Relating aerosol mass spectra to composition and nanostructure of soot particles

Malmborg, Vilhelm; Eriksson, Axel; Török, Sandra; Zhang, Yilong; Kling, Kirsten Inga; Martinsson, Johan; Fortner, Edward C.; Gren, Louise; Kook, Sanghoon; Onasch, T. B.; Bengtsson, Per-Erik; Pagels, Joakim

doi:10.1016/j.carbon.2018.10.072

Cited by 42 publications

(24 citation statements)

References 80 publications

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“…The high fraction of rOC at 10% intake O 2 (simulating LTC) is in agreement with studies performed with model flames that show a transition from EC to rOC for lowered combustion temperatures [60]. This suggests that the change in soot properties and PAHs observed in model flames and burners are also relevant to LTC in engines.…”

Section: Thermal Optical Analysis (Oc/ec) and Relationship To Pm Meassupporting

confidence: 88%

Effect of Renewable Fuels and Intake O2 Concentration on Diesel Engine Emission Characteristics and Reactive Oxygen Species (ROS) Formation

et al. 2020

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Renewable diesel fuels have the potential to reduce net CO2 emissions, and simultaneously decrease particulate matter (PM) emissions. This study characterized engine-out PM emissions and PM-induced reactive oxygen species (ROS) formation potential. Emissions from a modern heavy-duty diesel engine without external aftertreatment devices, and fueled with petroleum diesel, hydrotreated vegetable oil (HVO) or rapeseed methyl ester (RME) biodiesel were studied. Exhaust gas recirculation (EGR) allowed us to probe the effect of air intake O2 concentration, and thereby combustion temperature, on emissions and ROS formation potential. An increasing level of EGR (decreasing O2 concentration) resulted in a general increase of equivalent black carbon (eBC) emissions and decrease of NOx emissions. At a medium level of EGR (13% intake O2), eBC emissions were reduced for HVO and RME by 30 and 54% respectively compared to petroleum diesel. In general, substantially lower emissions of polycyclic aromatic hydrocarbons (PAHs), including nitro and oxy-PAHs, were observed for RME compared to both HVO and diesel. At low-temperature combustion (LTC, O2 < 10%), CO and hydrocarbon gas emissions increased and an increased fraction of refractory organic carbon and PAHs were found in the particle phase. These altered soot properties have implications for the design of aftertreatment systems and diesel PM measurements with optical techniques. The ROS formation potential per mass of particles increased with increasing engine O2 concentration intake. We hypothesize that this is because soot surface properties evolve with the combustion temperature and become more active as the soot matures into refractory BC, and secondly as the soot surface becomes altered by surface oxidation. At 13% intake O2, the ROS-producing ability was high and of similar magnitude per mass for all fuels. When normalizing by energy output, the lowered emissions for the renewable fuels led to a reduced ROS formation potential.

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Section: Thermal Optical Analysis (Oc/ec) and Relationship To Pm Meassupporting

confidence: 88%

Effect of Renewable Fuels and Intake O2 Concentration on Diesel Engine Emission Characteristics and Reactive Oxygen Species (ROS) Formation

et al. 2020

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“…Soot particles were produced by a propane-fueled Jing Ltd., miniature Combustion Aerosol STandard (miniCAST 4200) generator. Such types of burners and specifically the miniCAST burner have been used widely for the production of soot particles in laboratory studies (e.g., Durdina et al, 2016;Kim et al, 2015;Malmborg et al, 2018;Mamakos et al, 2013;Maricq, 2014;Mueller et al, 2015;. The miniCAST was operated at two different settings for the generation of soot samples with different organic carbon (OC) contents.…”

