Free convection heat transfer in a stratified medium – cavity problem

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2013
Kayserilioğlu, Yavuz Selim
A numerical study is performed in order to simulate a 2D cavity filled with water having one inlet and one outlet. Relatively warm water is fed to the cavity to charge it while relatively cooler water is drained from the outlet. The top surface of the cavity is exposed to ambient air. Bottom surface is insulated while vertical side surfaces are cooled. Mathematical model comprised of laminar 2D transient flow of an incompressible fluid. Momentum and energy equations are solved simultaneously with Boussinesq approximation since both forced and natural convection occur within cavity. The charging period of the cavity with relatively hot charging water is examined. Velocity and temperature fields for cavity are presented. Effects of initial temperature, ambient air temperature, inlet charging temperature, and solar radiation on free surface are examined. It is found that lower initial storage temperature, higher ambient air temperature, higher charging water temperature, and existence of solar radiation have positive effects on the performance of cavity. Heat removal period from cavity is examined. Basic heat removal tubes with rectangular cross-sections are modeled as negative heat generation sources. Heat removal process affects regions below the tubes more than regions above the tubes. The effect of heat removal is seen all the way down to bottom of the cavity whereas only a couple of centimeters above the heat removal tubes are affected. As a result, when heat is removed from a lower layer, stored energy content of cavity at the end of heat removal is higher.
Citation Formats
Y. S. Kayserilioğlu, “Free convection heat transfer in a stratified medium – cavity problem,” Ph.D. - Doctoral Program, Middle East Technical University, 2013.