Concurrent supersaturation of C2-C4 alcohols and water in a Condensation Particle Counter (CPC) to measure naturally charged flame-formed carbonaceous aerosols smaller than 3 nm
Farnaz Khosravi , Gregory S. Lewis , Arantzazu Eiguren Fernandez , Francesco Carbone
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引用次数: 0
Abstract
Combustion emissions impact air pollution, and the development of advanced tools to detect and monitor increasingly smaller flame-formed aerosols is vital for implementing ever-more effective air-quality regulations and reducing the environmental impact of combustion applications. Condensation Particle Counters (CPCs) can detect both charged and neutral aerosols in very low number concentrations and are of widespread use in atmospheric metrology thanks to their relative portability, affordability, and simplicity of operation. Still, their detection efficiency is influenced by the size, charge state, and morphology of the aerosols to be detected, in addition to their composition, which influences their wettability by the condensing fluid(s). As a result, calibrations are necessary to characterize the detection efficiency of a CPC, especially for flame-formed carbonaceous aerosols smaller than 3 nm, which can have quite polydisperse composition and properties. In this study, two-component (fluid-Water) CPCs resulting from coupling a Water CPC (WCPC) with a saturator inlet operated with either n-butanol (nBA), iso-propanol (IPA), or ethanol (EtOH) are characterized for the detection of naturally charged carbonaceous aerosols formed in an incipiently sooting premixed flame. Khosravi et al. (2023) operated the saturator inlet with Diethylene Glycol (DEG) and showed that the concurrent supersaturations of water and DEG (i.e., any fluid with Le > 1) established in the DEG-WCPC (i.e., any fluid-WCPC) enhance the detection of materials smaller than 3 nm. The results herein demonstrate that the nBA-WCPC, the IPA-WCPC, and the EtOH-WCP have not only comparable or even superior (surely in the case of the IPA-WCPC) performances in terms of the minimum sizes detectable with 50 % efficiency but also the advantages of minimal needs for cleaning the optics and composition-independent and steeper profiles of the size-dependent detection efficiency compared to the DEG-WCPC. This is the case even though the lengths of the CPC stages have not been optimized yet for using the tested C2-C4 alcohols in the saturator inlet. In particular, the use of EtOH as a performant CPC working fluid is the first-of-a-kind, with the EtOH-WCPC already achieving the steepest detection efficiency profiles, a feature attractive for studies requiring sizing resolution, and having the largest room for performance improvements.
期刊介绍:
Founded in 1970, the Journal of Aerosol Science considers itself the prime vehicle for the publication of original work as well as reviews related to fundamental and applied aerosol research, as well as aerosol instrumentation. Its content is directed at scientists working in engineering disciplines, as well as physics, chemistry, and environmental sciences.
The editors welcome submissions of papers describing recent experimental, numerical, and theoretical research related to the following topics:
1. Fundamental Aerosol Science.
2. Applied Aerosol Science.
3. Instrumentation & Measurement Methods.