Mechanistic Multidimensional Modeling of Forced Convection Boiling Heat Transfer

Abstract

Due to the importance of boiling heat transfer in general, and boiling crisis in particular, for the analysis of operation and safety of both nuclear reactors and conventional thermal power systems, extensive efforts have been made in the past to develop a variety of methods and tools to evaluate the boiling heat transfer coefficient and to assess the onset of temperature excursion and critical heat flux (CHF) at various operating conditions of boiling channels. The objective of this paper is to present mathematical modeling concepts behind the development of mechanistic multidimensional models of low-quality forced convection boiling, including the mechanisms leading to temperature excursion and the onset of CHF.

Toward Mechanistic Modeling of Boiling Heat Transfer

“…In both cases, the position dependent nearwall liquid velocity and temperature were taken as numerically calculated by Kurul and Podowski (1991) at the nextto-wall nodal points (ul = uP and Tl = TP) using the model given by Eqs. (17)- (19), combined with a k-ε model of turbulence.…”

Multi-Scale Modeling and Analysis of Convective Boiling: Towards the Prediction of CHF in Rod Bundles

“…More advanced methods based on phenomenological description of boiling up to the CHF conditions have been recently proposed (e.g. [8,9]), which aim to be implemented in system and CFD codes. These methods rely on a variety of closure laws for bubble dynamics, and treat the heat transfer process from the rod as disjointed from the bubble hydrodynamics.…”

Transient and local two-phase heat transport at macro-scales to nano-scales

“…The process is complex with many interrelated thermo-physical phenomena that occur at varying time-and length-scales. Most commonly, four key, transient mechanisms are attributed to the heat transfer process during the vapor-bubble ebullition cycle [7][8][9][10] (or forced convection boiling in general): microlayer evaporation, interline evaporation, transient conduction, and micro-convection-while other mechanisms such as condensation 11,12 and liquid imbibition [13][14][15][16] can contribute with varying significance at different heat flux conditions.…”