Large eddy simulation of vehicle emissions dispersion: Implications for on-road remote sensing measurements

Evaluating in-use vehicle emissions using air quality monitoring stations and on-road remote sensing systems

“…Since the effective plume path length and the amount of plume measured are influenced by a number of factors such as wind, turbulence, engine size and exhaust pipe height, RS can only determine the relative concentration ratios of pollutants over CO2 (i.e. CO/CO2, HC/CO2 and NO/CO2) (Huang et al, 2020). Meanwhile, the speed, acceleration and an image of the license plate of the passing vehicle are measured by the RS system.…”

Quantifying on-road vehicle emissions during traffic congestion using updated emission factors of light-duty gasoline vehicles and real-world traffic monitoring big data

“…In summary, the emission factors of CO, HC, and NO x under the slow driving conditions were 5-9 times higher than under the high-speed conditions (> 50 km/h) and 3-6 times higher than under the normal urban driving conditions. Emission factors under the slow driving conditions were significantly higher than previous studies (Huang et al, 2020a;Wang et al, 2017). One of the possible reasons might be that the emission data of second by second used in this study can better capture the ultra-high emissions at low speeds or even idling speeds.…”

Statistical evaluation of on-road vehicle emissions measurement using a dual remote sensing technique

“…Therefore, remote sensing is unable to measure the absolute emission concentrations. Instead, remote sensing can only measure the relative emission ratios of CO/CO2, HC/CO2 and NO/CO2 which are assumed to be constant for a given plume in the near wake region after the vehicle tailpipe exit (Bishop et al, 1989;Burgard et al, 2006;Huang et al, 2020a). For this reason, meteorological conditions are not measured in remote sensing but are taken into account before proceeding with measurements.…”