ISSN Online: 2377-424X
ISBN Print: 978-1-56700-421-2
International Heat Transfer Conference 15
Stability and Mode Transition of Boiling on a Flat Surface
Abstract
Stability and mode transition of boiling on a flat surface are theoretically modeled and investigated. The linear stability analysis method is used to analyze the boiling on a flat surface, and the boiling curve is modeled as an S-shape curve with critical heat flux (CHF) and minimum heat flux (MHF) points. For boiling on a flat surface with constant heat generation, the stability analysis indicates that nucleate and film boiling are both stable, while the transition boiling will lose stability with isoflux boundary. Under isothermal boundary condition, the transition boiling can be stable as the flat surface is small enough, while the transition boiling will lose stability on large flat surface. In the stability diagram, CHF and MHF are both saddle points, and they will lose stable only by a very small perturbation. In addition, the characteristic time near CHF is much smaller than those near MHF, so the mode transition near CHF is also much faster. For boiling on flat surface with heat flux transferred from isothermal base, the transition boiling with isoflux boundary can be stabilized by reducing the surface thickness. For stable transition boiling near CHF, the heating surface should be very thin as 0.003-0.01 m. For stable transition boiling near MHF, the thickness of surface can be thicker, and this mode is easier to control. According to the theoretical results, the required conditions for stable transition boiling including CHF and MHF on flat surface are described.