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What is an air purifier | Air purifier types | How the air purifier works

by jackjack on Oct 12, 2023

Air purifier, also known as "air cleaner", air purifier, purifier, refers to the adsorption, decomposition or conversion of various air pollutants (generally including PM2.5, dust, pollen, odor, formaldehyde and other decoration pollution, bacteria, allergens, etc.), can effectively improve air cleanliness products, mainly divided into household, commercial, industrial, building.

Oksou air purifier production background

Of the 4.3 million deaths from kitchen air pollution worldwide in 2012, 35 percent were caused by stroke, 22 percent by chronic obstructive pulmonary disease and 28 percent by ischaemic heart disease, and about 7 percent by lung cancer, according to the study.

A research project on disease risk assessment in the Lancet, a well-known British medical journal, has listed kitchen air pollution (smoke) as the biggest health risk after high blood pressure, smoking and alcohol abuse. More people die each year from continuing to inhale smoke from kitchen fires than malaria, tuberculosis and AIDS combined.

Main species

From the point of view of the working principle of the air purifier, it is mainly divided into three types: passive, active, active and passive hybrid.

According to the air purifier for the removal of particles in the air, there are mainly mechanical filter, electrostatic electret filter, high voltage electrostatic dust collection, negative ion and plasma method.

Mechanical filtration

Generally, particles are captured in the following four ways: direct interception, inertial collision, Brown diffusion mechanism, and screening effect, which has a good collection effect on fine particles but large wind resistance. In order to obtain high purification efficiency, the resistance of the filter screen is relatively large, and the filter screen needs to be dense, resulting in reduced life, which needs to be replaced regularly.

High voltage electrostatic dust collection

The dust collection method that uses high voltage electrostatic field to ionize the gas so that the dust particles are charged and adsorbed to the electrode has small wind resistance but poor effect on large particles and fibers, which will cause discharge, and it is difficult and time-consuming to clean, easy to produce ozone and form secondary pollution.

"High voltage electrostatic dust collection" is a way to ensure both air volume and adsorption of fine particles. This is the way that the particles are charged by loading a high voltage before passing through the filter, so that the particles are "easily adsorbed" to the filter under the action of electricity.

The high-voltage dust collecting part originally applied a high voltage to the two electrodes, which charged the passing dust when discharged at the two poles. Most of the dust is originally neutral or with weak charge, so the filter can only filter dust larger than the mesh. But narrowing the mesh of the filter element can cause blockage. The high-voltage electrostatic dust collection method can make the dust charged, and under the action of electricity, it is adsorbed to the specially processed and permanently charged filter, so that even if the mesh of the filter is too large (thick), it can indeed capture the dust.

Electrostatic electret filter

Relative mechanical filtration can only effectively remove particles above 10 microns, and when the particle size is reduced to 5 microns, 2 microns or even submicrons, an efficient mechanical filtration system will become more expensive, and the wind resistance will increase significantly. Through the electrostatic electret air filter material filtration, can achieve a high capture efficiency with low energy consumption, while combining the advantages of electrostatic dust removal and low wind resistance, but no external voltage of tens of thousands of volts, so no ozone is generated, and because of its composition of polypropylene material, it is easy to discard.

Electrostatic dust removal

It can filter dust, smoke and bacteria smaller than cells, and prevent diseases such as lung disease, lung cancer and liver cancer. The most harmful dust in the air to the human body is less than 2.5 microns, because it can penetrate cells and enter the blood. The ordinary purifier uses filter paper to filter the dust in the air, which is easy to block the filter hole, and the dust not only has no sterilization effect, but also easily causes secondary pollution.

Electrostatic sterilization

The use of high voltage electrostatic field of about 60 00 volts can completely kill bacteria and viruses attached to the dust in an instant to prevent colds, infectious diseases and other diseases. The mechanism of sterilization is to destroy 4 polypeptide chains of bacterial capsid protein and damage RNA.

The relevant standards of the national "Air purifier" define the air purifier as "equipment that separates and removes one or more pollutants from the air." A device capable of removing pollutants from the air. It mainly refers to the monomer air purifier used in the room and the modular air purifier in the central air conditioning ventilation system.

According to purification needs, air purifiers can be divided into:

(1) Pure purification type. If it is located in an area where the indoor humidity is moderate, or the air quality requirements are not too high, the purchase of a pure purification air purifier will meet the needs.

(2) Humidification and purification type. If it is located in a dry area, often open the air conditioner is dehumidified by the air conditioner and the indoor air is dry, or the air quality requirements are high, then the purchase of an air purifier with humidification and purification function will be the most suitable choice. LG air purifier also has a natural humidification technology, the use of scientific and technological means to achieve the vaporization of water, through the windmill or disk filter rotation, the harmful substances remain in the tray to eliminate, only discharge ultrafine and clean water molecules into the air.

