lnstitut für Sensorik und Elektronik
Dauerhafte URI für die Sammlunghttps://irf.fhnw.ch/handle/11654/28068
Listen
4 Ergebnisse
Ergebnisse nach Hochschule und Institut
Publikation Growth and structural change of combustion aerosols at high relative humidity(American Chemical Society, 01.12.1995) Weingartner, Ernest; Baltensperger, Urs; Burtscher, Heinz01A - Beitrag in wissenschaftlicher ZeitschriftPublikation Hygroscopic properties of carbon and diesel soot particles(Elsevier, 08/1997) Weingartner, Ernest; Burtscher, Heinz; Baltensperger, UrsLaboratory 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 ZeitschriftPublikation Separation of volatile and non-volatile aerosol fractions by thermodesorption. instrumental development and applications(Elsevier, 04/2001) Burtscher, Heinz; Baltensperger, Urs; Bukowiecki, Nicolas; Cohn, P.; Hüglin, Christoph; Mohr, Martin; Matter, Urs; Nyeki, Stephan; Schmatloch, Volker; Streit, Niklaus; Weingartner, ErnestAn instrument to remove volatile material from aerosol particles by thermal desorption is presented. The thermodesorber consists of a heated tube, where volatile material is desorbed from the particles, and a water- or air-cooled tube, consisting of activated charcoal. This last tube removes desorbed material and thus prevents it from re-adsorbing onto particles. Although designed for measuring particulate emissions from combustion processes it can also be applied to atmospheric aerosols. After theoretical and experimental determination of thermodesorber operating characteristics (temperature profile, losses, removal of desorbed material), examples of applications in several fields are given. Examples of atmospheric measurements at several remote and urban sites are presented. In combustion technology, the thermodesorber is applied to remove all volatile materials, allowing separation of volatile species and the non-volatile core (mainly elemental carbon) of combustion particles. Finally, the thermodesorber is used to study adsorption and desorption processes of polycyclic aromatic hydrocarbons on particles.01A - Beitrag in wissenschaftlicher ZeitschriftPublikation Real-time characterization of ultrafine and accumulation mode particles in ambient combustion aerosols(Elsevier, 08/2002) Bukowiecki, Nicolas; Kittelson, David B.; Watts, Winthrop F.; Burtscher, Heinz; Weingartner, Ernest; Baltensperger, UrsThe diffusion charging sensor (DC), photoelectric aerosol sensor (PAS) and condensation particle counter (CPC) are real-time particle instruments that have time resolutions < 10s and are suitable for field use. This paper shows how the relative fraction of nuclei mode particles (D ≤ 50nm) in ambient combustion aerosols can be determined, along with the coverage degree of the respective accumulation mode particles with a modal diameter of ~ 100nm. Main tools for interpretation are the diameter of average surface DAve,S (obtained from CPC and DC measurements) and PAS/DC versus DAve,S scatter plots. Compared to the scanning mobility particle sizer (SMPS), which is a standard instrument for aerosol particle size distribution measurements, the presented method has a limited accuracy, but is substantially faster. Additionally, it is experimentally less demanding than SMPS measurements, especially for field applications.01A - Beitrag in wissenschaftlicher Zeitschrift