A nanoparticle detection circuit

Abstract

The present invention relates to a nanoparticle detection circuit, comprising: a processor; a compression module for compressing a sample gas to a target state, the processor being connected to the compression module by signal; a standard release module for quickly releasing the compressed sample gas when the sample gas is compressed to the target state, the processor being connected to the standard release module by signal; a laser detection module for detecting the particle parameters of the compressed gas, the processor being connected to the laser detection module by signal. The present invention can accurately detect the particle parameters of nanometer-level particles, has a simple structure, is convenient to operate, has a low cost, is more suitable for practical use, and can be well applied to the fire prevention and monitoring process.

Description

Technical Field

[0001] The invention relates to the technical field of gas detection, and in particular to a nanoparticle detection circuit. Background Art

[0002] Monitoring parameters such as particle concentration and diameter in the air is an important way to prevent fires. On a macro scale, the combustion process of biomass materials can be divided into five stages, namely preheating, thermal decomposition, ignition, combustion and fire spread. When a substance is heated to the point of overheating, the chemical change causes thermal decomposition of the material, releasing invisible nanoparticles (about 0.002μm in diameter).

[0003] The preheating and thermal decomposition stages can be collectively referred to as the very early stages of a fire. In the very early stages, a large number of invisible nanoparticles are produced in the air, but no smoke particles are produced. At this time, conventional smoke sensors, smoke alarms and other products cannot detect the nanoparticles in the air and cannot monitor the very early stages of a fire in time. In the current existing technology, most of the nanoparticle detection equipment has a complex structure, inconvenient operation, and high cost, and cannot be well applied in the fire prevention and monitoring process. Therefore, a more practical nano-scale particle detection circuit is proposed, which is of great significance to the fire prevention and monitoring process. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a nanoparticle detection circuit in view of the above-mentioned defects of the prior art. The present invention can accurately detect the particle parameters of nano-level particles, has a simple structure, convenient operation, low cost, is more suitable for practical use, and can be well applied to the fire prevention and monitoring process.

[0005] The technical solution adopted by the present invention to solve its technical problem is:

[0006] A nanoparticle detection circuit is provided, comprising:

[0007] processor;

[0008] a compression module for compressing the sample gas to a target state, the processor being signal-connected to the compression module;

[0009] a target release module for quickly releasing the compressed sample gas when the sample gas is compressed to a target state, the processor being connected to the target release module by signal;

[0010] A laser detection module is used to detect parameters of compressed gas particles, and the processor is signal-connected to the laser detection module.

[0011] Preferably, the target release module comprises:

[0012] A state parameter detection element for detecting state parameters of a sample gas;

[0013] a release element for releasing the compressed sample gas;

[0014] The signal output end of the state parameter detection element is electrically connected to the signal input end of the processor, and the signal output end of the processor is electrically connected to the signal input end of the release element;

[0015] The processor is used for controlling the release element to release the compressed sample gas when the detection parameter of the state parameter detection element reaches a preset target parameter.

[0016] Preferably, the state parameter detection element includes an air pressure sensor.

[0017] Preferably, the state parameter detection element includes a temperature sensor.

[0018] Preferably, the state parameter detection element includes a humidity sensor.

[0019] Preferably, the release element comprises a solenoid valve.

[0020] Preferably, the laser detection module comprises at least one pair of matched laser emitting elements and laser receiving elements;

[0021] The signal output terminal of the processor is electrically connected to the signal input terminal of the laser emitting element, and the signal output terminal of the laser receiving element is electrically connected to the signal input terminal of the processor;

[0022] The laser emitted by the laser emitting element passes through the compressed sample gas and is received by the laser receiving element, so that the laser receiving element generates a corresponding induction signal.

[0023] Preferably, the compression module comprises a pressurized air pump.

[0024] Preferably, the nanoparticle detection circuit further comprises:

[0025] A communication module is signally connected to the processor.

[0026] Preferably, the communication module is a 4G module, a Bluetooth module, a WiFi module or a ZigBee module.

