Evolution under dark conditions of particles from old and modern diesel vehicles in a new environmental chamber characterized with fresh exhaust emissions

Abstract. Atmospheric particles have several impacts on health and the environment, especially in urban areas. Parts of those particles are not fresh and have undergone atmospheric chemical and physical processes. Due to a lack of representativeness of experimental conditions and experimental artifacts such as particle wall losses in chambers, there are uncertainties on the effects of physical processes (condensation, nucleation and coagulation) and their role in particle evolution from modern vehicles. This study develops a new method to correct wall losses, accounting for size dependence and experiment-to-experiment variations. It is applied to the evolution of fresh diesel exhaust particles to characterize the physical processes which they undergo. The correction method is based on the black carbon decay and a size-dependent coefficient to correct particle distributions. Six diesel passenger cars, Euro 3 to Euro 6, were driven on a chassis dynamometer with Artemis Urban cold start and Artemis Motorway cycles. Exhaust was injected in an 8 m3 chamber with Teflon walls. The physical evolution of particles was characterized during 6 to 10 h. Increase in particle mass is observed even without photochemical reactions due to the presence of intermediate-volatility organic compounds and semi-volatile organic compounds. These compounds were quantified at emission and induce a particle mass increase up to 17 % h−1, mainly for the older vehicles (Euro 3 and Euro 4). Condensation is 4 times faster when the available particle surface is multiplied by 6.5. If initial particle number concentration is below [8–9] × 104 cm−3, a nucleation mode seems to be present but not measured by a scanning mobility particle sizer (SMPS). The growth of nucleation-mode particles results in an increase in measured [PN]. Above this threshold, particle number concentration decreases due to coagulation, up to −27 % h−1. Under those conditions, the chamber and experimental setup are well suited to characterizing and quantifying the process of coagulation.

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Evolution under dark conditions of particles from old and modern diesel vehicles, in a new environmental chamber characterized with fresh exhaust emissions

10.5194/amt-2021-43 ◽

2021 ◽

Author(s):

Boris Vansevenant ◽

Cédric Louis ◽

Corinne Ferronato ◽

Ludovic Fine ◽

Patrick Tassel ◽

...

Keyword(s):

Organic Compounds ◽

Urban Areas ◽

Particle Number ◽

Particle Surface ◽

Number Concentration ◽

Photochemical Reactions ◽

Diesel Exhaust Particles ◽

Particle Number Concentration ◽

Physical Processes ◽

Wall Losses

Abstract. Atmospheric particles have several impacts on health and environment, especially in urban areas. Part of those particles is not fresh, and has undergone atmospheric chemical and physical processes. Due to not representative experimental conditions, and experimental artifacts such as particle wall losses in chambers, there are uncertainties on the effects of physical processes (condensation, nucleation and coagulation) and how they act on particles from modern vehicles. This study develops a new method to correct wall losses, accounting for size dependence and experiment-to-experiment variations, and applies it to the evolution of fresh diesel exhaust particles to characterize the physical processes acting on them. The correction method is based on the black carbon decay and a size-dependent coefficient to correct particle distributions. Exhaust from 6 diesel passenger cars, Euro 3 to Euro 6, driven on a chassis dynamometer with Artemis Urban cold start and Artemis Motorway cycles, was injected in an 8 m3 chamber with Teflon walls. The physical evolution of particles was characterized during 6 to 10 hours. Condensation occurs even without photochemical reactions, due to the presence of intermediate volatility organic compounds and semi-volatile organic compounds which were quantified at emission, and induces a particle mass increase up to 17 %.h−1, mainly for the older vehicles (Euro 3 and Euro 4). Condensation is 4 times faster when the available particle surface if multiplied by 3. If initial particle number concentration is below [8–9] × 104 #.cm−3, it can increase up to 25 %.h−1 due to nucleation or condensation on particles below 14 nm. Above this threshold, particle number concentration decreases due to coagulation, up to −27 %.h−1.

