A New Active DPF System for “Stop & Go” Duty Cycle Vehicles: Durability and Improvements 2005-01-1754
Diesel urban buses as well as refuse trucks are part of the particulate emissions sources that affect the city air quality.
Several Diesel Particulate Filters (DPF) systems were proposed to reduce such emissions. But the reliability and the durability of the current DPF systems remain an issue, due to the lack of the filter regeneration control during the “stop & go” duty cycles.
To fit particular this duty cycle requirements, a new active Diesel particulate filter system was developed with a new regeneration strategy in order to achieve the durability and reliability issues.
The DPF system consists of: particulate filter units; an oxidation catalyst placed in front of the filters; valves and actuators allowing thermal insulation of the filter units; temperature and pressure sensors; and an electronic control unit to control the positions of the insulation valves.
The strategy principle is based on an adjustable volume of filtration in combination with a global thermal management allowing the filters to regenerate in all driving conditions. Furthermore, in order to fully control the filters regeneration, an additional heat injection strategy, based on Diesel fuel injection over the oxidation catalyst, heats up the filters individually, according to the position of the insulation valves.
The DPF System was evaluated by the ADEME (French Agency for Environment and Energy Management) on refuse trucks (EURO2) applications over more than a 12 months program, using a standard European Diesel fuel (350ppm of Sulfur). The DPF System demonstrated high efficiency and durability, with more than 89% of particulate reduction (in mass per kilometer) over the duty driving cycle reference.
In parallel, in order to extend the field of applications, further improvements have been developed, such as association with a fuel-borne catalyst (FBC) to control the filters regeneration and limit the maintenance. The experiments have demonstrated the positive effects of FBC in the trap loading as well as the filter regeneration. In addition, the combination of the basic process and the FBC leads to a limitation in FBC dosing rate.
Details of experiments and results will be presented in the paper, as well as the VERT evaluations for European certification.