s.t. o’sullivan d.j. timoney university college dublin ireland on-road measurement of particulate...
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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
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?
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
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
Diesel Particulate Matter Legislation Current measurement techniques
– Optical– Filtration
New measurement technique Questions
Summary
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