Articles | Volume 10, issue 4
Atmos. Meas. Tech., 10, 1519–1537, 2017
Atmos. Meas. Tech., 10, 1519–1537, 2017

Research article 21 Apr 2017

Research article | 21 Apr 2017

A new oxidation flow reactor for measuring secondary aerosol formation of rapidly changing emission sources

Pauli Simonen1, Erkka Saukko1, Panu Karjalainen1, Hilkka Timonen2, Matthew Bloss2, Päivi Aakko-Saksa3, Topi Rönkkö1, Jorma Keskinen1, and Miikka Dal Maso1 Pauli Simonen et al.
  • 1Aerosol Physics Laboratory, Department of Physics, Tampere University of Technology, P.O. Box 692, 33101 Tampere, Finland
  • 2Finnish Meteorological Institute, Atmospheric Composition Research, P.O. Box 503, 00101 Helsinki, Finland
  • 3VTT Technical Research Centre of Finland Ltd., P.O. Box 1000, 02044 Espoo, Finland

Abstract. Oxidation flow reactors (OFRs) or environmental chambers can be used to estimate secondary aerosol formation potential of different emission sources. Emissions from anthropogenic sources, such as vehicles, often vary on short timescales. For example, to identify the vehicle driving conditions that lead to high potential secondary aerosol emissions, rapid oxidation of exhaust is needed. However, the residence times in environmental chambers and in most oxidation flow reactors are too long to study these transient effects ( ∼  100 s in flow reactors and several hours in environmental chambers). Here, we present a new oxidation flow reactor, TSAR (TUT Secondary Aerosol Reactor), which has a short residence time ( ∼  40 s) and near-laminar flow conditions. These improvements are achieved by reducing the reactor radius and volume. This allows studying, for example, the effect of vehicle driving conditions on the secondary aerosol formation potential of the exhaust. We show that the flow pattern in TSAR is nearly laminar and particle losses are negligible. The secondary organic aerosol (SOA) produced in TSAR has a similar mass spectrum to the SOA produced in the state-of-the-art reactor, PAM (potential aerosol mass). Both reactors produce the same amount of mass, but TSAR has a higher time resolution. We also show that TSAR is capable of measuring the secondary aerosol formation potential of a vehicle during a transient driving cycle and that the fast response of TSAR reveals how different driving conditions affect the amount of formed secondary aerosol. Thus, TSAR can be used to study rapidly changing emission sources, especially the vehicular emissions during transient driving.

Short summary
Atmospheric particles affect climate, health and visibility, and a large source of these particles is secondary aerosol formation. We developed a new oxidation flow reactor for studying the secondary aerosol formation potential of rapidly changing emission sources. Using laboratory measurements, we show that this flow reactor is suitable for studying the secondary aerosol potential of, for example, light duty vehicle emissions during a transient driving cycle.