Driven mainly by tightening of regulations, advance diesel emission control technologies are rapidly advancing. This paper will review the field with the intent of highlighting representative studies that illustrate the state-of-the-art. First, the author makes estimates of the emission control efficiency targets for heavy and light duty applications. Given the emerging significance of ultrafines to health, and to emission control technologies, an overview of the significant developments in ultrafine particulate science is provided, followed by an assessment of filter technology. Major deNOx catalyst developments, in addition to SCR and LNT progress is described. Finally, system integration examples are provided.
In general, progress is impressive and studies have demonstrated that high-efficiency systems are within reach in all sectors highway vehicle sectors. Engines are making impressive gains, and will increase the options for emission control. Regarding ultrafines, evidence suggests the aerosol nanoparticles come from lube oil. Filter technology is focusing on optimization, with work being done on better ways to regenerate the filter and improving system back pressure. SCR NOx control is focusing on urea injection algorithms, and system optimization, while NOx adsorbers are showing marked improvements in performs and durability. System integration of filters and NOx control is moving into heavy-duty systems, albeit mainly on the bench.