7
aerosols in nucleation modes in filtered exhaust were lower
than those in corresponding accumulation mode (Table 4).
The effects of the evaluated engines/configurations on
the CO, NO2, and NO concentrations were studied using
data summarized in Figure 5. The CO emissions for Engine
1, Engine 2, and Engine 3, all fitted with catalyzed devices,
were mutually comparable and substantially lower than
corresponding CO emission from Engine 4, in all exhaust
configurations (Figure 5a). The data showed that catalyzed
devices fitted to Engine 1, Engine 2, and Engine 3 were
more effective in oxidizing CO than the devices washcoated
with NO2-suppressing catalyst formulations and retrofitted
to Engine 4.
The NO2 emissions from the catalyzed system fitted to
Engine 1 and Engine 2 were substantially higher than cor-
responding NO2 emissions from Engine 3 and Engine 4 in
all tested configurations (Figure 5b). Effective oxidation of
NO to NO2 over a wide range of exhaust temperatures, in
the presence of the catalysts in the exhaust aftertreatment
device fitted to Engine 1 and Engine 2, is likely the primary
source for high concentrations of NO2 in the exhausts of
Engine 1 and Engine 2 (Figure 6).
The results of additional 900-second tests conducted at
intermediated and rated speeds showed that for the exhaust
temperatures in the range between 250 °C and 350 °C, the
observed fraction of NO2 in NOx (NOx =NO +NO2) in
the exhaust of Engine 1, expressed as a percentage, exceeded
sixty (Figure 6a). For the similar temperature range, in the
exhaust of Engine 2, the observed fraction of NO2 in NOx
expressed as a percentage exceeded forty (Figure 6b).
The NO emissions were decisively lowest in the
exhaust of Engine 3, fitted with the DOC/SCR/ASC sys-
tem (Figure 5c). The NO2 emissions from the same engine
were comparable to those of Engine 4 in all exhaust config-
urations (Figure 5b). The results of additional 900-second
tests conducted at intermediated and rated speeds showed
Table 4. Statistical parameters, count median diameter (CMD), spread (σ), and total concentrations, for size distribution of
aerosols emitted by the evaluated engines measured 10,800 seconds from the beginning of each test. The results for Engine 3
and Engine 4 were adopted from a previous publication [39]
Mode
Exhaust
Aftertreatment
Nucleation Accumulation 1 Accumulation 2
CMD σ
Total
Conc. CMD σ
Total
Conc. CMD σ
Total
Conc.
Nm -#/cm3 Nm -#/cm3 Nm -#/cm3
R100 Engine 1 37.9 1.690 6.19E+07
Engine 2 7.8 1.360 6.18E+05 55.5 1.510 6.82E+05
Engine 3 12.4 1.310 5.82E+05 48.7 1.760 7.31E+06
Engine 4 – Muffler 10.1 1.340 2.68E+06 72.6 1.570 7.38E+07
Engine 4 – DOC 71.5 1.570 4.08E+07
Engine 4 – DPF 10.0 1.130 4.72E+04 29.7 1.560 1.16E+05
R50 Engine 1 35.3 1.680 6.42E+07
Engine 2 10.0 1.130 1.25E+04 18.9 2.100 1.07E+05
Engine 3 13.7 1.400 9.12E+05 47.6 1.650 8.48E+06
Engine 4 – Muffler 12.1 1.400 1.05E+06 60.3 1.600 3.95E+07
Engine 4 – DOC 58.6 1.620 3.81E+07
Engine 4 – DPF 9.3 1.160 9.22E+03 31.3 1.190 2.84E+03 85.6 1.310 5.07E+03
I100 Engine 1 13.8 1.390 1.91E+06 45.5 1.590 1.40E+07
Engine 2 12.5 1.490 4.60E+05 56.3 1.590 1.10E+06
Engine 3 12.4 1.400 6.60E+05 51.5 1.910 2.61E+06
Engine 4 – Muffler 79.5 1.580 7.20E+07
Engine 4 – DOC 82.2 1.540 3.75E+07
Engine 4 – DPF 10.0 1.100 1.05E+05 31.4 1.350 7.71E+04 80.5 1.480 6.31E+05
I50 Engine 1 13.1 1.320 1.32E+06 39.7 1.550 9.63E+06
Engine 2 13.0 1.380 1.53E+04 56.1 1.550 4.71E+04
Engine 3 12.1 1.560 6.08E+05 56.5 1.740 3.95E+06
Engine 4 – Muffler 68.7 1.670 5.46E+07
Engine 4 – DOC 64.5 1.660 2.25E+07
Engine 4 – DPF 9.7 1.140 3.77E+04 26.8 1.380 3.28E+04 45.9 1.630 8.96E+04
aerosols in nucleation modes in filtered exhaust were lower
than those in corresponding accumulation mode (Table 4).
