Size Distribution of Diesel Particulate Matter From a Heavy Duty Diesel Engine During FTP Transient Cycle

Researchers concerned both with diesel exhaust health effects and with mechanisms of particulate matter (PM) formation have an interest in gaining understanding of PM size distributions from heavy-duty on-road diesel engines. Prior research has been done on particulate size measurement but the results fall short in understanding PM size distributions because of the response time or size range of the instruments used. This study reports the transient size distributions of PM from a 1992 Detroit Diesel Series 60 on an engine dynamometer from a full flow dilution tunnel for a FTP Transient Cycle using a Cambustion ® Differential Mobility spectrometer (DMS 500). The size bins selected for this study for the nucleation and accumulation modes were 20nm and 60nm bins, respectively. The accumulation mode during the accelerations and the nucleation mode during the decelerations were clearly observed from the distributions with respect to time. Distributions were also observed during the test cycle showing the transition between the two modes. From the results obtained from the analysis, no strong correlation between the 60nm particles and engine speed was observed even though higher counts of accumulation particles were observed at the same time that the vehicle activity occurred. Similarly, there was no correlation between the accumulation mode particles and power. When the distributions of nucleation and accumulation mode particles were plotted against each other, there was no correlation or anti-correlation. The average size distributions were also analyzed during the four periods of the FTP Transient cycle and the highest counts were observed during the Los Angeles Freeway (LAF) period. Also, higher counts at the second New York Non Freeway (NYNF) were observed during the cycle.