Air filter
An air filter is a device composed of fibrous or porous material that removes solid particles such as dust, pollen, mold and bacteria from the air. Air filters that contain adsorbents or catalysts also remove odors and gaseous pollutants.
The filtering principle of the air filter:
1: Intercepting effect: The fibers’ inside of the air filter are intricately arranged to form countless grids. When particles of a certain size move along the airflow to the vicinity of the fiber surface, if the particle size is larger than or equal to the fiber spacing, the particles will be on the fiber surface. Intercepted and deposited.
2: Inertial effect: When the dust airflow passes through the fiber layer of the air filter, due to the complex arrangement of the fibers, the airflow will turn violently many times. If the mass of the particles is large or the flow velocity is large, when the airflow turns, some of the particles cannot follow the airflow and bypass the fibers at the same time due to inertia, so they leave the airflow and approach the fibers, and collide with the fibers to deposit.
3: Diffusion effect: Brownian diffusion of particles is produced due to the collision of thermal motion of gas molecules on particles. The smaller the particle, the more significant the effect is. Brownian diffusion makes the particles have a greater chance to move to the fiber surface and deposit.
4: Gravity effect: When the particles pass through the air filter fiber layer, they will be displaced from the airflow under the action of gravity, they will be deposited on the fiber due to gravity sedimentation.
5: Electrostatic effect: When a substance with static electricity is close to another object with no static electricity, due to electrostatic induction, the object without static electricity will be charged with the opposite polarity of the charge carried by the charged object. Because the opposite charges attract each other, It will show the phenomenon of “electrostatic adsorption”. Electrostatic adsorption is particularly effective for particles smaller than 1 micron.
The above five functions basically explain the air filtration principle of the air filter, and can also let everyone clearly understand why we need to replace the air filter under the condition of long-term use.
