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- Martinsson, Johan, et al.
(författare)
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Impacts of Combustion Conditions and Photochemical Processing on the Light Absorption of Biomass Combustion Aerosol
- 2015
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Ingår i: Environmental Science and Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 49:24, s. 14663-14671
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Tidskriftsartikel (refereegranskat)abstract
- The aim was to identify relationships between combustion conditions, particle characteristics, and optical properties of fresh and photochemically processed emissions from biomass combustion. The combustion conditions included nominal and high burn rate operation and individual combustion phases from a conventional wood stove. Low temperature pyrolysis upon fuel addition resulted in "tar-ball" type particles dominated by organic aerosol with an absorption Angstrom exponent (AAE) of 2.5-2.7 and estimated Brown Carbon contributions of 50-70% to absorption at the climate relevant aethalometer-wavelength (520 nm). High temperature combustion during the intermediate (flaming) phase was dominated by soot agglomerates with AAE 1.0-1.2 and 85-100% of absorption at 520 nm attributed to Black Carbon. Intense photochemical processing of high burn rate flaming combustion emissions in an oxidation flow reactor led to strong formation of Secondary Organic Aerosol, with no or weak absorption. PM1 mass emission factors (mg/kg) of fresh emissions were about an order of magnitude higher for low temperature pyrolysis compared to high temperature combustion. However, emission factors describing the absorption cross section emitted per kg of fuel consumed (m(2)/kg) were of similar magnitude at 520 nm for the diverse combustion conditions investigated in this study. These results provide a link between biomass combustion conditions, emitted particle types, and their optical properties in fresh and processed plumes which can be of value for source apportionment and balanced mitigation of biomass combustion emissions from a climate and health perspective.
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- Visibile, Alberto, 1989, et al.
(författare)
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An Alternative Method of Measuring Area Specific Resistance of Chromia Scales Using Electrochemical Impedance Spectroscopy
- 2023
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Ingår i: Journal of the Electrochemical Society. - : The Electrochemical Society. - 0013-4651 .- 1945-7111. ; 170:3
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Tidskriftsartikel (refereegranskat)abstract
- A novel method that employs electrochemical impedance spectroscopy (EIS) is developed to characterize the oxide scale resistance and thickness of Crofer 22 APU after exposure at 800 degrees C in humidified air. Crofer 22 APU, is one of the most commonly used materials for solid oxide fuel cell (SOFC) interconnects, an application for which oxide scale resistance is of paramount importance. The kinetics of oxide growth were studied for up to 6,000 h using three different techniques: electron microscopy of cross-sections, gravimetry, and EIS capacitance measurements of the oxide scale. EIS was used to evaluate the scale thickness starting from the material capacitance, and the material resistance at high temperature was estimated using extrapolation of the impedance values at room temperature. The result obtained with this novel EIS method are comparable to those obtained using conventional techniques, and in addition, the new method is cheaper, faster, and more reliable. Moreover, it enables repetitive exposures of the same sample without altering the specimen properties.
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| 8. |
- Lovén, Karin, et al.
(författare)
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Size-resolved characterization of particles >10 nm emitted to air during metal recycling
- 2023
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Ingår i: Environment International. - : Elsevier Ltd. - 0160-4120 .- 1873-6750. ; 174
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Tidskriftsartikel (refereegranskat)abstract
- Background: In the strive towards a circular economy, metal waste recycling is a growing industry. During the recycling process, particulate matter containing toxic and allergenic metals will be emitted to the air causing unintentional exposure to humans and environment. Objective: In this study detailed characterization of particle emissions and workplace exposures were performed, covering the full size range from 10 nm to 10 µm, during recycling of three different material flows: Waste of electrical and electronic equipment (WEEE), metal scrap, and cables. Methods: Both direct-reading instruments (minute resolution), and time-integrated filter measurements for gravimetric and chemical analysis were used. Additionally, optical sensors were applied and evaluated for long-term online monitoring of air quality in industrial settings. Results: The highest concentrations, in all particle sizes, and with respect both to particle mass and number, were measured in the WEEE flow, followed by the metal scrap flow. The number fraction of nanoparticles was high for all material flows (0.66–0.86). The most abundant metals were Fe, Al, Zn, Pb and Cu. Other elements of toxicological interest were Mn, Ba and Co. Significance: The large fraction of nanoparticles, and the fact that their chemical composition deviate from that of the coarse particles, raises questions that needs to be further addressed including toxicological implications, both for humans and for the environment. © 2023 The Authors
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| 9. |
- Timonen, Hilkka, et al.
