Regeneration of Particulate Filters at Low Temperatures 830086
Due to good trapping abilities, the ceramic trap filter was chosen for the reduction of the particulate emission of Diesel engines.
Both, tests and the analysis of the regeneration kinetic show that in real-world application the lite-off limit of 500 °C may not be exceeded.
The minimum exhaust gas temperature necessary for regeneration without the use of a catalyst, can be reduced to approx. 200 °C to 250 °C with the use of fuel additives.
The use of additives for the filter regeneration showed excellent results in real-world conditions as well as with endurance tests.
There was no significant change in emissions or specific fuel consumption about 20,000 km as compared to the operation without additives.
The regeneration dependability however, is questionable because of the destruction of the filter. This destruction is caused by exceeding the melting point of the ceramic by thermal reactions due to erratic regeneration and by thermal reactions due to a high temperature increase rate after exceeding the lite-off limit.
For the increase of the service life of the trap, a ceramic material with a lower thermal expansion coefficient is required. The start of regeneration can be achieved simultaneously by significantly exceeding the lite-off limit.
Finally, with the control of the amount of oxygen in the exhaust gas (i.e. with EGR), it is possible to avoid exceeding the melting point of the ceramic.