Abstract
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.
Highlights
Aerosol particles in the atmosphere affect climate, health and visibility
We show that TUT Secondary Aerosol Reactor (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
We show that the fast response of TSAR gives valuable information on the effect of the driving condition on secondary aerosol formation potential
Summary
Aerosol particles in the atmosphere affect climate, health and visibility. To reduce these impacts, the sources of aerosol particles have to be resolved. The PAM reactor is not ideal for rapidly changing emission sources such as vehicular emissions, since the residence time (∼ 100 s) is still relatively long and the reactor outputs a distribution of different-aged aerosol (Lambe et al, 2011) This limitation is seen, for example, in Karjalainen et al (2016), where the cold start of a gasoline engine results in an exponentially decaying wide peak of SOA formed in PAM, whereas the concentration of total hydrocarbons measured from the exhaust shows a much more transient behavior. There are no methods to measure the absolute secondary aerosol formation potential, because the environmental chambers have their drawbacks (e.g., limited oxidant exposure and inability to measure time-resolved secondary aerosol potential; Bruns et al, 2015) Despite these artifacts, there is a need for the estimation of secondary aerosol formation from different emission sources. Actor related artifacts of TSAR by modeling the vapor losses caused by photolysis and the short residence time
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
