Characterization and testing of a new environmental chamber

Abstract

Abstract. A 29 m 3 Teflon chamber, designed for studies on the aging of combustion aerosols, at the University of Eastern Finland is described and characterized. The chamber is part of a research facility, called Ilmari, where small-scale combustion devices, a dynamometer for vehicle exhaust studies, dilution systems, the chamber, and cell and animal exposure devices are located side by side under the same roof. The small surface-to-volume ratio of the chamber enables reasonably long experiment times, with particle wall loss rate constants of 0.088, 0.080, 0.045, and 0.040 h −1 for polydisperse, 50, 100, and 200 nm monodisperse aerosols, respectively. The NO 2 photolysis rate can be adjusted from 0 to 0.62 min −1 . The irradiance spectrum is centered at either 350 or 365 nm, and the maximum irradiance, produced by up to 160 blacklight lamps, is 29.7 W m −2 , which corresponds to the ultraviolet (UV) irradiance in Central Finland at noon on a sunny day in the midsummer. The temperature inside the chamber is uniform and can be kept at 25 ± 1 • C. The chamber is kept in an overpressure with a moving top frame, which reduces sample dilution and entrance of contamination during an experiment. The functionality of the chamber was tested with oxidation experiments of toluene, resulting in secondary organic aerosol (SOA) yields of 12-42 %, depending on the initial conditions, such as NO x concentration and UV irradiation. The highest gaseous oxidation product yields of 12.4-19.5 % and 5.8-19.5 % were detected with ions corresponding to methyl glyoxal (m/z 73.029) and 4-oxo-2-pentenal (m/z 99.044), respectively. Overall, reasonable yields of SOA and gaseous reaction products, comparable to those obtained in other laboratories, were obtained.

Construction and Characterization of an Indoor Smog Chamber for the Measurement of the Optical and Physicochemical Properties of Aging Biomass Burning Aerosols Native to sub-Saharan Africa

“…The wall loss rate was faster initially and leveled off after 10 hours in the NCAT chamber. Similar observations were reported in the Ilmari chamber (Leskinen et al, 2015).…”

“…7. The maximum NO 2 photolysis rate in our chamber is comparable to those reported in other indoor chambers, such as 375 0.132 min −1 in the 29 m 3 Ilmari chamber (Leskinen et al, 2015); 0.12 min −1 in the 27 m 3 chamber at the Paul Scherrer Institute (Paulsen et al, 2005); 0.19 min −1 in the 90 m 3 environmental chamber at the University of California, Riverside (Carter et al, 2005); 1.5 min −1 in the 28 m 3 chamber at the California Institute of Technology (Cocker et al, 2001); and comparable to most recent chambers provided in Table 2. When only half of the lights were powered, values of 0.091 ± 0.005 min −1 and 0.0846 ± 0.0042 min −1 were obtained for the door side and 380 window side, respectively.…”

“…For D p = 100 nm the particle wall loss rate for NCAT chamber is comparable to other chambers reported for example 3.83 x 10 −3 min −1 for the Guangzhou (30 m 3 ) chamber (Wang et al, 2014) and 3.96 x 10 −3 min −1 for the 7 m 3 KNU chamber (Babar et al, 2016). A smaller value of 7.5 x 10 −4 min −1 was reported for the 29 m 3 Ilmari chamber (Leskinen et al, 2015). This is much lower than most reported particle wall losses.…”

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

“…1. To allow for extended aging durations of up to 12 h, the aerosol chamber was operated following the concept of the CSTR (Levenspiel, 1999). In accordance with this concept, soot particles were continuously added to the aerosol chamber inlet, simultaneous to the continuous withdrawal of aerosol samples from the chamber outlet for analysis.…”

Impact of Isolated Atmospheric Aging processes on the Cloud Condensation Nuclei-activation of Soot Particles

“…However, since those chambers are operated at oxidant conditions that are 3 to 4 orders of magnitude higher than in the atmosphere (Bruns et al, 2015), they might trigger atmospherically irrelevant chemical reactions and follow atmospherically non-relevant reaction pathways (McNeill et al, 2007). In contrast to the OFR, there are large aerosol chambers with several m 3 of volume in which aerosols can be exposed to atmospherically relevant concentrations of 30 oxidants and trace gases (Cocker et al, 2001;Leskinen et al, 2015;Nordin et al, 2013;Paulsen et al, 2005;Platt et al, 2013;Presto et al, 2005;Rohrer et al, 2005). Since those chambers are typically operated in batch-mode, they require elevated particle number concentrations in the feed-in flow in order to reach the desired aerosol concentration inside the chamber within a reasonable time.…”