The objective was to characterize diesel exhaust aerosols on road and to duplicate the results in the laboratory without altering the physical characteristics of the nuclei mode. On-road emissions from four, heavy-duty diesel truck engines were measured. The same engines were reevaluated in the manufacturers' laboratories. For highway cruise and acceleration conditions, all engines produced bimodal size distributions with the nuclei mode ranging in size from 6 to 11 nm and the accumulation mode from 52 to 62 nm. On-road size distribution measurements nearly always showed a nuclei mode while laboratory measurements showed a nuclei mode under many, but not all conditions. Laboratory studies showed that nuclei mode particles consisted mainly of heavy hydrocarbons. More than 97% of the volume of 12 and 30 nm particles disappeared on heating to 400 °C. The volatility resembled that of C24-C32 n-alkanes implying a significant contribution from lubricating oil.
Bibliographical noteFunding Information:
We gratefully acknowledge the support from the following sponsors: Coordinating Research Council, the Department of Energy's Office of Freedom CAR and Vehicle Technologies through the National Renewable Energy Laboratory, the Engine Manufacturers Association, the South Coast Air Quality Management District, the California Air Resources Board, the Volvo Truck Corporation, and the National Institute for Occupational Safety and Health (NIOSH). Special thanks to Shirish Shimpi and Cummins Engine Company, Inc., and Rob Graze and Caterpillar, Inc., for providing trucks and engines and making their corporate test facilities available to us.
- Diesel aerosol
- Diesel engine
- Heavy-duty vehicle
- On-road measurement