Convection inside a drop of aqueous salt solution of LiBr on a heated structured wall

Abstract

Experimental studies of the effect of the surface structure of AISI 321 steel on the average convection velocity Uav in the horizontal section of the drop by the MicroPIV method have been carried out. The initial concentration of LiBr salt in an aqueous solution is C0 = 60%. Wall temperature Tw = 90 °C. It was found that the strongest enhancement of Uav was observed for a surface with caverns with a diameter of d2 = 2.5 mm and at the initial time instant τ after the droplet was placed on a heated surface. The difference Uav between the structured and rough wall decreases with increasing τ. This decrease in Uav is associated with: 1) heating of the solution from the wall and a decrease in ΔT; 2) a decrease in the height of the droplets and an increase in the viscosity of the salt solution due to evaporation.