Section: Overviewmentioning

confidence: 99%

Impact of isolated atmospheric aging processes on the cloud condensation nuclei activation of soot particles

et al. 2019

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Abstract. The largest contributors to the uncertainty in assessing the anthropogenic contribution in radiative forcing are the direct and indirect effects of aerosol particles on the Earth's radiative budget. Soot particles are of special interest since their properties can change significantly due to aging processes once they are emitted into the atmosphere. Probably the largest obstacle for the investigation of these processes in the laboratory is the long atmospheric lifetime of 1 week, requiring tailored experiments that cover this time span. This work presents results on the ability of two types of soot, obtained using a miniCAST soot generator, to act as cloud condensation nuclei (CCN) after exposure to atmospherically relevant levels of ozone (O3) and humidity. Aging times of up to 12 h were achieved by successful application of the continuous-flow stirred tank reactor (CSTR) concept while allowing for size selection of particles prior to the aging step. Particles of 100 nm diameter and rich in organic carbon (OC) that were initially CCN inactive showed significant CCN activity at supersaturations (SS) down to 0.3 % after 10 h of exposure to 200 ppb of O3. While this process was not affected by different levels of relative humidity in the range of 5 %–75 %, a high sensitivity towards the ambient/reaction temperature was observed. Soot particles with a lower OC content required an approximately 4-fold longer aging duration to show CCN activity at the same SS. Prior to the slow change in the CCN activity, a rapid increase in the particle diameter was detected which occurred within several minutes. This study highlights the applicability of the CSTR approach for the simulation of atmospheric aging processes, as aging durations beyond 12 h can be achieved in comparably small aerosol chamber volumes (<3 m3). Implementation of our measurement results in a global aerosol-climate model, ECHAM6.3-HAM2.3, showed a statistically significant increase in the regional and global CCN burden and cloud droplet number concentration.

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“…Cloud droplets freeze homogeneously at temperatures near −38 • C (Pruppacher and Klett, 1997), but ice-nucleating particles (INPs) may catalyze freezing of supercooled cloud droplets at higher temperatures. A wide range of MPC properties including radiative properties and lifetime are sensitive to the formation of solid ice (Matus and L'Ecuyer, 2017), but there are significant gaps in our knowledge regarding INP concentrations within the MPCs and these important ice formation processes.…”

Section: Introductionmentioning

confidence: 99%

Ice-nucleating ability of particulate emissions from solid-biomass-fired cookstoves: an experimental study

et al. 2020

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Abstract. This research was part of the Salutary Umeå Study of Aerosols in Biomass Cookstove Emissions (SUSTAINE) laboratory experiment campaign. We studied ice-nucleating abilities of particulate emissions from solid-fuel-burning cookstoves, using a portable ice nuclei counter, Spectrometer Ice Nuclei (SPIN). These emissions were generated from two traditional cookstove types commonly used for household cooking in sub-Saharan Africa and two advanced gasifier stoves under research to promote sustainable development alternatives. The solid fuels studied included biomass from two different African tree species, Swedish softwood and agricultural residue products relevant to the region. Measurements were performed with a modified version of the standard water boiling test on polydisperse samples from flue gas during burning and size-selected accumulation mode soot particles from a 15 m3 aerosol-storage chamber. The studied soot particle sizes in nanometers were 250, 260, 300, 350, 400, 450 and 500. From this chamber, the particles were introduced to water-supersaturated freezing conditions (−32 to −43 ∘C) in the SPIN. Accumulation mode soot particles generally produced an ice-activated fraction of 10−3 in temperatures 1–1.5 ∘C higher than that required for homogeneous freezing at fixed RHw=115 %. In five special experiments, the combustion performance of one cookstove was intentionally modified. Two of these exhibited a significant increase in the ice-nucleating ability of the particles, resulting in a 10−3 ice activation at temperatures up to 5.9 ∘C higher than homogeneous freezing and the observed increased ice-nucleating ability. We investigated six different physico-chemical properties of the emission particles but found no clear correlation between them and increasing ice-nucleating ability. We conclude that the freshly emitted combustion aerosols form ice via immersion and condensation freezing at temperatures only moderately above homogeneous freezing conditions.

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Relating aerosol mass spectra to composition and nanostructure of soot particles

Cited by 42 publications

References 80 publications

Effect of Renewable Fuels and Intake O2 Concentration on Diesel Engine Emission Characteristics and Reactive Oxygen Species (ROS) Formation

Effect of Renewable Fuels and Intake O2 Concentration on Diesel Engine Emission Characteristics and Reactive Oxygen Species (ROS) Formation

Impact of isolated atmospheric aging processes on the cloud condensation nuclei activation of soot particles

Ice-nucleating ability of particulate emissions from solid-biomass-fired cookstoves: an experimental study

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