On-board Measurement of HCN and NH3 Emissions from Vehicles During Real-World Driving
Abstract
Emission control systems in light-duty motor vehicles have played an important role in improving regional air quality by dramatically reducing the concentration of criteria pollutants (carbon monoxide, hydrocarbons, and nitrogen oxides) in exhaust emissions. Unintended side-reactions occurring on the surface of three-way catalysts can, however, lead to emission of non-criteria pollutants such as ammonia (NH3) and hydrogen cyanide (HCN). A pair of spectrometers based on tunable diode lasers (TDL) emitting in the near-infrared (1529 nm) and mid-infrared (2975 nm) have been developed for determination of HCN and acetylene (C2H2) emission rates from light-duty motor vehicles in real-time, while driving. Both spectrometers have been evaluated extensively using standard gas mixtures in the laboratory and exhaust from idling and moving vehicles. The TDL spectrometers were incorporated into an on-board instrument suite containing instrumentation for measurement of CO2, HCN, C2H2, NH3 and amines, and exhaust flow rate. On-board measurements were carried out on a fleet of ten vehicles driving a 30 minute circuit representative of real-world urban driving conditions. These measurements afforded emission factors for NH3 (194 × 147 mg km-1) and HCN (3.33 × 3.61 mg km-1), as well as the first report of methylamine emission factors, 0.70 × 0.61 mg km-1. Emissions of both amines were highly correlated (R2 = 0.95). The temporally-resolved TDL spectrometer measurements indicate that the highest HCN and C2H2 emissions occur during specific emission modes that are a function of driving conditions.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2013
- Bibcode:
- 2013AGUFM.A31C0102M
- Keywords:
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- 0394 ATMOSPHERIC COMPOSITION AND STRUCTURE Instruments and techniques;
- 0345 ATMOSPHERIC COMPOSITION AND STRUCTURE Pollution: urban and regional