4
by subsonic critical orifices, installed in the manifolds
coupled to a single vacuum pump. The elemental carbon
(EC) and OC mass concentrations were determined using
thermal optical transmittance-evolved gas analysis (TOT-
EGA) (80) performed on the 1.5 cm2 filter segments using
an OC/EC Aerosol Analyzer (Sunset Laboratory Inc.,
Portland, OR). The results of the analysis performed on the
secondary QFFs were used as a dynamic blank correction
for the primary QFFs.
The aerosol sampling and measurements were per-
formed downstream of the two-stage partial dilution sys-
tem (Dekati, Tampere, Finland, Model FPS4000) in the
exhaust diluted nominally 30 times. The carbon analysis
was performed on the triplicate filter samples collected
using the custom-made sampling system. The samples were
collected on the tandem 37-mm quartz fiber filters (QFFs,
Pall Corporation, Ann Arbor, MI, 2500QAT-UP) enclosed
in five-piece cassettes (SKC, Eighty Four, PA, 225-3050LF
and 225-304). To minimize organic carbon (OC) contami-
nation of the media, the QFFs were pre-baked at 800 °C
for 4 hours. A nominal sampling flow rate of 12.0 lpm was
maintained by subsonic critical orifices, installed in the
manifolds coupled to a single vacuum pump. The EC and
OC mass concentrations were determined using thermal
optical transmittance-evolve gas analysis (TOT-EGA) [82]
performed on the 1.5 cm2 filter segments using an OC/
EC Aerosol Analyzer (Sunset Laboratory Inc., Portland,
OR). The results of the analysis performed on the second-
ary QFFs were used as a dynamic blank correction for the
primary QFFs.
Since the adverse effects of exposure to nanosized
and ultrafine aerosols were linked not only to their mass
concentrations but also to their number concentrations and
size (17,81,82,83), the mass measurements were comple-
mented with measurements of the number concentrations
and size distributions of aerosols with electrical mobility
diameters between 5.6 nm to 560 nm. Those were mea-
sured with the fast mobility particle sizer (FMPS) spec-
trometer (TSI, Model 3091). In order to enhance the
clarity of the figures, the aerosol size distributions were fit-
ted with log-normal curves using the DistFit software from
Chimera Technologies (Forest Lake, MN). The concentra-
tions of CO, NO, and NO2 in raw exhaust were measured
in 20-second intervals using a Fourier transform infrared
(FTIR) spectrometer (Gasmet Technologies Oy, Model
DX‑4000). The exhaust flow rates were calculated using
results of measurements of intake flow rates by the laminar
flow meters (Meriam, Models Z50MC2-6F and Z50MC2-
4) and fuel mass flow rated by the fuel metering system
(Max Machinery, Model 710).
RESULTS
The emissions of the aerosols and gases were compared on
the level of the tailpipe concentrations. During the post-
processing, the aerosol concentrations that were measured
in the diluted exhaust were corrected for the actual dilution
rates and reported as the raw exhaust concentrations. Since
the concentrations of criteria gases were measured directly
in raw exhaust, the dilution corrections were not necessary
for that set of data.
The average EC and OC mass concentrations for all
evaluated engines/configurations are shown in Figure 1.
For all test conditions, the EC and OC mass concentra-
tions were found to be substantially lower in the exhausts
Table 3. Engine operating conditions for the evaluated engines
Engine
Engine Operating
Conditions
Rated Speed
–100% Load
(R100)
Rated Speed –
50% Load (R50)
Intermediate
Speed –
100% Load
(I100)
Intermediate
Speed –
50% Load
(I50)
Engine 1 Engine Speed [rpm] 2600 2600 1400 1400
Torque [Nm] 184 92 233 116
Power [kW] 50 25 43 21
Engine 2 Engine Speed [rpm] 2700 2700 1600 1600
Torque [Nm] 122 61 142 71
Power [kW] 34 17 24 12
Engine 3 Engine Speed [rpm] 2200 2200 1400 1400
Torque [Nm] 542 271 719 359
Power [kW] 125 63 105 53
Engine 4 Engine Speed [rpm] 2200 2200 1400 1400
Torque [Nm] 515 258 637 319
Power [kW] 119 59 93 47
by subsonic critical orifices, installed in the manifolds
coupled to a single vacuum pump. The elemental carbon
(EC) and OC mass concentrations were determined using
thermal optical transmittance-evolved gas analysis (TOT-
EGA) (80) performed on the 1.5 cm2 filter segments using
an OC/EC Aerosol Analyzer (Sunset Laboratory Inc.,
Portland, OR). The results of the analysis performed on the
secondary QFFs were used as a dynamic blank correction
for the primary QFFs.