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Influence of medium range transport of particles from nucleation burst on particle number concentration within the urban airshed

Atmospheric Chemistry and Physics ◽

10.5194/acp-12-4951-2012 ◽

2012 ◽

Vol 12 (11) ◽

pp. 4951-4962 ◽

Cited By ~ 15

Author(s):

H. C. Cheung ◽

L. Morawska ◽

Z. D. Ristovski ◽

D. Wainwright

Keyword(s):

Particle Number ◽

Urban Pollution ◽

Urban Environments ◽

Number Concentration ◽

Photochemical Reactions ◽

Particle Number Concentration ◽

Wind Rose ◽

Peak Period ◽

Total Particle ◽

Urban Airshed

Abstract. An elevated particle number concentration (PNC) observed during nucleation events could play a significant contribution to the total particle load and therefore to the air pollution in the urban environments. Therefore, a field measurement study of PNC was commenced to investigate the temporal and spatial variations of PNC within the urban airshed of Brisbane, Australia. PNC was monitored at urban (QUT), roadside (WOO) and semi-urban (ROC) areas around the Brisbane region during 2009. During the morning traffic peak period, the highest relative fraction of PNC reached about 5% at QUT and WOO on weekdays. PNC peaks were observed around noon, which correlated with the highest solar radiation levels at all three stations, thus suggesting that high PNC levels were likely to be associated with new particle formation caused by photochemical reactions. Wind rose plots showed relatively higher PNC for the NE direction, which was associated with industrial pollution, accounting for 12%, 9% and 14% of overall PNC at QUT, WOO and ROC, respectively. Although there was no significant correlation between PNC at each station, the variation of PNC was well correlated among three stations during regional nucleation events. In addition, PNC at ROC was significantly influenced by upwind urban pollution during the nucleation burst events, with the average enrichment factor of 15.4. This study provides an insight into the influence of regional nucleation events on PNC in the Brisbane region and it the first study to quantify the effect of urban pollution on semi-urban PNC through the nucleation events.

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Variation of size-segregated particle number concentrations in wintertime Beijing

Atmospheric Chemistry and Physics ◽

10.5194/acp-20-1201-2020 ◽

2020 ◽

Vol 20 (2) ◽

pp. 1201-1216 ◽

Cited By ~ 10

Author(s):

Ying Zhou ◽

Lubna Dada ◽

Yiliang Liu ◽

Yueyun Fu ◽

Juha Kangasluoma ◽

...

Keyword(s):

Particle Number ◽

Particle Formation ◽

Number Concentration ◽

Spatial And Temporal Variability ◽

Particle Number Concentration ◽

New Particle Formation ◽

Accumulation Mode ◽

Nucleation Mode ◽

Secondary Sources ◽

Haze Days

Abstract. The spatial and temporal variability of the number size distribution of aerosol particles is an indicator of the dynamic behavior of Beijing's atmospheric pollution cocktail. This variation reflects the strength of different primary and secondary sources, such as traffic and new particle formation, as well as the main processes affecting the particle population. In this paper, we report size-segregated particle number concentrations observed at a newly developed Beijing station during the winter of 2018. Our measurements covered particle number size distributions over the diameter range of 1.5 nm–1 µm (cluster mode, nucleation mode, Aitken mode and accumulation mode), thus being descriptive of a major fraction of the processes taking place in the atmosphere of Beijing. Here we focus on explaining the concentration variations in the observed particle modes, by relating them to the potential aerosol sources and sinks, and on understanding the connections between these modes. We considered haze days and new particle formation event days separately. Our results show that during the new particle formation (NPF) event days increases in cluster mode particle number concentration were observed, whereas during the haze days high concentrations of accumulation mode particles were present. There was a tight connection between the cluster mode and nucleation mode on both NPF event and haze days. In addition, we correlated the particle number concentrations in different modes with concentrations of trace gases and other parameters measured at our station. Our results show that the particle number concentration in all the modes correlated with NOx, which reflects the contribution of traffic to the whole submicron size range. We also estimated the contribution of ion-induced nucleation in Beijing, and we found this contribution to be negligible.

