Further Experimental Study of Asymmetric Plugging Layout on DPFs: Effect of Wall Thickness on Pressure Drop and Soot Oxidation

In order to guide the development of asymmetric plugging layout Diesel Particulate Filters, hereafter referred to as “VPL-DPF”, in this paper we present some evaluation results regarding the effect of design parameters on the VPL-DPF performance. VPL-DPF samples which have different wall thicknesses (thin and thick walls) were evaluated in regards to their pressure drop and soot oxidation behaviors, with the aim to optimize the design of DPF structure. As a result of pressure drop evolution during soot loading, contrary to our expectation, in some cases, it was found out that VPL increases the transient pressure drop compared to the conventional plugging layout DPF. That meant there is an appropriate specific optimum wall thickness for adoption of VPL which has to be well defined at its structural design phase. Based on our previous research, it is expected that this result is due to interactions among the different (five) wall flows that exist in a VPL-DPF. Consequently, soot oxidation tests were conducted under certain flow gas conditions with a gas analyzer and it was confirmed that the VPL design slightly reduces the instantaneous soot oxidation rate for high values of soot conversion. That meant the VPL-DPF regenerates in a gentler fashion than the DPF with conventional plugging layout. It was, therefore, found that the adoption of VPL-DPF would increase the soot accumulation capacity of a DPF. Throughout these aforementioned tests, we were able to conclude that the developed VPL-DPF might have advantages from both pressure drop reduction and regeneration activity enhancement point of view.