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Air Purifier Solution
In order to provide people with clean and safe indoor air, technicians in the air purifier industry are conducting various research and development and innovative designs to meet the needs of users. The market has broad prospects and great development potential. As time goes by, In the future, the air purifier technology will be more perfect and have new breakthroughs.
1. Introduction to the principle of air purifier filtration
Air purifiers refer to equipment that can absorb, decompose or transform various air pollutants and effectively improve air cleanliness. At present, household and commercial air purifiers that remove indoor air pollution are the main ones. Human physical and mental health problems caused by air pollution are becoming more and more serious. Decoration pollution in indoor air pollution has become an important source of pollution in residents' lives. A large number of volatile gases, formaldehyde, xylene, etc. released by beautification and decoration materials are used, and other bacteria and viruses are mixed at the same time. Seriously endanger the health of residents. Now, the air purifier with the function of removing indoor air pollutants has become a new member of people's household appliances.
According to the principle of filtration - the filter material uses the rules of molecular motion to carry out effective filtration. There are three types (see Figure 1): ① Inertial collision adsorption refers to the particles colliding into the filter due to the linear motion of the inertial effect after the airflow direction changes. Adsorption on the material. ②Diffusion adsorption means that due to Brownian motion, particles diffuse from the airflow to the surface of the fiber, and are adsorbed to the fiber under the action of static electricity. Diffusion adsorption can only play an important role in gas filtration. ③ Direct adsorption means that when the particle diameter is larger than the channel aperture of the filter medium, it cannot pass through and be intercepted. Direct adsorption is the most basic characteristic of pore size distribution. The smaller the pore size, the higher the efficiency of direct adsorption and the higher the efficiency of particle removal.
2. Air purification technology
Figure 2 is an exploded schematic diagram of the basic structure of a common air filter, which consists of a chassis shell, air inlet and channels, filter components (primary filter layer, high-efficiency HEPA component filter layer, activated carbon adsorption layer), fan, air outlet and channels , its core is the filter screen assembly, that is, the air filter element (device), which plays the role of filtering and purifying the air. According to its basic structure, it can be seen that the main factors affecting the performance of the air filter are: filter material performance, filtered airflow properties, airflow velocity and filter structure.
In the air purification process shown in Figure 3, the toxic and harmful gases entering the air inlet are firstly pre-filtered (that is, the initial filtration stage). The filter materials in this stage are generally sponge filters and PP nylon filters. Antibacterial filter cotton, there are also composite materials of sponge and activated carbon, etc., for example, the PP nylon filter is made of nylon mesh, the filter material is made of PP fiber textile molding, and the outer frame is aluminum alloy, or galvanized frame, supported by wire. The nylon mesh is loaded into the frame after being tightened with the lining frame, and the number of layers of the nylon mesh can be determined according to the user's requirements. Its characteristics are good dust removal effect, acid and alkali resistance, good corrosion resistance, small resistance, light weight, moisture resistance, long life, etc. The pre-filter can remove large particles of dust suspended matter, pollen, large particles of mold, pet hair wait. Antibacterial filter cotton can remove dust, mold and bacteria and other microorganisms. If it is a composite material, such as activated carbon, it has already begun to remove odors, formaldehyde and other harmful gases.
Secondly, enter the second layer (high-efficiency filter layer), which is a HEPA component (High efficiency particulate air Filter). Air filtration and purification are mainly based on fiber filter materials. The particulate matter in the filter is intercepted by the fiber filter material, that is, the filtration principle shown in Figure 1, which separates the particulate matter from the air, thereby completing the further purification and filtration of the air. According to China's classification standards GB12218-89, GB/T14295-93, GB13554-92, the air filtration level can be roughly divided into three levels: primary filtration (particle size ≥ 5um), intermediate filtration (1um≤particle size<5um ), high-efficiency filtration (particle size ≤ 0.5um), the high-efficiency filter layer is mainly used to capture particulate dust and various suspended solids below 0.5um, and the filter material is ultra-fine glass fiber paper, etc. The advantages of this layer of HEPA components It is the air that can pass through, but the very fine particles in the air cannot pass through. The filtration efficiency of particles with a diameter of only 0.3um (1/200 of the diameter of a human hair) is over 99.7%, which is bacteria, extremely fine dust particles, smoke, etc. Effective filter media for pollutants.
The above-mentioned glass fiber paper is used as a high-efficiency filter medium, regardless of its particle size, its filtration feature is to capture solid particles, so this purification technology is for the purification of solid pollutants, and for the special material of activated carbon, the activated carbon adsorption technology is air purification. In the purification technology of gaseous pollutants, activated carbon is a kind of adsorbent with excellent performance that uses charcoal, bamboo charcoal, etc. as raw materials and processes raw materials through physical and chemical methods. The larger the surface area, the stronger the adsorption capacity.
Finally, the sterilizing cotton and activated carbon filter can effectively sterilize, deodorize, and deodorize again, and re-filter the microorganisms and virus bacteria missed in the air in the pre-filter layer, and finally output high-quality air for indoor residents to breathe.
