5
of the “clean” engines (Engine 1, Engine 2, and Engine 3)
than in the exhaust of the “traditional” engine (Engine 4).
Both EC and OC mass concentrations were two to three
orders of magnitude lower in the exhaust of the DOC/
DPF equipped Engine 2 than in the exhaust of Engine 4
fitted with muffler and comparable to those in the exhaust
of Engine 4 retrofitted with DPF (Figure 1). The EC and
OC mass concentrations were 74 to 96 percent and 48 to
99 percent, respectively, lower in the exhaust of DOC fitted
Engine 1 than the exhaust of Engine 4 operated with the
muffler and 64 to 94 percent and 36 to 96 percent, respec-
tively, in the exhaust of Engine 4 operated with the DOC
(Figure 1). In the exhaust of Engine 3, the EC and OC
mass concentrations were 72 to 88 percent and 23 to 93
percent, respectively, lower in the exhaust of DOC/SCR/
ASC fitted Engine 3 than the exhaust of Engine 4 operated
with muffler.
The fractions of EC in total carbon (TC=EC+OC)
were calculated for the selected cases shown in Figure 2.
Due to high uncertainty associated with establishing the
EC/TC ratios for the low-emitting Engine 2 (fitted with
DOC/DPF system), those results were excluded from this
analysis. The EC was found to make a large majority of TC
in the exhausts of Engine 1 and Engine 3 (Figure 2). Except
for the R50 test mode, the EC/TC ratios were higher for the
“clean” non-DPF engines (Engines 1 and Engine 3) than
for the “traditional” engine (Engine 4 with the muffler).
The average total number concentrations (TNCs) of
aerosol for all evaluated engines/configurations are shown
in Figure 3. Only in the case of two “clean” engines (Engine
Figure 1. Carbon concentrations: (a) EC and (b) OC. The
error bars represent one standard deviation of mean. The
results for Engine 3 and Engine 4 were adopted from a
previous publication [39]
Figure 2. EC in TC
Figure 3. Total aerosol number concentration. The error
bars represent one standard deviation of mean. The results
for Engine 3 and Engine 4 were adopted from a previous
publication [39]
of the “clean” engines (Engine 1, Engine 2, and Engine 3)
than in the exhaust of the “traditional” engine (Engine 4).
Both EC and OC mass concentrations were two to three
orders of magnitude lower in the exhaust of the DOC/
DPF equipped Engine 2 than in the exhaust of Engine 4
fitted with muffler and comparable to those in the exhaust
of Engine 4 retrofitted with DPF (Figure 1). The EC and
OC mass concentrations were 74 to 96 percent and 48 to
99 percent, respectively, lower in the exhaust of DOC fitted
Engine 1 than the exhaust of Engine 4 operated with the
muffler and 64 to 94 percent and 36 to 96 percent, respec-
tively, in the exhaust of Engine 4 operated with the DOC
(Figure 1). In the exhaust of Engine 3, the EC and OC
mass concentrations were 72 to 88 percent and 23 to 93
percent, respectively, lower in the exhaust of DOC/SCR/
ASC fitted Engine 3 than the exhaust of Engine 4 operated
with muffler.
The fractions of EC in total carbon (TC=EC+OC)
were calculated for the selected cases shown in Figure 2.
Due to high uncertainty associated with establishing the
EC/TC ratios for the low-emitting Engine 2 (fitted with
DOC/DPF system), those results were excluded from this
analysis. The EC was found to make a large majority of TC
in the exhausts of Engine 1 and Engine 3 (Figure 2). Except
for the R50 test mode, the EC/TC ratios were higher for the
“clean” non-DPF engines (Engines 1 and Engine 3) than
for the “traditional” engine (Engine 4 with the muffler).
The average total number concentrations (TNCs) of
aerosol for all evaluated engines/configurations are shown
in Figure 3. Only in the case of two “clean” engines (Engine
Figure 1. Carbon concentrations: (a) EC and (b) OC. The
error bars represent one standard deviation of mean. The
results for Engine 3 and Engine 4 were adopted from a
previous publication [39]
Figure 2. EC in TC
Figure 3. Total aerosol number concentration. The error
bars represent one standard deviation of mean. The results
for Engine 3 and Engine 4 were adopted from a previous
publication [39]