The Particulate Number Emissions from GDI Engines: Advanced Characterization and Reduction through a Gasoline Particulate Filter with Membrane Technology

The gasoline direct injection (GDI) engine technology is a good candidate to reduce the fuel consumption of vehicles. However, this engine emits more particles than its counterpart with indirect injection [1]. Then, it is necessary to take measures to comply with the future Euro 6c regulation as from 2017.
In this work, the particles emitted by the engine were first scrutinized at the engine test bench with several real-time on-line apparatus. It appears that a large number of particles were solid clusters, similar to those observed at Diesel engine exhaust. These findings were also confirmed by TEM analysis.
In order to abate the particulate number emissions, a dedicated gasoline particulate filter (GPF) was developed. A thin ceramic membrane was arranged at the porous substrate surface in order to trap the particles with a high level of efficiency. The comparison with a state-of-the-art filter shows a significant improvement of the particulate number reduction, both in steady-state and in transient operations. Now, even if the generated back pressure of the membrane filter is lower than a classic DPF, the current objective is to further cut down the pressure losses created by the membrane.