Collection performance of an electrostatic filtration system combined with a metallic flow-through filter for ultrafine diesel particulate matters

An electrostatic diesel particulate matter filtration system (EDPS) has been tested using 3000 cc diesel engines operating at steady state and standard (European Stationary Cycle (ESC) 13 mode) conditions. The system consisted of a flowthrough filter (FTF) and a charging device with a round perforated plate imposing an electrostatic field onto the FTF. An insulating device for the high-voltage electrode was protected from pollutant deposition by using an air slit at velocity of 7 m/s to maintain a stable corona discharge under an exhaust temperature exceeding 300°C. Under steady-state engine conditions, the performance test of the EDPS showed high collection performance (based on the particulate matter (PM) number) of nearly 80–99%, while the efficiency of the FTF remained at 15–50%. Comparing the performance of the EDPS with a commercialised diesel particulate filter (DPF) and an FTF under the ESC 13 mode, the EDPS was almost 40% more efficient than the FTF and 10% less efficient than the DPF, while achieving 73% lower pressure drop than the DPF. Thus, the novel filtration system can achieve collection performance similar to the DPF with significantly less pressure drop.