Field Experience of DPF Systems Retrofitted to Vehicles with Low Duty Operating Cycles

For many years now, epidemiologists have been highlighting the potential damage to health and the associated cost, caused by diesel particulate emissions. There is still debate concerning the crucial characteristics of these particles, however many authorities have concluded that it is their duty to legislate the reduction of such emissions. The most common approach is to legislate that all new vehicles should meet ever stricter emissions limits. This puts the onus and the cost on the engine manufacturers. The emissions limits in developing countries are inevitably less stringent than those in the developed world, this gives the indigenous manufacturers the opportunity to compete and develop. However, vehicle replacement intervals dictate that the effect of legislation controlling new vehicles takes many years to propagate throughout the existent vehicle fleet. As a result of this delay many authorities are introducing legislation or fiscal incentives to promote the “clean-up” of older vehicles.

One particularly effective retrofit solution is the diesel particulate filter which has been shown to reduce the number of diesel particles emitted by over 90%. The most attractive systems are those that allow passive operation. A widely used technology relies on a fuel borne catalyst to enable passive regeneration. This paper details the application of such a system to a series of vehicles that are considered as very challenging due to the low duty operating patterns.