(3) Intelligent type. If you like automated operation, intelligent monitoring of air quality, or reflect noble taste, or used for gifts need to be more decent, then buy an intelligent air purifier is the best choice.

(4) Vehicle type. If it is used for air purification in the car, it is necessary to purify the car odor, car formaldehyde and other internal pollution, and can be specially placed in the car air purifier, so the best choice is the car type air purifier.

(5) Desktop type. That is, an air purifier placed on the desktop to purify the air within a certain range around the desktop and protect the health of people near the desktop. If you often sit in front of a computer, a desk, or a desk, but the indoor area is not small, or is a public place, your own money to buy a large air purifier is not cost-effective, nor fashionable, then the desktop air purifier is the best choice.

(6) Large and medium-sized. It is mainly suitable for indoor occasions with large area, such as the hall in the home, senior bank office, senior administrative office, important lecture hall conference hall, senior hotel, hospital, beauty salon, kindergarten and other occasions.

(7) Central air conditioning system type. It is mainly suitable for the installation of central air conditioning, or a single room or multiple rooms with ceilings. [2]

Applicable object editing broadcast

  1. Applicable Places:
  2. Newly renovated or renovated residence.

(2) Accommodation for the elderly, children, pregnant women and newborns.

  1. The residence of persons with asthma, allergic rhinitis and pollen allergy.
  2. Housing for pets and livestock.
  3. Homes that are more enclosed or affected by second-hand smoke.
  4. Hotels, public places.
  5. A place for people willing to live a high quality of life.

8, hospitals, reduce infection, stop the spread of disease. [3]

  1. Applicable crowd:

1, pregnant women: pregnant women in the air pollution of serious indoor will feel general discomfort, dizziness, sweating, smoke dry tongue, chest tightness vomiting and other symptoms, have an adverse effect on the development of the fetus. The risk of heart disease is three times higher than that of a child born to a pregnant woman who breathes clean air. [3]

2, children: children's body is developing, the immune system is relatively fragile, vulnerable to the harm of indoor air pollution, resulting in decreased immunity, physical growth retardation, induce blood diseases, increase the incidence of children's asthma, so that children's intelligence is greatly reduced.

  1. Office workers: Working in high-end office buildings is an enviable career. However, in a constant temperature and closed air quality environment, it is easy to lead to dizziness, chest tightness, fatigue, mood swings and other uncomfortable symptoms, affecting work efficiency, causing various diseases, and even carcinogenic in severe cases.

4, the elderly: the old people's physical function decline, often a variety of chronic diseases. Air pollution not only causes respiratory diseases such as tracheitis, pharyngitis and pneumonia in the elderly. It can also induce hypertension, heart disease, cerebral hemorrhage and other cardiovascular diseases.

  1. Patients with respiratory diseases: living in polluted air for a long time will cause respiratory function to decline and respiratory symptoms to worsen, especially rhinitis, chronic bronchitis, bronchiolar asthma, emphysema and other diseases. The auxiliary and radical healing effect is achieved by breathing pure air.

6, driver: the car hypoxia, car exhaust pollution is serious.

Application field

Air purifiers are used in home, medical and industrial fields, and single-unit household air purifiers are the mainstream products in the market in the home field. The most important function is to remove particles in the air, including allergens, indoor PM2.5, etc., but also to solve the indoor, underground space, car volatile organic matter air pollution caused by decoration or other reasons. Since the release of air pollutants in a relatively closed space is characterized by persistence and uncertainty, the use of air purifiers to purify indoor air is one of the internationally recognized methods to improve indoor air quality.

Screen technique

HEPA filter

High efficiency particulate Air filters (HEPA) are one of the hottest technologies used in air purification. The standard HEPA filter can absorb 99.7% of the size of 0.3 micron suspended particulates (0.3 micron is the most difficult size to filter), but its wind resistance is also relatively large, generally rarely used in air purifiers, the actual air purifier manufacturers claim that HEPA is actually not the real HEPA, its filtration efficiency is slightly lower than HEPA. The wind resistance is also relatively low. Whether it is the real HEPA or the advertised HEPA, it makes the air inhaled fresher and cleaner. The filter absorbs chemical fumes, bacteria, dust particles and pollen, and after being filtered by the air purifier, the air is free of these pollutants.

The advantage of HEPA filter is that it is effective and safe, and it is the most important technology for removing particulate pollutants in the air, but the disadvantage is that it can only filter suspended particles and cannot filter harmful gases. The air purifier using HEPA must have a good airtight design, otherwise the air will bypass the filter and lose the filtering effect.

