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Title:Vapor Bubble Detachment in Subcooled Pool Boiling at Zero Gravity
Author(s):Lin, Hsiao Chu
Department / Program:Nuclear Engineering
Discipline:Nuclear Engineering
Degree Granting Institution:University of Illinois at Urbana-Champaign
Degree:Ph.D.
Genre:Dissertation
Subject(s):Physics, Fluid and Plasma
Abstract:The mechanism of vapor bubble detachment at zero gravity has been studied both analytically and numerically. Instead of analyzing the force balance, this study emphasizes momentum conservation, the time integral of the force. The liquid velocity is derived from the velocity potential. Heat and mass transfer across the interface are governed by a nonequilibrium model. The liquid temperature on the interface is regarded as a parameter. By introducing explicit forms for the velocity potential and the interface, the governing equations are transformed to a set of ordinary differential equations, which can be integrated numerically to find the motion of the bubble wall.
A spherical bubble, whose motion is known, is taken as a fictitious bubble to simplify the analysis. Under this mathematical model, the selected bubble should be able to generate the same liquid kinetic energy as that of the real bubble. The liquid momentum difference is finite and can be determined to find the bubble motion.
Depending on the distortion of its shape, a non-spherical bubble under constant pressure difference will either detach from the surface or form a liquid jet moving towards the wall. However, with variable vapor pressure inside the bubble, the vapor potential energy may cause the vapor-liquid interface to bounce back to prevent the occurrence of the above phenomenon. In a subcooled liquid, mass transfer across the interface will decrease the vapor pressure and, hence, reduce the possibility of rebounce of the bubble wall. Similarly, the effect of surface tension will work in the same way. By contrast, heat flux flowing into the bubble will delay its detachment.
Issue Date:1983
Type:Text
Description:146 p.
Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1983.
URI:http://hdl.handle.net/2142/70888
Other Identifier(s):(UMI)AAI8324596
Date Available in IDEALS:2014-12-16
Date Deposited:1983


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