Breakdown dynamics of a horizontal evaporating liquid layer when heated locally

Serafim Spesivtsev,D Markovich,D Zaitsev,A Semenov

doi:10.1051/epjconf/201715900049

Serafim Spesivtsev, D Markovich + Show 2 more

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https://doi.org/10.1051/epjconf/201715900049

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Abstract

Breakdown of liquid layer when heated from a localized hot spot was investigated experimentally. Water and ethanol were used as working liquids with a layer thickness of 300 μm. Basic steps of the breakdown process were found and mean velocities of the dry spot formation were determined. The formation of residual layer over the hot-spot before the breakdown has been found for both liquids. The creation of a droplet cluster near the heating region is observed when using water as a working fluid. It was shown that evaporation is one of the general factors influencing the process of layer breakdown and dry spot formation as well as thermocapillary effect.

Highlights

Study of heat transfer from a local heat source becomes one of the most important and complicated problems in modern thermophysics
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
The value of the critical heat flux density for ethanol equals to 12.6 W/cm2 at the substrate temperature in the heating area of 37.1°C, for water it is 117 W/cm2 at the substrate temperature of 133°C, respectively

Summary

Introduction

Study of heat transfer from a local heat source becomes one of the most important and complicated problems in modern thermophysics. The average heat flux density on the surface of chips of commercially available computers and other electronic devices is currently known to reach 100 W/cm. Continuous development and complication of microchip structure produce nonuniform heat flux distribution on the chip surface. This effect takes place due to the design features of computer chips, where the processor cores cause the formation of "hot" spots. Heat flux density in some regions is much higher than the chip average [2], of the order of 1 kW/cm. Heat flux density in some regions is much higher than the chip average [2], of the order of 1 kW/cm2 These specific regions called “hot spots” could have size from several hundred microns to 1-2 millimeters

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