Search Results

A test protocol, allowing for the evaluation of diesel particulate filters of different materials and of different sizes, located at various distances from the engine was developed. A total of 13 filter configurations were tested on a Euro I naturally aspirated diesel light duty truck with a fully passive trap system, utilizing only cerium-based additive in the fuel. It was proved that regeneration under constant urban driving conditions was always possible, at an exhaust gas temperature at the trap inlet in the range of 250 - 350°C. On a gravimetric basis, the efficiency of the traps tested concerning PM was in the order of 45 - 80% over the NEDC, depending on trap material and location along the exhaust pipe and reflecting the specific composition of the PM generated by the vehicle. No major effect on gaseous emissions (HC, NOx and CO) was observed.

A study has been initiated to understand the influence of coolant temperature on HC emissions employing a dual system cooling the cylinder head independently from the engine block. Especially, we have studied its influence on post-oxidation, fuel absorption-desorption, crevice volumes and fuel-air mixture preparation. The results show that the cylinder head temperature has more influence on HC emissions than the block temperature. It was also found that mixture preparation, absorption/desorption and crevice volumes with commercial gasoline is greatly improved by the cooling temperature. The post-oxidation process is also reduced for a decrease of the coolant temperature from 90°C to 35°C.

An extensive research program involving the French passenger car and heavy-duty (HD) vehicles manufacturers, sponsored by ADEME and realized by IFP, aimed to characterize in terms of size and composition the particulate emitted by the different engine technologies currently or soon available. The impact of engine settings and fuel composition was also studied. Numerous information was collected in this HD study revealing that fuel composition and particularly non-conventional fuels and engine settings strongly impact the particulate concentration and size distribution. Nucleation is likely to occur when there is less adsorption matter, for instance when post-injection is used or EGR is removed. Particulate composition, particularly PAH and sulfates content, is weakly bound to the size. Mineral elements distribution depends on their origin, lubrication oil or engine wear.