[0027] The nanoparticle detection circuit described in the present invention has the advantages that: the nanoparticle detection circuit of the present invention compresses the sample gas to the target state through the compression module and then quickly releases the compressed sample gas. After the sample gas is compressed and quickly released, the gas can produce a condensation nucleus phenomenon, that is, the invisible particles with a diameter of as small as 0.002 μm in the compressed gas are enlarged into detectable small water droplets with a diameter range of 10 μm-20 μm, and then the laser detection module is used to detect the formed detectable small water droplets. According to the measured signal, the parameters such as the particle size and distribution of the measured particles are calculated according to the MIE scattering principle of light, and the concentration of nanoparticles in the sample gas can be further calculated. The above parameters can be applied to the fire prevention and monitoring process to monitor and warn the very early stage of the fire. The present invention can accurately detect the particle parameters of nano-level particles, has a simple structure, convenient operation, low cost, is more suitable for practical use, and can be well applied to the fire prevention and monitoring process. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the present invention will be further described below in conjunction with the accompanying drawings and embodiments. The drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work:

[0029] Figure 1 It is a structural block diagram of a nanoparticle detection circuit according to the present invention;

[0030] Figure 2 It is a flow chart of the detection steps of a nanoparticle detection circuit described in the present invention.

[0031] Explanation of the reference numerals: 1-processor, 2-compression module, 3-standard release module, 31-state parameter detection element, 32-release element, 4-laser detection module, 41-laser emitting element, 42-laser receiving element, 5-communication module. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the following will be described clearly and completely in combination with the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are partial embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work belong to the protection scope of the present invention.

[0033] The embodiment of the present invention Figure 1 , Figure 2 As shown, a nanoparticle detection circuit according to the present invention comprises:

[0034] Processor 1, processor 1 is used for data and signal processing, receiving sensor signals from various sensor elements, and controlling the operation of various execution elements according to the sensor signals from various sensor elements. In some specific embodiments, processor 1 can be selected from MCU (Microcontroller Unit), CPU (central processing unit), PLC (Programmable Logic Controller) or other control elements with logic operation and data processing functions.

[0035] Compression module 2, compression module 2 is used to compress the sample gas to a target state, the processor 1 is connected to the compression module 2 signal, in a specific application example, the sample gas is usually passed into a gas chamber for detection, and the compression module 2 is connected to the gas chamber for pressurizing and compressing the sample gas therein.

[0036] The target release module 3 is used to quickly release the compressed sample gas when the sample gas is compressed to the target state. The processor 1 is connected to the signal of the target release module 3 to determine whether the sample gas reaches the target state, and controls whether to release the compressed sample gas based on the judgment result.

[0037] The laser detection module 4 is used to emit laser and detect the particle parameters of the compressed gas according to the scattering state of the laser in the compressed gas. The processor 1 is connected to the laser detection module 4 signal to control the operation of the laser detection module 4 and receive the detection signal for calculation.

[0038] The nanoparticle detection circuit of the present invention compresses the sample gas to the target state through the compression module 2 and then quickly releases the compressed sample gas. After the sample gas is compressed and quickly released, the gas can produce a condensation nucleus phenomenon, that is, the invisible particles with a diameter of as small as 0.002 μm in the compressed gas are enlarged into detectable small water droplets with a diameter range of 10 μm-20 μm, and then the laser detection module 4 is used to detect the formed detectable small water droplets. According to the measured signal, the parameters such as the particle size and distribution of the measured particles are calculated according to the MIE scattering principle of light, and the concentration of nanoparticles in the sample gas can be further calculated. The above parameters can be applied to the fire prevention monitoring process to monitor and warn the very early stage of the fire. The present invention can accurately detect the particle parameters of nano-level particles, has a simple structure, convenient operation, low cost, is more suitable for practical use, and can be well applied to the fire prevention monitoring process.

[0039] Furthermore, in this embodiment, the target release module 3 specifically includes:

[0040] The state parameter detection element 31 is used to detect the state parameter of the sample gas. When specifically configured, the detection end of the state parameter detection element 31 is usually extended into the gas chamber filled with the sample gas for detection;

[0041] The release element 32 is used to release the compressed sample gas. Usually, the release element 32 is arranged at the exhaust port of the gas chamber, and controls the opening and closing of the exhaust port through its own action to release the compressed sample gas in the gas chamber.

