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)

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