High temperature nonisothermal desorption in a water–salt droplet

• Experimental data on dynamics of nucleate boiling in the droplets of LiBr water solution were obtained.
• Kinetics of the bubble growth is mainly characterizes by the surface Marangoni flow.
• The Marangoni force is determined by a significant longitudinal gradient of salt concentration.
• At high crystallization rates the different crystalline-hydrate structures are formed.

Experimental data on dynamics of nucleate boiling in the droplets of LiBr water solution were obtained. Time dependences for a change in bubble geometry were determined and characteristic desorption regimes were distinguished. The rate of bubble growth decreases with a rise in salt concentration and boiling stops completely at high concentration of LiBr. An increase in salt concentration in a liquid layer of the bubble bottom leads to a considerable decrease in the rate of desorption, and the rate of bubble diameter increase decreases significantly, and a dry spot is not formed. The growth features of the crystalline-hydrate film depend on the rate of crystallization. Thermal measurements were carried out by means of thermal imager lenses with ten-fold magnification. The video and thermal recording allowed us to distinguish the self-organized crystalline-hydrate structures at high crystallization rates: rod-like, dendrite, and dome-shaped ones. Complex morphology of these structures promotes an increase in the rate of water desorption from the surface of crystalline-hydrate film.