APPLICATION OF LED-INTERFEROMETRY FOR DETERMINATION THE EVAPORATION CHARACTERISTICS OF LIQUID FILM IN A MICROCHANNEL

This work demonstrates the possibility of using an interferometric technique with a quasi-monochromatic light-emitting diode (LED) light source to determine the characteristics of liquid flow evaporation in a microchannel, such as the distribution of film thicknesses and the change in characteristic film thicknesses when a flat droplet is spread during heating. At the first stage, the technique has been tested on an evaporating drop with a free boundary on a solid substrate, which made it possible to obtain evaporation characteristics such as 3D distributions of droplet thicknesses over time. At the second stage, the visualization of the interference pattern of the movement and deformation of flat drops entrained by a gas flow in a 51.2-μm-high slit microchannel under the action of local heating has been carried out. The use of this visualization made it possible to restore the field of film thicknesses and determine the dependence of liquid film thickness rate of change on the heat transfer coefficient and gas mass flux. It was shown that the heat transfer coefficient increases with the film thickness rate of change.