Abstract
Thermocapillary breakdown of thin (0.3–0.7 mm) horizontal layers of liquid (ethanol) when heated from a localized hot spot was investigated experimentally. The effects of layer thickness and the surface properties of the substrates on the breakdown dynamics were studied. Visualization and control of the liquid layer were carried out using schlieren and shadowgraphy techniques. Main steps of the breakdown process were determined and average velocity of the dry spot formation was measured. Significant influence of the substrate properties on breakdown dynamics has been found. It was shown that one of the main factors affecting the dynamics of layer breakdown and the formation of dry spots in the heating area besides the thermocapillary effect is evaporation.
Highlights
Study of heat transfer from a local heat source becomes one of the most important problems in thermophysics
One of the promising methods for removing such high heat fluxes from a spotted heat source is technology based on evaporation of a thin liquid layer
The breakdown of liquid layer leads to dramatic decreasing of heat transfer from a spotted heat source [4]
Summary
Study of heat transfer from a local heat source becomes one of the most important problems in thermophysics. Heat flux density in some regions is much higher than the chip average [2], of the order of 1 kW/cm. One of the promising methods for removing such high heat fluxes from a spotted heat source is technology based on evaporation of a thin liquid layer. The breakdown of liquid layer leads to dramatic decreasing of heat transfer from a spotted heat source [4]. The goal of the present work is to study using schlieren technique the breakdown dynamics of a horizontal evaporating liquid layer when heated from a localized hot spot
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