Abstract
Keywords:
DPF, regeneration, CFD, post-injection.
Abstract:
The adoption of Diesel particulate filter (DPF) is nowadays accepted both by the technical community and the market as an effective solution for the reduction of particulate emission and it will be for sure a “default device” for euro5 Diesel engines. The requirement of exhaust gas temperature for DPF regeneration is mainly fulfilled thanks to a multiple injection strategy . Currently, during the DPF regeneration process, five injections are applied and the last one of this sequence occurs during the exhaust stroke when pressure and temperature in the combustion chamber are very low. This condition lead to have the fuel sprays hitting the combustion chamber walls: this cause a degeneration in engine oil characteristics due to dilution by presence of fuel. Optimization of injection strategies allows to minimize this aspect and the paper presents the results of CFD analysis focused on the modeling of the spray evolution in the combustion chamber for this 5th injection during the exhaust stroke. Results are very helpful in understanding the main features of this process (effects of injection timing, exhaust phase timing, sprays orientation, etc.). The comparison with the corresponding experimental data shows positive agreement in terms of trend but not yet for a quantitative analysis.