Electrostatic electret filter technology

The use of non-woven fabrics loaded with electrostatic electrets to collect dust is an upgraded version of HEPA technology. The advantages are low wind resistance, high efficiency, high dust capacity, and most importantly, safety. Represented by the "high-efficiency electrostatic air filter" on the market, it adopts a breakthrough filter material carrying permanent static electricity to effectively block particulate pollutants greater than 0.1 micron in the air, such as dust, dandruff, pollen, bacteria, etc., while ensuring ultra-low impedance to save energy. In addition, the deep dust tolerance design ensures a longer service life. As of 2013, it has been widely used in home and vehicle air conditioners (such as best-selling models of well-known brands such as SAIC, Volkswagen, GM) and some commercial buildings (such as Bird's Nest, Beijing Hotel, Capital Airport Phase III).

Activated carbon filter

Air purification activated carbon is an internationally recognized highly efficient adsorption material, as early as "World War I", it was used in gas masks. Activated carbon is widely used in cars and indoor air purification. Activated carbon is a kind of porous carbon-containing substance, and its developed void structure makes it have a large surface area, so it is easy to fully contact with toxic and harmful gases in the air. The strong adsorption force field around activated carbon holes will immediately inhale toxic gas molecules into the holes, so activated carbon has a strong adsorption capacity and is also the main technology for removing gaseous pollutants. Activated carbon adsorption technology is mainly divided into two categories: physical adsorption and chemical adsorption.

Physical adsorption is mainly for macromolecular organic gases (such as benzene and other TVOCs) through the activated carbon's own micropore structure adsorption of these macromolecular pollutants. Chemisorption is mainly for some small molecular gaseous pollutants such as formaldehyde, hydrogen sulfide, nitrogen oxides, etc., because small molecular gases are easily removed after adsorption to form secondary pollution, chemical treatment of activated carbon is necessary to make the adsorbed gas react with the chemical composition, so as to achieve the adsorption effect.

Dust collecting technique

The principle of high voltage electrostatic adsorption is used to remove particulate pollutants in the air, such as dust, soot, pollen, cigarette smell and kitchen fumes. The disadvantage of this technology is that it is easy to produce ozone, and it is only effective against large particles such as particles. The disadvantage is that it is necessary to pay attention to the safety of electrical appliances (high voltage sometimes reaches tens of thousands of volts), it is difficult to clean, and it is easy to produce ozone, and it must be properly designed to reduce the ozone emission below the safe concentration.

Ozone can kill bacteria, while killing some viruses and bacteria may also kill human white blood cells, which may lead to cancer. Therefore, it is generally not used for household air purification products. Ozone factor is mainly used to sterilize the air, ozone is a world recognized efficient sterilization detoxification oxidizer, can efficiently decompose all kinds of decoration pollutants, quickly kill a variety of viruses and bacteria. It can meet the special static treatment after decoration and stage, but because of the strong oxidation effect of ozone, it will cause harm to people and accelerate the aging of the surface of the object. It is necessary to remind that this treatment method requires personnel to avoid, and automatically reduces to oxygen after regular treatment for 30 minutes, which is a green oxidation decomposing agent without any chemical residue.

Ultraviolet light is used inside the machine to disinfect and sterilize, but it is also prone to produce too much ozone. To achieve effective disinfection function must ensure a certain irradiation time, air purifier general wind speed is large, so the ultraviolet sterilization capacity is limited, and the human body can not receive ultraviolet irradiation for a long time, the seal should be tight.

Physical technology

Photocatalyst is a general term for a photocatalytic photosemiconductor material represented by nanoscale titanium dioxide. It is coated on the surface of the substrate and produces catalytic degradation function under the action of light, which can degrade toxic and harmful gases in the air. A good photocatalytic air purification device with ultraviolet light source has a purification efficiency of 3%(calculated according to the difference in concentration of pollutants in the inlet and outlet of the device), and the best does not reach 5%. Therefore, its purification efficiency is very low, and relevant studies have shown that the photocatalytic process will produce highly toxic intermediates.

Anion and plasma method

It is settled by charging particles in the air, aggregating to form larger particles, but the particles are not actually removed, but are only attached to the nearby surface, which is easy to cause dust again. High pressure ion technology will produce by-products such as ozone in the process of operation.


Sesquiterpenoids often exist in volatile oils in the form of alcohol, ketone, lactone, etc., and have strong aroma and biological activity, which can effectively dissolve particles and bacteria in the air, and have the functions of sterilization, removal of odor, increase air oxygen content, and keep the air fresh. The plant itself carries a certain odor that remains in the air, and the odor will disappear quickly once the oxidation process is complete. Unlike other plant oils, they last a long time. The active ingredient terpene small molecules simultaneously surround, oxidize, decompose, remove or harmless aldehyde, benzene and ether harmful pollutants, and increase the effective oxygen content in the air, which has significantly improved the function of the human respiratory system. In developed countries in Asia, Singapore, Japan, Hong Kong and Taiwan, it has taken the lead in using this technology to purify the air in cities, homes and cars.

Polydissociation technique

ncco oxygen polylysis is a specialized treatment and decomposition of gaseous pollutants in the air

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