In this study, carefully designed experiments were combined with particle-scale model calculations to provide insight into the physics of water mass accommodation. We utilized an electrodynamic particle trap to examine the evaporation of individual high-purity water droplets. Droplets in the radius range from 15 to 50 microns were injected into the particle trap, where Mie-scattering techniques were used to provide high-precision measurements of their size as a function of time. The properties of the gaseous environment (T, total pressure, and dewpoint) were well-characterized. Least-squares fitting of a kinetic mass growth model was used to extract values of the mass accommodation coefficient from the experimental data.
The high quality of the least-squares fits demonstrates that the kinetic model provides an excellent description of the evaporation process. These new experimental results may also provide evidence for a molecular-level mechanism of the mass accommodation process, which may help to explain the disagreement between earlier measurements.