When studying the inertial mechanism, because trajectory calculation in the early years was too troublesome, people borrowed empirical formulas compiled by calculators. The most common one is the “pure inertial” single fiber efficiency without particle size parameters, even though a small number of empirical formulas include Particle size parameter, but its applicable range is often very limited. When studying the diffusion mechanism, the particle size parameter is added, but its range of use is often very limited. When studying the diffusion mechanism, due to the difficulty in integration after adding the particle size parameter, there is a “pure diffusion” single fiber efficiency of zero particle size. When people only have the calculation formulas for pure inertia and pure diffusion at hand, and additionally consider the influence of dust size, they take it for granted that the “ideal interception” with neither inertia nor diffusion is regarded as a separate entity alongside inertia and diffusion. Filtration mechanism. People often add pure inertia, pure diffusion and ideal interception to calculate the combined single fiber efficiency, and some researchers add or subtract certain correction terms in addition to the three.
In the air filter, the inertia and diffusion collision of dust occur simultaneously, and sometimes other filtration mechanisms also play a role, such as electrostatic, gravity sedimentation, screening resistance, etc. However, in theoretical research, due to mathematical difficulties, it is difficult to combine the parameters of several mechanisms into one mathematical model for calculation, so various filtration mechanisms are studied separately to find out the single fiber performance under the action of a separate mechanism. efficiency, and then use some method to combine the single fiber efficiencies of two or several mechanisms together in order to approximately estimate the single fiber efficiency under the joint action of tree species mechanisms. Various methods of incorporating single fiber efficiency in previous literature are documented.
In dealing with the problems of inertia and diffusion in the first two chapters, we have seen that the so-called ideal interception is nothing more than a mathematical extreme case. If the influence of dust size has been taken into account in the derivation of various mechanisms. Ideal interception should no longer be listed as a separate filtration mechanism, at least it should not be a filtration mechanism alongside inertia and diffusion.