The particulate filter (PF) used in the new model Citroën cars traps and burns the particles produced by the engine. With the direct-injection common rail technology, the level of particle emissions from the new generation HDi (direct-injection diesel) engine was already particularly low. With the PF, it drops still further to a level that is barely measurable. In this way, the engine goes well beyond the future environmental standards of the European Union.
The PF traps the particles on a filter and burns them at regular intervals.
The particles burn naturally at around 550 °C, but the initial temperature of the exhaust gases The PF modifies these two parameters through:
• a post-injection of fuel in the expansion phase, which generates post-combustion in the cylinder and raises the temperature of the gases by 200 °C to 250 °C, to around 350°C to 400 °C.
• additional post-combustion generated by an oxidation catalyser placed upstream of the filter, which treats the unburned hydrocarbons from the post-injection phase. The temperature may increase by a further 100 °C, up to 450°C or 500 °C.
• the fuel additive Eolys fuel additive. This additive lowers the natural particle combustion temperature to 450 °C.
