Diesel urban buses as well as garbage trucks are part of the particulate emissions sources that affect the city air quality. Retrofit programs have developed Diesel particulate filters approaches in order to limit the particulate emissions in the cities.
To fit the particular duty driving cycle requirements, a new active Diesel particulate filter (DPF) system is proposed to control the filters regeneration.
The DPF system consists of: several particulate filter units; an oxidation catalyst placed in front of the filters; valves and jacks actuators allowing thermal insulation of the filters; control valves actuators; temperature and pressure sensors; and an electronic control unit and monitoring of the DPF system.
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 electronic control and monitoring of the DPF system ensure the reliability and durability of the system in the duty driving conditions.
This new active DPF System was evaluated by Renault Trucks as an original exhaust part, and validated by UTAC on EURO III Premium 320 DCI 11 for refuse trucks applications.
In addition, the French Agency of Environment and Energy Management (ADEME) showed the efficiency, the reliability and the durability of DPF system on retrofitted EURO II Renault AGORA urban buses. High emission reductions were recorded with more than 90% for CO, hydrocarbons and particulates, over more than 12 months period of field evaluations.
Details on the field experiences and maintenance of the DPF system are also described in the paper.