Diesel particulate filter (soot filter)

Diesel particulate filter (soot filter)

Cutaway Model Diesel particulate filter (soot filter)

The particulate filter comprises a beehive-shaped ceramic body (silicon carbide). It is sub-divided into a number of small channels arranged in parallel, which have been positioned alternately.

The exhaust gas contains the following gases: carbon monoxide, carbon dioxide, nitrogen oxides, hydrocarbons, sulphur dioxide, as well as soot particles and an additive. The additive, which is mixed into the fuel in fine traces, lowers the ignition temperature of the carbon from 650 to 500 degrees.

Demonstration:

• The ceramic body, surrounded by fibre meterials and steel wool, is in the metal housing
• On the cutaway part and also on the front and face surfaces, one recognises the alternately closed and opened channels
• Gas particles can escape through the pores of the side walls into the adjacent tubes, whereas soot and additive, as a result of their size, remain in the middle tube
• Gas particles can escape to the back into the exhaust pipe
• After about 500 to 700 kilometres of driving, there is regeneration (the soot is burnt off).

With the help of pressure sensors in front of and behind the filter and of the exhaust gas temperature, the time when regeneration is necessary is calculated. Now, the filter is empty again.