[0042] The signal output end of the state parameter detection element 31 is electrically connected to the signal input end of the processor 1, and the signal output end of the processor 1 is electrically connected to the signal input end of the release element 32;

[0043] The processor 1 is used to control the release element 32 to operate when the detection parameter of the state parameter detection element 31 reaches a preset target parameter, so that the exhaust port is opened to release the compressed sample gas in the gas chamber. In a specific embodiment, the target parameters include but are not limited to target pressure, compression time, target temperature, target humidity; and / or other target parameters that can cause the invisible nanoparticles in the sample gas to condense into small water droplets with detectable diameters.

[0044] Example 1

[0045] When the target parameter is the target pressure, the state parameter detection element 31 can select a pressure sensor to detect the real-time pressure in the gas chamber and convert it into a corresponding electrical signal and send it to the processor 1. The processor 1 performs signal processing and compares the real-time pressure with the preset target pressure. When the real-time pressure reaches the target pressure, the processor 1 controls the release element 32 to release the compressed sample gas.

[0046] Example 2

[0047] When the target parameter is the target temperature, the state parameter detection element 31 can select a temperature sensor to detect the real-time temperature in the gas chamber and convert it into a corresponding electrical signal and send it to the processor 1. The processor 1 performs signal processing and compares the real-time temperature with the preset target temperature. When the real-time temperature reaches the target temperature, the processor 1 controls the release element 32 to release the compressed sample gas.

[0048] Example 3

[0049] When the target parameter is the target humidity, the state parameter detection element 31 may select a humidity sensor to detect the real-time humidity in the gas chamber and convert it into a corresponding electrical signal and send it to the processor 1. The processor 1 performs signal processing and compares the real-time humidity with the preset target humidity. When the real-time humidity reaches the target humidity, the processor 1 controls the release element 32 to release the compressed sample gas.

[0050] The above three different state parameter detection elements 31 can respectively detect the pressure, temperature and humidity of the compressed sample gas. These three indicators can reflect the compression degree of the gas and can be selected according to the actual situation. In other feasible embodiments, two or more target parameters can be set, and corresponding multiple state parameter detection elements 31 are set. When each state parameter detection element 31 reaches the target parameter, the release element 32 releases the compressed sample gas to ensure that the sample gas is compressed to the target state, thereby improving the accuracy of the detection result.

[0051] Furthermore, in this embodiment, the release element 32 is specifically a solenoid valve, which is usually arranged at the exhaust port of the gas chamber, and the signal output end of the processor 1 is connected to the control end of the solenoid valve. The processor 1 controls the opening and closing of the solenoid valve through the output signal, thereby controlling the release of the compressed sample gas. The solenoid valve has the advantage of being easy to control.

[0052] Furthermore, in this embodiment, the laser detection module 4 includes at least one pair of matched laser emitting elements 41 and laser receiving elements 42;

[0053] The signal output end of the processor 1 is electrically connected to the signal input end of the laser emitting element 41, so as to control the operation of the laser emitting element 41 and thus control the emission of the laser. The signal output end of the laser receiving element 42 is electrically connected to the signal input end of the processor 1, so as to send the sensing signal generated by the laser receiving element 42 to the processor 1.

[0054] The laser emitted by the laser emitting element 41 passes through the compressed sample gas and is scattered by the small water droplets condensed in the gas. After being scattered, the emitted laser is incident on the laser receiving element 42. The laser receiving element 42 generates a corresponding electrical signal through photoelectric induction and inputs the electrical signal into the processor 1. The processor 1 can convert the light intensity of the laser according to the level of the electrical signal, thereby calculating the particle concentration and other parameters in the compressed sample gas. The above-mentioned laser detection module 4 can calculate the particle concentration and other parameters in the compressed sample gas according to the degree of scattering of the laser in the compressed sample gas.

