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Since Euro 5 standard, Diesel Particulate Filter (DPF) technology has been widely introduced in Europe and Fuel Borne Catalysts (FBC) provide a powerful solution to achieve regeneration in all driving conditions. Ongoing new emission regulation constraints of Euro 6.b (2014) and forthcoming Euro 6.c standard in 2017, that will reduce the gap between emissions during homologation and in real driving conditions, will demand the support of optimized FBC formulated with Deposit Control Additive (DCA). This paper presents the impact on DPF regeneration performance of advanced FBC with a sharp particle size distribution of reduced nanoparticle size diameter. Small particle size FBC gives enhanced DPF regeneration, allowing regeneration at lower temperature (i.e. improving fuel economy) but also lower dosing rates in fuel. Thus, this implies reduced filter ash content and an extended maintenance interval.

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.

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.

Since the market introduction of the Diesel Particle Filter (DPF) system in serial applications in May 2000, more than 500,000 vehicles have been DPF-equipped. Tracking the serial production current situation, several themes for improvement have been identified, including system simplification to limit its total cost as well as proposition to optimize maintenance. The paper presents those upgrades that will be proposed in serial applications. Based on a DPF regeneration assisted by engine management systems in combination with the use of a Ceria-based fuel-borne catalyst, the first improvement is to limit the ash build up phenomenon of fuel-borne catalyst and then to limit the DPF clogging effect. In the first stage, catalytic activity of Ceria-based fuel-borne catalyst has been improved, by introducing Iron as a catalytic promoter.

A particulate trap with combined regeneration has been developed for use in light duty vehicles with diesel engines. This new system was tested first on an engine test rig. On-road vehicle tests are going on since August 1998. The results obtained clearly demonstrate the feasibility of this system. With this system trap regeneration has to be ensured under worst case conditions (exhaust gas temperature<400° C). To meet this requirement electrical heating in combination with a fuel-borne catalyst is applied. Different filter materials such as cordierite wall flow and silicon carbide monoliths were tested on the engine test rig. The paper reports on results from the engine test rig as well as from on-road vehicle testing. An overview about pre-heating and regeneration examples are given and energy balances are presented.

In urban areas, particulate emission from Diesel engines is one of the pollutants of most concern. As a result, particulate emission control from urban bus Diesel engines using particulate filter technology is being introducing in La Rochelle. The Diesel Particulate Filter (DPF) introduction on the existing urban bus fleet has been initiated by the CDA La Rochelle through a voluntary retrofit program. The class of urban bus to be retrofitted is based on EURO 1 and EURO 2 Diesel engines, using a standard European Diesel fuel with 300ppm of Sulphur content. In that case, the appropriated technology for DPF regeneration requires a very flexible strategy for DPF regeneration, such as the use of the Ceria-based Fuel-Borne Catalysts. The paper describes the practical approach developed to install and optimize the DPF System on the urban buses.

India is moving to Bharat Stage VI (BS-VI) from 2019 significantly lowering particulate mass (PM) , particle number (PN) and Nitrogen Oxides NOx emissions limits, as well as Carbon Dioxide CO2. BSVI’s particulate limits will require the use of diesel particulate filters (DPFs), which will need to operate properly under the driving conditions prevalent in India. Furthermore, NOx and CO2 emissions control will include advanced combustion modes with advanced fuel injectiontechnologies based on high pressure fuel injection and smaller injector holes, in combination with active NOx reduction measures. These advanced technologies will increase sensitivity to fuel quality, so will require tighter control of sulfur content, water contamination, fuel stability, lubricity and corrosion. These are real challenges for the robustness and durability of strategies developed for BS-VI and beyond.

The present paper reports the use of a cerium-based FBC in association with a DPF for delivery applications, with long series of stop and go sequences. Two different field trials totaling at least 10,000 km each were performed using delivery conditions with an average of 100 stop-and-go per day and standard diesel fuel (350ppm of sulfur). The US application was done with a medium-heavy duty engine and the European application with a light duty engine. The efficiency of the DPF was determined by measuring both soot and inorganic product emissions. After the trials, the DPF were dismantled and retained ashes were characterized and their localization in the filter analyzed.