Development and Qualification of a VH-TDMA for the Study of Pure Aerosols
We create and qualify a Volatility and Hygroscopicity Tandem Differential Mobility Analyzer (VH-TDMA) for the study of aerosols. This VH-TDMA measures size distributions, volatility, and hygroscopicity and includes an auxiliary conditioner that allows quick connection to other external aerosol conditioners. The differential mobility analyzers are not temperature controlled, allowing the surrounding environment to influence the measurement conditions, and this is fully accounted for when measuring aerosol volatility and hygroscopicity. For the volatility conditioner, the VH-TDMA uses a 15 m coil of tubing in an oven to evaporate aerosol samples at elevated temperatures. We measured several single component model aerosols to qualify the differential mobility particle sizer (DMPS) channel and each of the conditioners: hygroscopicity and volatility. Due to insufficient power supply calibration in this study, the TDMA channel is limited to particle sizes greater than 70 nm. The DMPS channel was able to reproduce ammonium sulfate size distributions when compared to common scanning mobility particle sizers. For hygroscopicity, the standard deviation in the measured ammonium sulfate growth factors was 0.03 over a 4-h experiment. From this data, the TDMA has an observed relative humidity error of ±0.6% with manufacturer reported error of ±1.2% relative humidity. The volatility channel reproduced the previously published saw tooth pattern of room temperature saturation vapor pressures from atomized C3-C9 diacids. The maximum percent difference in room temperature saturation vapor pressure was approximately 80%. The enthalpy of sublimation derived from the diacids increased monotonically (except for suberic acid) and resembled measurements from mass effusion techniques.
C. R. Oxford and C. M. Rapp and Y. Wang and P. Kumar and D. Watson and J. L. Portelli and E. A. Sussman and S. Dhawan and J. Jiang and B. J. Williams, "Development and Qualification of a VH-TDMA for the Study of Pure Aerosols," Aerosol Science and Technology, vol. 53, no. 2, pp. 120 - 132, Taylor & Francis, Feb 2019.
The definitive version is available at https://doi.org/10.1080/02786826.2018.1547358
Civil, Architectural and Environmental Engineering
Keywords and Phrases
Aerosols; Hydrostatic pressure; Nitrogen compounds; Particle size; Size distribution; Sulfur compounds; Vapor pressure; Differential mobility analyzers; Differential mobility particle sizer; Enthalpy of sublimation; Hygroscopicity-tandem differential mobility analyzers; Measurement conditions; Scanning mobility particle sizer; Surrounding environment; Temperature saturation; Time division multiple access; Ammonium sulfate; Carbromal; Aerosol; Analytical error; Article; Calibration; Enthalpy; Equipment design; Humidity; Particle size; Power supply; Priority journal; Room temperature; Sublimation (phase transition); Vapor pressure; Volatilization; Wettability
International Standard Serial Number (ISSN)
Article - Journal
© 2019 American Association for Aerosol Research, All rights reserved.
01 Feb 2019
The authors acknowledge funding in support of this work from NSF CAREER award number 1554061, NSF award number 1437933, and US EPA STAR grant number R835402.