Auflistung nach Autor:in "Kurtenbach, Ralf"

Gerade angezeigt 1 - 3 von 3

Aerosol and NOx emission factors and submicron particle number size distributions in two road tunnels with different traffic regimes
(Copernicus, 21.06.2006) Imhof, David; Weingartner, Ernest; Prévôt, André S.H.; Ordóñez, Carlos; Kurtenbach, Ralf; Wiesen, Peter; Rodler, Johannes; Sturm, Peter; McCrae, Ian; Ekström, M.; Baltensperger, Urs
Measurements of aerosol particle number size distributions (18–700 nm), mass concentrations (PM2.5 and PM10) and NOx were performed in the Plabutsch tunnel, Austria, and in the Kingsway tunnel, United Kingdom. These two tunnels show different characteristics regarding the roadway gradient, the composition of the vehicle fleet and the traffic frequency. The submicron particle size distributions contained a soot mode in the diameter range D=80–100 nm and a nucleation mode in the range of D=20–40 nm. In the Kingsway tunnel with a significantly lower particle number and volume concentration level than in the Plabutsch tunnel, a clear diurnal variation of nucleation and soot mode particles correlated to the traffic density was observed. In the Plabutsch tunnel, soot mode particles also revealed a diurnal variation, whereas no substantial variation was found for the nucleation mode particles. During the night a higher number concentration of nucleation mode particles were measured than soot mode particles and vice versa during the day. In this tunnel with very high soot emissions during daytime due to the heavy-duty vehicle (HDV) share of 18% and another 40% of diesel driven light-duty vehicles (LDV) semivolatile species condense on the pre-existing soot surface area rather than forming new particles by homogeneous nucleation. With the low concentration of soot mode particles in the Kingsway tunnel, also the nucleation mode particles exhibit a diurnal variation. From the measured parameters real-world traffic emission factors were estimated for the whole vehicle fleet as well as differentiated into the two categories LDV and HDV. In the particle size range D=18–700 nm, each vehicle of the mixed fleet emits (1.50±0.08)×10^14 particles km-1 (Plabutsch) and (1.26±0.10)×10^14 particles km-1 (Kingsway), while particle volume emission factors of 0.209±0.008 cm³ km-1 and 0.036±0.004 cm³ km-1, respectively, were obtained. PM1 emission factors of 104±4 mg km-1 (Plabutsch) and 41±4 mg km-1 (Kingsway) were calculated. Emission factors determined in this work were in good agreement with results from other studies.
01A - Beitrag in wissenschaftlicher Zeitschrift
Roadside measurements of particulate matter size distribution
(Elsevier, 10/2003) Sturm, Peter J.; Baltensperger, Urs; Bacher, Michael; Lechner, Bernhard; Hausberger, Stefan; Heiden, Bernhard; Imhof, David; Weingartner, Ernest; Prévôt, André S.H.; Kurtenbach, Ralf; Wiesen, Peter
Roadside measurements were performed in order to document the size distribution of particulate matter (PM) under dilution conditions similar to those found in real world. These activities covered measurements at engine test beds, at different locations in a road tunnel as well as in an urban environment. In order to get a clear picture of the evolution of the PM in different size classes, the in-tunnel locations ranged from curb-side to different locations inside the exhaust air system. Additional measurements were performed in the ambient air at curb-side at a street crossing as well as in urban background. At those times when heavy traffic occurs, tunnel measurements show size distributions similar to those derived from engine/vehicle measurements. During times with little traffic the size distributions are closer to those recorded in ambient air. As soon as the traffic load increases the size distribution changes, due to rapid coagulation of the smallest particles with the accumulation mode. As the travel time of the particles through the tunnel and up the stacks is very long “aging” effects could be observed. Thus, these spectra are quite different from ambient measurements in urban air, especially in the region above 30–40 nm.
01A - Beitrag in wissenschaftlicher Zeitschrift
Vertical distribution of aerosol particles and NOx close to a motorway
(Elsevier, 10/2005) Imhof, D.; Weingartner, Ernest; Vogt, Ulrich; Dreiseidler, Anja; Rosenbohm, E.; Scheer, Volker; Vogt, Rainer; Nielsen, Ole John; Kurtenbach, Ralf; Corsmeier, Ulrich; Kohler, M.; Baltensperger, Urs
In May 2001, the large-scale field project BAB II was performed at the highly frequented motorway BAB (Bundesautobahn) A656 with two traffic lanes in each direction between the German cities Heidelberg and Mannheim. Extensive measurements of air pollutants were carried out on both sides of the motorway. In a distance of 60 m (north side) and 84 m (south side) to the traffic lanes, two 52-m-high towers were installed, at which electrically powered elevators were fixed. In these elevators, two NOx analysers, an Electrical Low Pressure Impactor (ELPI; measurement of the particle number size distribution in the diameter range 𝐷 between 30 nm and 10 μm) and a Diffusion Charger (DC; measuring the particle surface area concentration), were operated to record continuous vertical profiles from 5 to 50 m above the earth's surface. On the upwind side, particle number and surface area concentration as well as NOx values were constant over the entire height profile. On the downwind side, increased concentrations appeared in the near-ground range: in the forenoon, a monotonous decrease in pollutant concentrations with increasing height was found, while around noon the concentration maximum of the particles was slightly shifted to 10 m above ground. This height dependence was found for two different size ranges, i.e., for particles with 𝐷<300nm (consisting of soot particles and nucleation mode particles formed by condensation as a result of cooling of the exhaust gas after emission), and for coarse particles (𝐷>1μm, abrasion and resuspension products). In the size range between 300 and 700 nm, no height dependence was found, corroborating the fact that motor traffic emits only few particles in this size range. On the downwind side of the motorway, only background concentrations were measured above 25 m. The results of the profile measurements were confirmed by stationary measurements of particle size distributions with Scanning Mobility Particle Sizers (SMPS) at various heights. A good correlation between particle surface area and NOx concentration was observed. Vehicle emission factors were determined for the particle surface area, number and volume of several size ranges.
01A - Beitrag in wissenschaftlicher Zeitschrift