Continuous regeneration of an electrically heated diesel particulate trap: Mechanism of particulate matter trapping and improvement of trapping efficiency

Abstract

The mechanisms of trapping and continuous regeneration of soot particles in a newly developed diesel particulate trap based on static-electric trapping (electrical diesel particulate trap, E-DPT) are investigated. It is found from a visualization experiment that soot particles trapped on the electro-plates form soot bridges over the 1.5 mm narrow space between the electro-plates and burn out by Joule's heating, due to the direct electrification through the bridges. The burning soot bridges trigger the burning of soot particles deposited throughout the electro-plates, achieving continuous regeneration. An experiment on the effect of particle charging on trapping efficiency showed that particle charging by corona discharge increases soot bridge formation, leading to a dramatic increase in soot trapping efficiency from 45 per cent for the case without particle charging to 85 per cent with particle charging. Size distribution measurements showed that the accumulation mode particles are trapped efficiently, but soot particles smaller than 80 nm increase at the exit of the E-DPT.