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International Heat Transfer Conference 16

ISSN: 2377-424X (online)
ISSN: 2377-4371 (flashdrive)

TEMPERATURE DISCONTINUITY AND RESISTANCE AT THE LIQUID−GAS INTERFACE OF THIN LIQUID FILM AND DROPLET UNDER HEATING

Elizaveta Ya. Gatapova
Kutateladze Institute of Thermophysics, Siberian Branch of Russian Academy of Sciences, 1 Lavrentyev Ave., 630090 Novosibirsk, Russia; Novosibirsk State University, 2 Pirogova Str., 630090 Novosibirsk, Russia

Oleg A. Kabov
Kutateladze Institute of Thermophysics of the Siberian Branch of the Russian Academy of Sciences, 1, Acad. Lavrentyev Ave., Novosibirsk, 630090, Russia; Institute of Power Engineering, National Tomsk Polytechnic Research University, 7, Usova Street, Tomsk, 634050, Russia; Novosibirsk State University, 2, Pirogova str., Novosibirsk, 630090, Russia

DOI: 10.1615/IHTC16.bae.024310
pages 1479-1484


KEY WORDS: Boiling and evaporation, Microscopic measurement, Liquid–gas interface, Temperature jump, Micro-thermocouple, Temperature measurements, Non-equilibrium, Thermal resistance

Abstract

The rapid development, miniaturization, and increase in the power density of electronics places to greater emphasis on the performance and limits of today's thermal management solutions. Of great interest to engineers and researchers is the possibility of using ultrahigh-intensity evaporation of thin liquid films. The transition between the continuum and molecular scales for a continuous description of phase transition is still an open challenge. We present new data on measurements of the temperature profile across the liquid−gas interface of a heated thin liquid film and small-sized droplet for different fluids. Microthermocouple with the sensor thickness less than 3 µm is used for measurements. A temperature jump at the liquid-gas interface was clearly detected even for small evaporation rate. This jump was measured for heater temperature varying in the range 23 − 80 ° C at normal atmospheric conditions. We found the increasing of the temperature jump with increasing of the heat flux and evaporation rate. An evolution of the temperature profile with increasing of the heater temperature is obtained. Depending on the ambient condition and type of fluids, the temperature in the gas phase near the liquid-gas interface can be higher or lower than that of the liquid. The temperature profiles with negligible temperature jump at liquid-gas interface are observed for some operating conditions. Finally, we estimate the thermal resistance of thin liquid film and droplet, which is useful for cooling systems such as micro-sized vapor chamber.

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