8th ETH Conference on Combustion Generated Particles
Zurich, 16th – 18th August 2004
Comparison of PAH in the soot made
by propane, gasoline and diesel using
the CAST technique
Dr. Lianpeng Jing
Jing Ltd
Zurich, 16th August 2004
CAST – a generator of real soot particle
• CAST = Combustion Aerosol Standard
• Soot particles are
- generated in a diffusion flame
Dilution
gas
Quenching gas
Smoke
Dilution
gas
- quenched subsequently
Flame
• Product = real smoke
Air Fuel Air
What does a CAST do?
Steady soot generating with high
reproducibility
Reference soot
particle
Particle size
adjustable
Soot sample with
adjustable
composition
CAST-liquid for liquid fuel
New possibility to investigate
soot from different fuel under
controllable and comparable
conditions
Applications of CAST-liquid
Independent from engine type
„ Comparison of fuel in regards to their sooting potential
„ Investigation of the influences on soot emissions due to fuel
quality (a cheaper and more efficient alternative)
„ Investigation of the influences of fuel additives
„ Reference soot and particle for research and calibration purposes
Examples of diesel soot
Adjustable particle size
2.
Diesel soot predominant
3.
Soot from smaller mean size contains more OC.
2.5E+07
part. conc. dN/dlog(Dp) [#/cm3
part. conc. dN/dlog(Dp) [#/cm3
1.
216 nm
2.0E+07
w ithout
diesel
1.5E+07
1.0E+07
5.0E+06
0.0E+00
10
9.0E+07
8.0E+07
7.0E+07
6.0E+07
5.0E+07
4.0E+07
3.0E+07
2.0E+07
1.0E+07
0.0E+00
100
1000
el. mobility diameter [nm]
130 nm
w ithout
diesel
Chem. composition of diesel soot from CAST
100%
80%
10
100
1000
el. mobility diameter [nm]
60%
80 nm
2.0E+07
w ithout
diesel
1.5E+07
1.0E+07
5.0E+06
0.0E+00
10
100
1000
el. mobility diameter [nm]
part. conc. dN/dlog(Dp) [#/cm3
part. conc. dN/dlog(Dp) [#/cm3
OC
2.5E+07
1.2E+07
53 nm
EC
40%
1.0E+07
w ithout
diesel
8.0E+06
20%
6.0E+06
0%
4.0E+06
220 nm
2.0E+06
0.0E+00
10
100
1000
el. mobility diameter [nm]
195 nm
123 nm
74 nm
57 nm
PAH analysis – Part 1
Particle size distribution
1. Soot from diffusion flame of
* Propane
* Diesel
2. Mode of 3 size distributions are
placed close to each other.
3. Gasoline soot contains more OC
than diesel soot.
4. Soot from gaseous fuel is drier
than from liquid fuel.
part. conc. [part./cm3]
* Gasoline (direct injection)
1.4E+08
1.2E+08
gasoline,
mode=163 nm
1.0E+08
propane,
mode=157 nm
8.0E+07
diesel,
mode=168 nm
6.0E+07
4.0E+07
2.0E+07
0.0E+00
10
100
1000
el. mobility diameter [nm]
soot type
EC
OC
gasoline
93%
7%
diesel
96%
4%
propane
98%
2%
PAH analysis : Part 2
1. Gasoline soot contains (7x) more PAH than diesel soot.
2. Gasoline soot: large PAH predominant
3. Diesel soot: small PAH predominant
4. Propane soot: small PAH predominant
diesel
Pyren
Benzo(g,h,i)perylen
Benzo(a)pyren
Benzo(k)fluoranthen
Pyren
Chrysen
Dibenzo(a,h)anthracen
propane
Indeno(1,2,3-cd)pyren
gasoline
Benzo(a)anthracen
0
Benzo(b)fluoranthen
1000
Fluoranthen
2000
400
200
0
Anthracen
3000
diesel
600
Fluoren
7 time more
4000
propane
Phenanthren
5000
gasoline
1000
800
Acenaphthen
6000
1400
1200
Acenaphthylen
7000
Detailed PAH content
Naphthalin
sum PAH [mg/kg total sample]
Total PAH found in soot
mass [mg/kg total sample]
5. Propane soot contains more PAH than diesel soot
Benzo(a)pyren
Explanation
low
volatility
Propane
sooting potential
Gasoline
Diesel
high
amount of gaseous fuel
These
Beside the soot there are following components in the diffusion flame
Propane
………… Soot
n C2H2
Gasoline
Diesel
……… Soot
Precursor
Soot
Time scale
Moment of quenching
Conclusions
„ CAST is not only a reference particle generator, but also an appropriate
device to investigate soot formation and particle emission.
„ PAH amount depends on the volatility of fuel: the more volatile, the
more PAH.
„ Size of predominant PAH depends on the size of fuel molecule.
„ Gasoline soot contains much more PAH and is to be recognized as
more harmful than Diesel soot.
„ A important reason for the control of the particulate emission from
gasoline and nature gas engines.
Acknowledgements
„ Swiss Agency for the Environment, Forests and Landscape (BUWAL)
„ Swiss Federal Office of Metrology and Accreditation (Metas)
„ Swiss National Accident Insurance Organisation (SUVA)
„ Swiss Federal Roads Office (Astra)