Temperature dependence of the evaporation coefficient of water in air and nitrogen under atmospheric pressure: Study in water droplets

Abstract

The evaporation and the thermal accommodation coefficients for water in nitrogen were investigated by means of the analysis of evaporation of pure water droplet as a function of temperature. The droplet was levitated in an electrodynamic trap placed in a climatic chamber. The levitation time was in the range of seconds, which corresponds to the characteristic time scales of cloud droplet growth. Droplet radius evo-lution and evaporation dynamics were studied as a function of temperature, by analyzing the angle-resolved light scattering Mie interference patterns. A model of droplet evolution, accounting for the kinetic effects near the droplet surface, was applied. The evaporation coefficient for the temperature range from 273.6 to 298.3 K was found to be between 0.054 and 0.12 with a minimum of 0.036 0.015 seemingly coinciding with water maximum density at 277.1 K. The average value of thermal accommodation coefficient over the temperature range from 277 to 289 K was found to be 0.7 0.2. 1.