an alternative techniques to estimate road traffic emissions · national university of colombia,...
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![Page 1: An Alternative Techniques to Estimate Road Traffic Emissions · National University of Colombia, campus Bogotá . lcbelalcazarc@unal.edu.co. 2 Laboratoire Image Ville Environnement,](https://reader035.vdocuments.mx/reader035/viewer/2022071015/5fcdf0684316c862e436599e/html5/thumbnails/1.jpg)
An Alternative Techniques to Estimate Road Traffic Emissions
Luis Carlos Belalcazar1; Alain Clappier2
1Department of Chemical and Environmental Engineering National University of Colombia, campus Bogotá
2Laboratoire Image Ville Environnement, Université de Strasbourg, F-67000 Strasbourg, France
EPA 2012 International Emission Inventory Conference Session 7: GIS Innovative Methods Remote Sensing
Tampa, FL, August 2012
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Vehicle emissions monitoring Exhaust pipe flux
Dynamometer
On-board
- Expensive - Limited number of pollutants - Small vehicles sample
Ambient concentrations
Tunnel
Inverse modelling
- Site specific - Uncertainties associated to the dispersion model used
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Motivation
Road traffic is one of the main sources of pollution in cities
Existing methods to assess road traffic emissions are expensive and not always accurate
It results difficult for a developing country to afford the existing techniques
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Objective
The aim of this work was to develop and to implement an alternative and cost effective techniques to estimate road traffic emission factors
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Measuring site: Ba Thang Hai street (BTH); Ho Chi Min City, Vietnam
14 000 motorcycles / hour (95% of the fleet)
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Ho Chi Minh City (HCMC) campaign, January - March 2007
[1] Tracer liberation - n-propane from LPG -12 h /day; 30 days
[3] Traffic flow video recording - 12 h /day; 30 days
[2] Monitoring station - NO, PM2.5 - 19 VOCs
[4] Meteorology
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Estimation of road traffic emission factors From a tracer study in HCMC
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Estimation of road traffic emission factors
Emission factor
[mg veh-1Km-1]
Measured concentration
[µg m-3] Dispersion
factor [s m-2]
Background concentration [µg m-3] Ci = q* Fi * Ni + Cb
Number of vehicles [veh s-1]
q
Ci
Cb
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Estimation of road traffic emission factors from a tracer study
Ci =q * Fi * Ni + Cb
Fi = Ct,i / E
E
Ci
Tracer concentration
[µg m-3]
Tracer emission
[µg m-1 s-1] Dispersion
factor [s m-2]
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Estimation of road traffic emission factors From a tracer study in HCMC
0
20
40
60
80
100
120
140
0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5
Fi * Ni (veh m-2)
Prop
ene
(ug
m-3
)
q = 19.1 mg/veh/Km; n = 524; CI = 9%’ R = 0.68
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Dispersion factor
Ftracer
Fvehicles
≠
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EFFECT OF THE EMISSION SOURCE POSITION
-To use the tracer study to validate a CFD model
-To use the CFD model to calculate the error produced by the source position used in HCMC and to correct the Efs
-To find a source configuration that better represent the vehicle emissions
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WinMiskam CFD model domain
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CFD model validation
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Evaluation of different source configurations
0.0
0.2
0.4
0.6
0.8
60 90 120 150 180
Wind direction
F (s
m-2
)
100 m left 100 m center 200 m center trafficTraffic
100 m HCMC
100 m 200 m
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Correction of the HCMC EFs
Fi,c = Fi / (1- error/100)
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Conclusions and perspectives
The developed methodologies may serve different purposes at the same time and their use can provide useful information for the urban air quality assessment:
• Estimation of EFs under real urban conditions
• Dispersion models validation
• Pollutants source identification
• Exposure studies
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Thank you very much