[0055] Furthermore, in this embodiment, the nanoparticle detection circuit also includes a communication module 5 connected to the processor 1 signal, and the communication module 5 is used to communicate with a host computer such as a PC, and can also communicate with a terminal device such as a smart terminal, and is used to send the calculation result of the processor 1 (i.e., the particle parameters of the compressed sample gas obtained by detection) to other devices, which can facilitate data transmission. More specifically, the communication module 5 can use a 4G module, a Bluetooth module, a WiFi module, or a ZigBee module for external communication.

[0056] The following will take a specific application process as an example to illustrate the detection process of the nanoparticle detection circuit of the present invention.

[0057] The process of compressing the sample gas by the compression module 2 is adiabatic compression, that is, the gas is compressed without heat exchange with the outside.

[0058] An ideal gas is described by the following equation (a):

[0059]

[0060] Where R is the gas constant and M is the molar mass of the gas.

[0061] The conservation formula of temperature T and pressure p in the adiabatic compression process is as follows (b):

[0062] T γ p 1-γ =K” (b);

[0063] The parameter γ is the ratio of the specific heat capacity of air at constant pressure to the specific heat capacity of air at constant volume. p / C v , K" is a constant. From this, the state parameter T0 of the compressed gas can be calculated.

[0064] According to the mechanical energy conservation equation (c):

[0065]

[0066] Among them, the first term in the above formula (c) is the internal energy of the gas, the second term is the kinetic energy released by the gas, and the third term is the work done by the gas due to atmospheric resistance.

[0067] During the process of releasing the compressed sample gas from the release element 32, the calculated speed of the high-pressure gas released through the exhaust port is as follows:

[0068]

[0069] Among them, p is the air pressure outside the cavity, p0 and T0 are the pressure and temperature inside the cavity, and C0 is a constant coefficient related to the structure.

[0070] According to the above formula, the relationship between the kinetic energy loss in the compression process and the atomization effect can be obtained, and the atomization effect can be quantitatively analyzed according to the detection results.

[0071] I. Kinetic Energy Loss

[0072] Assuming that the mass loss of gas in the cavity forms kinetic energy release, as the speed decreases with the gradual release of gas, the square of its average speed is calculated as half of the initial maximum speed, that is, the kinetic energy loss, as shown in the following formula (e):

[0073]

[0074] Among them, the mass of gas in the cavity after compression is m d =MVp0 / RT0, the mass of gas in the cavity before compression m=MVp / RT, V is the volume of the cavity.

[0075] II. Degree of condensation

[0076] The supersaturated humidification effect caused by the kinetic energy loss gradually diffuses in the cavity, and an ideal transition state is defined as a state in which the humidity of a portion of the gas in proportion rs is just in a saturated state.

[0077] Under the condition that the humidity in the cavity remains unchanged, first calculate the temperature T when the temperature reaches saturation r (Similar to dew point, it can be looked up in a table or calculated by an approximate formula), as shown in the following formula (f):

[0078]

[0079] The above formula (f) is based on the Magnus saturated vapor pressure formula, where H is the relative humidity outside the cavity and t is the temperature outside the cavity.

[0080] According to the formula of air molecular internal energy E = 3nRT, (the relationship between absolute temperature T and Celsius temperature t: T = t + 273.15), we can calculate how many moles of molecules can be reduced from the room temperature T to the dew point temperature T under the energy loss De. r , the calculation formula is as follows (g):

[0081]

[0082] Combined with the gas mole number n0 = Vp / RT in the standard state in the cavity, the saturated air ratio r can be calculated s =n s / n0, as shown in the following formula (h):

[0083]

[0084] III. Scattering and Detection

[0085] The total scattering cross section is proportional to the number of condensed particles, so the induction level I of the laser receiving element 42 is calculated as follows (i):

[0086] I=C1*n d *r s (i);

[0087] Among them, n d is the particle concentration to be measured, and C1 is a constant coefficient determined by the detection system.