3. Air filter performance testing method
From the schematic diagram of the air purification process in Figure 3, it can be seen that the key component of the air purifier to achieve high-efficiency purification is the high-efficiency air filter (HEPA filter). In other words, the performance of the air filter directly affects the purification function of the air purifier. Pros and cons. At present, the filtration efficiency detection methods of high-efficiency air filters include: D.O.P method, oil mist method, most penetrating particle size method MPPS, etc.
3.1 D.O.P method
When the DOP method is used to detect the filtration efficiency of the filter, it is necessary to manually manufacture the required dust source particle size (0.3um). A kind of dioctyl phthalate (DOP-DiOctyl-Phthalate) is used, which is a colorless transparent liquid. The liquid is heated and vaporized under strictly controlled conditions, and then mixed with cold air to condense it to produce droplets (0.3um) with the same size as the dust particles, which are used for experimental detection aerosols. A more common detection method.
3.2 Oil mist method
As a detection method, the oil mist method to detect the performance of the air filter also needs the dust source during the test to ensure the particle size of the dust source. On this basis, and under the specified detection conditions, it will be fully tested The uniformly mixed oil mist aerosol passes through the tested filter, and the oil mist concentration before and after the filter is measured, so as to calculate the oil mist filtration rate and transmittance.
3.3 MMPPS method
The most penetrating particle size method (The Most PenetratingParticle Size) MPPS, its basic principle is to use a special nozzle to bend and spray D.O.P, DEHS and other liquids to form a polydisperse aerosol of 0.01-1um, which is used as a dust source for experiments. Laser particle counters or condensation counters measure particle concentrations upstream and downstream of the filter to determine its efficiency.
4. Development trend of air purification technology
With the rapid development of the global industrial economy, while human beings are realizing a highly developed material civilization, they are in the midst of many contradictions, and environmental problems are becoming more and more serious. Among them, air pollution is rampant, such as industrial waste gas, automobile exhaust, and coal combustion Due to the lack of supervision and environmental protection testing, the use of dust and new indoor decoration materials, behind the greed for beauty, is the abuse of these chemical materials. The problem of indoor environmental pollution is becoming more and more prominent. People have entered the period of indoor air pollution, but at the same time, Human beings' awareness of their own health is also increasing. How to improve the home environment, breathe clean air, and live a healthy life is a common problem faced by countries all over the world.
Various air purifiers manufactured by adopting air purification technology have sprung up like mushrooms after rain. The early air purifiers had a single function and a simple structure, which was difficult to meet the needs. The development trend of the air purifiers currently designed is the technology compound type, which integrates various functions, and develops a new type of filter on the basis of the original purification technology. Materials, such as photocatalyst, whose main component is TiO2, has the function of disinfection, and has a good bactericidal effect on various common pathogenic bacteria. Therefore, the integration of various air purification technologies is the future development direction.
5. The overall design of the portable air purifier system
In recent years, the domestic smog phenomenon has become more and more serious, and many places in the country have been plagued by smog. Particles, bacteria, viruses and other harmful substances in the indoor and outdoor air pose a hazard to human health, especially for those who work for a long time or live in harsh environments. people. This paper designs a multifunctional portable air purifier, which can also use the filter layer and negative ion generator to improve the quality of the air inhaled by the human body while detecting the air quality, and transmit the real-time air quality to the server for analysis through the Internet of Things chip. This design can select the air volume and speed regulation mode according to the environment, and has the advantages of low energy consumption, simple maintenance and portability.
This design is based on STM32 single-chip microcomputer, which is composed of negative ion generator, micro fan, air filter and other systems. The micro fan makes the air flow, and the flowing air passes through the negative ion generator installed in the tuyere, which continuously ionizes the air, generates a large amount of negative ions, and forms a negative ion airflow, which passes through the coarse filter cotton, activated carbon filter element, and PM2.5 test paper in the machine in turn. Filter or adsorb various pollutants to achieve the purpose of cleaning and purifying the air.
In the haze environment, the sensor senses the surrounding air, and displays the PM2.5 value, temperature value and humidity value of the current unpurified air through the LCD screen. Through the function of the fan, the air first flows through the negative ion generator, and the charged large particles in the air are adsorbed to the wire filter net, the first layer of filtration is performed through the coarse filter cotton, the second layer of filtration is performed by the activated carbon net, and the PM2.5 filter paper filters the small Particles, and then purify the air through the negative ion generator, so that the human body can breathe clean air. In addition, this system can also be used as a car purifier with different types of air outlets.
5.1 Hardware Composition of Air Purifier System
System main control module: This design uses STM32 single-chip microcomputer as the data processing module, which can process data quickly, and can sample the data detected by the PM2.5 sensor and temperature and humidity sensor in real time, accurately calculate the dust concentration, temperature and humidity, and convert the real-time data It is transmitted to the OLED display screen, which has the characteristics of high cost performance and low power consumption.
