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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

Heat Transfer and Crisis Phenomena Development at Boiling and Evaporation in Falling Liquid Film at Stepwise Heat Generation

Get access (open in a dialog) DOI: 10.1615/IHTC15.evp.008693
pages 2525-2539

摘要

The aim of this work is experimental investigation of heat transfer and crisis phenomena development at boiling in falling liquid film subcooled at the inlet at stepwise heat generation. Distilled water under the atmospheric pressure was used as the working liquid. Experimental results of this research were obtained with the use of synchronized high-speed thermography (IR) and video recording (HSV). In this study the heating elements are constantan foils of 25x10-6 and 50x10-6 m thickness. The maps of transitional heat transfer regimes with different mechanisms of crisis development at different intensities of heat flux loading and irrigation degrees were plotted. It is shown that depending on the type of liquid, Reynolds number, heat flux density and liquid subcooling different mechanisms of crisis development at nonstationary heat release can be implemented. New data on the temperature of boiling incipience and transient heat transfer in the film of water were obtained depending on the heat flux density. It was found out that within the studied range of heat loads (from 104 to 4x106 W/m2) there are no crisis regimes with propagation of self-sustaining evaporation fronts in the falling films of water. Data on heat transfer in the wetted and non-wetted zones and temperature at the boundary between different heat transfer regimes are used for construction of numerical models for description of crisis phenomena development with physically correct boundary conditions. Experimental data on the velocity of repeated wetting of the superheated surface by the falling water film were obtained.