lnstitut für Sensorik und Elektronik

Dauerhafte URI für die Sammlunghttps://irf.fhnw.ch/handle/11654/28068

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1997 - 199912000 - 20021

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Hochschule: search.filters.hochschule.Hochschule für Technik und Umwelt FHNWThema: search.filters.subject.624 - Ingenieurbau und Umwelttechnik

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  • Kein Vorschaubild vorhanden
    Publikation
    Hygroscopic properties of carbon and diesel soot particles
    (Elsevier, 08/1997) Weingartner, Ernest; Burtscher, Heinz; Baltensperger, Urs
    Laboratory experiments were performed in order to study the hygroscopic properties of freshly produced carbon and diesel soot particles at subsaturations (i.e. at relative humidity < 100%). Wetted carbon aggregates collapsed to a more compact structure. In contrast, the diesel combustion particles exhibited a much smaller restructuring combined with condensational growth. The hygroscopicity of the diesel particles was enhanced when the sulfur content of the fuel was increased or when the particles were subjected to an ozone and UV pre-treatment. By extrapolating the data with a Köhler model critical supersaturations were calculated. Freshly emitted combustion particles are unlikely to act as cloud condensation nuclei whereas an aging of the particles will enhance their nucleation ability.
    01A - Beitrag in wissenschaftlicher Zeitschrift
  • Kein Vorschaubild vorhanden
    Publikation
    Urban and rural aerosol characterization of summer smog events during the PIPAPO field campaign in Milan, Italy
    (Wiley, 2002) Baltensperger, Urs; Streit, Niklaus; Weingartner, Ernest; Nyeki, Stephan; Prévôt, André S.H.; Van Dingenen, Rita; Virkkula, Aki; Putaud, Jean-Philippe; Even, A.; ten Brink, Harry; Blatter, Andreas; Neftel, Albrecht; Gäggeler, Heinz W.
    A comprehensive range of aerosol parameters was measured at an urban and a rural site in the Milan, Italy metropolitan region during summer smog events in summer 1998. Measurements were performed as part of the Pianura Padana Produzione di Ozono (PIPAPO) field campaign to determine the sensitivity of O3 production to NOₓ and volatile organic carbon concentrations at several ground stations. Primary aerosol parameters (i.e., direct emissions) such as aerosol black carbon showed a distinct diurnal variation with maxima at about 0000 and 0800 central European summer time (CEST), in contrast to secondary aerosol parameters such as sulfate and nitrate. Aerosol number size distributions were measured under ambient conditions as well as after conditioning with volatility and hygroscopicity systems. A mode at d = 20–30 nm in the number concentration was found at 0800 CEST and exhibited high volatility at 110°C (∼80% volume lost upon heating) but no hygroscopic behavior. Based on these measurements, small particles (d < 40 nm) are thought to consist mainly of hydrophobic particulate organic matter, rather than soot or H2SO4 aerosols. Two distinct hygroscopic modes with average growth factors d/d0 ∼ 1.02 and 1.21–1.28 were found for particles with dry (relative humidity of <30%) diameters d0 = 50–200 nm. Submicrometer aerosols exhibited lower volatility at the rural than at the urban site, which is attributed to additional particulate mass produced by secondary particle formation.
    01A - Beitrag in wissenschaftlicher Zeitschrift