The aerosol sampling and measurements were per-
formed downstream of the two-stage partial dilution sys-
tem (Dekati, Tampere, Finland, Model FPS4000) in the
exhaust diluted nominally 30 times. The carbon analysis
was performed on the triplicate filter samples collected
using the custom-made sampling system. The samples were
collected on the tandem 37-mm quartz fiber filters (QFFs,
Pall Corporation, Ann Arbor, MI, 2500QAT-UP) enclosed
in five-piece cassettes (SKC, Eighty Four, PA, 225-3050LF
and 225-304). To minimize organic carbon (OC) contami-
nation of the media, the QFFs were pre-baked at 800 °C
for 4 hours. A nominal sampling flow rate of 12.0 lpm was
maintained by subsonic critical orifices, installed in the
manifolds coupled to a single vacuum pump. The EC and
OC mass concentrations were determined using thermal
optical transmittance-evolve gas analysis (TOT-EGA) [82]
performed on the 1.5 cm2 filter segments using an OC/
EC Aerosol Analyzer (Sunset Laboratory Inc., Portland,
OR). The results of the analysis performed on the second-
ary QFFs were used as a dynamic blank correction for the
primary QFFs.
Since the adverse effects of exposure to nanosized
and ultrafine aerosols were linked not only to their mass
concentrations but also to their number concentrations and
size (17,81,82,83), the mass measurements were comple-
mented with measurements of the number concentrations
and size distributions of aerosols with electrical mobility
diameters between 5.6 nm to 560 nm. Those were mea-
sured with the fast mobility particle sizer (FMPS) spec-
trometer (TSI, Model 3091). In order to enhance the
clarity of the figures, the aerosol size distributions were fit-
ted with log-normal curves using the DistFit software from
Chimera Technologies (Forest Lake, MN). The concentra-
tions of CO, NO, and NO2 in raw exhaust were measured
in 20-second intervals using a Fourier transform infrared
(FTIR) spectrometer (Gasmet Technologies Oy, Model
DX‑4000). The exhaust flow rates were calculated using
results of measurements of intake flow rates by the laminar
flow meters (Meriam, Models Z50MC2-6F and Z50MC2-
4) and fuel mass flow rated by the fuel metering system
(Max Machinery, Model 710).
RESULTS
The emissions of the aerosols and gases were compared on
the level of the tailpipe concentrations. During the post-
processing, the aerosol concentrations that were measured
in the diluted exhaust were corrected for the actual dilution
rates and reported as the raw exhaust concentrations. Since
the concentrations of criteria gases were measured directly
in raw exhaust, the dilution corrections were not necessary
for that set of data.
The average EC and OC mass concentrations for all
evaluated engines/configurations are shown in Figure 1.
For all test conditions, the EC and OC mass concentra-
tions were found to be substantially lower in the exhausts
Table 3. Engine operating conditions for the evaluated engines
Engine
Engine Operating
Conditions
Rated Speed
–100% Load
(R100)
Rated Speed –
50% Load (R50)
Intermediate
Speed –
100% Load
(I100)
Intermediate
Speed –
50% Load
(I50)
Engine 1 Engine Speed [rpm] 2600 2600 1400 1400
Torque [Nm] 184 92 233 116
Power [kW] 50 25 43 21
Engine 2 Engine Speed [rpm] 2700 2700 1600 1600
Torque [Nm] 122 61 142 71
Power [kW] 34 17 24 12
Engine 3 Engine Speed [rpm] 2200 2200 1400 1400
Torque [Nm] 542 271 719 359
Power [kW] 125 63 105 53
Engine 4 Engine Speed [rpm] 2200 2200 1400 1400
Torque [Nm] 515 258 637 319
Power [kW] 119 59 93 47