الفهرس | Only 14 pages are availabe for public view |
Abstract Vehicles are provided with air filtration systems to clean the air before it enters the engines, hence protecting it and prolonging its service life. Three groups of filters (FI, FII and FIII) are manufactured having 28 pleats. Each group is made from a different material and with a different thickness. The air permeability of filter FI is 616 [l/m2s] that of filter FII is 270 [l/m2s] and that of filter FIII is 550 [l/m2s]. Their thicknesses are: 0.5, 0.66 and 0.71 [mm] respecvely. Tests are performed on a standard test rig for testing automotive air filters. A controlled heating unit is added to the test rig to change the temperature of air upstream the tested filters. In order to study the effect of the operating conditions on the performance of the filters, tests are conducted at several airflow rates varying from 0.12 to 2.59 [m³/min] and at temperatures that are changed from 30 to 70 [ºC]. These values are typical to the operating conditions to which an air filter is subjected. The displacement occurring in the pleats is measured with the help of a strain gages bonded to the surface of pleats. The values of these displacements are recorded on a PC using a data acquisition card. The displacement is found to increase as the air flow rate increased, yet the amount of increase decreased as the temperature increased. This increase is greatest when the filter is loaded with dust. The comparison between the displacements of the pleats of the three filters showed that at low temperatures and small amounts of trapped dust, the first two filters behaved nearly the same. At higher values of temperatures and greater amounts of trapped dust, the second type of filter exhibited higher displacements compared to the first filter and the difference between the behaviors of the two filters is highly recognized. On the other hand, the third filter always exhibited higher displacement values compared to those of the other two filters.It is found that when the amount of dust increased on the surface of the pleat, the effective filtration area decreased. The increase in filter efficiency is greatest at the beginning of filter’s operation, then this area decreases gradually with the increase in the amount of trapped dust due to contact between pleats. |