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ISSN Online: 2377-424X

ISBN Print: 978-1-56700-421-2

International Heat Transfer Conference 15
August, 10-15, 2014, Kyoto, Japan

Propagation Dynamics of Self-Sustained Evaporation Front and Characteristics of Small-Scale Perturbations at the Interface

Get access (open in a dialog) DOI: 10.1615/IHTC15.evp.008766
pages 2487-2500

摘要

In the range of low reduced pressures, the development of self-sustained evaporation front along the heat-releasing surface at non-stationary heat release is an important factor that determines possible transition to film boiling at heat fluxes, significantly lower than the critical heat fluxes at stationary heat release. This work is aimed at experimental investigation of the effect of different parameters (relative pressure, orientation and roughness of the heat-releasing surface, degree of liquid subcooling, additions of nanoparticles and conditions of reduced gravitation) on the dynamics of evaporation front propagation, as well as studying the dynamic and structural characteristics of the interface of the self-sustained evaporation front at non-stationary heat release. Experiments were carried out in freon R21 under the conditions of free convection at relative pressures 0.037 and 0.068. It is shown that the presence of two zones with different growth rates of the velocity of evaporation front propagation at increasing temperature difference is conditioned by significant change in the amplitude and frequency characteristics of perturbations on the interfacial surface. The addition of nanoparticles to the liquid has led to a significant increase in the velocity of front propagation in the range of high overheating of the heat-releasing surface. The diagram of stability of evaporation front interface, built on Landau theory, was proposed. The obtained experimental data were analyzed from the standpoint of instability development at intense evaporation.