Ways Toward the Clean Heavy-Duty Diesel

After a review of the current status of development of heavy-duty direct injection diesel engines (all turbocharged and intercooled) technologies to meet US-EPA 1994 heavy-duty diesel emission standards are discussed. Special attention is given to the NO_x-particulate trade-off and to the various particulate fractions (carbon, lube oil, sulfates), and to measures for their reduction by internal means. A major part of the paper addresses the application of oxidation catalysts as a very efficient and cost-effective aftertreatment device to burn off soluble particulate fractions, CO, HC, odorants and PAH. The paper concludes with an outlook on foreseeable developments of the heavy-duty diesel in the future.