The key feature of a reliable DPF system is the control over the amount of soot burnt during the regeneration. Since only an overall evaluation of the collected soot is possible on-board, only a DPF-system with homogeneous soot distribution can avoid areas of local overcharging which may lead to disastrous consequences during the filter regeneration. Hence, a system layout optimisation, which can ensure a good soot distribution also in the “worst-case” loading conditions, is necessary.
The major problem in the optimisation work is related to the lack of measurement methods which could be standardised for series development.
Indirect methods, such as the measurement of the velocity profile, provide only a rough estimation of the soot distribution, while other methods, like Computer Aided Tomography, are too complex and expensive for standard series investigations. For this reason an investigation method based on the integration of thermal emissions during a controlled regeneration was developed. Extensive investigations were conducted with DPF loaded on the engine bench in different operation points and loading conditions. The method was validated and two different cases of soot distribution for the same DPF were analysed and compared with LDA (Laser-Doppler Anemometry) measurements and CFD simulations. Thanks to the results, this investigation method is already being utilised in series development projects.