10th International Aerosol Conference September 2 - September 7, 2018 America's Center Convention Complex St. Louis, Missouri, USA
Abstract View
Study on CPC Time Response – Modelling and Measurements
JOONAS ENROTH, Juha Kangasluoma, Frans Korhonen, Joonas Vanhanen, Michel Attoui, Tuukka Petäjä, University of Helsinki
Abstract Number: 1290 Working Group: Instrumentation
Abstract Condensation particle counters (CPC) time response consist of multiple factors, such as the flow rates and instrument geometry. In practice, the measurement of the time response is complicated, and the results can easily be biased by an unfit measurement setup. Providing the ideal instantaneous step change in aerosol concentration, while using well defined aerosol composition and size range, and maintaining a stable concentration for extended time periods is in practice extremely difficult. This has led to numerous different approaches being used for response time measurements, for instance valves (Quant, 1992), differential mobility analyzers (Buzorius, 2001) and spark generators (Wang et al., 2002). Due to the aforementioned complexities, the problem lends itself well to modelling.
In this study we present a comparison of both modelled and measured time response results for the Airmodus A20 CPC. We also compare the impacts that individual processes play in determining the time response, i.e. influence of factors such as diffusional losses, particle growth and gravity, as well as the dependency on the test aerosol properties, such as the used particle size distribution. In addition, we present the measured time response data for numerous commercial CPC’s. The results of this work aim to further the understanding of basic aerosol physics as it is applied to instrument development and performance.