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Nanoparticles from road vehicle exhaust: an artefact or a reality?

concawe. Nanoparticles from road vehicle exhaust: an artefact or a reality?. Diane Hall BP/CONCAWE Lemnos Meeting: Round Table Discussion 11 th September 2003. Purpose of Discussion. To examine data which demonstrates the emission of nanoparticles from vehicles and engines

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Nanoparticles from road vehicle exhaust: an artefact or a reality?

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  1. concawe Nanoparticles from road vehicle exhaust: an artefact or a reality? Diane Hall BP/CONCAWE Lemnos Meeting: Round Table Discussion 11th September 2003

  2. Purpose of Discussion • To examine data which demonstrates the emission of nanoparticles from vehicles and engines • To understand whether these measurements reflect genuine real-time engine emissions or are affected by sampling and/or methodology

  3. concawe light duty investigation Gasoline vehicles at 120km/h • First research – had no explanation for consistency of distribution between vehicles • Possible explanation is that we were not seeing genuine engine emissions Source: concawe report 98/51 Source: CONCAWE Report 98/51; SAE paper 982600

  4. Total number of particles emitted per kilometer for each vehicle No. / km Diesel vehicles 10**15 Gasoline vehicles 10**14 10**13 10**12 10**11 10**10 50 km/h 120 km/h Hot MVEG (SMPS data averaged over all fuels) Source:concawe report 98/51 Source: CONCAWE Report 98/51; SAE paper 982600

  5. Stabilisation time is important • Accumulation mode particles stabilise instantaneously • Nucleation mode particles take time to stabilise Source: concawe report 01/51

  6. Nucleation mode sensitive totemperature • Accumulation mode unaffected by dilution ratio • Nucleation mode sensitive to dilution ratio • Temperature (rather than dilution ratio) is believed to be the dominating influence onnucleation particle formation Source: concawe report 01/51

  7. DETR/SMMT/CONCAWE Particulate Research Programme • Size of idle mode appears dependent on preceding test condition

  8. Implications from studies • Nanoparticles are emitted from Gasoline vehicles at high speed, independent of fuel and vehicle technology • Nanoparticles emitted during heavy duty engine testing are sensitive to sampling conditions • Nanoparticles measured during heavy duty testing are sensitive to preceding engine history

  9. BP Study – gasoline particle emissions at 120km/h (measured over a week) Source: SAE 2000-01-2957

  10. Relationship of particle emissionswith temperature Source: SAE 2000-01-2957

  11. On-road tests Source: SAE 2000-01-2957

  12. Indications • continual running at high speed was ‘clearing’ the system of particles • material appeared to be laid down on surfaces at cooler conditions with particle release appearing to be temperature related • Hypothesis tested with cut off piece of exhaust sampling pipe

  13. Tests on old exhaust pipe Source: SAE 2000-01-2957

  14. TEST PROGRAMME • Vehicle: • VW Golf 1.9l TDi, with and without oxicat • Fuels: • Current EN 590 (300ppm S) • Swedish Class 1 • Chassis Dynamometer at BP, with measurements by AEA Technology • SMPS (7-320nm); UPM total count >3nm

  15. RESULTS • At road load, no nucleation particles were observed at any of the test conditions, with either fuel and independent of the presence of the catalyst • Tests were repeated at high load (30kW)

  16. Summary of High Load Tests at 50km/h

  17. Summary • Nucleation particles were not seen under any test condition at road load • Nucleation particles were only seen at high load with the catalyst in place • appear to be temperature related • Test sequence and pre-conditioning critical

  18. ‘System release’ during heavy-duty sampling Stabilisation following fitting of ‘loaded’ trap System burn off Source: SAE 2003-01-3167

  19. Conclusions (1) • The formation of nanoparticles (nucleation mode) is extremely sensitive and varies with sampling (temperature, dilution, humidity); thus repeatable measurement requires tight control and carefully defined conditions • High concentrations of small particles have been measured from gasoline vehicles operating at high speeds and from Diesel vehicles at high load • These particles have been shown to be strongly linked to the temperature of both the exhaust and sampling system • Material emitted from the engine is deposited on cool surfaces and released as particles as the temperature profile increases

  20. Conclusions (2) • Sustained periods of high temperature will ‘clean’ the system and reduce the number concentration to that measured at low speed • Subsequent operation at progressively higher speeds will result in further release of deposited material • The measurement of particle numbers is strongly dependent on the pre-history of both vehicle and sampling system • Further research continues to be needed to understand the formation mechanism and atmospheric fate of nucleation particles

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