Visualization of Marangoni Convection induced by Surfactant in LiBr Aqueous Solution

Abstract

Surface tension induced (Marangoni-Benard) convection occurs at a surface of lithium bromide (LiBr) aqueous solution with addition of a small amount of surfactant was observed in order to investigate a mechanism of absorption enhancement by surfactant. Real time type laser holographic interferometry was used to visualize the transient phenomena occurred at/beneath the LiBr aqueous solution's surface in the very beginning(0-20msec) of steam absorption under vacuum condition(0.7kPa). Experiments were performed varying the initial surfactant concentration from 0 to 200ppm and the liquid layer thickness of 3-5mm. Pentagonal or hexagonal cell's patterns were observed at the surface clearly. And those cells evolved from small to large size instantly. Thereafter large scale chaotic eddies were induced at the surface.