Theoretical and Experimental Analysis of the Air Filtration Process in a Two-Stage Filter of a Special Purpose Vehicle

<ns3:p>Two-stage (multi-cyclone-pore-partition) air filters are what protects a vehicle's engine from sucking in mineral dust particles that cause an accelerated wear of internal components. Information on the air filtration process taking place in a two-stage system (multicyclone-baffle filter) of a vehicle's internal combustion engine is not provided often in the available literature. The purpose of this study was to experimentally evaluate paper filters operating directly behind and without a multicyclone system. An original methodology was used, consisting in testing a single cyclone and a paper filter with a suitably sized surface area. While testing the assembly (cyclone-paper filter test), parameters corresponding to those under which two-stage air filters actually operate were maintained, including filtration speed in the paper filter, dust concentration in the air and the cyclone’s inlet velocity. Filtration efficiency and accuracy, as well as pressure drop value were among the parameters determined as a function of dust mass delivered to the unit (cyclone-paper filter) or directly to the filter. The study showed that a paper filter operating downstream from a cyclone operates four times longer before reaching the permissible pressure drop value. During the initial (short) filtration period, separation efficiency values obtained were much lower (w0 = 93.3% without and wc0 = 53.6% with the cyclone, respectively) than the required threshold of 99.5%. The air behind the paper filter contained dust grains with a size of 35-40 m, compared to the required parameter of 2-5 m. Further operation of the filter is characterized by a high separation efficiency of 99.9%, a high accuracy dpmax of 2-5 m and a continuously increasing pressure drop, with the said drop being more intense in the filter without the cyclone system.</ns3:p>