Projects per year
Abstract
Using a comparative evaporation kinetics approach, we describe a new and accurate method for determining the equilibrium hygroscopic growth of aerosol droplets. The time-evolving size of an aqueous droplet, as it evaporates to a steady size and composition that is in equilibrium with the gas phase relative humidity, is used to determine the time-dependent mass flux of water, yielding information on the vapour pressure of water above the droplet surface at every instant in time. Accurate characterization of the gas phase relative humidity
is provided from a control measurement of the evaporation profile of a droplet of know equilibrium properties, either a pure water droplet or a sodium chloride droplet. In combination, and by comparison with simulations that account for both the heat and mass transport governing the droplet evaporation kinetics, these measurements allow accurate retrieval of the equilibrium properties of the solution droplet (i.e. the variations with water activity in the mass fraction of solute, diameter growth factor, osmotic coefficient or number of water molecules per solute molecule). Hygroscopicity measurements can be made over a wide range in water activity (from >0.99 to, in principle, <0.05) on timescales of <10 s for droplets containing involatile or volatile solutes. The approach is benchmarked for binary and ternary inorganic solution aerosols with typical
uncertainties in water activity of <±0.2 % at water activities >0.9 and ~±1 % below 80 % RH, and maximum uncertainties in diameter growth factor of ±0.7 %. For all of the inorganic systems examined, the timedependent data are consistent with large values of the mass accommodation (or evaporation) coefficient (>0.1).
Original language | English |
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Pages (from-to) | 4376-4388 |
Number of pages | 13 |
Journal | Journal of Physical Chemistry A |
Volume | 120 |
Issue number | 25 |
Early online date | 10 Jun 2016 |
DOIs | |
Publication status | Published - 30 Jun 2016 |
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Dive into the research topics of 'Accurate Measurements of Aerosol Hygroscopic Growth Over a Wide Range in Relative Humidity'. Together they form a unique fingerprint.Projects
- 1 Finished
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Linking Aerosol Physical Chemistry and Atmospheric Effects via kappa-Kohler Theory
Reid, J. P. (Principal Investigator)
1/01/16 → 30/06/18
Project: Research
Datasets
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Accurate Measurements of Aerosol Hygroscopic Growth Over a Wide Range in Relative Humidity
Willoughby, R. (Creator), Cotterell, M. (Creator), Rickards, A. (Creator), Haddrell, A. (Creator), Rovelli, G. (Creator), Miles, R. (Creator), Song, Y. C. (Creator), Marshall, F. (Creator), Reid, J. (Creator) & Marsh, A. (Creator), University of Bristol, 1 Jun 2016
DOI: 10.5523/bris.h8igni7g424s19a8ab3boyjb5, http://data.bris.ac.uk/data/dataset/h8igni7g424s19a8ab3boyjb5
Dataset