Theory and experiments on evaporating sessile drops of binary liquid mixtures

Abstract

Theoretical and experimental studies are performed to determine the size, history and lifetime of evaporating sessile drops of binary liquid mixtures. The minimum and maximum drop lifetimes (equivalent to the maximum and minimum vaporization rates, respectively) occur at the azeotropic compositions of the positive and negative azeotropes, respectively. The mechanisms leading to the extremum drop lifetime are due to the changes in composition of the more volatile component during the vaporization process. This composition change tends to suppress vaporization. A new dimensionless parameter is found to determine the intensity of vaporization of a binary liquid drop. Theoretical predictions of the drop size, history and lifetime agree satisfactorily with experimental results.