The Construction and Application of a Multipoint Sampling System for Vehicle Exhaust Plumes

Abstract

To study the formation process of secondary organic aerosols (SOA) in a vehicle exhaust plume near the exhaust gas discharge outlet, a new multipoint sampling system was established. The system has five sampling heads and includes a particulate matter multi-channel film sampling system, a CO 2 /CO analyzer system, a volatile organic compound (VOC) sampling system, a particulate matter real-time analyzer system, and sensor interfaces. The vehicle exhaust near the exhaust nozzle can be sampled at multiple locations simultaneously using the new multipoint sampling system. Additionally, the system can be used to measure and analyze variations in the fine particulate matter, including the carbonaceous and ionic components, and organic compounds in the plume near the exhaust nozzle. This paper introduces the construction and application of the multipoint sampling system. The motor vehicle exhaust multipoint sampling system is reliable and can accurately capture the characteristics of the exhaust plume near the discharge outlet area. Changes in the CO 2 concentration were used to determine whether exhaust was accurately collected at the sampling points. The relationship between the dilution rate and distance was calculated on the basis of on-road test results using the following equation: DR = 21.4X 1.16 . This equation can be used for modeling purposes, especially in comparisons of model results and observations and in the evaluation of dispersion models.

Variation of Particles in the Exhaust Plume of Gasoline Direct Injection Vehicles Based on a Multipoint Sampling System: Concentrations, Components, and Numbers

“…Furthermore, the quick reaction process in the area near the exhaust gas discharge outlet has not been considered in the current air quality and chemical transport models, which is probably one of the most important reasons for the large uncertainty in organic aerosol simulations. − It was reported that the predicted secondary organic aerosol (SOA) formed from known precursors could only explain less than 15% of the measured SOA for vehicles under cruising conditions . There have been studies trying to bridge the gap between SOA observations and simulations. − Shen et al , successfully captured diesel plume and attributed the gap to the inconsistency between SOA and primary organic aerosol (POA) definitions. The SOA identified in the observations contain all or part of the delayed PM that partition into the particle phase through physical adsorption/distribution, while this portion is excluded when modeling SOA .…”

“…16 There have been studies trying to bridge the gap between SOA observations and simulations. 17−19 Shen et al 19,20 successfully captured diesel plume and attributed the gap to the inconsistency between SOA and primary organic aerosol (POA) definitions. The SOA identified in the observations contain all or part of the delayed PM that partition into the particle phase through physical adsorption/distribution, while this portion is excluded when modeling SOA.…”

Study on Characteristics of Air Pollution at Highway Toll Stations in Dalian, China

“…Traffic air pollution, as a high proportion of ambient pollution in megacities [1,2], is becoming the main source of air pollution in the city. The data of gas emission of UK in 2010 showed that 18% of inhalable particulates (PM 10 ), 24% of particulate matter 2.5 (PM 2.5 ), 54% of carbon monoxide (CO), 32% of nitrogen oxide (NO x ) and 26% of benzene were derived from traffic emission [3].…”