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

S.T. O’Sullivan

D.J. Timoney

University College DublinIreland

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 Hydrocarbonsand sulphates

Primary Carbon Spherule0.005 - 0.05 µm diameter

Agglomerated Particle0.05 - 1 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?

0.02

0.6

0.5

0.4

0.1

0.2

0.3

82 4 6

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 already on 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

Io I

Opacity = 1 – Io/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

FilterPaper

Smoke Number

Io I

SN = 1- Io/I

I’/I

12.3

Gravimetric

Diesel Particulate Filter

Dynamometer2.5L Diesel

Engine

P1

P2

Filter

ControlValve

Pump

Main Flow

Split Flow

New Measurement Method

0

0.01

0.02

0.03

0.04

0.05

0.06

0.07

Time

To

tal M

as

s f

low

(k

g/s

)

0

0.001

0.002

0.003

0.004

0.005

0.006

0.007

0.008

0.009

Pa

rtia

l M

as

s f

low

(k

g/s

)

Total Mass Flow Partial Mass flowTime

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

QuestionsQuestions

0

0.05

0.1

0.15

0.2

0.25

0.001 0.010 0.10 1.0 10.0

Diameter (µm)

No

rmal

ized

Co

nce

ntr

atio

n

Mass Weighting Number Weighting Surface Weighting

Fine ParticlesDp < 2.5 µm

PM10Dp < 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)