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THE MASS ACCOMMODATION COEFFICIENT OF AMMONIUM NITRATE AEROSOL. (R823514)
Citation:
Dassios, K. G. AND S. N. Pandis. THE MASS ACCOMMODATION COEFFICIENT OF AMMONIUM NITRATE AEROSOL. (R823514). ATMOSPHERIC ENVIRONMENT. American Chemical Society, Washington, DC, 33:2993-3003, (1999).
Description:
The mass transfer rate of pure ammonium nitrate between the aerosol and gas phases was
quantified experimentally by the use of the tandem differential mobility analyzer/scanning mobility
particle sizer (TDMA/SMPS) technique. Ammonium nitrate particles 80-220 nm in diameter
evaporated in purified air in a laminar flow reactor under temperatures of 20-27 degrees C and
relative humidities in the vicinity of 10%. The evaporation rates were calculated by comparing the
initial and final size distributions. A theoretical expression of the evaporation rate incorporating the
Kelvin effect and the effect of relative humidity on the equilibrium constant is developed. The
measurements were consistent with the theoretical predictions but there was evidence of a small
kinetic resistance to the mass transfer rate. The discrepancy can be explained by a mass
accommodation coefficient ranging from 0.8 to 0.5 as temperature increases from 20-27 degrees C.
The corresponding timescale of evaporation for submicron NH,NO, particles in the atmosphere is of
the order of a few seconds to 20 min. (C) 1999 Elsevier Science Ltd. All rights reserved. (31
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