Diesel Exhaust Particulate Characterization
- Influence on DPF Filling Performance D. Foster, T. Root, T. Kawai, E. Wirojsakunchai, E. Schroeder, N. Schmidt, C. Kolodziej, R. Yapaulo
Objective:
Diesel particulate filter (DPF) performance is influenced by a wide
variety of parameters. Identifying the key variables is an area of ongoing
research. A single cylinder Cummins N14 research engine, with a high
pressure unit injector, was operated over a range of loads and speeds to gain
understanding of fundamental mechanisms at work.
Engine Operating Conditions
Exhaust
Montajir et al.
SAE 2005-01-0187
1.E+09
EC
Group 1: Particle Cores
1.E+08
dN/d(logDp) [#/cm ]
See Section 2.1
3
47 mm Filters
M5
Group 3
Group 3: Accumulation Mode
80%
Mode 3
Mode 4
Mode 5
Speed
1800
1200
1200
Torque [% of max]
50
25
100
Intake Pressure [psig]
6.1
8.4
7.3
Mass Fuel Flow [lbs/min]
0.155
0.076
0.254
Flow Divider
FTIR
OC
100%
Group 2: Volatile Fraction (Nucleation Mode)
Secondary Diluter Ejector
Instrumentation
Primary Diluter Perforated Tube Probe
EEPS
Secondary
Dilution Air
(from valve unit)
PM mass & composition
SMPS
Pressure
Transducers
Gas phase emissions
TEOM
Primary
Dilution Air
(from valve unit)
Real-time particle size distribution
Pre-probe
Particle size distribution
MEXA 1230 PM
Dilution Air
Heater
Real-time PM mass
Primary Probe
Heater
Real-time PM mass & composition
Soot particles display different
filling behavior depending on
size and chemical composition
3 Steady State Engine
Operating Conditions
are chosen to represent
the various types of soot
encountered in diesel
exhaust
Lab Setup:
DPF
Engine Out Particle Characteristics
Mass Air Flow [lbs/min]
7
5.3
4.8
Equivalence Ratio
0.32
0.2
0.76
Soot Emissions [g/kW-hr]
0.10
0.09
0.94
Group 2
1.E+07
M3
60%
M4
1.E+06
Group 1
40%
1.E+05
20%
Mode 3
Mode 4
Mode 5
1.E+04
0%
1
10
100
1000
Mode 3
Midpoint Diameter Dp [nm]
Mode 4
Mode 5
EC = Elemental Carbon (solid soot particles)
OC = Organic Carbon (adsorbed hydrocarbons)
Substrate
Corning EX 80 100/17
SiC 300/10
Cordierite
Silicon-Carbide
Cell Density N
100 CPSI
Geometric Filter
Area
m2/l
0.65
Wall Thickness
wth
m2/l
10 mil
3
2
10
8
6
Bare Cordierite DPF
4
2.65 l
yes
0 g/l
0 g/l
yes
Washcoated Cordierite
DPF
0
3 g/l
500
1000
1500
2000
Mode 3, Cordierite
yes
200
150
Mode 3
100
Mode 4
12
10
1.E+06
8
1.E+05
6
4
1.E+04
2
2500
3000
Fill Time [s]
3500
4000
4500
TC M3
0
5000
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
6
4
5
3
4
2
delta P M3
900
t [s]
1400
1900
16
1.E+07
12
10
1.E+06
8
1.E+05
6
4
2
TC M4
Cordierite Substrate
SiC Substrate
0
2000
4000
6000
8000
10000
12000
14000
Filtration efficiency is
poor until a soot cake
begins to form
1.E+04
1
Merkel, G.A. et al
Significant soot
breakthrough occurs
during the first 2000 s
14
2
1
Mode 3, Cordierite
0
400
1.E+08
Magnitude of DPF pressure drop varies widely
with substrate, engine mode and catalyst coating,
7
3
1.E+03
-100
4.5
Soot fed to DPF [g]
Mode 3, SiC
1 g/l
Different DPF
substrates, filter
geometries and
catalytic coatings are
selected
1.E+07
Mode 5
0
no
250
50
Catalyzed Cordierite DPF
2
2.5 l
300
12
Filter Pressure Drop [kPa]
Precious Metal
Loading (Pt)
1
17 mil
Substrate
Volume Vs
Washcoat
300 CPSI
4
14
Filter Pressure Drop [kPa]
DPF Designation
Significant soot
breakthrough occurs
during the first 900 s
14
Pressure Drop [kPa]
16
Pressure Drop [kPa]
7
16
3
4&5
1.E+08
Mode 3,4 & 5, catalyzed Cordierite
350
3
3&6
Soot Cake
Filtration
Transition
DPF Filling Performance (Filtration Efficiency)
Total Particulate Concentration [#/cm ]
1&2
Wall
Filtration
Delta P / Exhaust Mass Flow Rate
(kPa-sec/kg)
DPF Number
DPF Filling Performance (Pressure Drop)
Total Particulate Concentration [#/cm ]
DPF Specifications
1.E+03
-100
delta P M4
0
400
Fill Time [s]
University of Wisconsin Engine Research Center
900
t [s]
1400
1900
Mode 4, Cordierite