Analysis of the filtration process of inlet air to an internal combustion engine in a two-stage filter

The influence of mineral dust particles on accelerated wear of engine components is discussed. The necessity of using two-stage (multi-cyclone-baffle) air intake filters for commercial vehicle engines in conditions of high air dustiness is demonstrated. The aim of the work was to experimentally evaluate the filtration properties of paper filters operating directly behind the cyclone and without the cyclone. An original research methodology was used, consisting in testing a single cyclone and a paper filter with an appropriately selected surface area. During the tests of the assembly (cyclone-paper filter), conditions corresponding to the actual operating condi-tions of a two-stage air filter were maintained, including the filtration speed in the paper filter, the dust concen-tration in the inlet air and the cyclone inlet speed. The characteristics of efficiency, filtration accuracy and pressure drop were determined as a function of the dust mass supplied to the assembly (cyclone-paper filter) or directly to the filter. The tests showed that the paper filter operating behind the cyclone achieves a four-times longer operating time limited by reaching a specific permissible pressure drop value. In the initial (short) filtra-tion period, the filtration efficiency achieved significantly lower values than the required value of 99.9%, in the air behind the paper filter there were dust grains with a maximum size of 13.5 µm with the required 2-5 µm. This is a dangerous phenomenon and may cause accelerated engine wear.