Particle Size Distributions following Condensational Growth in Continuous Flow Aerosol Reactors as Derived from Residence Time Distributions: Theoretical Development and Application to Secondary Organic Aerosol

Abstract

Condensational growth in continuous flow reactors, such as continuously mixed flow reactors (CMFRs) and flow tube reactors, is widely employed in the field of aerosol science and technology to produce particles for industrial use and scientific research. The development of analytical equations for the number-diameter distribution n(d) of the particles in the outflow from these reactors is advantageous both for the inversion of data sets to obtain thermodynamic and kinetic parameters as well as for the rational design of experiments. In this study, equations are derived that relate the number-diameter distribution n(d) to the probability density function p(t) of particle residence time. Specifically, the condensational growth rate is used to derive n(d) based on p(t). Analytical equations are developed for CMFRs, laminar-flow reactors, and dispersive plug-flow reactors, with a focus on CMFRs. The CMFR equation accurately describes data sets collected for α-pinene and β-caryophyllene ozonolysis in the Harvard Environmental Chamber (HEC). The interpretation is that condensational growth can be considered as the principal mechanism for change in particle diameter in these experiments.

Phase State and Deliquescence Hysteresis of Ammonium-Sulfate-Seeded Secondary Organic Aerosol

“…In the reaction chamber, the oxidized precursor was condensed onto the seed particles, resulting in a size distribution characteristic of a continuous reactor (Kuwata and Martin 2012). After a period of about 12 h to allow the smog chamber and aerosol production to stabilize, measurements were started.…”

An Analytic Equation for the Volume Fraction of Condensationally Grown Mixed Particles and Applications to Secondary Organic Material Produced in Continuously Mixed Flow Reactors

“…Additional considerations related to the physical interpretation of terms λ and β are discussed in Seinfeld et al (2003) and Kuwata and Martin (2012). These studies have shown that even with the myriad compounds of secondary organic aerosol, the number-diameter distributions of actual data sets, such as those of α-pinene or β-caryophyllene ozonolysis, are adequately represented by…”

“…Kuwata and Martin (2012) previously compared the number-diameter distributions obtained by Equations (4) and (6) to observed distributions exiting the Harvard Environmental Chamber. The model was based on condensational growth described by Equations (6) and (7) in a CMFR (Seinfeld et al 2003;Kuwata and Martin 2012).The model could describe the data for secondary organic material produced by ozonolysis of α-pinene and β-caryophyllene. The interpretation is that condensational growth can be considered as the principal mechanism for change in particle diameter in these experiments.…”

“…As described in Seinfeld et al (2003) and Kuwata and Martin (2012), the condensational diameter growth rate I(d), describing dd/dt, is assumed to be adequately described by…”

“…A common atmospheric particle type observed by microscopy consists of a primary particle coated by secondary organic material (Pöschl et al 2010). Secondary organic material is produced by multiple pathways (Hallquist et al 2009), and for certain reaction conditions condensational growth can be the dominant pathway (Seinfeld et al 2003;Kuwata and Martin 2012). The production pathways of secondary organic material have been widely simulated in laboratory environmental chambers in efforts to understand and quantify the involved chemistry and associated environmental effects (Hallquist et al 2009).…”