The effects of the evaluated engines/configurations on
the CO, NO2, and NO concentrations were studied using
data summarized in Figure 5. The CO emissions for Engine
1, Engine 2, and Engine 3, all fitted with catalyzed devices,
were mutually comparable and substantially lower than
corresponding CO emission from Engine 4, in all exhaust
configurations (Figure 5a). The data showed that catalyzed
devices fitted to Engine 1, Engine 2, and Engine 3 were
more effective in oxidizing CO than the devices washcoated
with NO2-suppressing catalyst formulations and retrofitted
to Engine 4.
The NO2 emissions from the catalyzed system fitted to
Engine 1 and Engine 2 were substantially higher than cor-
responding NO2 emissions from Engine 3 and Engine 4 in
all tested configurations (Figure 5b). Effective oxidation of
NO to NO2 over a wide range of exhaust temperatures, in
the presence of the catalysts in the exhaust aftertreatment
device fitted to Engine 1 and Engine 2, is likely the primary
source for high concentrations of NO2 in the exhausts of
Engine 1 and Engine 2 (Figure 6).
The results of additional 900-second tests conducted at
intermediated and rated speeds showed that for the exhaust
temperatures in the range between 250 °C and 350 °C, the
observed fraction of NO2 in NOx (NOx =NO +NO2) in
the exhaust of Engine 1, expressed as a percentage, exceeded
sixty (Figure 6a). For the similar temperature range, in the
exhaust of Engine 2, the observed fraction of NO2 in NOx
expressed as a percentage exceeded forty (Figure 6b).
The NO emissions were decisively lowest in the
exhaust of Engine 3, fitted with the DOC/SCR/ASC sys-
tem (Figure 5c). The NO2 emissions from the same engine
were comparable to those of Engine 4 in all exhaust config-
urations (Figure 5b). The results of additional 900-second
tests conducted at intermediated and rated speeds showed
Table 4. Statistical parameters, count median diameter (CMD), spread (σ), and total concentrations, for size distribution of
aerosols emitted by the evaluated engines measured 10,800 seconds from the beginning of each test. The results for Engine 3
and Engine 4 were adopted from a previous publication [39]
Mode
Exhaust
Aftertreatment
Nucleation Accumulation 1 Accumulation 2
CMD σ
Total
Conc. CMD σ
Total
Conc. CMD σ
Total
Conc.
Nm -#/cm3 Nm -#/cm3 Nm -#/cm3
R100 Engine 1 37.9 1.690 6.19E+07
Engine 2 7.8 1.360 6.18E+05 55.5 1.510 6.82E+05
Engine 3 12.4 1.310 5.82E+05 48.7 1.760 7.31E+06
Engine 4 – Muffler 10.1 1.340 2.68E+06 72.6 1.570 7.38E+07
Engine 4 – DOC 71.5 1.570 4.08E+07
Engine 4 – DPF 10.0 1.130 4.72E+04 29.7 1.560 1.16E+05
R50 Engine 1 35.3 1.680 6.42E+07
Engine 2 10.0 1.130 1.25E+04 18.9 2.100 1.07E+05
Engine 3 13.7 1.400 9.12E+05 47.6 1.650 8.48E+06
Engine 4 – Muffler 12.1 1.400 1.05E+06 60.3 1.600 3.95E+07
Engine 4 – DOC 58.6 1.620 3.81E+07
Engine 4 – DPF 9.3 1.160 9.22E+03 31.3 1.190 2.84E+03 85.6 1.310 5.07E+03
I100 Engine 1 13.8 1.390 1.91E+06 45.5 1.590 1.40E+07
Engine 2 12.5 1.490 4.60E+05 56.3 1.590 1.10E+06
Engine 3 12.4 1.400 6.60E+05 51.5 1.910 2.61E+06
Engine 4 – Muffler 79.5 1.580 7.20E+07
Engine 4 – DOC 82.2 1.540 3.75E+07
Engine 4 – DPF 10.0 1.100 1.05E+05 31.4 1.350 7.71E+04 80.5 1.480 6.31E+05
I50 Engine 1 13.1 1.320 1.32E+06 39.7 1.550 9.63E+06
Engine 2 13.0 1.380 1.53E+04 56.1 1.550 4.71E+04
Engine 3 12.1 1.560 6.08E+05 56.5 1.740 3.95E+06
Engine 4 – Muffler 68.7 1.670 5.46E+07
Engine 4 – DOC 64.5 1.660 2.25E+07
Engine 4 – DPF 9.7 1.140 3.77E+04 26.8 1.380 3.28E+04 45.9 1.630 8.96E+04