NH3 and N2O Real World Emissions Measurement from a CNG Heavy Duty Vehicle Using On-Board Measurement Systems

Abstract

The development and utilization of a series of after-treatment devices in modern vehicles has led to an increase in emissions of NH3 and/or N2O with respect to the past. N2O is a long-lived greenhouse gas and an ozone-depleting substance, while NH3 is a precursor of secondary aerosols in the atmosphere. Certain regions, e.g., the EU and the USA, have introduced limits to the emissions of NH3 or N2O for vehicles tested in the laboratory. However, due to the lack of on-board systems that allow for the measurement of these compounds when the regulations were developed, these vehicles’ real-world emissions have not been regulated. This work evaluates on-board systems that could allow measuring real-world emissions of NH3 and N2O from heavy-duty vehicles. In particular, emissions of NH3 or N2O from a Euro VI Step D urban/interurban bus fueled with Compressed Natural Gas were measured using the HORIBA’s OBS-ONE-XL, which is based on a specifically developed technique called Infrared Laser Absorption Modulation, and uses a Quantum Cascade Laser as a light source. They were also measured using the PEMS-LAB, which is a more conventional FTIR-based system. Emissions were measured under real-world driving conditions on the road and in a climatic test cell at different ambient temperatures. For most of the conditions tested, the on-board systems correlated well with a laboratory-grade FTIR used as reference. In addition, a good correlation with R2 > 0.9 was found for the N2O concentrations measured by OBS-ONE-XL and PEMS-LAB during on-road testing.

Robust Evidence of 14C, 13C, and 15N Analyses Indicating Fossil Fuel Sources for Total Carbon and Ammonium in Fine Aerosols in Seoul Megacity

“…NH 3 emissions from vehicle exhaust have been reported in laboratory experiments and on-road measurements as undesirable side effects associated with three-way catalytic converters (TWC) and selective catalytic reduction (SCR) equipped in gasoline powered vehicles and diesel-powered vehicles, respectively. − The results of the present study are basically in line with a recent study in urban Seoul, where a strong positive correlation ( R 2 = 0.94) was reported between the NH 3 concentration and the traffic load multiplied by ambient temperature. The discrepancy between experimental studies and inventories indicates that our current understanding of NH 3 emissions is poor and further studies are required.…”

Measuring Emissions from a Demonstrator Heavy-Duty Diesel Vehicle under Real-World Conditions—Moving Forward to Euro VII

“…The upper panels show that the OBS-ONE-XL and both laboratory grade instruments excellently correlated, with an R 2 > 0.96 in both cases and a very good linearity, with angular coefficient equal to 1 ± 0.05 and intercept < 0.2. These results were well in line with those obtained for a CNG M1 bus and discussed in [11].…”

“…The acquisition frequency was 10 Hz. This instrument had been already tested in VELA7 with a compressed natural gas (CNG) vehicle; additional information can be found in [11].…”

Emissions from a Modern Euro 6d Diesel Plug-In Hybrid

“…On-road, unregulated pollutants were measured with a portable FTIR instrument (instrument (PEMS-LAB from CERTAM and ADDAIR, Saint-Étiennedu-Rouvray, France) used in parallel to the PEMS. The instrument was validated in a previous study [18].…”