High spatio-temporal resolution pollutant measurements of on-board vehicle emissions using ultra-fast response gas analyzers

• Published in: Atmospheric measurement techniques Vol. 11; no. 6; pp. 3559 - 3567
• Main Authors: Irwin, Martin, Bradley, Harry, Duckhouse, Matthew, Hammond, Matthew, Peckham, Mark S
• Format: Journal Article
• Language: English
• Published: Katlenburg-Lindau Copernicus GmbH 20.06.2018; Copernicus Publications
• Subjects: Air; Air pollution; Air quality; Analyzers; Automotive electronics; Automotive emissions; Carbon dioxide; Data; Driving; Driving ability; Emission measurements; Engine control; Engines; Exhaust emissions; Exhaust gases; Gas analyzers; Gas detectors; Global positioning systems; GPS; Hydrocarbons; Internal combustion engines; Measurement; Modelling; Nitrogen compounds; Nitrogen oxides; Outdoor air quality; Pollutants; Ramps; Resolution; Response time; Road humps; Temporal resolution; Traffic signals; Traffic speed; Urban air; Urban air quality; Vehicle emissions
• ISSN: 1867-8548; 1867-1381; 1867-8548
• DOI: 10.5194/amt-11-3559-2018

Existing ultra-fast response engine exhaust emissions analyzers have been adapted for on-board vehicle use combined with GPS data. We present, for the first time, how high spatio-temporal resolution data products allow transient features associated with internal combustion engines to be examined in detail during on-road driving. Such data are both useful to examine the circumstances leading to high emissions, and reveals the accurate position of urban air quality “hot spots” as deposited by the candidate vehicle, useful for source attribution and dispersion modelling. The fast response time of the analyzers, which results in 100 Hz data, makes accurate time-alignment with the vehicle's engine control unit (ECU) signals possible. This enables correlation with transient air fuel ratio, engine speed, load, and other engine parameters, which helps to explain the causes of the emissions “spikes” that portable emissions measurement systems (PEMS) and conventional slow response analyzers would miss or smooth out due to mixing within their sampling systems. The data presented is from NO and NOx analyzers, but other fast analyzers (e.g. total hydrocarbons (THC), CO and CO2) can be used similarly. The high levels of NOx pollution associated with accelerating on entry ramps to motorways, driving over speed bumps, accelerating away from traffic lights, are explored in detail. The time-aligned ultra-fast analyzers offer unique insight allowing more accurate quantification and better interpretation of engine and driver activity and the associated emissions impact on local air quality.