Evaluation of various strategies for continuous regeneration of particulate filters

Diesel particulate filters are fairly effective in cleaning exhaust gases. However, in order to maintain a clean filter and to keep its flow resistance low. filter regeneration is required. Under full load conditions, the exhaust gas temperature is usually high enough to provide continuous filter regeneration. Under high engine load conditions, this may be attainable by reducing the ignition temperature of the particulates by means of suitable fuel additives, or by means of an appropriate catalytic coating of the relevant filter components. However, under medium- and low-engine loads, the exhaust gas temperature is typically too low and another sensible method has to be considered. Evidently, the minimum required exhaust temperature can be achieved over a fairly wide range of engine operation conditions by using several simple-to-employ means. These include inlet throttling (IAT), inlet pre-heating (IAP), exhaust gas recirculation (EGR), exhaust throttling (EGT), etc.