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
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)
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