On-road detection of trucks with high NOx emissions from a patrol vehicle with on-board FTIR analyzer

Michal Vojtisek-Lom; Alden Fred Arul Raj; Petr Jindra; David Macoun; Martin Pechout

doi:10.1016/j.scitotenv.2020.139753

On-road detection of trucks with high NOx emissions from a patrol vehicle with on-board FTIR analyzer

Sci Total Environ. 2020 Oct 10:738:139753. doi: 10.1016/j.scitotenv.2020.139753. Epub 2020 May 28.

Authors

Michal Vojtisek-Lom¹, Alden Fred Arul Raj², Petr Jindra³, David Macoun³, Martin Pechout⁴

Affiliations

¹ Department of Automotive, Combustion Engine and Railway Engineering, Faculty of Mechanical Engineering, Czech Technical University of Prague, Technicka 4, 166 07 Prague, Czech Republic; Department of Vehicles and Engines, Faculty of Mechanical Engineering, Technical University of Liberec, Studentska 2, 461 17 Liberec, Czech Republic. Electronic address: michal.vojtisek@fs.cvut.cz.
² Department of Automotive, Combustion Engine and Railway Engineering, Faculty of Mechanical Engineering, Czech Technical University of Prague, Technicka 4, 166 07 Prague, Czech Republic.
³ Department of Vehicles and Ground Transport, Faculty of Engineering, Czech University of Life Sciences, Kamycka 127, 165 21, Praha-Suchdol, Czech Republic.
⁴ Department of Vehicles and Engines, Faculty of Mechanical Engineering, Technical University of Liberec, Studentska 2, 461 17 Liberec, Czech Republic; Department of Vehicles and Ground Transport, Faculty of Engineering, Czech University of Life Sciences, Kamycka 127, 165 21, Praha-Suchdol, Czech Republic.

PMID: 32531593
DOI: 10.1016/j.scitotenv.2020.139753

Abstract

Technological advances in heavy-duty vehicle engines, allowing them to reach NO_x emissions comparable to European diesel passenger cars per km driven, are being compromised by aftermarket defeat devices such as selective catalytic reduction (SCR) emulators, many of which can be quickly deactivated by the driver. In a pilot study, the prevalence of trucks with excess NO_x emissions on Czech motorways was evaluated using an ordinary Customs Administration patrol vehicle temporarily fitted with a portable fast-response Fourier Transform Infra Red (FTIR) analyzer, acting as an impromptu chase vehicle. The Euro emissions category of the truck was provided from the motorway toll collection transponders. A total of 222 unique trucks were measured during a one-week pilot project. Of these, 66% were Euro VI, 25% were Euro V, and 9% were older categories. NO/CO₂ ratios were calculated as a ratio of numerical integrals of the peaks of measured concentrations, as a ratio of maximum measured concentrations, and by linear regression, with the regression approach yielding most realistic results and mean calculated error of 0.2 g/kWh NO. At assumed 85% NO in NO_x and 634 g/kWh mean CO₂ emissions, the mean emissions of the cleanest 83% of Euro V and cleanest 63% of Euro VI trucks were within the corresponding NO_x limit (2 g/kWh for Euro V, 0.46 g/kWh for Euro VI) multiplied by a factor of 1.5. Providing for some allowance for legitimate occurrences of high NO_x emissions, about 10-15% of Euro V and about 10-25% of Euro VI trucks are believed to be excess emitters, with no SCR functionality on about 10-15% of Euro VI trucks. The portable FTIR, temporarily mounted on a law enforcement vehicle, can be readily used as a screening tool, identifying vehicles to be stopped for additional inspection, but also during roadside emissions inspections.

Keywords: Chase vehicle; FTIR; High emitter; Nitrogen oxides; On-road emissions; SCR.