Characterization of three new condensation particle counters for sub-3 nm particle detection during the Helsinki CPC workshop: the ADI versatile water CPC, TSI 3777 nano enhancer and boosted TSI 3010

摘要

In this study we characterized the performance of three new particle countersable to detect particles smaller than 3 nm during the Helsinki condensationparticle counter (CPC) workshop in summer 2016: the Aerosol Dynamics Inc.(ADI; Berkeley, USA) versatile water condensation particle counter (vWCPC),TSI 3777 nano enhancer (TSI Inc., Shoreview, USA) and modified and boostedTSI 3010-type CPC from Université Blaise Pascal called a B3010. The performance of all CPCs wasfirst measured with charged tungsten oxide test particles at temperaturesettings which resulted in supersaturation low enough to not detect any ionsproduced by a radioactive source. Due to similar measured detectionefficiencies, additional comparison between the 3777 and vWCPC were conductedusing electrically neutral tungsten oxide test particles and with positivelycharged tetradodecylammonium bromide. Furthermore, the detection efficienciesof the 3777 and vWCPC were measured with boosted temperature settingsyielding supersaturation which was at the onset of homogeneous nucleation forthe 3777 or confined within the range of liquid water for the ADI vWCPC.Finally, CPC-specific tests were conducted to probe the response of the 3777to various inlet flow relative humidities, of the B3010 to various inlet flow rates and of the vWCPC tovarious particle concentrations. For the 3777 and vWCPC the measured 50 %detection diameters (d50s) were in the range of 1.3–2.4 nm for the tungstenoxide particles, depending on the particle charging state and CPC temperaturesettings, between 2.5 and 3.3 nm for the organic test aerosol, and in therange of 3.2–3.4 nm for tungsten oxide for the B3010.