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

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

concawe concawe light duty investigation Source: CONCAWE Report 98/51; SAE paper 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 Gasoline vehicles at 120km/h

concawe (SMPS data averaged over all fuels) Diesel vehicles No. / km 10**10 10**11 10**12 10**13 10**14 10**15 50 km/h120 km/hHot MVEG Gasoline vehicles Total number of particles emitted per kilometer for each vehicle Source: CONCAWE Report 98/51; SAE paper Source:concawe report 98/51

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

concawe Accumulation mode unaffected by dilution ratio Nucleation mode sensitive to dilution ratio Temperature (rather than dilution ratio) is believed to be the dominating influence on nucleation particle formation Nucleation mode sensitive to temperature Source: concawe report 01/51

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

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

concawe BP Study – gasoline particle emissions at 120km/h (measured over a week) Source: SAE

concawe Relationship of particle emissions with temperature Source: SAE

concawe On-road tests Source: SAE

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

concawe Tests on old exhaust pipe Source: SAE

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

concawe RESULTS u 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 u Tests were repeated at high load (30kW)

concawe Summary of High Load Tests at 50km/h

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

concawe ‘System release’ during heavy-duty sampling System burn off Stabilisation following fitting of ‘loaded’ trap Source: SAE

concawe Conclusions (1) u 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 u High concentrations of small particles have been measured from gasoline vehicles operating at high speeds and from Diesel vehicles at high load u These particles have been shown to be strongly linked to the temperature of both the exhaust and sampling system u Material emitted from the engine is deposited on cool surfaces and released as particles as the temperature profile increases

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