New Asymmetric Plugging Layout of Diesel Particulate Filters for the Pressure Drop Reduction

Diesel particulate filters (DPFs) equipped with diesel vehicles have become indispensable components to capture the soot emitted from the engines from a viewpoint of both human health and global warming problems as well as the prevailing regulations. Meanwhile, the pressure drop caused by them leads to a direct increase of fuel consumption. In order to reduce it guaranteeing the sufficient soot filtration efficiency, we have developed the new concept of asymmetric plugging layout for the DPF design, so-called Valuable Plugging Layout (VPL), on the basis of octosquare (OS) structure and have clarified the advantage of the pressure drop reduction both experimentally and theoretically. The VPL-DPF consists of two kinds of octagonal/square inlet channels and octagonal outlet channels, and there are thought to be five filtration velocity modes as well as four kinds of soot deposit layers on each side of the inlet channel walls. No deterioration of the soot filtration performance and the reduction of the transient pressure drop of the VPL-DPF during the soot loading have been confirmed through the engine bench tests compared to those of the OS-DPF. Additionally, the flow field as well as the soot deposition process inside the VPL-DPF has been revealed by the theoretical calculations and these results were in good agreement with experimentally observed ones. As a consequence, it is found that the VPL brings a 16% reduction of the transient pressure drop at the 4 g/L soot loading without any deterioration of the soot filtration performance compared to the conventional OS structure.