A Method for Assessing the Low Temperature Regeneration Performance of Diesel Particulate Filters and Fuel-borne Catalysts 2000-01-1922

Fuel-borne catalysts are now an accepted means of aiding the self-regeneration of diesel particulate filters (DPFs). In the past it has been possible to assess the effect of these fuel additives by investigating the temperature at which the filter reaches a pressure drop equilibrium. Under these temperature conditions, the particulate matter is oxidised at the same rate as it is being deposited and there is thus no change in pressure drop across the filter. This technique adequately demonstrates the oxidation temperature of the carbon in the presence of the catalyst. However, it is now well known that such fuel additives also influence the low temperature oxidation of particulate bound hydrocarbons. This phenomenon is not detected by the filter equilibrium technique.

Study of the regeneration performance of filter/additive combinations at a range of steady state engine operating conditions has indicated a series of operating points that demonstrate different modes of regeneration behavior and highlight the low temperature regeneration characteristics of such systems. A seventy-hour test procedure has been developed to allow comparison of different fuel additives and different DPF technologies.

This procedure has been used to quantify the relative performance of three organo-metallic fuel additives and six DPF types. The effect of an oxidation catalyst before one of these filters has also been investigated. The work shows significant differences between fuel additives but little difference between most DPFs.