Review of diesel particulate matter sampling - Department of ...

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Figure 11. - Average size distribution obtained from chase experiments, heavy-duty diesel (From Kittelson, et al. 1988) Figure 12. - Average size distribution obtained from laboratory experiments using a Volkswagen Rabbit light-duty engine (From Kittelson, et al. 1988) 01/14/99 Page 34
Figure 13. - Volume fraction versus extractable fraction in the nuclei mode (From Kittelson, et al. 1988) • Coagulation increases the mean diameter of the nuclei mode and transfers mass from the nuclei mode into the accumulation mode, thus moving the two modes closer together and reducing the mass in the nuclei mode. It also increases the mean diameter of the accumulation mode, but much more slowly. The decrease in the mass and number of nuclei mode particles takes place on a time scale ranging from minutes for highly polluted urban conditions to hours for clean rural conditions. Thus, coagulation may significantly alter the size distributions of diesel particles as they exist in the atmosphere. • For the highway cruise conditions the dilution ratio increased nearly linearly with time and typically took only 1-2 s to reach 1,000. Under these dilution conditions little coagulation occurs. The time scale of dilution for particles emitted from the engine test cell stacks was much longer than that of roadway dilution. In the worst cases over 100 s were required to reach a dilution ratio of 1,000. With this relatively slow dilution, coagulation during dilution was significant and reductions in the number of nuclei mode particles and the number to volume ratio by as much as a factor of 3 were observed. Although the dilution conditions of the test cell study may appear to be somewhat non-representative, the time scale of dilution is not very different from that associated with slow moving congested urban traffic, where coagulation during dilution will probably also be important. 01/14/99 Page 35
Page 1 and 2: REVIEW OF DIESEL PARTICULATE MATTER
Page 3 and 4: ABSTRACT Federal government regulat
Page 5 and 6: INTRODUCTION Federal government reg
Page 7 and 8: • to critically evaluate methods
Page 9 and 10: Table 2. Changes in diesel engine t
Page 11 and 12: AEROSOL SIZE DISTRIBUTION Figure 3
Page 13 and 14: Figure 5. - Schematic illustrating
Page 15 and 16: Heat transfer during sampling and d
Page 17 and 18: • humidity and temperature • ba
Page 19 and 20: Doyle (1961) predicted that homogen
Page 21 and 22: Engine Emission Characteristics Eng
Page 23 and 24: accumulation mode particle diameter
Page 25 and 26: Adverse health effects of respirabl
Page 27 and 28: content of the particle. (Burtscher
Page 29 and 30: Table 7. Instrument summary Miscell
Page 31 and 32: Table 8. Studies Measuring Diesel A
Page 33: slowly moving diesel trucks, and a
Page 37 and 38: Table 10. N/VT Ratios (Number of pa
Page 39 and 40: Figure 15. - Relationship between d
Page 41 and 42: Exhaust Constituents The nature of
Page 43 and 44: increased number concentrations of
Page 45 and 46: system, volatile particles evaporat
Page 47 and 48: With low carbon emission engines, t
Page 49 and 50: Kreso, et al. (1998a,b) looked at t
Page 51 and 52: • Treatment of sample dilution ai
Page 53 and 54: somewhat larger, 60 - 70 nm. The ma
Page 55 and 56: Bagley, S. T., et al. 1996. Charact
Page 57 and 58: Doyle, G.J. 1961. Self-Nucleation i
Page 59 and 60: Keady, P.B., F. R. Quant, and G. J.
Page 61 and 62: Seminar on Particle Size Distributi
Page 63 and 64: Watson, J. G. et al. 1998. Northern

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