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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

Local Heat Removal by Liquid Film on the Expansion of Dry Area on a Superheated Copper Wall

Get access (open in a dialog) DOI: 10.1615/IHTC15.pbl.009048
pages 6137-6148

要約

Heat removal on bubble growth and receding of liquid film has been investigated. First half part has been devoted to make clear the limitation of heat flux estimation by solving inverse heat conduction using temperatures measured at discrete locations. The investigation has been performed for a situation in which square-shaped heat flux pulse travels on a surface. It was revealed that (1) heat flux is valid if heat flux distribution has a length scale larger than the pitch at which temperatures have been measured, (2) when the scale is much less than the pitch, the product of the height and width of heat flux pulse can be obtain in a good accuracy, and (3) the length scale of heat flux variation can be estimated as the product of the time scale of heat flux variation and traveling speed. The rest is for experiment. Over 70 thermocouples were installed just below the surface to estimate heat flux distribution and its history. The sampling of temperature signals and high-speed photographic observation were performed with synchronization while the system pressure was suddenly reduced, a single bubble formed, then dry patch grew under it. It is found that (4) heat flux of the order of 0.5MW/m2 is removed from the surface due to the evaporation of liquid film, (5) heat removal due to triple contact line is summarized as 24kW/(mK) times wall superheat, and (6) heat flux due to liquid rush to the surface takes an order of 1MW/m2.