(författare)
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Influence of fuel ethanol content on primary emissions and secondary aerosol formation potential for a modern flex-fuel gasoline vehicle
- 2017
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Ingår i: Atmospheric Chemistry and Physics. - : Copernicus GmbH. - 1680-7316 .- 1680-7324. ; 17:8, s. 5311-5329
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Tidskriftsartikel (refereegranskat)abstract
- The effect of fuel ethanol content (10, 85 and 100 %) on primary emissions and on subsequent secondary aerosol formation was investigated for a Euro 5 flex-fuel gasoline vehicle. Emissions were characterized during a New European Driving Cycle (NEDC) using a comprehensive setup of high time-resolution instruments. A detailed chemical composition of the exhaust particulate matter (PM) was studied using a soot particle aerosol mass spectrometer (SPAMS), and secondary aerosol formation was studied using a potential aerosol mass (PAM) chamber. For the primary gaseous compounds, an increase in total hydrocarbon emissions and a decrease in aromatic BTEX (benzene, toluene, ethylbenzene and xylenes) compounds was observed when the amount of ethanol in the fuel increased. In regard to particles, the largest primary particulate matter concentrations and potential for secondary particle formation was measured for the E10 fuel (10% ethanol). As the ethanol content of the fuel increased, a significant decrease in the average primary particulate matter concentrations over the NEDC was found. The PM emissions were 0.45, 0.25 and 0.15 mgm-3 for E10, E85 and E100, respectively. Similarly, a clear decrease in secondary aerosol formation potential was observed with a larger contribution of ethanol in the fuel. The secondary-toprimary PM ratios were 13.4 and 1.5 for E10 and E85, respectively. For E100, a slight decrease in PM mass was observed after the PAM chamber, indicating that the PM produced by secondary aerosol formation was less than the PM lost through wall losses or the degradation of the primary organic aerosol (POA) in the chamber. For all fuel blends, the formed secondary aerosol consisted mostly of organic compounds. For E10, the contribution of organic compounds containing oxygen increased from 35 %, measured for primary organics, to 62% after the PAM chamber. For E85, the contribution of organic compounds containing oxygen increased from 42% (primary) to 57% (after the PAM chamber), whereas for E100 the amount of oxidized organics remained the same (approximately 62 %) with the PAM chamber when compared to the primary emissions.
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- Vierth, Inge, 1959-, et al.
(författare)
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Elanvändning för längre och tyngre tåg : sammanfattning av resultat, erfarenheter och lärdomar från ELVIS-demonstrationsprojekt
- 2015
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Projektet som redovisas i detta notat analyserar hur godstransporterna på järnväg kan effektiviseras. Hypoteserna är att transporterna kan effektiviseras genom att använda längre respektive tyngre godståg, genom att genomföra energibesparande åtgärder samt att det kan finnas andra typer av nyttor för företagen och hela samhället. I rapporten sammanfattas resultat och erfarenheter från tre tidigare delrapporter framtagna inom ramen för projektet. Skogsindustriföretagen och andra varuägare och transportföretag ser möjligheter att minska transportkostnaderna genom att använda längre och tyngre tåg och/eller att effektivisera elanvändningen. Trafikverket ser att längre och tyngre tåg möjliggör att den befintliga järnvägsinfrastrukturen utnyttjas mer effektivt. Trafikverket ser även effektiviseringsmöjligheter genom en konsekvent mätning av elanvändningen och analys av faktorerna som påverkar elanvändningen. Forskare, företag och Trafikverket slutsatsen att det finns stora behov att kvalitetssäkra de data som tas fram i de befintliga databaserna på Trafikverket. Detta gäller såväl information om elanvändningen som uppgifter om de faktorer som kan påverka elanvändningen, till exempel tågens längd, tågens bruttovikt, antalet stopp, hastighet och topografi. Inom ramen för tre fallstudier, Gävle-Malmö, Holmsund–Skövde och Mora-Gävle genomfördes försök med olika förklarande variabler. Med hänsyn till fallstudiernas och försökens olika förutsättningar och tyngdpunkter är det svårt att göra direkta jämförelser. Några övergripande slutsatser med avseende på elanvändningen kan dock dras, exempelvis: • Tågets vikt (i antal ton) och längd (antal vagnar) ökar elanvändningen i försöken. • I vissa försök finns stöd för att det finns skalfördelar. • Lokförarens körstil (bland annat återmatning) påverkar elanvändningen.
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