Search Results

Repeatabilities of PM measurements on a heavy-duty diesel engine equipped with a diesel particulate filter (DPF) using a filter weighing method and a number counting method with a full flow dilution system and a partial flow system were evaluated. The filter method with partial flow exhibited the best repeatability. However, a good correlation between the full flow and the partial flow number counting results suggests that the fluctuations observed using the number counting method were caused by changes in the engine exhaust. Applying a strict preconditioning procedure should improve the repeatability of the number counting method because this method is more sensitive than the filter weighing method. In addition, the effects of the specifications for the number counting method were evaluated. The results indicate that the hose length from the tip of the sampling probe to the inlet of the number counting system had a negligible effect.

Periodic increases of PN, PM, and regulated gases associated with DPF regeneration from a heavy-duty truck equipped with a diesel particulate filter (DPF; non-SCR truck) and from a heavy-duty diesel engine equipped with a DPF and a urea-SCR (SCR engine) were investigated. Both met Japanese 2009 regulations. From both exhausts, PN emissions two orders of magnitude higher than the European legislation limit were observed in the regeneration cycle, and these emissions gradually decreased in subsequent cycles. This can be explained by the relation between the filtering efficiency and the amount of loaded soot in the DPF. No emissions particular to regeneration, such as soot fragments, were observed. In some cases, higher PN emissions were observed from the SCR engine. This may be because of the difference in DPF performance, but there is a possibility that some particles were produced in the urea-SCR system.