PM2.5 detection module: This design uses the sharp PM2.5 dust sensor GP2Y1010AU0F detection module, which uses an optical air quality sensor to sense dust particles in the air. The internal infrared light-emitting diode and phototransistor enable it to detect the reflected light of dust in the air, and judge the dust content by detecting the light refracted by the dust in the air. The output of the sensor is an analog voltage, and its value is proportional to the dust concentration. Through the sampling data of the STM32 microcontroller, the Kalman filter algorithm is used to accurately calculate the dust concentration and measure the content of PM2.5.
Fan module: The fan is the power source for the air flow of the purifier, and the air volume determines the speed of purification. This design uses a DC12V micro fan, controls the PWM speed through the STM32 microcontroller, changes the cycle duty cycle to control the fan terminal voltage, and then controls the fan speed.
Temperature and humidity detection module: This design uses a digital temperature and humidity sensor DHT22 module. DHT22 digital temperature and humidity sensor is a temperature and humidity composite sensor with calibrated digital signal output, which has high reliability and stability. The sensor includes a capacitive humidity sensing element and an NTC temperature measuring element. The single-wire serial communication between this module and STM32 single-chip microcomputer is simple and fast. Through the real-time calibration procedure of STM32 single-chip microcomputer, the temperature and humidity data are more accurate.
Negative ion generator module: Through the pulse oscillation circuit of the negative ion generator, the low voltage is boosted to DC negative high voltage through the high voltage module, and the negative DC high corona is continuously generated through the carbon fiber tip, and a large number of electrons are emitted at high speed, which will immediately Captured by oxygen molecules in the air, forming negative ions. This design uses negative ion generators to react harmful gases such as formaldehyde and benzene in the air, decompose them into carbon dioxide and water, and achieve the purpose of dust removal, sterilization and air purification.
Power supply module: This design selects DC12V, 5000mA capacity lithium battery as the power supply for the system. The power supply provides stable voltage and current for each external sensor module and single-chip microcomputer module, and the ripple is small. In addition, when the power of the system is insufficient, the low battery can be displayed on the OLED display to remind the user to charge in time.
CC2530 chip: The communication module chooses CC2530F256 of American TI Company, which contains a standard enhanced 8051 CPU, 256KB programmable flash memory, 8-KBRAM and advanced RF transceiver, combined with ZigBee protocol stack, can realize powerful and complete wireless communication . In this design, the STM32 single-chip microcomputer and the CC2530 chip are set at the same baud rate for serial communication, and the PM2.5 and temperature and humidity data are transmitted to the adjacent server.
5.2 Air purifier system test
Connect each module, first test the operation of each module, observe its status change, the system status value can be observed on the OLED screen and the oscilloscope to observe the waveform display. Finally, each module is assembled and tested.
Fan module monitoring: By changing the duty cycle in each cycle to control the voltage across the fan, and then control the fan speed. In this design, the duty cycle is set to four levels of 0.25, 0.5, 0.75, and 1, and the output duty cycle of the STM32 microcontroller is detected by an oscilloscope.
PM2.5 module monitoring: Test the PM2.5 detection module. When there is no smoke in the room, the LCD screen displays a PM2.5 value of 40, and when there is smoke in the room, the LCD screen displays a PM2.5 value of 250, indicating that the module detects high sensitivity.
Temperature and humidity module monitoring: When the normal greenhouse is 15.5°C, the relative humidity is 64.4%. When a heat source is added around the temperature and humidity sensor, the temperature rises to 18.7°C. When a humidifier is placed around the temperature and humidity sensor, the relative humidity rises to 88.8%. , indicating that the performance of the temperature and humidity sensor is good.
OLED display module monitoring: OLED module and STM32 single-chip microcomputer realize data transmission through IIC, the data detected by PM2.5 sensor and temperature and humidity sensor are sent to STM32 single-chip microcomputer for data processing and analysis, and the processed data is sent to OLED display screen, Display the PM2.5 value and air temperature and humidity before and after purification by the purifier.
Summarize
Through the test, the portable air purifier can effectively purify the air inhaled by the human body, and minimize the bacteria and harmful gases suspended in the indoor and outdoor air. Interconnected, providing pedestrians with a safe and comfortable outdoor breathing environment.
The above are the details of the portable air purifier solution introduced by Shenzhen Zuchuang Microelectronics Co., Ltd. for you. If you have the development and design needs of air purifiers, you can rest assured to entrust them to us. We have rich experience in custom development of electronic products, and can evaluate the development cycle and IC price as soon as possible, and can also calculate the PCBA quotation. We are a number of chip agents at home and abroad: Songhan, Yingguang, Jieli, Ankai, Quanzhi, realtek, with MCU, voice IC, Bluetooth IC and module, wifi module. Our development capabilities cover PCB design, single-chip microcomputer development, Bluetooth technology development, software customization development, APP customization development, WeChat official account development and other hardware and software design. It can also undertake the research and development of smart electronic products, the design of household appliances, the development of beauty equipment, the development of Internet of Things applications, the design of smart home solutions, the development of TWS earphones, the development of Bluetooth earphone speakers, the development of children's toys, and the development of electronic education products.
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