Abstract
The Jing Ltd. miniature combustion aerosol standard (Mini-CAST) soot generator is a portable, commercially available burner that is widely used for laboratory measurements of soot processes. While many studies have used the Mini-CAST to generate soot with known size, concentration, and organic carbon fraction under a single or few conditions, there has been no systematic study of the burner operation over a wide range of operating conditions. Here, we present a comprehensive characterization of the microphysical, chemical, morphological, and hygroscopic properties of Mini-CAST soot over the full range of oxidation air and mixing N2 flow rates. Very fuel-rich and fuel-lean flame conditions are found to produce organic-dominated soot with mode diameters of 10–60 nm, and the highest particle number concentrations are produced under fuel-rich conditions. The lowest organic fraction and largest diameter soot (70–130 nm) occur under slightly fuel-lean conditions. Moving from fuel-rich to fuel-lean conditions al...
Highlights
Soot particles emitted by combustion processes have been shown to be second only to carbon dioxide in terms of cli-matic importance (Jacobson 2001; Bond et al 2013) and induce deleterious human health impacts upon inhalation (Kumfer and Kennedy 2007; Janssen et al 2011)
Soot Size and Concentration Measurements of the soot size distribution were made with the Scanning Mobility Particle Sizer (SMPS) at varying Qoxi and Qmix, and the distributions were typically found to be monomodal with mode diameters ranging from less than 10 to 130 nm
It is useful to speak in terms of the overall fuel/air flame equivalence ratio, φ, which is shown on the lower axis of Figure 2: φ mfuel/mairst where mfuel and mair are the fuel and air mass flows, respectively, and the subscript “st” denotes the stoichiometric flow ratio
Summary
Soot particles emitted by combustion processes have been shown to be second only to carbon dioxide in terms of cli-matic importance (Jacobson 2001; Bond et al 2013) and induce deleterious human health impacts upon inhalation (Kumfer and Kennedy 2007; Janssen et al 2011). Combining different measurement types enables real-time characterization of combustion-derived atmospheric aerosols For this to happen, though, it is necessary to compare, calibrate, and validate instrument responses using a standard reference soot, whose properties are stable and well known (Cross et al 2010; Baumgardner et al 2012). Though, it is necessary to compare, calibrate, and validate instrument responses using a standard reference soot, whose properties are stable and well known (Cross et al 2010; Baumgardner et al 2012) To address this need, a number of soots and soot surrogates (e.g., carbon black, fullerene soot, and Aquadag) are commercially available, and continuous soot production can be achieved via spark discharge or by using different burner and fuel combinations. Each have their advantages and disadvantages in terms of portability, ease of use, and representative properties, and there is no single reference material that lends itself for calibration and testing of analytical instrumentation. Baumgardner et al (2012) discuss the applicability of a number of potential soot reference materials to different light absorption, laser incandescence, and
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