PROGRESS IN DIESEL-ENGINE EMISSIONS CONTROL

A considerable amount of work was carried out in the mid-1980s to develop heavy-duty diesel engines that could meet limits on particulate emissions. These limits, although high by today's standards, were considered very restrictive. Some manufacturers struggled to achieve the 0.6 g/bhp-h particulate matter limit with enough margin for production variabilities and to account for the deterioration factor. Significant progress was achieved in diesel emissions control through engine and fuel system design changes. This eventually made it possible to meet a particulate level of 0.25 g/bhp-h for 1991. The next target level for particulate emissions is 0.1 g/bhp-h for the 1994 heavy-duty engine. To meet the challenge, engine developers are not only considering engine and injection system design changes but also fuel improvements and exhaust after treatment. This paper includes a review of past and current strategies used to control emissions in the modern diesel engine.