S.T. O’Sullivan D.J. Timoney University College Dublin Ireland On-road measurement of particulate emissions from diesel engined vehicles

Outline Diesel Particulate Matter Legislation Emissions from in-use vehicles Current measurement techniques – Optical – Filtration New measurement technique Questions

Diesel Particulate Matter (DPM) DPM is a complex aggregate of solid and liquid material whose origins lie in the carbonaceous particles generated during the combustion phase Adsorbed Hydrocarbons and sulphates Primary Carbon Spherule µm diameter Agglomerated Particle µm diameter Carbon Core

Vehicle Tailpipe Emissions Legislation Ambient Air Quality Standards Ambient Air Quality Standards

What metric to use? Number? Surface area? Chemical composition? Size Range? Mass? Mass Number? Surface area? Chemical composition? Size Range?

Euro I (1992) Euro II (1996) Euro III (2000) Euro IV (2005) Euro V (2008) PM [g/kWh] EU Heavy Duty Diesel Emissions NOx [g/kWhr]

Impact of Emission Standards Diesel engines typically have a long operating life Fleet turnover of commercial vehicles is not as rapid as private vehicles EU standards for new vehicle emissions take several years before they have a practical impact on air quality What about vehicles alreadyon our roads?

Real world driving Older technology engines Varying states of Maintenance Gross emitters On-road emission from in-use vehicles How much PM is actually being emitted by vehicles?

Laboratory based legislated method

Current Measurement Techniques Regulatory Method: Dilution, filtering and weighing Opacity meter Bosch Smoke Meter Tapered Element Oscillating Microbalance (TEOM)

Measurement Methods I: Opacity Measurement Photo sensor Light source IoIo I Opacity = 1 – I o /I = 1 – Exp (-kL) L

Smoke not mass Snap acceleration test Unrealistically high acceleration rates Can wrongly identify vehicles as faulty Inspection and maintenance programmes

Measurement Methods II: Filtration Methods Filter Paper Smoke Number IoIo I SN = 1- I o /I I’/I 12.3 Gravimetric

Diesel Particulate Filter

Dynamometer 2.5L Diesel Engine P1P1 P2P2 Filter Control Valve Pump Main Flow Split Flow New Measurement Method

Time  kept within ±0.5% of target percentage Transient Response

Advantages Pump overcomes back pressure so engine sees no restriction on exhaust manifold Able to run for long time Cheap and easy to install Large amounts of DPM collected for weighing

Collected PM

Diesel Particulate Matter Legislation Current measurement techniques – Optical – Filtration New measurement technique Questions Summary

Questions

Diameter (µm) Normalized Concentration Mass WeightingNumber WeightingSurface Weighting Fine Particles Dp < 2.5 µm PM10 Dp < 10 µm Diesel Particulate Emissions: Number, Mass & Surface Area Nuclei Mode Accumulation Mode Course Mode

Electron Microscope Picture of Agglomerated Particles Diesel Particulate Matter (DPM)