[0088] The particle concentration is calculated as:

[0089] 1) Through the aforementioned gas dynamic process, combined with the ambient air parameters T, p, H, the gas parameters under the compression and valve opening deflation states in the cavity are calculated and determined: T0, T r ;

[0090] 2) Use a standard particle generation tool to introduce particles of known concentration into the cavity, and calibrate the product constant related to C0 and C1 by combining the cavity structure parameter V and other parameters;

[0091] 3) In actual measurement, the induction level I of the laser receiving element 42 is measured, and the particle concentration n d It is the following formula (j):

[0092]

[0093] Through the above calculation process, the nanoparticle detection circuit of the present invention can calculate the particle concentration n in the sample gas according to the sensing level I of the laser receiving element 42 after the sample gas is condensed into detectable small water droplets. d ,This parameter can be applied in the fire prevention monitoring process to monitor and warn of the very early stages of fire.

[0094] It should be understood that those skilled in the art can make improvements or changes based on the above description, and all these improvements and changes should fall within the scope of protection of the appended claims of the present invention.

Claims

1. A nanoparticle detection circuit, characterized in that: include: processor; a compression module for compressing the sample gas to a target state, the processor being signal-connected to the compression module; a target release module for quickly releasing the compressed sample gas when the sample gas is compressed to a target state, the processor being connected to the target release module by signal; A laser detection module for detecting parameters of compressed gas particles, wherein the processor is signal-connected to the laser detection module; Through the gas dynamic process, combined with the ambient air parameters temperature T, pressure p, and relative humidity H outside the cavity, the gas parameters under the compression and valve-opening deflation conditions in the cavity are calculated: the cavity temperature T0, the temperature when the temperature reaches saturation T r ; The known concentration of particles is introduced into the cavity by a standard particle generation tool, and the product constant related to the constant coefficient C0 related to the structure and the constant coefficient C1 determined by the detection system is calibrated in combination with the cavity structure parameter V; The induction level I of the receiving element of the laser detection module is measured to obtain the kinetic energy loss, condensation degree and scattered light intensity during the compression process, and then the concentration nd of the nanoparticles is obtained by combining them; the particle concentration nd is calculated as follows: Among them, P is the air pressure outside the cavity, P0 is the pressure inside the cavity, and the parameter γ is the ratio of the specific heat capacity of air at constant pressure to the specific heat capacity of air at constant volume.

2. The nanoparticle detection circuit according to claim 1, characterized in that: The target release module comprises: A state parameter detection element for detecting state parameters of a sample gas; a release element for releasing the compressed sample gas; The signal output end of the state parameter detection element is electrically connected to the signal input end of the processor, and the signal output end of the processor is electrically connected to the signal input end of the release element; The processor is used for controlling the release element to release the compressed sample gas when the detection parameter of the state parameter detection element reaches a preset target parameter.

3. The nanoparticle detection circuit according to claim 2, characterized in that: The state parameter detection element includes an air pressure sensor.

4. The nanoparticle detection circuit according to claim 2, characterized in that: The state parameter detection element includes a temperature sensor.

5. The nanoparticle detection circuit according to claim 2, characterized in that: The state parameter detection element includes a humidity sensor.

6. The nanoparticle detection circuit according to any one of claims 2 to 5, characterized in that: The release element comprises a solenoid valve.

7. The nanoparticle detection circuit according to claim 1, characterized in that: The laser detection module includes at least one pair of matched laser emitting elements and laser receiving elements; The signal output terminal of the processor is electrically connected to the signal input terminal of the laser emitting element, and the signal output terminal of the laser receiving element is electrically connected to the signal input terminal of the processor; The laser emitted by the laser emitting element passes through the compressed sample gas and is received by the laser receiving element, so that the laser receiving element generates a corresponding induction signal.

8. The nanoparticle detection circuit according to claim 1, characterized in that: The compression module includes a pressurized air pump.

9. The nanoparticle detection circuit according to claim 1, characterized in that: Also includes: A communication module is signally connected to the processor.

10. The nanoparticle detection circuit according to claim 9, characterized in that: The communication module is a 4G module, a Bluetooth module, a WiFi module or a ZigBee module.

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