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Influence of medium range transport of particles from nucleation burst on particle number concentration within the urban airshed

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-11-32965-2011 ◽

2011 ◽

Vol 11 (12) ◽

pp. 32965-32992 ◽

Cited By ~ 3

Author(s):

H. C. Cheung ◽

L. Morawska ◽

Z. D. Ristovski ◽

D. Wainwright

Keyword(s):

Significant Contribution ◽

Particle Number ◽

Urban Pollution ◽

Urban Environments ◽

Number Concentration ◽

Photochemical Reactions ◽

Particle Number Concentration ◽

Wind Rose ◽

Total Particle ◽

Urban Airshed

Abstract. Elevated particle number concentration (PNC) observed during nucleation events could make a significant contribution to the total particle load and thus air pollution in urban environments. Therefore, a field measurement study of PNC was conducted to investigate the temporal and spatial variations of PNC within the urban airshed of Brisbane, Australia. PNC was monitored at urban (QUT), roadside (WOO) and semi-urban (ROC) areas around the Brisbane region during 2009. The results showed that morning traffic exhaust emissions were the main contributor to high PNCs at QUT and WOO which contributed 5.5% and 5.1 5 during the week, respectively, with a less significant contribution on weekends. PNC peaks were observed around noon, which correlated with the highest solar radiation levels at all three stations, thus suggesting that high PNC levels were likely to be associated with new particle formation caused by photochemical reactions. Wind rose plots showed relatively higher PNC for the NE direction, which was associated with industrial pollution, accounting for 12%, 9% and 14% of overall PNC at QUT, WOO and ROC, respectively. Although there was no significant correlation between PNC at each station, the variation of PNC was well correlated among three stations during regional nucleation events. In addition, PNC at ROC was significantly influenced by upwind urban pollution during the nucleation burst events, with the average enrichment factor of 15.4. This study provides an insight into the influence of regional nucleation events on PNC in the Brisbane region and is the first study to quantify the effect of urban pollution on semi-urban PNC through the nucleation events.

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Characteristics of Particulate Matter about Emissions in a Heavy-Duty Diesel Engine with Biodiesel Blends

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.852.802 ◽

2014 ◽

Vol 852 ◽

pp. 802-807

Author(s):

Di Ming Lou ◽

Tian Yu Shen ◽

Yi Zhou ◽

Zhi Yuan Hu ◽

Pi Qiang Tan ◽

...

Keyword(s):

Diesel Engine ◽

Particle Number ◽

Number Concentration ◽

Particle Number Concentration ◽

Heavy Duty ◽

Full Load ◽

Nucleation Mode ◽

Heavy Duty Diesel Engine ◽

Load Characteristics ◽

Heavy Duty Diesel

A China-V Heavy-duty diesel engine fueled with blends of 5%, 10%, 20%, 50% waste cooking oil biodiesel and diesel (marked separately BD5, BD10, BD20, BD50), pure biodiesel (BD100) and pure diesel (D100), was tested on full load speed characteristics and 1400 r/min and 2200 r/min load characteristics to study influence of biodiesel fuel and engine conditions on particle size distributions and particle number concentration. The results show that when fueled with blends containing less than 50% biodiesel, the particle number concentrations show single peak distribution curves (nucleation mode), for the pure biodiesel, particle number concentrations show bimodal distribution including nucleation mode and accumulation mode on full load speed characteristics and 1400 r/min and 2200 r/min load characteristics; on full load speed characteristics, for BD100, the peak of particle number concentration of BD100 is lowest, compared with D100, it is about one order of magnitude lower; on 1400r/min load characteristics, with the biodiesel proportion increasing, the number of nucleation mode and accumulation mode particles decreases; on lower than 1800 r/min full load speed characteristics and 1400 r/min and 2200 r/min load characteristics, with the biodiesel proportion increasing, the particle number concentration decreases.

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