering the optical detection chamber (13) through the focusing lens (19). When the particles in the mixed airflow are irradiated by the light beam, light scattering occurs. Particles of different sizes scatter light of different intensities. The scattered light is guided to the photomultiplier tube (18) through the receiving lens (15). The photomultiplier tube (18) amplifies the received scattered light and converts it into an electrical signal. S7, the photomultiplier tube (18) sends the converted electrical signal to the signal processing module (27), and the signal processing module (27) filters and corrects the received signal to obtain the number of particles, particle size distribution and particle concentration information.

10. The operating method of the small hybrid condensation particle counter according to claim 9, characterized in that: The temperature of the conditioning chamber (23) and the growth chamber (21) is stabilized at 5°C, and the temperature of the saturation chamber (34), the vapor diffusion chamber (12) and the optical detection chamber (13) is stabilized at 50°C.

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